mldsa-mu

A small Python library for generating external μ (mu) values as specified by ML-DSA (FIPS 204).

This library is intended for use in systems that need to compute μ outside of a full ML-DSA signing implementation (for example: KMS-style services, HSM adapters, or test tooling).

What is μ?

In ML-DSA, the value μ is defined as:

μ = SHAKE256(tr || M', 64)

where:

• tr = SHAKE256(public_key, 64)
• M' = 0x00 || len(context) || context || message

This library implements exactly that construction.

Features

• Deterministic μ generation per FIPS 204
• Supports optional domain-separation context
• Utilities for extracting raw public keys from (base64) PKIX / SPKI encodings

Installation

pip install mldsa-mu

Usage

Example: generate μ from a raw public key

from mldsa_mu import generate

public_key = b"\x01" * 64
message = b"hello world"

mu = generate(public_key, message)
print(mu)

Example: generate μ with a domain-separation context

from mldsa_mu import generate

public_key = b"\x02" * 64
message = b"important message"
context = b"my-protocol-v1"

mu = generate(public_key, message, context=context)
print(mu)

Example: extract raw public key from DER-encoded PKIX (SPKI) and generate μ

from mldsa_mu import generate, public_key_from_pkix

with open("public_key.spki.der", "rb") as f:
    spki_der = f.read()

public_key = public_key_from_pkix(spki_der)

mu = generate(public_key, b"hello world")
print(mu)

Example: extract raw public key from base64-encoded PKIX (SPKI)

from mldsa_mu import generate, public_key_from_pkix_b64

spki_b64 = (
    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A..."
)

public_key = public_key_from_pkix_b64(spki_b64)

mu = generate(public_key, b"hello world")
print(mu)

Development

Create (and remove if needed) the Hatch dev environment.

hatch env remove dev
hatch env create dev

Run tests: hatch run dev:fmt

Run code linting: hatch run dev:pytest

Run code type checking: hatch run dev:typing

License

mldsa-mu is distributed under the terms of the MIT license.

Python written by humans. English written by AI.