1 /** 2 * \file psa/crypto_sizes.h 3 * 4 * \brief PSA cryptography module: Mbed TLS buffer size macros 5 * 6 * \note This file may not be included directly. Applications must 7 * include psa/crypto.h. 8 * 9 * This file contains the definitions of macros that are useful to 10 * compute buffer sizes. The signatures and semantics of these macros 11 * are standardized, but the definitions are not, because they depend on 12 * the available algorithms and, in some cases, on permitted tolerances 13 * on buffer sizes. 14 * 15 * In implementations with isolation between the application and the 16 * cryptography module, implementers should take care to ensure that 17 * the definitions that are exposed to applications match what the 18 * module implements. 19 * 20 * Macros that compute sizes whose values do not depend on the 21 * implementation are in crypto.h. 22 */ 23 /* 24 * Copyright The Mbed TLS Contributors 25 * SPDX-License-Identifier: Apache-2.0 26 * 27 * Licensed under the Apache License, Version 2.0 (the "License"); you may 28 * not use this file except in compliance with the License. 29 * You may obtain a copy of the License at 30 * 31 * http://www.apache.org/licenses/LICENSE-2.0 32 * 33 * Unless required by applicable law or agreed to in writing, software 34 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 35 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 36 * See the License for the specific language governing permissions and 37 * limitations under the License. 38 */ 39 40 #ifndef PSA_CRYPTO_SIZES_H 41 #define PSA_CRYPTO_SIZES_H 42 43 /* Include the Mbed TLS configuration file, the way Mbed TLS does it 44 * in each of its header files. */ 45 #if !defined(MBEDTLS_CONFIG_FILE) 46 #include "mbedtls/config.h" 47 #else 48 #include MBEDTLS_CONFIG_FILE 49 #endif 50 51 #define PSA_BITS_TO_BYTES(bits) (((bits) + 7) / 8) 52 #define PSA_BYTES_TO_BITS(bytes) ((bytes) * 8) 53 54 #define PSA_ROUND_UP_TO_MULTIPLE(block_size, length) \ 55 (((length) + (block_size) - 1) / (block_size) * (block_size)) 56 57 /** The size of the output of psa_hash_finish(), in bytes. 58 * 59 * This is also the hash size that psa_hash_verify() expects. 60 * 61 * \param alg A hash algorithm (\c PSA_ALG_XXX value such that 62 * #PSA_ALG_IS_HASH(\p alg) is true), or an HMAC algorithm 63 * (#PSA_ALG_HMAC(\c hash_alg) where \c hash_alg is a 64 * hash algorithm). 65 * 66 * \return The hash size for the specified hash algorithm. 67 * If the hash algorithm is not recognized, return 0. 68 * An implementation may return either 0 or the correct size 69 * for a hash algorithm that it recognizes, but does not support. 70 */ 71 #define PSA_HASH_SIZE(alg) \ 72 ( \ 73 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD2 ? 16 : \ 74 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD4 ? 16 : \ 75 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD5 ? 16 : \ 76 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_RIPEMD160 ? 20 : \ 77 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_1 ? 20 : \ 78 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_224 ? 28 : \ 79 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_256 ? 32 : \ 80 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_384 ? 48 : \ 81 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512 ? 64 : \ 82 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_224 ? 28 : \ 83 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_256 ? 32 : \ 84 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_224 ? 28 : \ 85 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_256 ? 32 : \ 86 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_384 ? 48 : \ 87 PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_512 ? 64 : \ 88 0) 89 90 /** \def PSA_HASH_MAX_SIZE 91 * 92 * Maximum size of a hash. 93 * 94 * This macro must expand to a compile-time constant integer. This value 95 * should be the maximum size of a hash supported by the implementation, 96 * in bytes, and must be no smaller than this maximum. 