CyberReliant Corp Data at Rest
(DaR) Service (Native)
(ASPP11/FEEP10) Security Target
Version 0.6
10/21/15
Prepared for:
CyberReliant Corp.
175 Admiral Cochrane Drive
Suite 404
Annapolis. MD 21401
Prepared By:
www.gossamersec.com
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1. SECURITY TARGET INTRODUCTION........................................................................................................3
1.1 SECURITY TARGET REFERENCE......................................................................................................................3
1.2 TOE REFERENCE............................................................................................................................................3
1.3 TOE OVERVIEW .............................................................................................................................................4
1.4 TOE DESCRIPTION .........................................................................................................................................4
1.4.1 TOE Architecture...................................................................................................................................4
1.4.2 TOE Documentation ..............................................................................................................................6
2. CONFORMANCE CLAIMS..............................................................................................................................7
2.1 CONFORMANCE RATIONALE...........................................................................................................................7
3. SECURITY OBJECTIVES ................................................................................................................................8
4. EXTENDED COMPONENTS DEFINITION ..................................................................................................9
5. SECURITY REQUIREMENTS.......................................................................................................................10
5.1 TOE SECURITY FUNCTIONAL REQUIREMENTS .............................................................................................10
5.1.1 Cryptographic support (FCS)..............................................................................................................11
5.1.2 User data protection (FDP).................................................................................................................13
5.1.3 Identification and authentication (FIA) ...............................................................................................13
5.1.4 Security management (FMT) ...............................................................................................................14
5.1.5 Protection of the TSF (FPT) ................................................................................................................14
5.1.6 Trusted path/channels (FTP) ...............................................................................................................15
5.2 TOE SECURITY ASSURANCE REQUIREMENTS...............................................................................................15
5.2.1 Development (ADV).............................................................................................................................16
5.2.2 Guidance documents (AGD)................................................................................................................16
5.2.3 Life-cycle support (ALC) .....................................................................................................................17
5.2.4 Tests (ATE) ..........................................................................................................................................18
5.2.5 Vulnerability assessment (AVA)...........................................................................................................18
6. TOE SUMMARY SPECIFICATION..............................................................................................................19
6.1 CRYPTOGRAPHIC SUPPORT ...........................................................................................................................19
6.2 USER DATA PROTECTION ..............................................................................................................................23
6.3 IDENTIFICATION AND AUTHENTICATION.......................................................................................................23
6.4 SECURITY MANAGEMENT .............................................................................................................................24
6.5 PROTECTION OF THE TSF .............................................................................................................................24
6.6 TRUSTED PATH/CHANNELS ...........................................................................................................................25
LIST OF TABLES
Table 1 TOE Security Functional Components ......................................................................................................11
Table 2 EAL 1 Assurance Components ...................................................................................................................16
Table 3 Algorithm Certificate Table........................................................................................................................19
Table 4 NIST SP800-56B Conformance ..................................................................................................................20
Table 5 Key Destruction............................................................................................................................................21
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1. Security Target Introduction
This section identifies the Security Target (ST) and Target of Evaluation (TOE) identification, ST conventions, ST
conformance claims, and the ST organization. The TOE is Data at Rest (DaR) Service (Native) provided by
CyberReliant Corp. The TOE is being evaluated as a software application with file encryption capabilities.
The Security Target contains the following additional sections:
 Conformance Claims (Section 2)
 Security Objectives (Section 3)
 Extended Components Definition (Section 4)
 Security Requirements (Section 5)
 TOE Summary Specification (Section 6)
Conventions
The following conventions have been applied in this document:
 Security Functional Requirements – Part 2 of the CC defines the approved set of operations that may be
applied to functional requirements: iteration, assignment, selection, and refinement.
o Iteration: allows a component to be used more than once with varying operations. In the ST,
iteration is indicated by a letter placed at the end of the component. For example FDP_ACC.1a
and FDP_ACC.1b indicate that the ST includes two iterations of the FDP_ACC.1 requirement, a
and b.
o Assignment: allows the specification of an identified parameter. Assignments are indicated using
bold and are surrounded by brackets (e.g., [assignment]). Note that an assignment within a
selection would be identified in italics and with embedded bold brackets (e.g., [[selected-
assignment]]).
o Selection: allows the specification of one or more elements from a list. Selections are indicated
using bold italics and are surrounded by brackets (e.g., [selection]).
o Refinement: allows the addition of details. Refinements are indicated using bold, for additions,
and strike-through, for deletions (e.g., “… all objects …” or “… some big things …”).
 The NDPP uses an additional convention – the ‘case’ – which defines parts of an SFR that apply only when
corresponding selections are made or some other identified conditions exist. Only the applicable cases are
identified in this ST and they are identified using bold text.
 Other sections of the ST – Other sections of the ST use bolding to highlight text of special interest, such as
captions.
1.1 Security Target Reference
ST Title – CyberReliant Corp. Data at Rest (DaR) Service (Native) (ASPP11/FEEP10) Security Target
ST Version – Version 0.6
ST Date – 10/21/2015
1.2 TOE Reference
TOE Identification – CyberReliant Corp. Data at Rest (DaR) Service (Native) Version 1.0.0 (Version Code 2)
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TOE Developer – CyberReliant Corp.
Evaluation Sponsor – CyberReliant Corp.
1.3 TOE Overview
The Target of Evaluation (TOE) is CyberReliant Corporation’s (CRC) Data at Rest (DaR) Service (Native) Version
1.0.0 (Version Code 2) software application package residing on evaluated mobile devices running Android 4.4.
The TOE is a software solution providing the capability to handle file encryption on mobile devices. The TOE is
tested on a Samsung Galaxy Note 3. Below are the current evaluated platforms:
 Samsung Galaxy S4, Note 3 and NotePRO tablet
 Samsung Galaxy S5 & Note 10.1 2014 Edition
 LG G3 Smartphone
 Samsung Galaxy Note 4, Note Edge, Galaxy Alpha, Galaxy Tab S 8.4 LTE & 10.5 LTE
 Samsung Galaxy S5 with KNOX 2
 Samsung Galaxy Note 4, Note Edge, Alpha, Galaxy Tab S 8.4 LTE & 10.5 LTE, Galaxy Tab Active with
KNOX 2
 Samsung Galaxy Note Edge & Galaxy Tab Active
1.4 TOE Description
CRC’s DaR Service (Native) provides file level encryption through an APK and a library implementation. DaR
Service (Native) contain Java interfaces in order to support majority of android application storage requirements.
The implementation and functionality for java is provided by the TOE.
The DaR’s Management Service implementation is a straight Java DaR Service (Native) APK and a library to be
included into one’s mobile application (and then one can use the API). The Management Service (Native) runs in the
background and uses both Android and BouncyCastle keystores to provide the File Encryption Key Encryption Key
(FEKEK) to each of the applications. The DaR Service (Native) also uses the Android keystore to store an RSA key
pair used by the Management service, and a per application android keystore to store each application’s RSA
keypair to wrap the AES-wrapped file encryption key encryption key. The Management Service handles necessary
user authentication and key management. The file level encryption suite is an API designed to support the use of
specialized file level encryption for Android applications. Encryption is provided by the native Android
cryptographic API.
