Red Hat Enterprise Linux 8 Kernel Cryptographic API

Certificate

Derived Review-Risk Graph (review prompts, not findings)

flowchart LR
  %% Deterministic review-risk graph for Red Hat Enterprise Linux 8 Kernel Cryptographic API
  %% Review prompts and evidence gaps, NOT vulnerability findings.
  subgraph CMVP["CMVP-disclosed clues"]
    C2["[low] Firmware update / recovery<br/>/ rollback (referenced in<br/>text)<br/><i>Recovery</i>"]
    C3["[low] Self-test / status surface<br/>(referenced in text)<br/><i>Self-Test<br/>UnAuth</i>"]
    C5["[low] Protocol / secure-channel<br/>references (may be KDF<br/>names, not a live channel)<br/><i>IKEV<br/>IPSEC<br/>HTTPS</i>"]
    C6["[low] Operating system / runtime<br/>referenced (boundary<br/>membership not asserted)<br/><i>operating system<br/>linux<br/>kernel</i>"]
  end
  subgraph Inference["Derived inference"]
    I2["Possible only, trusted<br/>code is reachable through<br/>update and recovery paths."]
    I3["Possible only, some<br/>services may process input<br/>before, or without,<br/>operator authentication."]
    I5["Possible only, a protocol<br/>is referenced, but whether<br/>it is a live channel or<br/>only a KDF/algorithm name<br/>is unconfirmed."]
    I6["Possible only, a<br/>runtime/OS is referenced,<br/>but its membership in the<br/>cryptographic boundary is<br/>not established."]
  end
  subgraph Risk["Reviewer question"]
    R2["Are update images<br/>authenticated before<br/>parsing, and are<br/>downgrade/rollback paths<br/>constrained?"]
    R3["Can unauthenticated<br/>services leak state,<br/>consume resources, or<br/>transition security state?"]
    R5["If a live TLS/SSH/IKE<br/>channel exists, could<br/>library CVEs apply, or is<br/>this only a<br/>KDF/documentation name?"]
    R6["If the OS/runtime is<br/>in-boundary, could its<br/>CVEs be hidden by<br/>firmware-only versioning?"]
  end
  subgraph Evidence["Evidence needed to close"]
    E2["confirm the disclosure<br/>itself (keyword hit,<br/>context unverified) ·<br/>update image format ·<br/>signature-before-parse<br/>proof · anti-rollback /<br/>downgrade policy"]
    E3["confirm the disclosure<br/>itself (keyword hit,<br/>context unverified) ·<br/>pre-auth reachability<br/>matrix · rate limits and<br/>output redaction ·<br/>abuse-case tests"]
    E5["confirm the disclosure<br/>itself (keyword hit,<br/>context unverified) ·<br/>library identity and<br/>version ·<br/>certificate-validation<br/>behaviour · protocol-CVE<br/>disposition"]
    E6["confirm the disclosure<br/>itself (keyword hit,<br/>context unverified) ·<br/>runtime identity and<br/>config · kernel/runtime<br/>hardening profile ·<br/>patch/backport manifest"]
  end
  C2 --> I2 --> R2 --> E2
  C3 --> I3 --> R3 --> E3
  C5 --> I5 --> R5 --> E5
  C6 --> I6 --> R6 --> E6
  classDef clue fill:#eef3f9,stroke:#6f7f91,color:#1f3a5f;
  classDef infer fill:#fff7e6,stroke:#b98500,color:#6b4e00;
  classDef risk fill:#fbe9e9,stroke:#b02a2a,color:#7a1f1f;
  classDef evidence fill:#e6f4ea,stroke:#1e7d34,color:#14532d;
  class C2,C3,C5,C6 clue;
  class I2,I3,I5,I6 infer;
  class R2,R3,R5,R6 risk;
  class E2,E3,E5,E6 evidence;

