THD89—EAL6A-ST-lite-V1.0
THD89 Secure Microcontroller with
Crypto Library
Security Target Lite
Version 1.0
Tongxin Microelectronics Co.,Ltd.
2020 – 06
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Revision History
No. Version Date Change By
1 1.0 June 17 2020 Create Lei SUN
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Contents
1. ST Introduction...............................................................................................................5
1.1. ST and TOE reference...............................................................................................5
1.2. TOE overview...........................................................................................................5
1.3. TOE description........................................................................................................6
1.3.1. Physical architecture ..........................................................................................6
1.3.2. Logical Scope.....................................................................................................7
1.3.3. TOE components................................................................................................9
1.4. Life cycle and delivery..............................................................................................9
2. Conformance claim.......................................................................................................11
2.1. CC Conformance ....................................................................................................11
2.2. PP Claim.................................................................................................................11
2.3. Package claim.........................................................................................................11
2.4. Conformance claim rationale...................................................................................11
3. Security problem definition...........................................................................................13
3.1. Description of Assets ..............................................................................................13
3.2. Threats....................................................................................................................13
3.3. Organisational security policies...............................................................................13
3.4. Assumptions ...........................................................................................................14
4. Security objectives........................................................................................................15
4.1. Security objectives for the TOE ..............................................................................15
4.2. Security objectives for the security IC embedded software......................................15
4.3. Security objectives for the operational environment ................................................16
4.4. Security objectives rationale....................................................................................16
5. Extended Components Definitions................................................................................18
6. Security requirements ...................................................................................................19
6.1. Definitions ..............................................................................................................19
6.2. Security Functional Requirements (SFR) ................................................................19
6.2.1. SFRs derived from the Security IC Platform Protection Profile.........................19
6.2.2. SFRs regarding cryptographic functionality......................................................22
6.3. Definition of ADV_SPM.........................................................................................23
6.4. Security Assurance Requirements (SAR) ................................................................23
6.5. Security requirements rationale ...............................................................................24
6.5.1. Security Functional Requirements (SFR)..........................................................24
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6.5.2. Dependencies of the SFRs................................................................................25
6.5.3. Security Assurance Requirements (SAR) .........................................................26
6.5.4. Dependencies of the SARs ...............................................................................27
7. TOE summary specification..........................................................................................28
7.1. Malfunction ............................................................................................................28
7.2. Leakage ..................................................................................................................28
7.3. Physical manipulation and probing..........................................................................28
7.4. Abuse of functionality and Identification.................................................................29
7.5. Random numbers ....................................................................................................29
7.6. Cryptographic functionality.....................................................................................29
7.7. Security architectural information ...........................................................................29
8. References ....................................................................................................................30
1. ST Introduction
This Security Target (ST) is built upon the Security IC Platform Protection Profile with
Augmentation Packages [1], registered and Certified by BundesamtfürSicherheit in der
Informationstechnik (BSI) under the reference BSI-CC-PP-0084-2014.
This chapter presents the ST reference, the reference for the Target of Evaluation (TOE), a
TOE overview description and a description of the logical and physical scope of the TOE.
1.1. ST and TOE reference
Table 1 Description of ST reference and TOE reference
ST reference: THD89 Secure Microcontroller with Crypto Library Security Target Lite,
version 1.0, June 2020
TOE reference: THD89 Secure Microcontroller version 1.0 with Crypto Library version 1.01
1.2. TOE overview
The TOE is a secure microcontroller with crypto library suitable for instance to support ID
cards, Banking cards, ePassport applications, etc.
The TOE consists of hardware and IC dedicated software. The hardware is based on a 32-bit
CPU with ROM (Non-Volatile Read-Only Memory), NVM (Non-volatile Programmable
Memory) and RAM (Volatile Memory). The hardware of the TOE also incorporates
communication peripherals and cryptographic coprocessors for execution and acceleration of
symmetric and asymmetric cryptographic algorithms. The IC dedicated software consists of
boot code and a library of cryptographic services.
The TOE supports the following communication interfaces:
 ISO/IEC 7816 contact interface.
 ISO/IEC 14443 contactless interface
 SPI interface
 I2C interface
The TOE is delivered to a composite product manufacturer. The security IC embedded
software is developed by the composite product manufacturer. The security IC embedded
software is not part of the TOE.
The TOE has been designed to provide a platform for Security IC Embedded Software which
ensures that the critical user data of the Composite TOE are stored and processed in a secure
way. To this end the TOE has the following security features:
 Hardware coprocessor for DES/TDES
 True Random Number Generator
 Hardware for RSA support
 Protection against power analysis,
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 Protection against physical attacks,
 Protection against perturbation attacks,
 Software library with cryptographic services for TDES, RSA and TRNG.
1.3. TOE description
This section presents the physical and logical scope of the TOE.
1.3.1. Physical architecture
The main functional blocks of the TOE hardware is depicted below.