97 */ 98 /* Note: for HMAC-SHA-3, the block size is 144 bytes for HMAC-SHA3-226, 99 * 136 bytes for HMAC-SHA3-256, 104 bytes for SHA3-384, 72 bytes for 100 * HMAC-SHA3-512. */ 101 #if defined(MBEDTLS_SHA512_C) 102 #define PSA_HASH_MAX_SIZE 64 103 #define PSA_HMAC_MAX_HASH_BLOCK_SIZE 128 104 #else 105 #define PSA_HASH_MAX_SIZE 32 106 #define PSA_HMAC_MAX_HASH_BLOCK_SIZE 64 107 #endif 108 109 /** \def PSA_MAC_MAX_SIZE 110 * 111 * Maximum size of a MAC. 112 * 113 * This macro must expand to a compile-time constant integer. This value 114 * should be the maximum size of a MAC supported by the implementation, 115 * in bytes, and must be no smaller than this maximum. 116 */ 117 /* All non-HMAC MACs have a maximum size that's smaller than the 118 * minimum possible value of PSA_HASH_MAX_SIZE in this implementation. */ 119 /* Note that the encoding of truncated MAC algorithms limits this value 120 * to 64 bytes. 121 */ 122 #define PSA_MAC_MAX_SIZE PSA_HASH_MAX_SIZE 123 124 /** The tag size for an AEAD algorithm, in bytes. 125 * 126 * \param alg An AEAD algorithm 127 * (\c PSA_ALG_XXX value such that 128 * #PSA_ALG_IS_AEAD(\p alg) is true). 129 * 130 * \return The tag size for the specified algorithm. 131 * If the AEAD algorithm does not have an identified 132 * tag that can be distinguished from the rest of 133 * the ciphertext, return 0. 134 * If the AEAD algorithm is not recognized, return 0. 135 * An implementation may return either 0 or a 136 * correct size for an AEAD algorithm that it 137 * recognizes, but does not support. 138 */ 139 #define PSA_AEAD_TAG_LENGTH(alg) \ 140 (PSA_ALG_IS_AEAD(alg) ? \ 141 (((alg) & PSA_ALG_AEAD_TAG_LENGTH_MASK) >> PSA_AEAD_TAG_LENGTH_OFFSET) : \ 142 0) 143 144 /* The maximum size of an RSA key on this implementation, in bits. 145 * This is a vendor-specific macro. 146 * 147 * Mbed TLS does not set a hard limit on the size of RSA keys: any key 148 * whose parameters fit in a bignum is accepted. However large keys can 149 * induce a large memory usage and long computation times. Unlike other 150 * auxiliary macros in this file and in crypto.h, which reflect how the 151 * library is configured, this macro defines how the library is 152 * configured. This implementation refuses to import or generate an 153 * RSA key whose size is larger than the value defined here. 154 * 155 * Note that an implementation may set different size limits for different 156 * operations, and does not need to accept all key sizes up to the limit. */ 157 #define PSA_VENDOR_RSA_MAX_KEY_BITS 4096 158 159 /* The maximum size of an ECC key on this implementation, in bits. 160 * This is a vendor-specific macro. */ 161 #if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED) 162 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 521 163 #elif defined(MBEDTLS_ECP_DP_BP512R1_ENABLED) 164 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 512 165 #elif defined(MBEDTLS_ECP_DP_CURVE448_ENABLED) 166 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 448 167 #elif defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) 168 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 384 169 #elif defined(MBEDTLS_ECP_DP_BP384R1_ENABLED) 170 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 384 171 #elif defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) 172 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 256 173 #elif defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED) 174 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 256 175 #elif defined(MBEDTLS_ECP_DP_BP256R1_ENABLED) 176 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 256 177 #elif defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED) 178 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 255 179 #elif defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) 180 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 224 181 #elif defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED) 182 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 224 183 #elif defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) 184 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 192 185 #elif defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED) 186 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 192 187 #else 188 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 0 189 #endif 190 191 /** \def PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN 192 * 193 * This macro returns the maximum length of the PSK supported 194 * by the TLS-1.2 PSK-to-MS key derivation. 