1.4.1 TOE Architecture
The TOE is software installed on an evaluated mobile device running Android 4.4. The TOE software is installed as
a Management Service as well as a TSF interface library that is compiled into other applications. References to
applications noted in this Security Target are regarded as applications that are compiled with the TSF interface API
library. The Management Service is responsible for handling the File Encryption Key Encryption Keys (FEKEKs)
necessary to unwrap the FEK. The Management Service obtains the DaR password from the user and double wraps
the FEKEK by using RSA-2048 first and then wrapping it again using AES-256.
The TOE’s interface library is compiled into another application’s package. The library allows the other application
to invoke the TOE’s services. This library allows the application to call the TOE’s file encryption services. The
application must register itself with the DaR Management Service. Applications registered to the TOE have a unique
RSA public/private keypair, so applications pass their RSA public keys to the DaR Management Service along with
a certificate fingerprint (which is what the application uses as the password to the application’s BouncyCastle key
store). Android’s keystore protects keys by storing them in a container with limited access to the keys through
Android’s keystore API. The TOE allows only a single user at a time.
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The TOE stores the double wrapped FEKEKs in the Management Service’s BouncyCastle keystore and the single
wrapped FEKEKs in the Application’s specific BouncyCastle keystore. The keys are protected by requiring a
password to load both the Management Service and Application’s BouncyCastle keystore. In order for other
applications to access its FEK, the application must use the TOE’s interface library API in order to request the
Management Service’s functions. The management service uses the application’s public key to wrap the FEKEK
(via RSA-OAEP) so that it can be passed to the Application by placing the single wrapped FEKEK into the
Application’s BouncyCastle keystore. The wrapped FEKEKs in each application’s BouncyCastle keystore are
ephemeral1
. The Management Service has a configurable timer in which all BouncyCastle keystores will be wiped
once the timer expires.
The TOE relies on the evaluated platform’s Android API for generating keys as well as performing cryptographic
operations. The TOE invokes Android’s cryptographic API to generate AES-256 bit keys.
During evaluation testing, Gossamer tested the CRC DaR on the Samsung Galaxy Note 3 running Android 4.4.
1.4.1.1 Physical Boundaries
The physical boundary of the TOE is the physical perimeter of the evaluated device (Android 4.4) on which the
TOE resides.
1.4.1.2 Logical Boundaries
This section summarizes the security functions provided by CRC DaR Service (Native):
- Cryptographic support
- User data protection
- Identification and authentication
- Security management
- Protection of the TSF
- Trusted path/channels
1.4.1.2.1 Cryptographic support
The TOE uses the cryptographic services from the evaluated platform. The evaluated platform runs Android 4.4
operating system. Android’s APIs allow generation of keys through KeyGenerator, and random numbers are
generated using SecureRandom. Keys are used to protect data belonging to the applications that use the TOE.
1.4.1.2.2 User data protection
The TOE protects user data by providing encryption services for applications to encrypt their data. The TOE allows
encryption of data using AES-256 bit keys.
1.4.1.2.3 Identification and authentication
The TOE authenticates applications by requiring a PIN/passphrase to unlock the application’s file encryption key. A
wrong password results in the unsuccessful loading of the application’s BouncyCastle keystore. Without the correct
keystore, the application cannot load the keys necessary for file encryption/decryption.
1.4.1.2.4 Security management
The TOE’s services/options are inaccessible until a configuration has been created. The TOE does not allow
invocation of its services without configuration of the TOE’s settings upon first start up. The TOE allows the
changing of passwords for management purposes.
1
RSA-OAEP key transport scheme allows the single wrapped FEKEK to be different each time it is encrypted
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1.4.1.2.5 Protection of the TSF
The TOE relies on the physical boundary of the evaluated platform as well as the Android operating system for the
protection of the TOE’s application components.
The TOE checks for updates by selecting the check current version option on its menu. If an update is needed, CRC
shall deliver, via email or other agreed upon method, an updated application. The TOE’s software is digitally signed
by CyberReliant. Each update is accompanied by documentation outlining changes to the overall service, as well as
compatible versions of the CRC API.
The native Android cryptographic library, which provides the TOE’s cryptographic services, have built-in self-tests
that are run at power-up to ensure that the algorithms are correct. If any of the self-tests fail, the TOE will not be
able to perform its cryptographic services.
1.4.1.2.6 Trusted path/channels
The TOE does not transmit any data between itself and another product. All of the data managed by the TOE resides
on the evaluated platform (Android 4.4).
1.4.2 TOE Documentation
CyberReliant Corp offers documents that describe the operation and maintenance for the TOE. The following list of
documents was examined as part of the evaluation.
[OM] Data at Rest (DaR) Data Encryption/Security Solution, CRC DaR Service Operations &
Maintenance Manual, version 1.0.1, October 27, 2015.
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2. Conformance Claims
This TOE is conformant to the following CC specifications:
 Common Criteria for Information Technology Security Evaluation Part 2: Security functional components,
Version 3.1, Revision 4, September 2012.
 Part 2 Extended
 Common Criteria for Information Technology Security Evaluation Part 3: Security assurance components,
Version 3.1 Revision 4, September 2012.
 Part 3 Extended
 Protection Profile for Application Software, Version: 1.1, 5 November 2014 (ASPP11) with Application
Software Protection Profile Extended Package: File Encryption. Version 1.0, 11/10/2014
(ASPP11/FEEP10)
 Package Claims:
 Assurance Level: EAL 1 conformant
2.1 Conformance Rationale
The ST conforms to the ASPP11/FEEP10. As explained previously, the security problem definition, security
objectives, and security requirements have been drawn from the PP.
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3. Security Objectives
The Security Problem Definition may be found in the ASPP11/FEEP10 and this section reproduces only the
corresponding Security Objectives for operational environment for reader convenience. The ASPP11/FEEP10 offers
additional information about the identified security objectives, but that has not been reproduced here and the
ASPP11/FEEP10 should be consulted if there is interest in that material.
In general, the ASPP11/FEEP10 has defined Security Objectives appropriate for software applications, and as such
are applicable to the Data at Rest (DaR) Management TOE.
No objective statements have been provided.
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4. Extended Components Definition
All of the extended requirements in this ST have been drawn from the ASPP11/FEEP10. The ASPP11/FEEP10
defines the following extended requirements and since they are not redefined in this ST the ASPP11/FEEP10 should
be consulted for more information in regard to those CC extensions.
Extended SFRs:
- FCS_CKM_EXT.1: Cryptographic Key Generation Services
- FCS_CKM_EXT.2: Key Encrypting Key (KEK) Support
- FCS_CKM_EXT.4: Extended: Cryptographic Key Destruction
- FCS_IV_EXT.1: Extended: Initialization Vector Generation
- FCS_KYC_EXT.1: Key Chaining and Key Storage
- FCS_RBG_EXT.1: Random Bit Generation Services
- FCS_STO_EXT.1: Storage of Secrets
- FDP_DAR_EXT.1: Encryption Of Sensitive Application Data
- FDP_DEC_EXT.1: Access to Platform Resources
- FDP_PRT_EXT.1: Extended: Protection of Selected User Data
- FIA_AUT_EXT.1: Authentication and Failure Handling
- FIA_FCT_EXT.1(2): Extended: User Authorization with Password/Passphrase Authorization Factors
- FMT_CFG_EXT.1: Secure by Default Configuration
- FMT_MEC_EXT.1: Supported Configuration Mechanism
- FPT_AEX_EXT.1: AntiExploitation Capabilities
- FPT_API_EXT.1: Use of Supported Services and APIs
- FPT_FEK_EXT.1: File Encryption Key (FEK) Support
- FPT_KYP_EXT.1: Extended: Protection of Key and Key Material
- FPT_LIB_EXT.1: Use of Third Party Libraries
- FPT_TUD_EXT.1: Integrity for Installation and Update
- FTP_DIT_EXT.1: Protection of Data in Transit
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5. Security Requirements
This section defines the Security Functional Requirements (SFRs) and Security Assurance Requirements (SARs)
that serve to represent the security functional claims for the Target of Evaluation (TOE) and to scope the evaluation
effort.
