1 /* 2 * Copyright 2024-2025 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #ifndef OPENSSL_HEADER_ML_KEM_H 11 #define OPENSSL_HEADER_ML_KEM_H 12 #pragma once 13 14 #include <openssl/e_os2.h> 15 #include <openssl/bio.h> 16 #include <openssl/core_dispatch.h> 17 #include <crypto/evp.h> 18 19 #define ML_KEM_DEGREE 256 20 /* 21 * With (q-1) an odd multiple of 256, and 17 ("zeta") as a primitive 256th root 22 * of unity, the polynomial (X^256+1) splits in Z_q[X] into 128 irreducible 23 * quadratic factors of the form (X^2 - zeta^(2i + 1)). This is used to 24 * implement efficient multiplication in the ring R_q via the "NTT" transform. 25 */ 26 #define ML_KEM_PRIME (ML_KEM_DEGREE * 13 + 1) 27 28 /* 29 * Various ML-KEM primitives need random input, 32-bytes at a time. Key 30 * generation consumes two random values (d, z) with "d" plus the rank (domain 31 * separation) further expanded to two derived seeds "rho" and "sigma", with 32 * "rho" used to generate the public matrix "A", and sigma to generate the 33 * private vector "s" and error vector "e". 34 * 35 * Encapsulation also consumes one random value m, that is 32-bytes long. The 36 * resulting shared secret "K" (also 32 bytes) and an internal random value "r" 37 * are derived from "m" concatenated with a digest of the received public key. 38 * Use of the public key hash means that the derived shared secret is 39 * "contributary", it uses randomness from both parties. 40 * 41 * The seed "rho" is appended to the public key and allows the recipient of the 42 * public key to re-compute the matrix "A" when performing encapsulation. 43 * 44 * Note that the matrix "m" we store in the public key is the transpose of the 45 * "A" matrix from FIPS 203! 46 */ 47 #define ML_KEM_RANDOM_BYTES 32 /* rho, sigma, ... */ 48 #define ML_KEM_SEED_BYTES (ML_KEM_RANDOM_BYTES * 2) /* Keygen (d, z) */ 49 50 #define ML_KEM_PKHASH_BYTES 32 /* Salts the shared-secret */ 51 #define ML_KEM_SHARED_SECRET_BYTES 32 52 53 #if ML_KEM_PKHASH_BYTES != ML_KEM_RANDOM_BYTES 54 #error "unexpected ML-KEM public key hash size" 55 #endif 56 57 /*- 58 * The ML-KEM specification can be found in 59 * https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf 60 * 61 * Section 8, Table 2, lists the parameters for the three variants: 62 * 63 * Variant n q k eta1 eta2 du dv secbits 64 * ---------- --- ---- - ---- ---- -- -- ------- 65 * ML-KEM-512 256 3329 2 3 2 10 4 128 66 * ML-KEM-768 256 3329 3 2 2 10 4 192 67 * ML-KEM-1024 256 3329 4 2 2 11 5 256 68 * 69 * where: 70 * 71 * - "n" (ML_KEM_DEGREE above) is the fixed degree of the quotient polynomial 72 * in the ring: "R_q" = Z[X]/(X^n + 1). 73 * - "q" (ML_KEM_PRIME above) is the fixed prime (256 * 13 + 1 = 3329) used in 74 * all ML-KEM variants. 75 * - "k" is the row rank of the square matrix "A", with entries in R_q, that 76 * defines the "noisy" linear equations: t = A * s + e. Also the rank of 77 * of the associated vectors. 78 * - "eta1" determines the amplitude of "s" and "e" vectors in key generation 79 * and the "y" vector in ML-KEM encapsulation (K-PKE encryption). 80 * - "eta2" determines the amplitude of "e1" and "e2" noise terms in ML-KEM 81 * encapsulation (K-PKE encryption). 82 * - "du" determines how many bits of each coefficient are retained in the 83 * compressed form of the "u" vector in the encapsulation ciphertext. 