195 * 196 * Quoting RFC 4279, Sect 5.3: 197 * TLS implementations supporting these ciphersuites MUST support 198 * arbitrary PSK identities up to 128 octets in length, and arbitrary 199 * PSKs up to 64 octets in length. Supporting longer identities and 200 * keys is RECOMMENDED. 201 * 202 * Therefore, no implementation should define a value smaller than 64 203 * for #PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN. 204 */ 205 #define PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN 128 206 207 /** The maximum size of a block cipher supported by the implementation. */ 208 #define PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE 16 209 210 /** The size of the output of psa_mac_sign_finish(), in bytes. 211 * 212 * This is also the MAC size that psa_mac_verify_finish() expects. 213 * 214 * \param key_type The type of the MAC key. 215 * \param key_bits The size of the MAC key in bits. 216 * \param alg A MAC algorithm (\c PSA_ALG_XXX value such that 217 * #PSA_ALG_IS_MAC(\p alg) is true). 218 * 219 * \return The MAC size for the specified algorithm with 220 * the specified key parameters. 221 * \return 0 if the MAC algorithm is not recognized. 222 * \return Either 0 or the correct size for a MAC algorithm that 223 * the implementation recognizes, but does not support. 224 * \return Unspecified if the key parameters are not consistent 225 * with the algorithm. 226 */ 227 #define PSA_MAC_FINAL_SIZE(key_type, key_bits, alg) \ 228 ((alg) & PSA_ALG_MAC_TRUNCATION_MASK ? PSA_MAC_TRUNCATED_LENGTH(alg) : \ 229 PSA_ALG_IS_HMAC(alg) ? PSA_HASH_SIZE(PSA_ALG_HMAC_GET_HASH(alg)) : \ 230 PSA_ALG_IS_BLOCK_CIPHER_MAC(alg) ? PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) : \ 231 ((void)(key_type), (void)(key_bits), 0)) 232 233 /** The maximum size of the output of psa_aead_encrypt(), in bytes. 234 * 235 * If the size of the ciphertext buffer is at least this large, it is 236 * guaranteed that psa_aead_encrypt() will not fail due to an 237 * insufficient buffer size. Depending on the algorithm, the actual size of 238 * the ciphertext may be smaller. 239 * 240 * \param alg An AEAD algorithm 241 * (\c PSA_ALG_XXX value such that 242 * #PSA_ALG_IS_AEAD(\p alg) is true). 243 * \param plaintext_length Size of the plaintext in bytes. 244 * 245 * \return The AEAD ciphertext size for the specified 246 * algorithm. 247 * If the AEAD algorithm is not recognized, return 0. 248 * An implementation may return either 0 or a 249 * correct size for an AEAD algorithm that it 250 * recognizes, but does not support. 251 */ 252 #define PSA_AEAD_ENCRYPT_OUTPUT_SIZE(alg, plaintext_length) \ 253 (PSA_AEAD_TAG_LENGTH(alg) != 0 ? \ 254 (plaintext_length) + PSA_AEAD_TAG_LENGTH(alg) : \ 255 0) 256 257 /** The maximum size of the output of psa_aead_decrypt(), in bytes. 258 * 259 * If the size of the plaintext buffer is at least this large, it is 260 * guaranteed that psa_aead_decrypt() will not fail due to an 261 * insufficient buffer size. Depending on the algorithm, the actual size of 262 * the plaintext may be smaller. 263 * 264 * \param alg An AEAD algorithm 265 * (\c PSA_ALG_XXX value such that 266 * #PSA_ALG_IS_AEAD(\p alg) is true). 267 * \param ciphertext_length Size of the plaintext in bytes. 268 * 269 * \return The AEAD ciphertext size for the specified 270 * algorithm. 271 * If the AEAD algorithm is not recognized, return 0. 272 * An implementation may return either 0 or a 273 * correct size for an AEAD algorithm that it 274 * recognizes, but does not support. 275 */ 276 #define PSA_AEAD_DECRYPT_OUTPUT_SIZE(alg, ciphertext_length) \ 277 (PSA_AEAD_TAG_LENGTH(alg) != 0 ? \ 278 (ciphertext_length) - PSA_AEAD_TAG_LENGTH(alg) : \ 279 0) 280 281 /** A sufficient output buffer size for psa_aead_update(). 