The SFRs have all been drawn from the ASPP11/FEEP10. The refinements and operations already performed in the
ASPP11/FEEP10 are not identified (e.g., highlighted) here, rather the requirements have been copied from the
ASPP11/FEEP10 and any residual operations have been completed herein. Of particular note, the ASPP11/FEEP10
made a number of refinements and completed some of the SFR operations defined in the Common Criteria (CC) and
that PP should be consulted to identify those changes if necessary.
The SARs are also drawn from the ASPP11/FEEP10 which includes all the SARs for EAL 1. However, the SARs
are effectively refined since requirement-specific 'Assurance Activities' are defined in the ASPP11/FEEP10 that
serve to ensure corresponding evaluations will yield more practical and consistent assurance than the EAL 1
assurance requirements alone. The ASPP11/FEEP10 should be consulted for the assurance activity definitions.
5.1 TOE Security Functional Requirements
The following table identifies the SFRs that are satisfied by Data at Rest (DaR) Management TOE.
Requirement Class Requirement Component
FCS: Cryptographic support FCS_CKM_EXT.1(A): Cryptographic key generation
(Password/Passphrase conditioning)
FCS_CKM_EXT.1: Key Encryption Key (KEK) Support
FCS_CKM_EXT.2: Cryptographic Key Generation (FEK)
FCS_CKM_EXT.4: Extended: Cryptographic Key Destruction
FCS_COP.1(1): Cryptographic Operation Encryption
FCS_COP.1(4): Cryptographic Operation (Keyed-Hash Message
Authentication)
FCS_COP.1(5): Cryptographic Operation (Key Wrapping)
FCS_IV_EXT.1: Extended: Initialization Vector Generation
FCS_KYC_EXT.1: Key Chaining and Key Storage
FCS_RBG_EXT.1: Random Bit Generation Services
FCS_STO_EXT.1: Storage of Secrets
FDP: User data protection FDP_DAR_EXT.1: Encryption Of Sensitive Application Data
FDP_DEC_EXT.1: Access to Platform Resources
FDP_PRT_EXT.1: Extended: Protection of Selected User Data
FIA: Identification and
authentication
FIA_AUT_EXT.1: Authentication and Failure Handling
FIA_FCT_EXT.1(2): Extended: User Authorization with
Password/Passphrase Authorization Factors
FMT: Security management FMT_CFG_EXT.1: Secure by Default Configuration
FMT_MEC_EXT.1: Supported Configuration Mechanism
FMT_SMF.1: Specification of Management Functions
FPT: Protection of the TSF FPT_AEX_EXT.1: AntiExploitation Capabilities
FPT_API_EXT.1: Use of Supported Services and APIs
FPT_FEK_EXT.1: File Encryption Key (FEK) Support
FPT_KYP_EXT.1: Extended: Protection of Key and Key Material
FPT_LIB_EXT.1: Use of Third Party Libraries
FPT_TUD_EXT.1: Integrity for Installation and Update
FTP: Trusted path/channels FTP_DIT_EXT.1: Protection of Data in Transit
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Table 1 TOE Security Functional Components
5.1.1 Cryptographic support (FCS)
5.1.1.1 Cryptographic key generation (Password/Passphrase conditioning) (FCS_CKM_EXT.1(A))
FCS_CKM_EXT.1.1(A)
The TSF shall support a password/passphrase of up to [74] characters used to generate a password
authorization factor.
FCS_CKM_EXT.1.2(A)
The TSF shall allow passwords to be composed of any combination of upper case characters,
lower case characters, numbers, and the following special characters: “!”, “@”, “#”, “$”, “%”, “^”,
“&”, “*”, “(“, and “)”, and [no other characters].
FCS_CKM_EXT.1.3(A)
The TSF shall perform Password-based Key Derivation Functions in accordance with a specified
cryptographic algorithm [HMAC-[selection: SHA- 512]], with [4096] iterations, and output
cryptographic key sizes [256] that meet the following: [NIST SP 800-132].
FCS_CKM_EXT.1.4(A)
The TSF shall not accept passwords less than [a value settable by the administrator] and greater
than the maximum password length defined in FCS_CKM_EXT.1.1(A).
FCS_CKM_EXT.1.5(A)
The TSF shall generate all salts using a RBG that meets FCS_RBG_EXT.1 (from the AS PP) and
with entropy corresponding to the security strength selected for PBKDF in
FCS_CKM_EXT.1.3(A).
5.1.1.2 Key Encrypting Key (KEK) Support (EXT.1)
FCS_CKM_EXT.1.1
The TSF shall support KEK in the following manner based on the selection chosen in
FPT_FEK_EXT.1: [derive a KEK using a password-based authorization factor conditioned as
defined in FCS_CKM_EXT.1(A) and in accordance with FIA_FCT_EXT.1(2), using a Random
Bit Generator as specified in FCS_RBG_EXT.1 (from the AS PP) and with entropy
corresponding to the security strength of AES key sizes of [256 bit]].
FCS_CKM_EXT.1.2
All KEKs shall be [256-bit] keys corresponding to at least the security strength of the keys
encrypted by the KEK..
5.1.1.3 Cryptographic Key Generation (FEK) (FCS_CKM_EXT.2)
FCS_CKM_EXT.2.1
The TSF shall generate FEK cryptographic keys [using a Random Bit Generator as specified in
FCS_RBG_EXT.1 (from the AS PP) and with entropy corresponding to the security strength of
AES key sizes of [256 bit]].
FCS_CKM_EXT.2.2
The TSF shall create a unique FEK for each file (or set of files) using the mechanism on the client
as specified in FCS_CKM_EXT.2.1.
FCS_CKM_EXT.2.3
The FEKs must be generated by the TOE.
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5.1.1.4 Extended: Cryptographic Key Destruction (FCS_CKM_EXT.4)
FCS_CKM_EXT.4.1
The application shall [invoke platform-provided key destruction] for destroying all plaintext
keying material and cryptographic security parameters when no longer needed.
5.1.1.5 Cryptographic Operation Encryption (FCS_COP.1(1))
FCS_COP.1.1(1)
Refinement: The application shall [implement invoke platform-provided AES encryption] shall
perform data encryption and decryption in accordance with a specified cryptographic algorithm
AES used in [CBC (as defined in NIST SP 800-38A)] mode and cryptographic key sizes [256-
bits].
