Use Tink to meet FIPS 140-2 security requirements

Tink itself is not FIPS 140-2 validated. However, it supports several FIPS 140-2 approved algorithms and the underlying implementations can utilize validated cryptographic modules like BoringSSLs BoringCrypto. Tink includes a WORKSPACE for building BoringSSL in FIPS mode.

Note that the workspace gives no inherent guarantee that your use of BoringSSL is FIPS compliant. We strongly recommend that you read the official security policy for BoringCrypto.

Supported algorithms

The following algorithms in Tink are approved according to FIPS 140-2 (see more information at FIPS 140-2 Annex A):

  • Authenticated Encryption
    • AES-GCM
  • MAC
    • HMAC-SHA256
    • AES-CMAC
  • Digital Signatures
    • ECDSA

FIPS-only mode in C++

If you are required to use FIPS 140-2 approved algorithms and validated implementations, you can build Tink in FIPS-only mode. This restricts usage to approved algorithms and checks if Tink is utilizing a validated cryptographic module.

This changes the behavior of Tink in the following ways:

  • Register() functions only register algorithms that have a FIPS validated implementation. This means that you are only able to use Keysets for algorithms that use a validated cryptographic module.
  • Tink checks if BoringSSL has been built with the BoringCrypto module. Calls to primitives return an INTERNAL error when the module is not available.
  • Using primitives in subtle/ is restricted to algorithms that utilize a validated cryptographic module.


Tink uses BoringCrypto in C++ to provide access to a validated cryptographic module. Its current validation status imposes the following additional constraints on available algorithms when in FIPS-only mode:

  • AES-CMAC has not been validated and is not available
  • RSA-SSA-PKCS1 is restricted to 3072-bit modulus
  • RSA-SSA-PSS is restricted to 3072-bit modulus

To use the BoringCrypto module with Bazel, you can uncomment the local_repository definition for boringssl in the C++ WORKSPACE.

Enable at compile time

To build Tink in FIPS-only mode, set a flag at compile time:

bazel build ... --//third_party/tink/cc/config:use_only_fips=True

If you want to check at runtime whether Tink has been built in FIPS only mode, you can include the header internal/fips_utils.h which provides the constant kUseOnlyFips.

If you are not building Tink in FIPS only mode, it can still utilize validated implementations for some algorithms but not restrict the usage of other algorithms.

Enable at run time

As an alternative to building Tink in FIPS-only mode, you can call crypto::tink::RestrictToFips() from config/tink_fips.h which sets a flag at runtime to enable the restrictions to FIPS primitives.

WARNING: If you use the runtime option, then crypto::tink::RestrictToFips() must be called before handling any key material, registering key manager, or other Tink functionalities. Additionally, you must ensure that BoringSSL has been built with the BoringCrypto module, otherwise Tink does not allow you to process any data.