ROM Sensors
ARM
SC000
CPU
AHBMMU
RAM
Interfaces/IO
Clock Circuitry
Reset
Circuitry
NVM
TRNG DES/
TDES
System
control
circuitry
Security Circuitry
Power
Management
Unit
Crytp Co-
Processor
Test
circuitry
Timers
Chinese
domestic
crypto Co-
processor
CRC
DRNG AES
Figure 1 The block diagram of the TOE hardware
The hardware of the TOE has the following components:
 ARMSC000 CPU
 NVM (192kB)
 ROM (384kB)
 RAM (14kB)
 AHBMMU
 Interfaces I/O
o ISO/IEC 14443 contactless interface
o ISO/IEC 7816 contact interface
o SPI interface
o I2C interface
 True Random Number Generator
 Deterministic Random Number Generator
 DES/TDES Co-Processor
 AES Co-Processor
 Hardware Crypto Co-Processor for RSA support
 CRC Co-Processor
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 Chinese domestic crypto Co-Processor
 System control circuitry
 Test circuitry
 Timers
 Security Circuitry
 Sensors
o Voltage sensor
o Glitch sensor
o Frequency sensor
o High frequency filter
o Temperature sensor
o Light sensor
 Power Management Circuitry
 Clock circuitry
 Reset circuitry
The AHBMMU is a bus component which also provides user controllable bus masking.
The following components are not in the scope of the evaluation.
 Chinese domestic crypto Co-Processor
 AES Co-Processor
 CRC Co-Processor
The Deterministic Random Number Generator hardware component is used internally by the
TOE. However, the service provided to the user is not under the scope of the evaluation
ISO/IEC 14443 contactless interface and ISO/IEC 7816 contact interface are the interfaces
available for the user. The security of SPI and I2C interfaces is not provided to the user.
1.3.2. Logical Scope
The TOE distinguishes three modes:
1. Boot mode
2. Test mode
3. Normal mode
Boot mode is the initial mode after the chip is powered up. This mode is not available to the
Security IC embedded software. It can either switch to test mode under the purpose of testing
or initialization, or switch to normal mode.
Test mode is also not available for the Security IC embedded software. It is utilized to
perform the TOE testing before the TOE is delivered to the end user. Test mode is strictly
protected by a combination of hardware and software security features.
Normal mode is utilized for the end user, Security IC embedded software can be executed
under this mode. Normal mode cannot switch back to boot mode and test mode.
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The TOE provides ROM for executing the boot code and crypto library code, NVM for the
code and data access, and RAM for the temporary data access.
The Memory management unit is performed by the AHBMMU, and it also performs the
access control of boot mode, test mode and normal mode.
There are two communication interfaces available, including ISO/IEC 14443 contactless
interface, ISO/IEC 7816 contact interface. The security of SPI and I2C interfaces is not
provided to the user.
The TOE provides the system control functions to handle the reset, clock, interrupt signals,
etc.
The TOE provides the test circuitry to perform the TOE testing under the test mode.
The TOE provides the timers for the security IC embedded software to abort irregular
executions of the program.
The TOE provides power management functionality under boot mode, test mode, and normal
mode, also contact and contactless interfaces.
The TOE provides strong security functionalities against malfunction, including the
environmental sensors to monitor if environmental conditions are within the specified range,
the abnormality check of TRNG to verify the quality of the generated random data, also the
integrity to monitor if the data is manipulated.
The TOE provides strong security functionalities against leakage, including memory
encryption and bus masking, ARMSC000 random branch insertion to obscures the cycle
timing of code by inserting branch to self-instruction, and random OSC clock jitter to
configure the oscillator frequency to a random value for each cycle.
The TOE provides strong security functionalities against physical manipulation and probing,
including the dedicated shielding techniques, data integrity check for verifying the integrity of
the data, also the memory and bus encryption.
The TOE provides strong security functionalities against abuse of functionality and
identification by the means of test access control mechanism. It is implemented by a
combination with hardware fuse and software access control mechanism.
The TOE provides a true random number generator, which is accessible by the crypto library.
The true random number generator is composed of entropy sources, self-test circuit and post-
processing circuit. The self-test circuit includes the total failure test and online test. The total
failure test is performed on the entropy source. The on line testing is performed on the raw
random number sequence, aiming to prevent malfunctioning. The true random number also
fulfils the AIS20/31 PTG.2 level.
The TOE provides the following cryptographic services to the Security IC embedded
software:
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 TDES
 RSA
The TOE implements the Triple-DES algorithm by means of a hardware co-processor and the
software crypto library. It supports the Triple-DES algorithm with two or three 56 bit keys for
Triple DES supporting ECB mode. The keys for the DES algorithms shall be provided by the
security IC embedded software.
The TOE provides the RSA CRT algorithm according to the paper [11] to meet the security
requirement FCS_COP.1[RSA]. The TSF implement the RSA CRT algorithm with the
cryptographic key sizes is 256 bits to 4096 bits. The RSA CRT algorithm is accessed by the
crypto library.