5.1.1.6 Cryptographic Operation (Keyed-Hash Message Authentication) (FCS_COP.1.1(4))
FCS_COP.1.1(4)
Refinement: The application shall [invoke platform-provided functionality] to perform keyed-
hash message authentication in accordance with a specified cryptographic algorithm HMAC-
[SHA-384, SHA-512], key size [384,512], and message digest size of [384, 512] bits that meet the
following: FIPS PUB 198-1, “The Keyed-Hash Message Authentication Code”, and FIPS PUB
180-4, “Secure Hash Standard”.
5.1.1.7 Cryptographic Operation (Key Wrapping) (FCS_COP.1(5))
FCS_COP.1.1(5)
Refinement: The application shall [use platform provided functionality to perform Key
Wrapping] in accordance with a specified cryptographic algorithm [AES Key Wrap, RSA using
the KTS-OAEP-basic scheme] and the cryptographic key size [256 bits (AES), 2048 (RSA)] that
meet the following: [NIST SP 800-38F' for Key Wrap (section 6.2) and Key Wrap with Padding
(section 6.3), NIST SP 800-56B' for RSA using the KTS-OAEP-basic (section 9.2.3) and KTS-
OAEP-receiver-confirmation (section9.2.4) scheme].
5.1.1.8 Extended: Initialization Vector Generation (FCS_IV_EXT.1)
FCS_IV_EXT.1.1
The application shall [implement invoke platform-provided functionality to generate IVs] in
accordance with Appendix H: Initialization Vector Requirements for NIST-Approved Cipher
Modes.
5.1.1.9 Key Chaining and Key Storage (FCS_KYC_EXT.1)
FCS_KYC_EXT.1.1
The TSF shall maintain a key chain of: [KEKs originating from one or more authorization
factors(s) to the FEK(s) using the following method(s): [utilization of the platform key storage;
implement key wrapping as specified in FCS_COP.1(5)] while maintaining an effective strength
of [256 bits]].
5.1.1.10 Random Bit Generation Services (FCS_RBG_EXT.1)
FCS_RBG_EXT.1.1
The application shall [invoke platform provided DRBG functionality] for its cryptographic
operations.
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5.1.1.11 Storage of Secrets (FCS_STO_EXT.1)
FCS_STO_EXT.1.1
The application shall [invoke the functionality provided by the platform to securely store [keys]]
to nonvolatile memory.
5.1.2 User data protection (FDP)
5.1.2.1 Encryption Of Sensitive Application Data (FDP_DAR_EXT.1)
FDP_DAR_EXT.1.1
The application shall [implement functionality to encrypt sensitive data] in nonvolatile memory.
5.1.2.2 Access to Platform Resources (FDP_DEC_EXT.1)
FDP_DEC_EXT.1.1
The application shall provide user awareness of its intent to access [SD card].
FDP_DEC_EXT.1.2
The application shall provide user awareness of its intent to access [no sensitive information
repositories].
FDP_DEC_EXT.1.3
The application shall only seek access to those resources for which it has provided a justification
to access.
FDP_DEC_EXT.1.4
The application shall restrict network communication to [no network communication].
FDP_DEC_EXT.1.5
The application shall [not transmit PII over a network].
5.1.2.3 Extended: Protection of Selected User Data (FDP_PRT_EXT.1)
FDP_PRT_EXT.1.1
The TSF shall perform encryption and decryption of the user-selected file (or set of files) in
accordance with FCS_COP.1(1).
FDP_PRT_EXT.1.2
The application shall [invoke platform-provided functionality] to ensure that all sensitive data
created by the TOE when decrypting/encrypting the user-selected file (or set of files) are destroyed
in volatile and non-volatile memory upon completion of the decryption/encryption operation.
5.1.3 Identification and authentication (FIA)
5.1.3.1 Authentication Failure Handling (FIA_AUT_EXT.1)
FIA_AUT_EXT.1.1
The application shall [provide user authorization] based on [password/passphrase authorization
factors].
5.1.3.2 Extended: User Authorization with Password/Passphrase Authorization Factors
(FIA_FCT_EXT.1(2))
FIA_FCT_EXT.1.1(2)
The TSF shall provide a mechanism as defined in FCS_CKM_EXT.1 and FCS_COP.1(4) to
perform user authorization.
FIA_FCT_EXT.1.2(2)
The TSF shall perform user authorization using the mechanism provided in FIA_FCT_EXT.1.1(2)
before allowing decryption of user data.
FIA_FCT_EXT.1.3(2)
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The TSF shall support the use of multiple instances of authorization factors that result in unique
encryption keys.
FIA_FCT_EXT.1.4(2)
The TSF shall verify that the user-entered authorization factors are valid before decrypting the
user’s encrypted files.
FIA_FCT_EXT.1.5(2)
The TSF shall ensure that the method of validation for each authorization factor does not expose
or reduce the effective strength of the KEK, FEK, or CSPs used to derive the KEK or FEK.
FIA_FCT_EXT.1.6(2)
The TSF shall perform user authorization using the mechanism provided in FIA_FCT_EXT.1.1(2)
before allowing the user to change the passphrase-based authorization factor as specified in
FMT_SMF.1(c).
5.1.4 Security management (FMT)
5.1.4.1 Secure by Default Configuration (FMT_CFG_EXT.1)
FMT_CFG_EXT.1.1
The application shall only provide enough functionality to set new credentials when configured
with default credentials or no credentials.
FMT_CFG_EXT.1.2
The application shall be configured by default with file permissions which protect it and its data
from unauthorized access.
5.1.4.2 Supported Configuration Mechanism (FMT_MEC_EXT.1)
FMT_MEC_EXT.1.1
The application shall invoke the mechanisms recommended by the platform vendor for storing and
setting configuration options.
5.1.4.3 Specification of Management Functions (FMT_SMF.1)
FMT_SMF.1.1
The TSF shall be capable of performing the following management functions: [change
password/passphrase authentication, configure password/passphrase complexity setting].
5.1.5 Protection of the TSF (FPT)
5.1.5.1 AntiExploitation Capabilities (FPT_AEX_EXT.1)
FPT_AEX_EXT.1.1
The application shall not request to map memory at an explicit address except for [none].
FPT_AEX_EXT.1.2
The application shall [not allocate any memory region with both write and execute permissions].
FPT_AEX_EXT.1.3
The application shall be compatible with security features provided by the platform vendor.
FPT_AEX_EXT.1.4
The application shall not write user-modifiable files to directories that contain executable files
unless explicitly directed by the user to do so.
FPT_AEX_EXT.1.5
The application shall be compiled with stack-based buffer overflow protection enabled.
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5.1.5.2 Use of Supported Services and APIs (FPT_API_EXT.1)
FPT_API_EXT.1.1
The application shall only use supported platform APIs.
5.1.5.3 File Encryption Key (FEK) Support (FPT_FEK_EXT.1)
FPT_FEK_EXT.1.1
The TSF shall [- Store a FEK in Non-Volatile memory conformant with FPT_KYP_EXT.1].
5.1.5.4 Extended: Protection of Key and Key Material (FPT_KYP_EXT.1)
FPT_KYP_EXT.1.1
The TSF shall [only store keys in non-volatile memory when wrapped as specified in
FCS_COP.1(5)unless the key meets any one of the following criteria [-The plaintext key is used
to wrap a key as specified in FCS_COP.1(5) that is already wrapped as specified in
FCS_COP.1(5).]].
