# ML-DSA keys in AWS KMS
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AWS Key Management Service (AWS 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](https://csrc.nist.gov/pubs/fips/204/final) to help protect against future quantum computing threats. AWS 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 AWS KMS offers three distinct security levels through different key specifications, ML\$1DSA\$144, ML\$1DSA\$165, and ML\$1DSA\$187.

AWS 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 AWS KMS [Sign](https://docs.aws.amazon.com/kms/latest/APIReference/API_Sign.html) 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.

For more information about using ML-DSA and the EXTERNAL\$1MU message type, see [ML-DSA key specs](symm-asymm-choose-key-spec.md#key-spec-mldsa).

For an example of using ML-DSA and the EXTERNAL\$1MU message type, see [Offline verification with ML-DSA key pairs](offline-operations.md#mldsa-offline-verification).