84 * - "dv" determines how many bits of each coefficient are retained in the 85 * compressed form of the "v" value in encapsulation ciphertext 86 * - "secbits" is required security strength of the RNG for the random inputs. 87 */ 88 89 /* 90 * Variant-specific constants and structures 91 * ----------------------------------------- 92 */ 93 #define EVP_PKEY_ML_KEM_512 NID_ML_KEM_512 94 #define ML_KEM_512_BITS 512 95 #define ML_KEM_512_RANK 2 96 #define ML_KEM_512_ETA1 3 97 #define ML_KEM_512_ETA2 2 98 #define ML_KEM_512_DU 10 99 #define ML_KEM_512_DV 4 100 #define ML_KEM_512_SECBITS 128 101 102 #define EVP_PKEY_ML_KEM_768 NID_ML_KEM_768 103 #define ML_KEM_768_BITS 768 104 #define ML_KEM_768_RANK 3 105 #define ML_KEM_768_ETA1 2 106 #define ML_KEM_768_ETA2 2 107 #define ML_KEM_768_DU 10 108 #define ML_KEM_768_DV 4 109 #define ML_KEM_768_SECBITS 192 110 111 #define EVP_PKEY_ML_KEM_1024 NID_ML_KEM_1024 112 #define ML_KEM_1024_BITS 1024 113 #define ML_KEM_1024_RANK 4 114 #define ML_KEM_1024_ETA1 2 115 #define ML_KEM_1024_ETA2 2 116 #define ML_KEM_1024_DU 11 117 #define ML_KEM_1024_DV 5 118 #define ML_KEM_1024_SECBITS 256 119 120 #define ML_KEM_KEY_RANDOM_PCT (1 << 0) 121 #define ML_KEM_KEY_FIXED_PCT (1 << 1) 122 #define ML_KEM_KEY_PREFER_SEED (1 << 2) 123 #define ML_KEM_KEY_RETAIN_SEED (1 << 3) 124 /* Mask to check whether PCT on import is enabled */ 125 #define ML_KEM_KEY_PCT_TYPE \ 126 (ML_KEM_KEY_RANDOM_PCT | ML_KEM_KEY_FIXED_PCT) 127 /* Default provider flags */ 128 #define ML_KEM_KEY_PROV_FLAGS_DEFAULT \ 129 (ML_KEM_KEY_RANDOM_PCT | ML_KEM_KEY_PREFER_SEED | ML_KEM_KEY_RETAIN_SEED) 130 131 /* 132 * External variant-specific API 133 * ----------------------------- 134 */ 135 136 typedef struct { 137 const char *algorithm_name; 138 size_t prvkey_bytes; 139 size_t prvalloc; 140 size_t pubkey_bytes; 141 size_t puballoc; 142 size_t ctext_bytes; 143 size_t vector_bytes; 144 size_t u_vector_bytes; 145 int evp_type; 146 int bits; 147 int rank; 148 int du; 149 int dv; 150 int secbits; 151 } ML_KEM_VINFO; 152 153 /* Retrieve global variant-specific parameters */ 154 const ML_KEM_VINFO *ossl_ml_kem_get_vinfo(int evp_type); 155 156 /* Known as ML_KEM_KEY via crypto/types.h */ 157 typedef struct ossl_ml_kem_key_st { 158 /* Variant metadata, for one of ML-KEM-{512,768,1024} */ 159 const ML_KEM_VINFO *vinfo; 160 161 /* 162 * Library context, initially used to fetch the SHA3 MDs, and later for 163 * random number generation. 164 */ 165 OSSL_LIB_CTX *libctx; 166 167 /* Pre-fetched SHA3 */ 168 EVP_MD *shake128_md; 169 EVP_MD *shake256_md; 170 EVP_MD *sha3_256_md; 171 EVP_MD *sha3_512_md; 172 173 /* 174 * Pointers into variable size storage, initially all NULL. Appropriate 175 * storage is allocated once a public or private key is specified, at 176 * which point the key becomes immutable. 177 */ 178 uint8_t *rho; /* Public matrix seed */ 179 uint8_t *pkhash; /* Public key hash */ 180 struct ossl_ml_kem_scalar_st *t; /* Public key vector */ 181 struct ossl_ml_kem_scalar_st *m; /* Pre-computed pubkey matrix */ 182 struct ossl_ml_kem_scalar_st *s; /* Private key secret vector */ 183 uint8_t *z; /* Private key FO failure secret */ 184 uint8_t *d; /* Private key seed */ 185 int prov_flags; /* prefer/retain seed and PCT flags */ 186 187 /* 188 * Fixed-size built-in buffer, which holds the |rho| and the public key 189 * |pkhash| in that order, once we have expanded key material. 