5.1.5.5 Use of Third Party Libraries (FPT_LIB_EXT.1)
FPT_LIB_EXT.1.1
The application shall be packaged with only [libcrytopp.so].
5.1.5.6 Integrity for Installation and Update (FPT_TUD_EXT.1)
FPT_TUD_EXT.1.1
The application shall [leverage the platform] to check for updates and patches to the application
software.
FPT_TUD_EXT.1.2
The application shall be distributed using the format of the platform-supported package manager.
FPT_TUD_EXT.1.3
The application shall be packaged such that its removal results in the deletion of all traces of the
application, with the exception of configuration settings, outputfiles, and audit/log events.
FPT_TUD_EXT.1.4
The application shall not download, modify, replace or update its own binary code.
FPT_TUD_EXT.1.5
The application shall [provide the ability] to query the current version of the application software.
FPT_TUD_EXT.1.6
The application installation package and its updates shall be digitally signed such that its platform
can cryptographically verify them prior to installation.
5.1.6 Trusted path/channels (FTP)
5.1.6.1 Protection of Data in Transit (FTP_DIT_EXT.1)
FTP_DIT_EXT.1.1
The application shall [not transmit any sensitive data] between itself and another trusted IT
product.
5.2 TOE Security Assurance Requirements
The SARs for the TOE are the EAL 1 components as specified in Part 3 of the Common Criteria. Note that the
SARs have effectively been refined with the assurance activities explicitly defined in association with both the SFRs
and SARs.
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Requirement Class Requirement Component
ADV: Development ADV_FSP.1: Basic functional specification
AGD: Guidance documents AGD_OPE.1: Operational user guidance
AGD_PRE.1: Preparative procedures
ALC: Life-cycle support ALC_CMC.1: Labelling of the TOE
ALC_CMS.1: TOE CM coverage
ATE: Tests ATE_IND.1: Independent testing - conformance
AVA: Vulnerability assessment AVA_VAN.1: Vulnerability survey
Table 2 EAL 1 Assurance Components
5.2.1 Development (ADV)
5.2.1.1 Basic functional specification (ADV_FSP.1)
ADV_FSP.1.1d
The developer shall provide a functional specification.
ADV_FSP.1.2d
The developer shall provide a tracing from the functional specification to the SFRs.
ADV_FSP.1.1c
The functional specification shall describe the purpose and method of use for each SFR-enforcing
and SFR-supporting TSFI.
ADV_FSP.1.2c
The functional specification shall identify all parameters associated with each SFR-enforcing and
SFR-supporting TSFI.
ADV_FSP.1.3c
The functional specification shall provide rationale for the implicit categorisation of interfaces as
SFR-non-interfering.
ADV_FSP.1.4c
The tracing shall demonstrate that the SFRs trace to TSFIs in the functional specification.
ADV_FSP.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
ADV_FSP.1.2e
The evaluator shall determine that the functional specification is an accurate and complete
instantiation of the SFRs.
5.2.2 Guidance documents (AGD)
5.2.2.1 Operational user guidance (AGD_OPE.1)
AGD_OPE.1.1d
The developer shall provide operational user guidance.
AGD_OPE.1.1c
The operational user guidance shall describe, for each user role, the user-accessible functions and
privileges that should be controlled in a secure processing environment, including appropriate
warnings.
AGD_OPE.1.2c
The operational user guidance shall describe, for each user role, how to use the available interfaces
provided by the TOE in a secure manner.
AGD_OPE.1.3c
The operational user guidance shall describe, for each user role, the available functions and
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interfaces, in particular all security parameters under the control of the user, indicating secure
values as appropriate.
AGD_OPE.1.4c
The operational user guidance shall, for each user role, clearly present each type of security-
relevant event relative to the user-accessible functions that need to be performed, including
changing the security characteristics of entities under the control of the TSF.
AGD_OPE.1.5c
The operational user guidance shall identify all possible modes of operation of the TOE (including
operation following failure or operational error), their consequences and implications for
maintaining secure operation.
AGD_OPE.1.6c
The operational user guidance shall, for each user role, describe the security measures to be
followed in order to fulfil the security objectives for the operational environment as described in
the ST.
AGD_OPE.1.7c
The operational user guidance shall be clear and reasonable.
AGD_OPE.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
5.2.2.2 Preparative procedures (AGD_PRE.1)
AGD_PRE.1.1d
The developer shall provide the TOE including its preparative procedures.
AGD_PRE.1.1c
The preparative procedures shall describe all the steps necessary for secure acceptance of the
delivered TOE in accordance with the developer's delivery procedures.
AGD_PRE.1.2c
The preparative procedures shall describe all the steps necessary for secure installation of the TOE
and for the secure preparation of the operational environment in accordance with the security
objectives for the operational environment as described in the ST.
AGD_PRE.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
AGD_PRE.1.2e
The evaluator shall apply the preparative procedures to confirm that the TOE can be prepared
securely for operation.
5.2.3 Life-cycle support (ALC)
5.2.3.1 Labelling of the TOE (ALC_CMC.1)
ALC_CMC.1.1d
The developer shall provide the TOE and a reference for the TOE.
ALC_CMC.1.1c
The TOE shall be labelled with its unique reference.
ALC_CMC.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
5.2.3.2 TOE CM coverage (ALC_CMS.1)
ALC_CMS.1.1d
The developer shall provide a configuration list for the TOE.
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ALC_CMS.1.1c
The configuration list shall include the following: the TOE itself; and the evaluation evidence
required by the SARs.
ALC_CMS.1.2c
The configuration list shall uniquely identify the configuration items.
ALC_CMS.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
5.2.4 Tests (ATE)
5.2.4.1 Independent testing - conformance (ATE_IND.1)
ATE_IND.1.1d
The developer shall provide the TOE for testing.
ATE_IND.1.1c
The TOE shall be suitable for testing.
ATE_IND.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
ATE_IND.1.2e
The evaluator shall test a subset of the TSF to confirm that the TSF operates as specified.
5.2.5 Vulnerability assessment (AVA)
5.2.5.1 Vulnerability survey (AVA_VAN.1)
AVA_VAN.1.1d
The developer shall provide the TOE for testing.
AVA_VAN.1.1c
The TOE shall be suitable for testing.
AVA_VAN.1.1e
The evaluator shall confirm that the information provided meets all requirements for content and
presentation of evidence.
AVA_VAN.1.2e
The evaluator shall perform a search of public domain sources to identify potential vulnerabilities
in the TOE.
AVA_VAN.1.3e
The evaluator shall conduct penetration testing, based on the identified potential vulnerabilities, to
determine that the TOE is resistant to attacks performed by an attacker possessing Basic attack
potential.
