ML-DSA keys in Amazon KMS

Amazon Key Management Service (Amazon KMS) supports Module-Lattice Digital Signature Algorithm (ML-DSA) for post-quantum cryptographic signatures. This implementation follows the Federal Information Processing Standards (FIPS) 204 standard to help protect against future quantum computing threats. Amazon KMS creates and protects all ML-DSA keys and signature operations in FIPS 140-3 Security Level 3 validated hardware security modules. To help balance security with performance, ML-DSA in Amazon KMS offers three distinct security levels through different key specifications, ML-DSA-44, ML-DSA-65, and ML-DSA-87.

Amazon KMS supports asymmetric key signatures for messages up to 4 KB using the RAW message type. For larger messages, you must externally compute the 64-byte message representation μ used in ML-DSA signing as defined in NIST FIPS 204 section 6.2. Use the EXTERNAL_MU message type in the Amazon KMS Sign operation to specify this pre-processed 64-byte message. The signatures produced by the externally computed μ are the same as the RAW ones when using the same message and private key. Note that this signing is different from the "pre-hash" ML-DSA or HashML-DSA from section 5.4 of NIST FIPS 204.

Amazon KMS supports asymmetric key signatures for messages up to 4 KB using the RAW message type. For larger messages, you must compute an EXTERNAL_MU value. Use the EXTERNAL_MU message type to identify these pre-processed messages when signing.

For more information about using ML-DSA and the EXTERNAL_MU message type, see ML-DSA key specs.

For an example of using ML-DSA and the EXTERNAL_MU message type, see Offline verification with ML-DSA key pairs.