282 * 283 * If the size of the output buffer is at least this large, it is 284 * guaranteed that psa_aead_update() will not fail due to an 285 * insufficient buffer size. The actual size of the output may be smaller 286 * in any given call. 287 * 288 * \param alg An AEAD algorithm 289 * (\c PSA_ALG_XXX value such that 290 * #PSA_ALG_IS_AEAD(\p alg) is true). 291 * \param input_length Size of the input in bytes. 292 * 293 * \return A sufficient output buffer size for the specified 294 * algorithm. 295 * If the AEAD algorithm is not recognized, return 0. 296 * An implementation may return either 0 or a 297 * correct size for an AEAD algorithm that it 298 * recognizes, but does not support. 299 */ 300 /* For all the AEAD modes defined in this specification, it is possible 301 * to emit output without delay. However, hardware may not always be 302 * capable of this. So for modes based on a block cipher, allow the 303 * implementation to delay the output until it has a full block. */ 304 #define PSA_AEAD_UPDATE_OUTPUT_SIZE(alg, input_length) \ 305 (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \ 306 PSA_ROUND_UP_TO_MULTIPLE(PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE, (input_length)) : \ 307 (input_length)) 308 309 /** A sufficient ciphertext buffer size for psa_aead_finish(). 310 * 311 * If the size of the ciphertext buffer is at least this large, it is 312 * guaranteed that psa_aead_finish() will not fail due to an 313 * insufficient ciphertext buffer size. The actual size of the output may 314 * be smaller in any given call. 315 * 316 * \param alg An AEAD algorithm 317 * (\c PSA_ALG_XXX value such that 318 * #PSA_ALG_IS_AEAD(\p alg) is true). 319 * 320 * \return A sufficient ciphertext buffer size for the 321 * specified algorithm. 322 * If the AEAD algorithm is not recognized, return 0. 323 * An implementation may return either 0 or a 324 * correct size for an AEAD algorithm that it 325 * recognizes, but does not support. 326 */ 327 #define PSA_AEAD_FINISH_OUTPUT_SIZE(alg) \ 328 (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \ 329 PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE : \ 330 0) 331 332 /** A sufficient plaintext buffer size for psa_aead_verify(). 333 * 334 * If the size of the plaintext buffer is at least this large, it is 335 * guaranteed that psa_aead_verify() will not fail due to an 336 * insufficient plaintext buffer size. The actual size of the output may 337 * be smaller in any given call. 338 * 339 * \param alg An AEAD algorithm 340 * (\c PSA_ALG_XXX value such that 341 * #PSA_ALG_IS_AEAD(\p alg) is true). 342 * 343 * \return A sufficient plaintext buffer size for the 344 * specified algorithm. 345 * If the AEAD algorithm is not recognized, return 0. 346 * An implementation may return either 0 or a 347 * correct size for an AEAD algorithm that it 348 * recognizes, but does not support. 349 */ 350 #define PSA_AEAD_VERIFY_OUTPUT_SIZE(alg) \ 351 (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ? \ 352 PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE : \ 353 0) 354 355 #define PSA_RSA_MINIMUM_PADDING_SIZE(alg) \ 356 (PSA_ALG_IS_RSA_OAEP(alg) ? \ 357 2 * PSA_HASH_SIZE(PSA_ALG_RSA_OAEP_GET_HASH(alg)) + 1 : \ 358 11 /*PKCS#1v1.5*/) 359 360 /** 361 * \brief ECDSA signature size for a given curve bit size 362 * 363 * \param curve_bits Curve size in bits. 364 * \return Signature size in bytes. 365 * 366 * \note This macro returns a compile-time constant if its argument is one. 367 */ 368 #define PSA_ECDSA_SIGNATURE_SIZE(curve_bits) \ 369 (PSA_BITS_TO_BYTES(curve_bits) * 2) 370 371 /** Sufficient signature buffer size for psa_sign_hash(). 372 * 373 * This macro returns a sufficient buffer size for a signature using a key 374 * of the specified type and size, with the specified algorithm. 375 * Note that the actual size of the signature may be smaller 376 * (some algorithms produce a variable-size signature). 377 * 378 * \warning This function may call its arguments multiple times or 379 * zero times, so you should not pass arguments that contain 380 * side effects. 381 * 382 * \param key_type An asymmetric key type (this may indifferently be a 383 * key pair type or a public key type). 384 * \param key_bits The size of the key in bits. 385 * \param alg The signature algorithm. 