A precise engineering specification for serializing ML-KEM public keys, private keys, and ciphertexts across standard protocol containers.
FIPS 203 specifies exact byte array mappings: ML-KEM-768 public keys consist of 1,152 bytes (1,120 bytes of compressed polynomial vector t plus 32 bytes of seed rho). Private keys require 2,400 bytes, combining the secret vector s, the public key, the hash of the public key H(pk), and seed z. Ciphertexts occupy 1,088 bytes.
To integrate ML-KEM keys into existing X.509 certificate authorities and PKI tooling, keys must be encapsulated in ASN.1 SubjectPublicKeyInfo structures using standardized Object Identifiers (OIDs). We examine the IETF LAMPS working group drafts and demonstrate compliant PEM and DER serialization.
In bandwidth-constrained environments such as smart meters and satellite links, ASN.1 overhead is prohibitive. We detail CBOR Object Signing and Encryption (COSE) encodings that minimize header metadata while preserving strict FIPS 203 compliance.