190 * With seed-only keys, that are not yet expanded, this instead holds the 191 * |z| and |d| components in that order. 192 */ 193 uint8_t seedbuf[64]; /* |rho| + |pkhash| / |z| + |d| */ 194 uint8_t *encoded_dk; /* Unparsed P8 private key */ 195 } ML_KEM_KEY; 196 197 /* The public key is always present, when the private is */ 198 #define ossl_ml_kem_key_vinfo(key) ((key)->vinfo) 199 #define ossl_ml_kem_have_pubkey(key) ((key)->t != NULL) 200 #define ossl_ml_kem_have_prvkey(key) ((key)->s != NULL) 201 #define ossl_ml_kem_have_seed(key) ((key)->d != NULL) 202 #define ossl_ml_kem_have_dkenc(key) ((key)->encoded_dk != NULL) 203 #define ossl_ml_kem_decoded_key(key) ((key)->encoded_dk != NULL \ 204 || ((key)->s == NULL && (key)->d != NULL)) 205 206 /* 207 * ----- ML-KEM key lifecycle 208 */ 209 210 /* 211 * Allocate a "bare" key for given ML-KEM variant. Initially without any public 212 * or private key material. 213 */ 214 ML_KEM_KEY *ossl_ml_kem_key_new(OSSL_LIB_CTX *libctx, const char *properties, 215 int evp_type); 216 /* Reset a key clearing all public and private key material */ 217 void ossl_ml_kem_key_reset(ML_KEM_KEY *key); 218 /* Deallocate the key */ 219 void ossl_ml_kem_key_free(ML_KEM_KEY *key); 220 /* 221 * Duplicate a key, optionally including some key material, per the 222 * |selection|, see <openssl/core_dispatch.h>. 223 */ 224 ML_KEM_KEY *ossl_ml_kem_key_dup(const ML_KEM_KEY *key, int selection); 225 226 /* 227 * ----- Import or generate key material. 228 */ 229 230 /* 231 * Functions that augment "bare ML-KEM keys" with key material deserialised 232 * from an input buffer. It is an error for any key material to already be 233 * present. 234 * 235 * Return 1 on success, 0 otherwise. 236 */ 237 __owur int ossl_ml_kem_parse_public_key(const uint8_t *in, size_t len, 238 ML_KEM_KEY *key); 239 __owur int ossl_ml_kem_parse_private_key(const uint8_t *in, size_t len, 240 ML_KEM_KEY *key); 241 ML_KEM_KEY *ossl_ml_kem_set_seed(const uint8_t *seed, size_t seedlen, 242 ML_KEM_KEY *key); 243 __owur int ossl_ml_kem_genkey(uint8_t *pubenc, size_t publen, ML_KEM_KEY *key); 244 245 /* 246 * Perform an ML-KEM operation with a given ML-KEM key. The key can generally 247 * be either a private or public key, with the exception of encoding a private 248 * key or performing KEM decapsulation. 249 */ 250 __owur int ossl_ml_kem_encode_public_key(uint8_t *out, size_t len, 251 const ML_KEM_KEY *key); 252 __owur int ossl_ml_kem_encode_private_key(uint8_t *out, size_t len, 253 const ML_KEM_KEY *key); 254 __owur int ossl_ml_kem_encode_seed(uint8_t *out, size_t len, 255 const ML_KEM_KEY *key); 256 257 __owur int ossl_ml_kem_encap_seed(uint8_t *ctext, size_t clen, 258 uint8_t *shared_secret, size_t slen, 259 const uint8_t *entropy, size_t elen, 260 const ML_KEM_KEY *key); 261 __owur int ossl_ml_kem_encap_rand(uint8_t *ctext, size_t clen, 262 uint8_t *shared_secret, size_t slen, 263 const ML_KEM_KEY *key); 264 __owur int ossl_ml_kem_decap(uint8_t *shared_secret, size_t slen, 265 const uint8_t *ctext, size_t clen, 266 const ML_KEM_KEY *key); 267 268 /* Compare the public key hashes of two keys */ 269 __owur int ossl_ml_kem_pubkey_cmp(const ML_KEM_KEY *key1, const ML_KEM_KEY *key2); 270 271 #endif /* OPENSSL_HEADER_ML_KEM_H */ 272