The TOE crypto library also includes functionality for SHA1, SHA256, ECC, AES and
Chinese domestic crypto algorithms. The security of these is not claimed by the TOE.
1.3.3. TOE components
The TOE consists of the following components that are delivered to the composite product
manufacturer:
Table 2 List of TOE components
Type Name Version Package Delivery Method
Hardware THD89 1.0 Module Courier
Software Crypto Library 1.01 Software library in
ROM
Courier
Boot code 1.0 Boot code in ROM Courier
Header file 0.1 cryptolib.h Email encrypted with
PGP
Document Operational
guidance[6]
1.5 Document Email encrypted with
PGP
Preparatory
guidance[7]
1.7 Document Email encrypted with
PGP
Security
guidelines[12]
1.2 Document Email encrypted with
PGP
Cryptographic
Algorithm
API[13]
1.9 Document Email encrypted with
PGP
1.4. Life cycle and delivery
The end-consumer environment of the TOE is phase 7 of the Security IC product life-cycle as
defined in the PP [1]. In this phase the TOE is in usage by the end-consumer. Its method of
use now depends on the Security IC Embedded Software. Examples of use cases are ID cards
or Bank cards.
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The scope of the assurance components referring to the TOE’s life cycle is limited to phases
2, 3 and 4. These phases are under the control of the TOE manufacturer. At the end of phase 4
the TOE components described in 1.3.3 are delivered to the Composite Manufacturer.
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2. Conformance claim
This chapter presents conformance claim and the conformance claim rationale.
2.1. CC Conformance
This Security Target and the TOE claim to be conformant to the Common Criteria version
3.1:
• Part 1 revision 5 [2].
• Part 2 revision 5 [3]
• Part 3 revision 5 [4]
For the evaluation will be used the methodology in Common Criteria Evaluation
Methodology version 3.1 CEM revision 5 [5]
This Security Target and the TOE claim to be CC Part 2 extended and CC Part 3 conformant.
2.2. PP Claim
This Security Target claims strict conformance to the Security IC Platform Protection Profile
[1].
The TOE also provides additional functionality, which is not covered in [1].
2.3. Package claim
This Security Target claims conformance to the assurance package EAL6 augmented with
ASE_TSS.2. This assurance level is in line with the Security IC Platform Protection Profile
[1].
2.4. Conformance claim rationale
The TOE is a Security IC equivalent to the TOE type defined in [1] as it is composed by:
 Processing unit (ARM SC000 CPU)
 Security components (e.g. sensors)
 I/O ports (contact and contactless interfaces)
 Volatile memory (e.g. RAM)
 Non-Volatile memory ( e.g. NVM)
 Dedicated software (Crypto library)
The TOE provides additionally cryptographic functionalities which are not part of the claimed
Security IC Platform Protection Profile [1]:
 Organisational Security Policy P.Crypto-Service is defined to require TDES and RSA
cryptographic functions
 Security Objectives O.TDES and O.RSA are included in the ST to meet P.Crypto-
Service
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 Security Functional Requirements FCS_COP.1[TDES] and FCS_COP.1[RSA] are
included in the ST to meet O.TDES and O.RSA.
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3. Security problem definition
This chapter presents the threats, organisational security policies and assumptions for the
TOE.
The Assets, Assumptions, Threats and Organisational Security Policies are completely taken
from the Security IC Platform Protection Profile [1].
3.1. Description of Assets
Since this Security Target claims conformance to the Security IC Platform Protection Profile
[1], the assets defined in section 3.1 of the Protection Profile are applied.
3.2. Threats
This Security Target claims conformance to the Security IC Platform Protection Profile [1].
The Threats that apply to this Security Target are defined in section 3.2 of the Protection
Profile. The following table lists the threats of the Protection Profile.
Table 3 Threats defined in the Protection Profile
Threat Title
T.Leak-Inherent Inherent Information Leakage
T.Phys-Probing Physical Probing
T.Malfunction Malfunction due to Environmental Stress
T.Phys-
Manipulation
Physical Manipulation
T.Leak-Forced Forced Information Leakage
T.Abuse-Func Abuse of Functionality
T.RND Deficiency of Random Numbers
3.3. Organisational security policies
This Security Target claims conformance to the Security IC Platform Protection Profile [1].
The Organisational Security Policies that apply to this Security Target are defined in section
3.3 of the Protection Profile, they are:
P.Process-TOE Protection during TOE Development and Production
The following Organisational Security is the additional Organisational security policy defined
by the TOE :
P.Crypto-Service Cryptographic services of the TOE
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The TOE provides secure hardware based cryptographic services for
the IC Embedded Software.
3.4. Assumptions
This Security Target claims conformance to the Security IC Platform Protection Profile [1].
The assumptions claimed in this Security Target defined in section 3.4 of the Protection
Profile. They are specified below.