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6. TOE Summary Specification
This chapter describes the security functions:
- Cryptographic support
- User data protection
- Identification and authentication
- Security management
- Protection of the TSF
- Trusted path/channels
6.1 Cryptographic support
The TOE operates on an evaluated Android 4.4 device and uses Android’s cryptographic API for encryption
services and random number generation. The TOE’s platforms support the following algorithms:
Functions Standards Certificates
Encryption/Decryption
 AES CBC and Key Wrapping (256
bits)
FIPS PUB 197
NIST SP 800-38A
NIST SP 800-38F
1884 & 3011 (LG G3 only)
Cryptographic hashing
 SHA-1, SHA-256, SHA-384, and
SHA-512 (digest sizes 160, 256,
384, and 512 bits)
FIPS Pub 180-3 1655 & 2519 (LG G3 only)
Keyed-hash message authentication
 HMAC-SHA-1(digest size 160) FIPS Pub 198-1
FIPS Pub 180-3
1126 & 1903 (LG G3 only)
Random bit generation
 AES-256 CTR_DRBG with
software based noise sources with a
minimum of 256 bits of non-
determinism
NIST SP 800-90 157 & 573 (LG G3 only)
Asymmetric algorithms
 RSA FIPS Pub 186-4 960 & 1571 (LG G3 only)
Table 3 Algorithm Certificate Table
The TOE generally fulfills all of the NIST SP 800-56B requirements without extensions, the following table
specifically identifies the “should”, “should not”, and “shall not” conditions from the publication along with an
indication of how the TOE conforms to those conditions.
NIST SP800-56B
Section Reference
“should”, “should not”, or
“shall not”
Implemented? Rationale for deviation
5.6 Should Yes Not applicable
5.8 shall not No Not applicable
5.9 shall not (first occurrence) No Not applicable
5.9 shall not (second occurrence) No Not applicable
6.1 should not No Not applicable
6.1 should (first occurrence) Yes Not applicable
6.1 should (second occurrence) Yes Not applicable
6.1 should (third occurrence) Yes Not applicable
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NIST SP800-56B
Section Reference
“should”, “should not”, or
“shall not”
Implemented? Rationale for deviation
6.1 should (fourth occurrence) Yes Not applicable
6.1 shall not (first occurrence) No Not applicable
6.1 shall not (second occurrence) No Not applicable
6.2.3 Should Yes Not applicable
6.5.1 Should Yes Not applicable
6.5.2 Should Yes Not applicable
6.5.2.1 Should Yes Not applicable
6.6 shall not No Not applicable
7.1.2 Should Yes Not applicable
7.2.1.3 Should Yes Not applicable
7.2.1.3 should not No Not applicable
7.2.2.3 should (first occurrence) Yes Not applicable
7.2.2.3 should (second occurrence) Yes Not applicable
7.2.2.3 should (third occurrence) Yes Not applicable
7.2.2.3 should (fourth occurrence) Yes Not applicable
7.2.2.3 should not No Not applicable
7.2.2.3 shall not No Not applicable
7.2.3.3 should (first occurrence) Yes Not applicable
7.2.3.3 should (second occurrence) Yes Not applicable
7.2.3.3 should (third occurrence) Yes Not applicable
7.2.3.3 should (fourth occurrence) Yes Not applicable
7.2.3.3 should (fifth occurrence) Yes Not applicable
7.2.3.3 should not No Not applicable
8 Should Yes Not applicable
8.3.2 should not No Not applicable
Table 4 NIST SP800-56B Conformance
The Cryptographic support function is designed to satisfy the following security functional requirements:
 FCS_CKM_EXT.1(A): The TOE allows the use of DaR passwords that support all special characters
mentioned in FCS_CKM_EXT.1(A). The TOE encodes the DaR password using UTF-8 before the DaR
password is passed into the evaluated Android platform’s cryptographic APIs to perform Password-Based
key derivation (SP 800-132 PBKDF2) using HMAC-SHA-512 pseudo-random function. Note that this DaR
password does not derive the FEK. The password input into the PBKDF2 function derives a key that serves
as a secondary AES wrap on the FEFEK in conjunction with an asymmetric key wrap using RSA key pair
stored in the Android keystore. The TOE enforces a minimum password length of 6 characters, and can
support a maximum password of 74 characters.
The TOE performs 4096 iterations of the key derivation function in PBKDF2 to increase the computation
needed to derive a key from the DaR password. With a thousand iterations on the evaluated platform, the
average derivation time is 249.035 milliseconds.
The salt used in the PBKDF2 operations is generated by the platform’s java.security.SecureRandom
cryptographic API. First, a byte array is declared. The byte arrays are then filled with a random value from
the platform’s nextBytes method from SecureRandom. SecureRandom uses /dev/random. The salts are
saved in /data/data, which is Android’s protected directory. The salt lengths are 64 bytes.
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 FCS_CKM_EXT.1: The TOE generates keys using the Android platform’s API (KeyGenerator) as
described here. The API uses an SP 800-90A AES-256 CTR DRBG that is seeded with sufficient entropy
from the platform itself. The file encryption key encryption key (FEKEK) is generated using the
KeyGenerator API. The FEKEK is stored in the Management Service’s BouncyCastle keystore. The
FEKEK is wrapped twice, once using RSA and one more time using AES. The AES key used to wrap the
FEKEK is derived from the DaR password using PBKDF2. Both the Management Service and
Application’s RSA keys used to wrap the FEKEK are generated using the KeyGenerator API. If the DaR
password provided by the user is not correct, then the Management Service’s BouncyCastle keystore will
not properly load, preventing the Management Service from accessing its keystore. Furthermore, an
incorrect DaR password results in the incorrect derivation of the PBKDF2 derived AES key, therefore the
FEKEK will not be unwrapped properly. The AES-256 file encryption key (FEK) is generated using the
platform’s DRBG.
 FCS_CKM_EXT.2: The TOE generates file encrypton keys (FEKs) using the evaluated Android platform’s
cryptographic API by calling the KeyGenerator API. The KeyGenerator API uses the platform’s SP 800-
90A AES-256 CTR DRBG. The DRBG is seeded with sufficient entropy to generate keys with 256 bits of
security strength by using seeding material collected by the evaluated platform. The FEKs are generated
every time a new file is going to be encrypted. The TOE associates a FEK with an individual file that’s
being encrypted by storing the wrapped FEK in the same hidden directory as the encrypted file. The TOE
automatically generates a FEK (without user action) whenever the application attempts to encrypt a new
file.
 FCS_CKM_EXT.4: The TOE relies on the platform for destroying keys. The platform utilizes Java
Garbage Collection in order to clear memory. The TOE releases all references to objects (e.g. keys) when
they are no longer needed, and the Java Garbage Collection clears out the memory that is no longer in use.
Key Name
Cleartext
Storage
Location
Destruction
Entity
responsible for
Destruction
When it is destroyed
FEK RAM Java Garbage Collection Platform key
destruction API
After file encryption/decryption
Management
service unwrapped
FEKEK
RAM Java Garbage Collection Platform key
destruction API
After storing FEKEK to
Application’s BouncyCastle
keystore
Application
unwrapped FEKEK
RAM Java Garbage Collection Platform key
destruction API
After encrypting/decrypting the
FEK
PBKDF2 derived
key
RAM Java Garbage Collection Platform key
destruction API
After AES unwrapping double
wrapped FEKEK
Management
Service’s private
RSA key
TrustZone TrustZone TrustZone After RSA unwrapping of
double-wrapped FEKEK
Application’s
private RSA key
TrustZone TrustZone TrustZone After RSA unwrapping of
single-wrapped FEKEK
Table 5 Key Destruction
 FCS_COP.1(1): The TOE invokes the evaluated Android platform’s cryptographic APIs to perform AES-
256-CBC encryption and AES key wrapping. The TOE invokes the Android cryptographic API’s AES
implementation to perform AES 256-CBC encryption when encrypting files using the 256-bit FEK.