flowchart LR
  %% Deterministic clue tier for Red Hat Enterprise Linux 8 Kernel Cryptographic API
  %% confidence: high = structured record field; medium = structured but soft; low (dashed) = bare keyword hit, context unverified
  subgraph CMVP["CMVP-disclosed clues (deterministic)"]
    C2["[low] Firmware update / recovery / rollback (referenced in text)<br/><i>Recovery</i><br/>src: text:keyword"]
    C3["[low] Self-test / status surface (referenced in text)<br/><i>Self-Test<br/>UnAuth</i><br/>src: text:keyword"]
    C5["[low] Protocol / secure-channel references (may be KDF names, not a live channel)<br/><i>IKEV<br/>IPSEC<br/>HTTPS</i><br/>src: text:keyword"]
    C6["[low] Operating system / runtime referenced (boundary membership not asserted)<br/><i>operating system<br/>linux<br/>kernel</i><br/>src: text:keyword"]
  end
  classDef clueHigh fill:#eef3f9,stroke:#2f6fb0,stroke-width:2px,color:#1f3a5f;
  classDef clueMedium fill:#eef3f9,stroke:#6f7f91,color:#1f3a5f;
  classDef clueLow fill:#f7f7f7,stroke:#999,stroke-dasharray:4 4,color:#444;
  class C2,C3,C5,C6 clueLow;

Security Policy, page by page

Red Hat, Inc. Red Hat Enterprise Linux 8 Kernel Cryptographic API Document Version: 1.1 Last Modified: 22/10/2025 Prepared by: atsec information security corporation

4516 Seton Center Parkway, Suite 250

Austin, TX 78759 www.atsec.com © 2025 Red Hat, Inc./ atsec information security corporation.

© 2025 Red Hat, Inc./ atsec information security corporation.

This document is the non-proprietary FIPS 140-3 Security Policy for version kernel 4.18.0477.72.1.el8_8; libkcapi 1.2.0-3.el8_8 of the Red Hat Enterprise Linux 8 Kernel Cryptographic API module. It contains the security rules under which the module must operate and describes how this module meets the requirements as specified in FIPS PUB 140-3 (Federal Information Processing Standards Publication 140-3) for an overall Security Level 1 module. intact and including this notice. Other documentation is proprietary to their authors.

In preparing the Security Policy document, the laboratory formatted the vendor-supplied documentation for consolidation without altering the technical statements therein contained. The further refining of the Security Policy document was conducted iteratively throughout the conformance testing, wherein the Security Policy was submitted to the vendor, who would then edit, modify, and add technical contents. The vendor would also supply additional documentation, which the laboratory formatted into the existing Security Policy, and resubmitted to the vendor for their final editing.

Table 1: Security Levels © 2025 Red Hat, Inc./ atsec information security corporation.

Purpose and Use: The Red Hat Enterprise Linux 8 Kernel Cryptographic API (hereafter referred to as “the module”) provides a C language application program interface (API) for use by other (kernel space and user space) processes that require cryptographic functionality. The module operates on a general-purpose computer as part of the Linux kernel. Its cryptographic functionality can be accessed using the Linux Kernel Crypto API. Module Type: Software Module Embodiment: MultiChipStand Cryptographic Boundary: The cryptographic boundary of the module is defined as the kernel binary and the kernel crypto object files, the libkcapi library, and the sha512hmac binary, which is used to verify the integrity of the software components. In addition, the cryptographic boundary contains the .hmac files which store the expected integrity values for each of the software components. Tested Operational Environment’s Physical Perimeter (TOEPP): The TOEPP of the module is defined as the general-purpose computer on which the module is installed. The PAA/PAI provided by the processor is located within the module’s physical perimeter and outside of the module’s cryptographic boundary. © 2025 Red Hat, Inc./ atsec information security corporation.

Tested Module Identification

• Hardware: N/A for this module. Tested Module Identification
• Software, Firmware, Hybrid (Executable Code Sets): © 2025 Red Hat, Inc./ atsec information security corporation.

Package or File Name 477.72.1.el8_8.x86_64/kernel/arch/x86/crypto; /usr/lib64/libkcapi.so.1.2.0, /usr/bin/sha512hmac

Software/ Firmware Version

Features

Integrity Test

Table 2: Tested Module Identification

• Software, Firmware, Hybrid (Executable Code Sets) Tested Module Identification
• Hybrid Disjoint Hardware: N/A for this module. Tested Operational Environments - Software, Firmware, Hybrid: Table 3: Tested Operational Environments - Software, Firmware, Hybrid Vendor-Affirmed Operational Environments - Software, Firmware, Hybrid: Table 4: Vendor-Affirmed Operational Environments - Software, Firmware, Hybrid CMVP makes no statement as to the correct operation of the module or the security strengths of the generated keys when so ported if the specific operational environment is not listed on the validation certificate.