Table 4 Assumptions defined in the Protection Profile
Assumption Title
A.Process-Sec-IC Protection during Packaging, Finishing and
Personalisation
A.Resp-Appl Treatment of User Data
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4. Security objectives
This chapter provides the statement of security objectives and the security objective rationale.
For this chapter the Security IC Platform Protection Profile [1] can be applied completely.
Only a short overview is given in the following.
4.1. Security objectives for the TOE
All objectives described in the section 4.1 of the Security IC Platform Protection Profile [1]
are claimed for the TOE, these are:
Table 5 Security objectives for the TOE defined in the Protection Profile
Security Objective Title
O.Phys-
Manipulation
Protection against Physical Manipulation
O.Phys-Probing Protection against Physical Probing
O.Malfunction Protection against Malfunctions
O.Leak-Inherent Protection against Inherent Information Leakage
O.Leak-Forced Protection against Forced Information Leakage
O.Abuse-Func Protection against Abuse of Functionality
O.Identification TOE Identification
O.RND Random Numbers
In addition the TOE defines the following objectives:
O.TDES TDES functionality
The TOE shall provide secure cryptographic services implementing the TDES
cryptographic algorithm for encryption and decryption.
O.RSA RSA functionality
The TOE shall provide secure cryptographic services implementing the RSA
cryptographic algorithm for encryption and decryption.
4.2. Security objectives for the security IC embedded software
The security IC Embedded Software defines the operational use of the TOE. This section
describes the security objective for the Security IC Embedded Software, which is taken from
section 4.2 of the Security IC Platform Protection Profile [1].
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Table 6 Security Objectives for the security IC embedded software environment defined in the Protection Profile
Security Objective Title
OE.Resp-Appl Treatment of User Data of the composite TOE
4.3. Security objectives for the operational environment
This section describes the security objective for the operational environment, which is taken
from section 4.3 of the Security IC Platform Protection Profile [1].
Table 7 Security Objectives for the operational environment defined in the Protection Profile
Security Objective Title
OE.Process-Sec-IC Protection during composite product
manufacturing
4.4. Security objectives rationale
Section 4.4 in the Protection Profile provides a rationale how the assumptions, threats and
organisational security policies are addressed by the objectives. The table below shows this
relationship.
Table 8 Addressing of assumptions, threats and organisational security policies to objectives
Assumption, Threat or
Organisational Security Policy
Security Objective
A.Resp-Appl OE.Resp-Appl
P.Process-TOE O.Identification
A.Process-Sec-IC OE.Process-Sec-IC
T.Leak-Inherent O.Leak-Inherent
T.Phys-Probing O.Phys-Probing
T.Malfunction O.Malfunction
T.Phys-Manipulation O.Phys-Manipulation
T.Leak-Forced O.Leak-Forced
T.Abuse-Func O.Abuse-Func
T.RND O.RND
For the justification of the above mapping please refer to the Protection Profile.
The table below shows how the additional organisational security policies are addressed by
objectives for the TOE.
Table 9 Addressing of assumptions, threats and organisational security policies to additional objectives
Assumption, Threat or
Organisational Security Policy
Security Objective
P.Crypto-Service O.TDES
O.RSA
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The objective O.TDES and O.RSA implements specific crypto services as required by
P.Crypto-Service.
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5. Extended Components Definitions
This Security Target uses the extended security functional requirements defined in chapter 5
of the Security IC Platform Protection Profile [1].
This Security Target does not define extended components in addition to the Protection
Profile.
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6. Security requirements
This chapter presents the statement of security requirements for the TOE and the security
requirements rationale. This chapter applies the Security IC Platform Protection Profile [1].
6.1. Definitions
In the next sections the following notation is used:
 The iteration operation is used when a component is claimed with varying operations,
it is denoted by adding “[XXX]” to the component name.
 Refinement, selection or assignment operations are used to add details or assign
specific values to components, they are indicated by italic text and explained in
footnotes.
6.2. Security Functional Requirements (SFR)
To support a better understanding of the combination Security IC Platform Protection Profile
vs. Security Target, the TOE Security Functional Requirements are presented in the following
several different sections.
6.2.1. SFRs derived from the Security IC Platform Protection Profile
The table below lists the Security Functional Requirements that are taken from the Security
IC Platform Protection Profile [1].
Table 10 List of Security Functional Requirements on the security IC platform Protection Profile
Security functional
requirement
Title
FRU_FLT.2 “Limited fault tolerance“
FPT_FLS.1 “Failure with preservation of secure state”
FMT_LIM.1 “Limited capabilities”
FMT_LIM.2 “Limited availability”
FAU_SAS.1 “Audit storage”
FPT_PHP.3 “Resistance to physical attack”
FDP_ITT.1 “Basic internal transfer protection”
FDP_IFC.1 “Subset information flow control”
FPT_ITT.1 “Basic internal TSF data transfer protection”
FDP_SDC.1 “Stored data confidentiality”
FDP_SDI.2 “Stored data integrity monitoring and action”
FCS_RNG.1[PTG.2] “Quality metric for random numbers”
The SFRs FRU_FLT.2, FMT_LIM.1, FMT_LIM.2, FDP_ITT.1, FDP_IFC.1 and FPT_ITT.1
are copied directly from the IC Platform Protection Profile [1]. All the assignments and
selections operations are taken as defined in the protection profile.