 FCS_COP.1(4): The TOE uses the platform’s HMAC-SHA-384 to hash the DaR password with a salt
generated by the platform’s DRBG. The hash value is used as an authentication factor to load the
Management Service’s BouncyCastle keystore, which houses an RSA wrapped file encryption key
encryption key (FEKEK). If the DaR password is incorrect, the keystore will not load, and the calling
application does not gain access to the key used to decrypt its files. The TOE uses the platform’s HMAC-
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SHA-512 to hash a PBKDF2 derived key with a second salt to produce a key used to further unwrap the
FEKEK using AES keywrap, after the FEKEK has been unwrapped using RSA-OAEP.
 FCS_COP.1(5): The TOE uses the evaluated platform’s approved cryptographic API (e.g.
cipher.init(Cipher.WRAP_MODE, aesWrappingKey), cipher.init(Cipher.UNWRAP_MODE,
aesWrappingKey), OAEPEncoding(rsa, digest, null), cipher.wrap and cipher.unwrap) to perform key
wrapping functions. The evaluated platform’s API performs AES key wrapping in accordance with SP 800-
38F and RSA key wrapping in accordance with SP 800-56B. The TOE’s Operations and Maintenance
manual [OM] contains the full list of APIs used by the TOE.
 FCS_IV_EXT.1: The TOE uses the evaluated platform’s approved cryptographic API to perform
Initialization vector generation using the platform’s DRBG. The TOE calls the platform’s SecureRandom()
API to generate a 128-bit (16-byte) initialization vector. SecureRandom uses /dev/random. The TOE’s
Operations and Maintenance manual [OM] contains the full list of APIs used by the TOE. The TOE uses
initialization vectors when performing AES-256 encryption/decryption of only user data using the FEK.
IVs are not used as part of any key wrap/unwrap process.
 FCS_KYC_EXT.1: The DaR password is used in two places. First, it is hashed using SHA-384 with a salt
(generated using the platform’s DRBG) and used to load the Management Service’s BouncyCastle
keystore. The DaR password is used as input to PBKDF2 with 4096 iterations and HMAC-SHA-512 PRF
along with a second salt value (also generated using the platform’s DRBG).
The platform retrieves the double-wrapped FEKEK from the Management Service’s BouncyCastle
keystore. The double wrapped FEKEK is AES unwrapped using the 256-bit PBKDF2 derived key,
resulting in an RSA wrapped FEKEK.
The RSA wrapped FEKEK is unwrapped using the Management Service’s RSA keypair, resulting in a
cleartext FEKEK that is re-encrypted using the Application’s RSA public key. The Management Service
passes this single wrapped FEKEK to the application by temporarily2 placing it in the Application’s
BouncyCastle keystore. The Management Service obtains the Application’s RSA public key as well as the
Application’s certificate fingerprint when the Application registers itself to the Management Service
(performed once). The Application’s RSA public key is kept within Android’s SharedPreferences under
MODE_PRIVATE.
The Management Service uses the Application’s certificate fingerprint to read/write to the Application’s
BouncyCastle keystore.
When the Application needs to access the FEKEK, it obtains its RSA keypair from its own Android
keystore and the single wrapped FEKEK from its own BouncyCastle keystore. The Application performs
RSA-2048 unwrapping on the single wrapped FEKEK to obtain a cleartext FEKEK. The FEKEK is used as
256-bit AES key to unwrap the FEK. The FEK is a 256-bit AES key used to decrypt user data.
 FCS_RBG_EXT.1: TOE relies on the evaluated Android platform’s cryptographic API for random number
generation, which utilizes an SP 800-90A AES-256 CTR DRBG.
 FCS_STO_EXT.1: All keystores live in Android’s protected directory /data/misc/keystore, which is also on
the platform’s flash storage.
- The TOE uses the evaluated Android platform’s Android keystore to store all RSA keypairs
- Upon registration, each Application passes its public key to the Management Service, which is
stored in Android’s SharedPreferences under MODE_PRIVATE
- The TOE uses the Management Service’s BouncyCastle keystore to store the double wrapped
FEKEK
- The TOE uses the Application’s BouncyCastle keystore to store the single wrapped FEKEK.
2
The Management Service erases the single wrapped FEKEK from the application’s keystore when the password
timer expires.
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- The wrapped FEK and IV are stored in the same hidden directory as the encrypted file, which is
all stored on flash.
6.2 User data protection
The TOE protects user data by providing encryption of user selected data. The TOE uses 256-bit AES keys to
encrypt the files stored to flash. These keys are derived from DaR passwords through a key derivation and key
wrapping process. If an application does not enter the right DaR password, the file encryption key will never be
derived correctly, thus preventing the application from decrypting its files. The AES keys are generated using the
evaluated platform’s API. The Android 4.4 cryptographic API was evaluated for application use using the Mobile
Device Fundamentals PP and the API utilizes an approved implementation of SP 800-90A AES-256-CTR DRBG.
The random data collected to seed the DRBG comes from the evaluated device’s /dev/urandom.
The User data protection function is designed to satisfy the following security functional requirements:
 FDP_DAR_EXT.1: The TOE implements functionality to encrypt data and store it securely on the
evaluated platform. The TOE uses the evaluated platform’s Android cryptographic API (KeyGenerator) to
generate AES-256 bit keys for file encryption.
 FDP_DEC_EXT.1: The TOE only uses the READ_EXTERNAL_STORAGE to write to an external SD
Card. The TOE does not access any of the listed sensitive information repositories. The TOE does not
communicate over any networks, therefore it does not transmit PII data over a network. According to the
TOE’s Operations and Maintenance manual [OM], the DaR can read/write data to any directory based on
the permissions of the integrated application. These directories can reside either in the internal Android SD
Card or in expandable memory.
 FDP_PRT_EXT.1: The TOE encrypts each individual file separately. The encrypted files are stored in a
hidden directory at the same directory level as the original files. Before encryption, the TOE splits a file
into chunks so that access to specific parts within an encrypted file is easier. Using the platform’s
encryption API, each chunk is then encrypted separately. The original file is replaced with a directory
structure of different files after chunking and encryption. The directory structure of the encrypted file
includes a metadata file that describes the chunking structure, a hidden folder for every chunk that includes
a header file, and the encrypted file chunks split into encrypted pieces. The TOE implements functionality
to ensure that sensitive data is destroyed in volatile and non-volatile memory upon completion of either a
decrypt or encrypt operation of the sensitive files. The DaR returns the plaintext data out of our API to the
application for processing. The DaR clears all internal buffers of the data. The TOE does not create any
temporary resources.
Each chunk is decrypted separately (using the platform’s decryption API). This allows much faster access
to read/write encrypted data to the encrypted file (e.g. random access files). For example, if data is added to
the middle of an encrypted file that hasn’t been chunked, the entire file needs to be decrypted, and the data
needs to be inserted in before the file is re-encrypted. In the same scenario, if the encrypted file was
chunked, then the first half of the chunks can be skipped before reaching the point at which the data needs
to be encrypted and inserted. The DaR chunks the data set on 10MB boundaries, so if only a subset of the
data is needed, the system will only encrypt the 10MB chunk that contains the desired data set. If the data
in the file wishes to be changed, then the whole file must be re-encrypted. Decrypted pieces are retained for
caching purposes for up to 30 seconds, before they are purged and the memory is wiped. Each file has a
unique FEK and IV, which is used to encrypt/decrypt each chunk. The wrapped FEK and IV are stored in a
hidden directory that resides in the same directory as the encrypted file.