There are no components within the cryptographic boundary excluded from the FIPS 140-3 requirements.

Modes List and Description: © 2025 Red Hat, Inc./ atsec information security corporation.

Table 5: Modes List and Description After the module is powered on, it performs all the pre-operational self-tests and cryptographic algorithm self-tests without operator intervention. Only after all the self-tests are successful, the module automatically transitions to the approved mode. Mode Change Instructions and Status: The module automatically switches between the approved and non-approved modes depending on the services requested by the operator. The status indicator of the mode of operation is equivalent to the indicator of the service that was requested. The module does not implement a degraded mode of operation.

Approved Algorithms: © 2025 Red Hat, Inc./ atsec information security corporation.

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Table 6: Approved Algorithms Vendor-Affirmed Algorithms: N/A for this module. Non-Approved, Allowed Algorithms: N/A for this module. Non-Approved, Allowed Algorithms with No Security Claimed: N/A for this module. Non-Approved, Not Allowed Algorithms: Table 7: Non-Approved, Not Allowed Algorithms

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Table 8: Security Function Implementations

The Crypto Officer shall consider the following requirements and restrictions when using the module. For IPsec, the module offers the AES GCM implementation and uses the context of Scenario

1 of FIPS 140-3 IG C.H. The mechanism for IV generation is compliant with RFC 4106. IVs

generated using this mechanism may only be used in the context of AES GCM encryption within the IPsec protocol. The module does not implement IPsec. The module’s implementation of AES GCM is used together with an application that runs outside the module’s cryptographic boundary. This application must use RFC 7296 compliant IKEv2 to establish the shared secret SKEYSEED from which the AES GCM encryption keys are derived. The design of the IPsec protocol implicitly ensures that the counter (the nonce_explicit part of the IV) does not exhaust the maximum number of possible values for a given session key. In the event the module’s power is lost and restored, the consuming application must ensure that a new key for use with the AES GCM key encryption or decryption under this scenario shall be established. The module also provides a non-approved AES GCM encryption service which accepts arbitrary external IVs from the operator. This service can be requested by invoking the crypto_aead_encrypt API function with an AES GCM handle. When this is the case, the API will not set an approved service indicator, as described in Section 4.3.

The length of a single data unit encrypted or decrypted with AES XTS shall not exceed 220 AES blocks, that is 16MB, of data per XTS instance. An XTS instance is defined in Section 4 of SP 800-38E. To meet the requirement stated in IG C.I, the module implements a check to ensure that the two AES keys used in AES XTS mode are not identical. The XTS mode shall only be used for the cryptographic protection of data on storage devices. It shall not be used for other purposes, such as the encryption of data in transit. © 2025 Red Hat, Inc./ atsec information security corporation.

For RSA signature verification, the module supports modulus size 3072 bits. The supported modulus size has been CAVP tested.

The module provides SHA-3 hash functions compliant with IG C.C. Every implementation of each SHA-3 function was tested and validated on all the module’s operating environments. SHAKE functions are not implemented. SHA-3 hash functions are also used as part of a higher-level algorithm for HMAC.

Table 9: Entropy Certificates Table 10: Entropy Sources The module implements three different Deterministic Random Bit Generator (DRBG) implementations based on SP 800-90Ar1: CTR_DRBG, Hash_DRBG, and HMAC_DRBG. Each of these DRBG implementations can be instantiated by the operator of the module. When instantiated, these DRBGs can be used to generate random numbers for external usage. Additionally, the module employs a specific HMAC-SHA2-512 DRBG implementation for internal purposes (e.g. to generate initialization vectors). This DRBG is initially seeded with

384 output bits from the entropy source (343 bits of entropy) and reseeded with 256 output

bits from the entropy source (229 bits of entropy).

The module does not provide key generation.

The module does not provide key establishment.

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AES GCM with internal IV generation in the approved mode is compliant with RFC 4106 and shall only be used in conjunction with the IPsec protocol. No parts of this protocol, other than the AES GCM implementation, have been tested by the CAVP and CMVP. © 2025 Red Hat, Inc./ atsec information security corporation.

Table 11: Ports and Interfaces The logical interfaces are the APIs through which the applications request services. These logical interfaces are logically separated from each other by the API design, AF_ALG type socket that allows the applications running in the user space to request cryptographic services from the module. The module does not support a control output interface. © 2025 Red Hat, Inc./ atsec information security corporation.

