/* * Copyright 2024-2025 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #ifndef OPENSSL_HEADER_ML_KEM_H # define OPENSSL_HEADER_ML_KEM_H # pragma once # include # include # include # include # define ML_KEM_DEGREE 256 /* * With (q-1) an odd multiple of 256, and 17 ("zeta") as a primitive 256th root * of unity, the polynomial (X^256+1) splits in Z_q[X] into 128 irreducible * quadratic factors of the form (X^2 - zeta^(2i + 1)). This is used to * implement efficient multiplication in the ring R_q via the "NTT" transform. */ # define ML_KEM_PRIME (ML_KEM_DEGREE * 13 + 1) /* * Various ML-KEM primitives need random input, 32-bytes at a time. Key * generation consumes two random values (d, z) with "d" plus the rank (domain * separation) further expanded to two derived seeds "rho" and "sigma", with * "rho" used to generate the public matrix "A", and sigma to generate the * private vector "s" and error vector "e". * * Encapsulation also consumes one random value m, that is 32-bytes long. The * resulting shared secret "K" (also 32 bytes) and an internal random value "r" * are derived from "m" concatenated with a digest of the received public key. * Use of the public key hash means that the derived shared secret is * "contributary", it uses randomness from both parties. * * The seed "rho" is appended to the public key and allows the recipient of the * public key to re-compute the matrix "A" when performing encapsulation. * * Note that the matrix "m" we store in the public key is the transpose of the * "A" matrix from FIPS 203! */ # define ML_KEM_RANDOM_BYTES 32 /* rho, sigma, ... */ # define ML_KEM_SEED_BYTES (ML_KEM_RANDOM_BYTES * 2) /* Keygen (d, z) */ # define ML_KEM_PKHASH_BYTES 32 /* Salts the shared-secret */ # define ML_KEM_SHARED_SECRET_BYTES 32 # if ML_KEM_PKHASH_BYTES != ML_KEM_RANDOM_BYTES # error "unexpected ML-KEM public key hash size" # endif /*- * The ML-KEM specification can be found in * https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf * * Section 8, Table 2, lists the parameters for the three variants: * * Variant n q k eta1 eta2 du dv secbits * ---------- --- ---- - ---- ---- -- -- ------- * ML-KEM-512 256 3329 2 3 2 10 4 128 * ML-KEM-768 256 3329 3 2 2 10 4 192 * ML-KEM-1024 256 3329 4 2 2 11 5 256 * * where: * * - "n" (ML_KEM_DEGREE above) is the fixed degree of the quotient polynomial * in the ring: "R_q" = Z[X]/(X^n + 1). * - "q" (ML_KEM_PRIME above) is the fixed prime (256 * 13 + 1 = 3329) used in * all ML-KEM variants. * - "k" is the row rank of the square matrix "A", with entries in R_q, that * defines the "noisy" linear equations: t = A * s + e. Also the rank of * of the associated vectors. * - "eta1" determines the amplitude of "s" and "e" vectors in key generation * and the "y" vector in ML-KEM encapsulation (K-PKE encryption). * - "eta2" determines the amplitude of "e1" and "e2" noise terms in ML-KEM * encapsulation (K-PKE encryption). * - "du" determines how many bits of each coefficient are retained in the * compressed form of the "u" vector in the encapsulation ciphertext. * - "dv" determines how many bits of each coefficient are retained in the * compressed form of the "v" value in encapsulation ciphertext * - "secbits" is required security strength of the RNG for the random inputs. */ /* * Variant-specific constants and structures * ----------------------------------------- */ # define EVP_PKEY_ML_KEM_512 NID_ML_KEM_512 # define ML_KEM_512_BITS 512 # define ML_KEM_512_RANK 2 # define ML_KEM_512_ETA1 3 # define ML_KEM_512_ETA2 2 # define ML_KEM_512_DU 10 # define ML_KEM_512_DV 4 # define ML_KEM_512_SECBITS 128 # define EVP_PKEY_ML_KEM_768 NID_ML_KEM_768 # define ML_KEM_768_BITS 768 # define ML_KEM_768_RANK 3 # define ML_KEM_768_ETA1 2 # define ML_KEM_768_ETA2 2 # define ML_KEM_768_DU 10 # define ML_KEM_768_DV 4 # define ML_KEM_768_SECBITS 192 # define EVP_PKEY_ML_KEM_1024 NID_ML_KEM_1024 # define ML_KEM_1024_BITS 1024 # define ML_KEM_1024_RANK 4 # define ML_KEM_1024_ETA1 2 # define ML_KEM_1024_ETA2 2 # define ML_KEM_1024_DU 11 # define ML_KEM_1024_DV 5 # define ML_KEM_1024_SECBITS 256 # define ML_KEM_KEY_RANDOM_PCT (1 << 0) # define ML_KEM_KEY_FIXED_PCT (1 << 1) # define ML_KEM_KEY_PREFER_SEED (1 << 2) # define ML_KEM_KEY_RETAIN_SEED (1 << 3) /* Mask to check whether PCT on import is enabled */ # define ML_KEM_KEY_PCT_TYPE \ (ML_KEM_KEY_RANDOM_PCT | ML_KEM_KEY_FIXED_PCT) /* Default provider flags */ # define ML_KEM_KEY_PROV_FLAGS_DEFAULT \ (ML_KEM_KEY_RANDOM_PCT | ML_KEM_KEY_PREFER_SEED | ML_KEM_KEY_RETAIN_SEED) /* * External variant-specific API * ----------------------------- */ typedef struct { const char *algorithm_name; size_t prvkey_bytes; size_t prvalloc; size_t pubkey_bytes; size_t puballoc; size_t ctext_bytes; size_t vector_bytes; size_t u_vector_bytes; int evp_type; int bits; int rank; int du; int dv; int secbits; } ML_KEM_VINFO; /* Retrive global variant-specific parameters */ const ML_KEM_VINFO *ossl_ml_kem_get_vinfo(int evp_type); /* Known as ML_KEM_KEY via crypto/types.h */ typedef struct ossl_ml_kem_key_st { /* Variant metadata, for one of ML-KEM-{512,768,1024} */ const ML_KEM_VINFO *vinfo; /* * Library context, initially used to fetch the SHA3 MDs, and later for * random number generation. */ OSSL_LIB_CTX *libctx; /* Pre-fetched SHA3 */ EVP_MD *shake128_md; EVP_MD *shake256_md; EVP_MD *sha3_256_md; EVP_MD *sha3_512_md; /* * Pointers into variable size storage, initially all NULL. Appropriate * storage is allocated once a public or private key is specified, at * which point the key becomes immutable. */ uint8_t *rho; /* Public matrix seed */ uint8_t *pkhash; /* Public key hash */ struct ossl_ml_kem_scalar_st *t; /* Public key vector */ struct ossl_ml_kem_scalar_st *m; /* Pre-computed pubkey matrix */ struct ossl_ml_kem_scalar_st *s; /* Private key secret vector */ uint8_t *z; /* Private key FO failure secret */ uint8_t *d; /* Private key seed */ int prov_flags; /* prefer/retain seed and PCT flags */ /* * Fixed-size built-in buffer, which holds the |rho| and the public key * |pkhash| in that order, once we have expanded key material. * With seed-only keys, that are not yet expanded, this instead holds the * |z| and |d| components in that order. */ uint8_t seedbuf[64]; /* |rho| + |pkhash| / |z| + |d| */ uint8_t *encoded_dk; /* Unparsed P8 private key */ } ML_KEM_KEY; /* The public key is always present, when the private is */ # define ossl_ml_kem_key_vinfo(key) ((key)->vinfo) # define ossl_ml_kem_have_pubkey(key) ((key)->t != NULL) # define ossl_ml_kem_have_prvkey(key) ((key)->s != NULL) # define ossl_ml_kem_have_seed(key) ((key)->d != NULL) # define ossl_ml_kem_have_dkenc(key) ((key)->encoded_dk != NULL) # define ossl_ml_kem_decoded_key(key) ((key)->encoded_dk != NULL \ || ((key)->s == NULL && (key)->d != NULL)) /* * ----- ML-KEM key lifecycle */ /* * Allocate a "bare" key for given ML-KEM variant. Initially without any public * or private key material. */ ML_KEM_KEY *ossl_ml_kem_key_new(OSSL_LIB_CTX *libctx, const char *properties, int evp_type); /* Reset a key clearing all public and private key material */ void ossl_ml_kem_key_reset(ML_KEM_KEY *key); /* Deallocate the key */ void ossl_ml_kem_key_free(ML_KEM_KEY *key); /* * Duplicate a key, optionally including some key material, per the * |selection|, see . */ ML_KEM_KEY *ossl_ml_kem_key_dup(const ML_KEM_KEY *key, int selection); /* * ----- Import or generate key material. */ /* * Functions that augment "bare ML-KEM keys" with key material deserialised * from an input buffer. It is an error for any key material to already be * present. * * Return 1 on success, 0 otherwise. */ __owur int ossl_ml_kem_parse_public_key(const uint8_t *in, size_t len, ML_KEM_KEY *key); __owur int ossl_ml_kem_parse_private_key(const uint8_t *in, size_t len, ML_KEM_KEY *key); ML_KEM_KEY *ossl_ml_kem_set_seed(const uint8_t *seed, size_t seedlen, ML_KEM_KEY *key); __owur int ossl_ml_kem_genkey(uint8_t *pubenc, size_t publen, ML_KEM_KEY *key); /* * Perform an ML-KEM operation with a given ML-KEM key. The key can generally * be either a private or public key, with the exception of encoding a private * key or performing KEM decapsulation. */ __owur int ossl_ml_kem_encode_public_key(uint8_t *out, size_t len, const ML_KEM_KEY *key); __owur int ossl_ml_kem_encode_private_key(uint8_t *out, size_t len, const ML_KEM_KEY *key); __owur int ossl_ml_kem_encode_seed(uint8_t *out, size_t len, const ML_KEM_KEY *key); __owur int ossl_ml_kem_encap_seed(uint8_t *ctext, size_t clen, uint8_t *shared_secret, size_t slen, const uint8_t *entropy, size_t elen, const ML_KEM_KEY *key); __owur int ossl_ml_kem_encap_rand(uint8_t *ctext, size_t clen, uint8_t *shared_secret, size_t slen, const ML_KEM_KEY *key); __owur int ossl_ml_kem_decap(uint8_t *shared_secret, size_t slen, const uint8_t *ctext, size_t clen, const ML_KEM_KEY *key); /* Compare the public key hashes of two keys */ __owur int ossl_ml_kem_pubkey_cmp(const ML_KEM_KEY *key1, const ML_KEM_KEY *key2); #endif /* OPENSSL_HEADER_ML_KEM_H */