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The SFRs FAU_SAS.1, FDP_SDC.1, FDP_SDI.2 and FCS_RNG.1[PTG.2] are taken from
the IC Platform Protection Profile [1]. The open assignment and selection operations are
instantiated in the following way:
 In FAU_SAS.1 the left open assignment is the type of persistent memory;
 In FDP_SDC.1 the left open assignment is the memory area;
 In FDP_SDI.2 the left open assignments are the user data attributes and the action to
be taken;
 In the FCS_RNG.1[PTG.2] the left open definition is the quality metric for the
random numbers.
The following statements define these completed SFRs.
FAU_SAS.1 Audit storage
Hierarchical to: No other components.
FAU_SAS.1.1 The TSF shall provide the test process before TOE Delivery1
with the
capability to store Initialisation Data2
in the OTP3
.
Dependencies: No dependencies.
FDP_SDC.1 Stored data confidentiality
Hierarchical to: No other components.
FDP_SDC.1.1 The TSF shall ensure the confidentiality of the information of the user
data while it is stored in the NVM, ROM and RAM4
.
Dependencies: No dependencies.
FDP_SDI.2 Stored data integrity monitoring and action
Hierarchical to: FDP_SDI.1 Stored data integrity monitoring
FDP_SDI.2.1 The TSF shall monitor user data stored in containers controlled by the
TSF for integrity errors 5
on all objects, based on the following
attributes: redundancy bits6
.
FDP_SDI.2.2 Upon detection of a data integrity error, the TSF shall reset7
.
Dependencies: No dependencies.
FCS_RNG.1 [PTG.2] Random number generation
Hierarchical to: No other components.
FCS_RNG.1.1[PTG.2] The TSF shall provide a physical8
random number generator that
1
[assignment: list of subjects]
2
[assignment: list of audit information]
3
[assignment: type of persistent memory]
4
[assignment: memory area]
5
[assignment: integrity errors]
6
[assignment: user data attributes]
7
[assignment: action to be taken]
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Implements:
 A Total failure test detects a total failure of entropy source
immediately when the RNG has started. When a total failure is
detected, no random numbers will be output.
 If a total failure of the entropy source occurs while the RNG is
being operated, the RNG prevents the output of any internal
random number that depends on some raw random numbers that
have been generated after the total failure of the entropy source9
.
 The online test shall detect non-tolerable statistical defects of the
raw random number sequence (i) immediately when the RNG has
started. And (ii) while the RNG is being operated. The TSF must
not output any random numbers before the power-up online test has
finished successfully or when a defect has been detected.
 The online test procedure shall be effective to detect non-tolerable
weakness of the random numbers soon.
 The online test procedure checks the quality of the raw random
number sequence. It is triggered applied upon specified internal
events10
. The online test is suitable for detecting non-tolerable
statistical defects of the statistical properties of the raw random
numbers within an acceptable period of time
FCS_RNG.1.2[PTG.2] The TSF shall provide 32 bit random number words11
that meet:
 test procedure A and no other test suites12
does not distinguish the
internal random numbers from output sequences of an ideal RNG.
 The average Shannon entropy per internal random bit exceeds
0.997.
Dependencies: No dependencies.
The SFRs FPT_FLS.1 and FPT_PHP.3 are copied directly from the IC Platform Protection
Profile [1]. An application note has been applied for each SFR.
FPT_FLS.1 Failure with preservation of secure state
Hierarchical to: No other components.
Dependencies: No dependencies.
FPT_FLS.1.1 The TSF shall preserve a secure state when the following types of
failures occur: exposure to operating conditions which may not be
tolerated according to the requirement Limited fault tolerance
(FRU_FLT.2) and where therefore a malfunction could occur13
.
8
[selection: physical, non-physical true, deterministic, hybrid physical, hybrid deterministic]
9
[selection: prevents the output of any internal random number that depends on some raw random numbers that
have been generated after the total failure of the entropy source, generates the internal random numbers with a
post-processing algorithm of class DRG.2 as long as its internal state entropy guarantees the claimed output
entropy].
10
[selection: externally, at regular intervals, continuously, applied upon specified internal events].
11
[selection: bits, octets of bits, numbers [assignment: format of the numbers]]
12
[assignment: additional standard test suites]
13
[assignment: list of types of failures in the TSF]
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Refinement: The term “failure” above also covers “circumstances”. The TOE
prevents failures for the “circumstances” defined above.
Application note: The occurred failures will cause the alarm signals to be triggered, which
will result in a reset (secure state).
FPT_PHP.3 Resistance to physical attack
Hierarchical to: No other components.
Dependencies: No dependencies.