N/A for this module. The module does not implement authentication.

Table 12: Roles The module supports the Crypto Officer role only. This sole role is implicitly and always assumed by the operator of the module. No support is provided for multiple concurrent operators.

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s e G,E G,E G,E © 2025 Red Hat, Inc./ atsec information security corporation.

s G,W,E G,W,E C): G,W,E s © 2025 Red Hat, Inc./ atsec information security corporation.

s © 2025 Red Hat, Inc./ atsec information security corporation.

Name

Descript ion

Indicator

Inputs

Outputs

Security Function s

SSP Access Internal State (V, Key): Z - Hash_DR BG Internal State (V, C): Z - CTR_DR BG Seed: Z - Hash_DR BG Seed: Z - HMAC_D RBG Seed: Z

s C): Z Table 13: Approved Services The table above lists the approved services. The following convention is used to specify access rights to SSPs:

• Generate (G): The module generates or derives the SSP.
• Read (R): The SSP is read from the module (e.g. the SSP is output).
• Write (W): The SSP is updated, imported, or written to the module.
• Execute (E): The module uses the SSP in performing a cryptographic operation.
• Zeroize (Z): The module zeroizes the SSP.

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Table 14: Non-Approved Services

The module does not load external software or firmware. © 2025 Red Hat, Inc./ atsec information security corporation.

The static kernel binary is integrity tested using an HMAC-SHA2-512 calculation performed by the sha512hmac utility (which utilizes the module’s HMAC and SHA-512 implementations). An HMAC-SHA2-512 calculation is also performed on the sha512hmac utility and the libkcapi library to verify their integrity. The libkcapi checks the integrity of the binary of the sha512hmac utility first. The sha512hmac utility is then used to perform an HMAC-SHA2-512 calculation of the kernel’s binary to verify its integrity. After the integrity of the kernel’s binary has been verified, the self-test for the RSA signature verification implementation is run. Upon the successful run of this self-test, the RSA signature verification implementation of the kernel (with PKCS#1 v1.5 padding, SHA-256, and a 3072-bit key) is used to verify the integrity of the crypto object files listed in Section

Integrity tests are performed as part of the pre-operational self-tests, which are executed when the module is initialized. The integrity tests can be invoked on demand by unloading and subsequently re-initializing the module, which will perform (among others) the software integrity tests. © 2025 Red Hat, Inc./ atsec information security corporation.

Type of Operational Environment: Modifiable How Requirements are Satisfied: The operating system provides process isolation and memory protection mechanisms that ensure appropriate separation for memory access among the processes on the system. Each process has control over its own data and uncontrolled access to the data of other processes is prevented.

The module shall be installed as stated in Section 11.1. Instrumentation tools like the ptrace system call, gdb and strace, as well as other tracing mechanisms offered by the Linux environment such as ftrace or systemtap, shall not be used in the operational environments. The use of any of these tools implies that the cryptographic module is running in a non-validated operational environment.

The Red Hat Enterprise Linux operating system is used as the basis of other products which include but are not limited to:

• Red Hat Enterprise Linux CoreOS
• Red Hat Ansible Automation Platform
• Red Hat OpenStack Platform
• Red Hat OpenShift
• Red Hat Gluster Storage
• Red Hat Satellite Compliance is maintained for these products whenever the binary is found unchanged. © 2025 Red Hat, Inc./ atsec information security corporation.

The module is comprised of software only and therefore this Section is not applicable. © 2025 Red Hat, Inc./ atsec information security corporation.

This module does not implement any non-invasive security mechanism and therefore this Section is not applicable. © 2025 Red Hat, Inc./ atsec information security corporation.

Name API input parameters; AF_ALG_typ e sockets (input)

From Operator calling applicatio n (TOEPP)

To Cryptographi c module

Format Type Plaintex t

Distributio n Type Manual

Entry Type Electroni c

SFI or Algorith m

Table 15: Storage Areas The module does not perform persistent storage of SSPs. The SSPs are temporarily stored in the RAM in plaintext form. SSPs are provided to the module by the calling process and are destroyed when released by the appropriate zeroization function calls.

m Table 16: SSP Input-Output Methods © 2025 Red Hat, Inc./ atsec information security corporation.

Zeroization Method

Description

Rationale successful removal of power implicitly indicates that the zeroization is complete.