The TOE programmatically destroys all keys in volatile memory (such as keys stored in RAM and used by
the TOE) by calling Android’s Arrays.fill method in order to zero out the key array.
6.3 Identification and authentication
The TOE maintains identification and authentication by using DaR passwords. In order for an application to unlock
its files, the application must provide the correct DaR password. The DaR password is used to derive the necessary
keys in order to obtain the file encryption key, which is used to decrypt the files.
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The Identification and authentication function is designed to satisfy the following security functional requirements:
 FIA_AUT_EXT.1: The TOE provides a DaR password based authorization factor in order to authenticate
to the DaR service.
 FIA_FCT_EXT.1(2): The TOE allows a single user to login to the TOE with their own DaR password
(a.k.a., authorization factor). The TOE provides user authorization by requiring a user to provide a DaR
password to gain access to the DaR service as well as the user’s associated keys for the specific application.
The DaR password is used to obtain two unique keys used to recover the file encryption key encryption key
(FEKEK). The DaR password is first hashed using HMAC-SHA384. The resulting hash is used as a DaR
password to load the Management Service’s BouncyCastle keystore. If the DaR password is incorrect, the
keystore will not load, and the wrapped FEKEK cannot be loaded. The DaR password previously provided
is then used to derive a key using PBKDF2 with HMAC-SHA-512 as the pseudo-random function. This
key is used to further unwrap the FEKEK. If the DaR password is incorrect, the key derived using PBKDF2
will not be able to successfully unwrap the FEKEK retrieved from the Management Service’s
BouncyCastle keystore. The FEKEK is ultimately used to decrypt the actual file encryption key used to
encrypt/decrypt files. In order to change a DaR password, the user must provide the previous DaR
password to retrieve the FEKEK. If authentication is successful, the FEKEK is loaded, and the TOE will
then use the new DaR password to derive keys to rewrap the FEKEK.
6.4 Security management
The TOE does not allow invocation of its services until a configuration file has been created. The configuration
options are stored in the evaluated Android 4.4 OS’s defined private area on flash memory. The TOE allows users to
change DaR passwords as part of its security management.
The Security management function is designed to satisfy the following security functional requirements:
 FMT_CFG_EXT.1: The TOE restricts access to its services upon first use. The services are grayed out until
a configuration file is created. This allows the TOE to force the user to configure the TOE before accessing
the TOE’s services. There are no default credentials within the TOE.
 FMT_MEC_EXT.1: The TOE’s evaluated Android platform automatically uses
/data/data/package/shared_prefs/ to store configuration options and settings. The Time-outs, Lock-outs, and
SALTs for PBKDFv2 are stored in private files in the file directory.
 FMT_SMF.1: The TOE provides the ability to change DaR passwords/passphrases and configure the DaR
password/passphrase complexity setting.
6.5 Protection of the TSF
The TOE is physically protected by the boundary of the evaluated device. The TOE is executed on an evaluated
Android 4.4 OS. The TOE utilizes the evaluated platform’s APIs only. Android’s application management requires
application updates to be signed with an Android key, thus allowing the secure updates of its applications. The
Android OS Linux kernel is capable of ASLR (address space layout randomization), ensuring that no application
uses the same address layout on two different devices. Keys are also stored in memory, which can be wiped by
rebooting the device.
The Protection of the TSF function is designed to satisfy the following security functional requirements:
 FPT_AEX_EXT.1: The application is compiled with “-v -DBUILD_JNI -DANDROID -DCRC -O2 -
fstack-protector-all –fexceptions” in order to enable ASLR and stack-based buffer overflow protection. The
Linux kernel of the TOE’s Android operating system also provides address space layout randomization
utilizing the get_random_int(void) kernel random function to provide eight unpredictable bits to the base
address of any user-space memory mapping. The random function, though not cryptographic, ensures that
one cannot predict the value of the bits.
 FPT_API_EXT.1: The TOE uses only platform provided APIs and does not import any third party APIs.
The TOE’s Operations and Maintenance manual [OM] contains the full list of APIs used by the TOE.
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 FPT_FEK_EXT.1: The TOE stores keys in non-volatile memory in conformance with FPT_KYP_EXT.1.
When keys are no longer needed, they are destroyed by the platform’s mechanism. The TOE destroys keys
in volatile memory (such as keys stored in RAM and used by the TOE) by calling Android’s Arrays.fill
method in order to zero out the key array. The TOE programmatically destroys these keys in memory after
they are no longer needed by the TOE (i.e. after encryption/decryption). The TOE relies on Android’s
platform application protections to prevent disclosure of application memory, which can lead to recovery of
keys.
 FPT_KYP_EXT.1: The TOE stores keys in nonvolatile memory by relying on the Android and
BouncyCastle keystores. The TOE uses the Management Service’s BouncyCastle keystore to store the
double wrapped FEKEK. The TOE uses the Android keystore to store all RSA public/private keys, which
are used to unwrap the double wrapped FEKEKS. The unwrapped FEKEKs are further unwrapped using
AES key wrap. The TOE wraps the file encryption keys (FEK, used for encrypting files) with another AES
key, and then stores the wrapped FEK in both the Android and BouncyCastle keystores on the evaluated
device’s flash memory. The TOE utilizes the evaluated Android platform’s AES key wrap and RSA OAEP
key wrap functions to protect keys. The keys are stored in non-volatile memory using Android’s keystore
API.
 FPT_LIB_EXT.1: The TOE only uses the third party library libcrytopp.so.
 FPT_TUD_EXT.1: If a security vulnerability was found by a user, then the user must report it to CRC’s
email at suppert@cyberreliant.com. In the case that the vulnerability impacts the CRC DaR API: CRC will
deliver updated API Code, as well as additional developers documentation outlining any potential changes
in the implementation. In order to deliver the final resolution to the end-user, the partner developer or
customer will need to implement the updated code into their target applications. The time for final delivery
will be dependent on their ability to update the end-user application, and to distribute to users via Mobile
Device Management Service, application store, or other delivery mechanism.
In the case the vulnerability directly relates to the CRC Management Service APK: CRC shall deliver, via
email or other agreed upon method, an updated application with security vulnerabilities addressed. The
delivered software shall be accompanied by documentation outlining changes to the overall service, as well
as compatible versions of the CRC API. Once delivered to the customer or partner, the application can be
delivered to end-users via Internal MDM instances, Internal “App Stores” or other agreed upon
methodologies.
The TOE’s software is digitally signed by CyberReliant. Each update is accompanied by documentation
outlining changes to the overall service, as well as compatible versions of the CRC API.
Checking for updates can be done in the app by selecting
A popup will appear indicating whether an update is necessary and instructions on how to retrieve it
6.6 Trusted path/channels
The TOE does not transmit data to any other products.
The Trusted path/channels function is designed to satisfy the following security functional requirements:
 FTP_DIT_EXT.1: The TOE does not transmit any data between itself and other products.