FPT_PHP.3.1 The TSF shall resist physical manipulation and physical probing14
to the
TSF15
by responding automatically such that the SFRs are always
enforced.
Refinement: The TSF will implement appropriate mechanism to continuously counter
physical manipulation and physical probing. Due to the nature of these
attacks (especially manipulation) the TSF can by no means detect
attacks on all of its elements. Therefore, permanent protection against
these attack is required ensuring that security functional requirements
are enforced. Hence, “automatic response” means here (i) assuming
that there might be an attack at any time and (ii) countermeasures are
provided at any time.
Application note: If a physical manipulation or physical probing attack is detected, an
alarm will be automatically triggered by the hardware, which will cause
the chip to be reset.
6.2.2. SFRs regarding cryptographic functionality
FCS_COP.1 [TDES] Cryptographic operation – TDES
Hierarchical to: No other components.
FCS_COP.1.1 [TDES] The TSF shall perform encryption and decryption16
in accordance
with a specified cryptographic algorithm TDES in ECB mode17
and
cryptographic key sizes of 112/168 bit18
that meet the following: NIST
SP800-67[8] and NIST SP800-38A19
[9].
Dependencies: [FDP_ITC.1 Import of user data without security attributes,
or FDP_ITC.2 Import of user data with security attributes, or
FCS_CKM.1 Cryptographic key generation]
FCS_CKM.4 Cryptographic key destruction
Application note: The TOE also supports single DES. However the security of the single
14
[assignment: physical tampering scenarios]
15
[assignment: list of TSF devices/elements]
16
[assignment: list of cryptographic operations]
17
[assignment: cryptographic algorithm]
18
[assignment: cryptographic key sizes]
19
[assignment: list of standards]
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DES algorithm is not resistant against attacks with a high attack
potential. Therefore the application of single DES shall not be used in
parts of the Security Embedded Software that require high security.
FCS_COP.1 [RSA] Cryptographic operation – RSA
Hierarchical to: No other components.
FCS_COP.1.1[RSA] The TSF shall perform encryption and decryption20
operation in
accordance with a specified cryptographic algorithm RSA21
and
cryptographic key sizes of 256 bits to 4096 bits22
that meet the
following: RSA standard [11]23
.
Dependencies: [FDP_ITC.1 Import of user data without security attributes,
or FDP_ITC.2 Import of user data with security attributes, or
FCS_CKM.1 Cryptographic key generation]
FCS_CKM.4 Cryptographic key destruction
Application note: The security IC embedded software shall make a choice regarding the
RSA key length. Key lengths >= 1900 bits is the legacy mechanism
only, and key lengths >= 3000 bits is the recommended.
6.3. Definition of ADV_SPM
ADV_SPM.1 Formal TOE security policy model
Hierarchical to: No other components.
Dependencies: ADV_FSP.4 Complete functional specification.
ADV_SPM.1.1D The developer shall provide a formal security policy model for the
Flow Control Policy and Limited Capability and Availability Policy24
.
ADV_SPM.1.2D For each policy covered by the formal security policy model, the model
shall identify the relevant portions of the statement of SFRs that make
up that policy.
ADV_SPM.1.3D The developer shall provide a formal proof of correspondence between
the model and any formal functional specification.
ADV_SPM.1.4D The developer shall provide a demonstration of correspondence
between the model and the functional specification.
6.4. Security Assurance Requirements (SAR)
This Security Target will be evaluated according to Security Target evaluation (Class ASE)
The Security Assurance Requirements for the evaluation of the TOE are the components in
Assurance Evaluation level EAL6 augmented by the components ASE_TSS.2. The table
below shows the details of these assurance requirements.
20
[assignment: list of cryptographic operations]
21
[assignment: cryptographic algorithm]
22
[assignment: cryptographic key sizes]
23
[assignment: list of standards]
24
[assignment: list of policies that are formally modelled]
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Table 11 TOE assurance requirements
Security assurance
requirements
Titles
Class ADV: Development
ADV_ARC.1 Architectural design
ADV_FSP.5 Functional specification
ADV_IMP.2 Implementation representation
ADV_INT.3 TSF internals
ADV_SPM.1 Security policy modelling
ADV_TDS.5 TOE design
Class AGD: Guidance documents
AGD_OPE.1 Operational user guidance
AGD_PRE.1 Preparative user guidance
Class ALC: Life-cycle support
ALC_CMC.5 CM capabilities
ALC_CMS.5 CM scope
ALC_DEL.1 Delivery
ALC_DVS.2 Development security
ALC_LCD.1 Life-cycle definition
ALC_TAT.3 Tools and techniques
Class ASE: Security Target evaluation
ASE_CCL.1 Conformance claims
ASE_ECD.1 Extended components definition
ASE_INT.1 ST introduction
ASE_OBJ.2 Security objectives
ASE_REQ.2 Derived security requirements
ASE_SPD.1 Security problem definition
ASE_TSS.2 TOE summary specification
Class ATE: Tests
ATE_COV.3 Coverage
ATE_DPT.3 Depth
ATE_FUN.2 Functional testing
ATE_IND.2 Independent testing
Class AVA: Vulnerability analysis
AVA_VAN.5 Vulnerability analysis
6.5. Security requirements rationale
6.5.1. Security Functional Requirements (SFR)
The table below provides an overview of how the security functional requirements are
combined to meet the security objectives.