Operator Initiation

Table 17: SSP Zeroization Methods All data output is inhibited during zeroization.

h D.L. D.L. © 2025 Red Hat, Inc./ atsec information security corporation.

h D.L. D.L. D.L. D.L. D.L. Table 18: SSP Table 1 © 2025 Red Hat, Inc./ atsec information security corporation.

The SHA-1 algorithm as implemented by the module will be non-approved for all purposes, starting January 1, 2031. © 2025 Red Hat, Inc./ atsec information security corporation.

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Table 20: Pre-Operational Self-Tests The pre-operational software integrity tests are performed automatically when the module is powered on, before the module transitions into the operational state. The algorithms used CASTs before the integrity test is performed. While the module is executing the self-tests, services are not available, and data output (via the data output interface) is inhibited until the pre-operational software integrity self-tests are successfully completed. The module transitions to the operational state only after the pre-operational self-tests are passed successfully.

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Table 21: Conditional Self-Tests The module performs self-tests on all approved cryptographic algorithms as part of the approved services supported in the approved mode of operation, using the tests shown in the table above. Services are not available, and data output (via the data output interface) is inhibited during the conditional self-tests. If any of these tests fails, the module transitions to the Error State.

Table 22: Pre-Operational Periodic Information © 2025 Red Hat, Inc./ atsec information security corporation.

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Table 23: Conditional Periodic Information

Table 24: Error States © 2025 Red Hat, Inc./ atsec information security corporation.

In the Error State, the output interface is inhibited, and the module accepts no more inputs or requests (as the module is no longer running).

All self-tests, with the exception of the continuous health tests, can be invoked on demand by unloading and subsequently re-initializing the module. © 2025 Red Hat, Inc./ atsec information security corporation.

The module is distributed as a part of the Red Hat Enterprise Linux 8 (RHEL 8) package in the form of the kernel-4.18.0-477.72.1.el8_8, libkcapi-1.2.0-3.el8_8, and libkcapi-hmaccalc1.2.0-3.el8_8 RPM packages. The module can achieve the FIPS validated configuration as follows.

• During the system installation, add the fips=1 option to the kernel command line. During the software selection stage, do not install any third-party software. More information can be found at the vendor documentation.
• After the installation, to switch the system into the approved mode, first execute the fips-mode-setup --enable command, then restart the system. More information can be found at the vendor documentation. In both cases, the Crypto Officer must verify the RHEL 8 system operates in the approved mode by executing the “fips-mode-setup --check” command, which should output “FIPS mode is enabled.”

After installation of the kernel-4.18.0-477.72.1.el8_8, libkcapi-1.2.0-3.el8_8, and libkcapihmaccalc-1.2.0-3.el8_8 RPM packages, the Crypto Officer must execute the “cat /proc/sys/crypto/fips_name” command. The Crypto Officer must ensure that the proper name is listed in the output as follows: Red Hat Enterprise Linux 8 - Kernel Cryptographic API Then, the Crypto Officer must execute the “cat /proc/sys/crypto/fips_version” and “rpm -q libkcapi” commands. These commands must output the following (one line per output): 4.18.0-477.72.1.el8_8.x86_64 libkcapi-1.2.0-3.el8_8.x86_64

There is no non-administrator guidance.

As the module does not persistently store SSPs, secure sanitization of the module consists of unloading the module. This will zeroize all SSPs in volatile memory. Then, if desired, the kernel-4.18.0-477.72.1.el8_8, libkcapi-1.2.0-3.el8_8, and libkcapi-hmaccalc-1.2.0-3.el8_8 RPM packages can be uninstalled from the RHEL 8 system. © 2025 Red Hat, Inc./ atsec information security corporation.

The module does not offer mitigation of other attacks and therefore this Section is not applicable. © 2025 Red Hat, Inc./ atsec information security corporation.

Appendix A. Glossary and Abbreviations

SP 800-38E Recommendation for Block Cipher Modes of Operation: The XTS AES Mode for Confidentiality on Storage Devices January 2010 https://csrc.nist.gov/publications/nistpubs/800-38E/nist-sp-800-38E.pdf SP 800-90Ar1 Recommendation for Random Number Generation Using Deterministic Random Bit Generators June 2015 https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-90Ar1.pdf © 2025 Red Hat, Inc./ atsec information security corporation.