Table 12 Mapping of security functional requirements to security objectives
Security
Objectives for the
TOE
Security Functional
Requirements
Fulfilment of mapping
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O.Leak-Inherent FDP_ITT.1
FDP_IFC.1
FPT_ITT.1
See PP
O.Phys-Probing FDP_SDC.1
FPT_PHP.3
See PP
O.Malfunction FRU_FLT.2
FPT_FLS.1
See PP
O.Phys-
Manipulation
FDP_SDI.2
FPT_PHP.3
See PP
O.Leak-Forced FDP_ITT.1
FDP_IFC.1
FPT_ITT.1
FRU_FLT.2
FPT_FLS.1
FPT_PHP.3
See PP
O.Abuse-Func FMT_LIM.1
FMT_LIM.2
FDP_ITT.1
FPT_ITT.1
FDP_IFC.1
FPT_PHP.3
FRU_FLT.2
FPT_FLS.1
See PP
O.Identification FAU_SAS.1 See PP
O.RND FCS_RNG.1[PTG.
2]
FDP_ITT.1
FPT_ITT.1
FDP_IFC.1
FPT_PHP.3
FRU_FLT.2
FPT_FLS.1
See PP
O.TDES FCS_COP.1
[TDES]
O.TDES requires the TOE to support DES
encryption and decryption with its
specified key lengths. The claim for
FCS_COP.1 [TDES] is suitable to meet the
objective O.TDES.
O.RSA FCS_COP.1 [RSA] O.RSA requires the TOE to support RSA
CRT encryption and decryption with its
specified key lengths. The claim for
FCS_COP.1 [RSA] is suitable to meet the
objective O. RSA.
6.5.2. Dependencies of the SFRs
The dependencies for the SFRs claimed according to the Protection Profile are all satisfied in
the set of SFRs claimed in the Protection Profile.
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In the following table the dependencies of the SFRs claimed in addition to Protection Profile
is indicated.
Table 13 Dependencies of SFRs in addition to PP
Security functional
requirement
Dependencies Fulfilled by security requirements in this
Security Target
FCS_COP.1[TDES] FDP_ITC.1 or
FDP_ITC.2 or
FCS_CKM.1,
FCS_CKM.4
See explanation below this table
FCS_COP.1[RSA] FDP_ITC.1 or
FDP_ITC.2 or
FCS_CKM.1,
FCS_CKM.4
See explanation below this table
The developer of the Security IC Embedded Software must ensure that the implemented
additional security functional requirements FCS_COP.1[TDES] and FCS_COP.1[RSA] and
FCS_RNG.1[PTG.2] are used as specified and that the User Data processed by the related
security functionality is protected as defined for the application context.
The dependent requirements for FCS_COP.1[TDES] and FCS_COP.1[RSA] address the
appropriate management of cryptographic keys used by the specified cryptographic function.
All requirements concerning these management functions shall be fulfilled by the
environment (Security IC Embedded Software).
The functional requirements [FDP_ITC.1, or FDP_ITC.2 or FCS_CKM.1] and FCS_CKM.4
are not included in this Security Target since the TOE only provides a pure engine for
encryption and decryption without additional features for the handling of cryptographic keys.
Therefore the Security IC Embedded Software must fulfil these requirements related to the
needs of the realised application.
6.5.3. Security Assurance Requirements (SAR)
The chosen assurance package EAL6 is augmented with ASE_TSS.2. This assurance level is
chosen in order to meet assurance expectations of financial applications. Moreover, the
conformity with [1] is satisfied given that the PP requires at least EAL4.
The TOE intends to be used in Scenarios with high security requirements. Therefore, it should
provide adequate level of defence against sophisticated attacks.
This assurance level is chosen because the product is designed to give maximum security
assurance from application of security engineering techniques based on good commercial
practices in order to produce a premium TOE for protecting against significant risks.
EAL6 is chosen to ensure by formal methods that the TOE has been well designed, to extend
the testing of the TOE and to demonstrate that the TOE design is not overly complex.
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ASE_TSS.2 augmentation is chosen because Security Target document is a window for
customers to comprehend the TOE. The understanding of security architecture of the TOE has
an important impact to the security level of embedded software developed by customers.
ASE_TSS.2 gives architecture information on the security functionality of the TOE.
6.5.4. Dependencies of the SARs
The assurance level EAL6 augmented with ASE_TSS.2 is chosen. The assurance package
EAL6 is a well pre-defined level of CC. The assurance components in an EAL package are
built in a mutually supportive and systematic way. The requirement chosen for augmentation
add one dependency which is between ASE_TSS.2 and ADV_ARC.1. This dependency is
also fulfilled. Therefore, the internal dependencies of the SARs are met.
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7. TOE summary specification
This chapter provides general information to potential users of the TOE on how the TOE
implements the Security Functional Requirements in terms of “Security Functionality”.
7.1. Malfunction
Malfunctioning relates to the security functional requirements FRU_FLT.2 and FPT_FLS.1.
The TOE meets these SFRs by a group of security measures that guarantee correct operation
of the TOE.
The TOE ensures its correct operation and prevents any malfunction while the security IC
embedded software is executed by implementation of the following security features:
• Environmental sensors
7.2. Leakage
Leakages relates to the security functional requirements FDP_ITT.1, FDP_IFC.1 and
FPT_ITT.1. The TOE meets these SFRs by implementing several measures that provide
logical protection against leakage:
• Bus masking
• ARMSC000 random branch insertion
• Random OSC clock jitter
7.3. Physical manipulation and probing
Physical manipulation and probing relates to the security functional requirements
FPT_PHP.3, FDP_SDC.1 and FDP_SDI.2. The TOE meets this SFR by implementing
security measures that provides physical protection against physical probing and
manipulation.
The security measures protect the TOE against manipulation of
(i) The hardware.
(ii) The security IC embedded software in the ROM
(iii) The application data in the NVM including the configuration data.
It also protects User Data or TSF data against disclosure by physical probing when stored or
while being processed by the TOE.
The protection of the TOE comprises different features within the design and construction,
which make reverse-engineering and tamper attacks more difficult. These features comprise
of
• Active shielding
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• Data integrity checking
• Memory encryption
7.4. Abuse of functionality and Identification
Abuse of functionality and Identification relates to the security functional requirements
FMT_LIM.1, FMT_LIM.2, FAU_SAS.1 by implementation of a test mode access control
mechanism that prevents abuse of test functionality delivered as part of the TOE.
7.5. Random numbers
Random numbers relate to the security requirement FCS_RNG.1[PTG.2]. The TOE meets this
SFR by providing a random number generator.
7.6. Cryptographic functionality
The TOE provides Triple-DES algorithm according to the NIST SP800-67[8], NIST SP800-
38A25
[9] Standard to meet the security requirement FCS_COP.1[TDES].
The TOE provides the RSA CRT algorithm according to the paper [11] to meet the security
requirement FCS_COP.1[RSA]. The TSF implement the RSA CRT algorithm with the
cryptographic key sizes is 256 bits to 4096 bits.
7.7. Security architectural information
This section provides information of security architectural on a high level view to inform
potential customers on how the TOE protect it-self against interference, logical tampering and
bypass. These aspects are covered by self-protection and non-bypassability in the security
architecture context.
The Security Mechanisms and the Security Functions collaborate to take care that the TOE
protects itself from tampering by un-trusted entities. The TOE intends to defend against
sophisticated attacks to protect itself against interference and logical tampering.
It has been considered carefully during development of the TOE to avoid bypass of security
functions.
25
[assignment: list of standards]
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8. References
Ref Title Version Date
[1] Security IC Platform Protection Profile, BSI-CC-PP-
0084-2014
Version 1.0 13.01.2014
[2] Common Criteria for Information Technology
Security Evaluation,
Part 1: Introduction and General Model
CCMB-2012-09-001
Version 3.1
Revision 5
April 2017
[3] Common Criteria for Information Technology
Security Evaluation,
Part 2: Security Functional Requirements
CCMB-2012-09-002
Version 3.1
Revision 5
April 2017
[4] Common Criteria for Information Technology
Security Evaluation,
Part 3: Security Assurance Requirements
CCMB-2012-09-003
Version 3.1
Revision 5
April 2017
[5] Common Methodology for Information Technology
Security Evaluation (CEM), Evaluation
Methodology
CCMB-2012-09-004
Version 3.1
Revision 5
April 2017
[6] THD89 Operational Guidance Version 1.5 May, 2020
[7] THD89 Preparative Guidance Version 1.7 May, 2020
[8] NIST SP 800-67, Recommendation for the Triple
Data Encryption Algorithm (TDEA) Block Cipher,
revised January 2012, National Institute of
Standards and Technology
Revision 1 January
2012
[9] NIST SP 800-38A Recommendation for Block
Cipher Modes of Operation, 2001, with Addendum
Recommendation for Block Cipher Modes of
Operation: Three Variants of Ciphertext Stealing for
CBC Mode, October 2010
2001 ED October
2010
[10] SC000 Detailed Description Revision:
r0p0-01re10
2011
[11] PKCS #1: RSA Cryptography Standard, RSA
Laboratories
Version 2.2 2012
[12] THD89 Secure Microcontroller Security guideline Version 1.2 May, 2020
[13] THD89 Cryptographic Algorithm API Version 1.9 Dec, 2019