386 * 387 * \return If the parameters are valid and supported, return 388 * a buffer size in bytes that guarantees that 389 * psa_sign_hash() will not fail with 390 * #PSA_ERROR_BUFFER_TOO_SMALL. 391 * If the parameters are a valid combination that is not supported 392 * by the implementation, this macro shall return either a 393 * sensible size or 0. 394 * If the parameters are not valid, the 395 * return value is unspecified. 396 */ 397 #define PSA_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) \ 398 (PSA_KEY_TYPE_IS_RSA(key_type) ? ((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \ 399 PSA_KEY_TYPE_IS_ECC(key_type) ? PSA_ECDSA_SIGNATURE_SIZE(key_bits) : \ 400 ((void)alg, 0)) 401 402 #define PSA_VENDOR_ECDSA_SIGNATURE_MAX_SIZE \ 403 PSA_ECDSA_SIGNATURE_SIZE(PSA_VENDOR_ECC_MAX_CURVE_BITS) 404 405 /** \def PSA_SIGNATURE_MAX_SIZE 406 * 407 * Maximum size of an asymmetric signature. 408 * 409 * This macro must expand to a compile-time constant integer. This value 410 * should be the maximum size of a signature supported by the implementation, 411 * in bytes, and must be no smaller than this maximum. 412 */ 413 #define PSA_SIGNATURE_MAX_SIZE \ 414 (PSA_BITS_TO_BYTES(PSA_VENDOR_RSA_MAX_KEY_BITS) > PSA_VENDOR_ECDSA_SIGNATURE_MAX_SIZE ? \ 415 PSA_BITS_TO_BYTES(PSA_VENDOR_RSA_MAX_KEY_BITS) : \ 416 PSA_VENDOR_ECDSA_SIGNATURE_MAX_SIZE) 417 418 /** Sufficient output buffer size for psa_asymmetric_encrypt(). 419 * 420 * This macro returns a sufficient buffer size for a ciphertext produced using 421 * a key of the specified type and size, with the specified algorithm. 422 * Note that the actual size of the ciphertext may be smaller, depending 423 * on the algorithm. 424 * 425 * \warning This function may call its arguments multiple times or 426 * zero times, so you should not pass arguments that contain 427 * side effects. 428 * 429 * \param key_type An asymmetric key type (this may indifferently be a 430 * key pair type or a public key type). 431 * \param key_bits The size of the key in bits. 432 * \param alg The asymmetric encryption algorithm. 433 * 434 * \return If the parameters are valid and supported, return 435 * a buffer size in bytes that guarantees that 436 * psa_asymmetric_encrypt() will not fail with 437 * #PSA_ERROR_BUFFER_TOO_SMALL. 438 * If the parameters are a valid combination that is not supported 439 * by the implementation, this macro shall return either a 440 * sensible size or 0. 441 * If the parameters are not valid, the 442 * return value is unspecified. 443 */ 444 #define PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \ 445 (PSA_KEY_TYPE_IS_RSA(key_type) ? \ 446 ((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \ 447 0) 448 449 /** Sufficient output buffer size for psa_asymmetric_decrypt(). 450 * 451 * This macro returns a sufficient buffer size for a plaintext produced using 452 * a key of the specified type and size, with the specified algorithm. 453 * Note that the actual size of the plaintext may be smaller, depending 454 * on the algorithm. 455 * 456 * \warning This function may call its arguments multiple times or 457 * zero times, so you should not pass arguments that contain 458 * side effects. 459 * 460 * \param key_type An asymmetric key type (this may indifferently be a 461 * key pair type or a public key type). 462 * \param key_bits The size of the key in bits. 463 * \param alg The asymmetric encryption algorithm. 464 * 465 * \return If the parameters are valid and supported, return 466 * a buffer size in bytes that guarantees that 467 * psa_asymmetric_decrypt() will not fail with 468 * #PSA_ERROR_BUFFER_TOO_SMALL. 469 * If the parameters are a valid combination that is not supported 470 * by the implementation, this macro shall return either a 471 * sensible size or 0. 472 * If the parameters are not valid, the 473 * return value is unspecified. 474 */ 475 #define PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \ 476 (PSA_KEY_TYPE_IS_RSA(key_type) ? \ 477 PSA_BITS_TO_BYTES(key_bits) - PSA_RSA_MINIMUM_PADDING_SIZE(alg) : \ 478 0) 479 480 /* Maximum size of the ASN.1 encoding of an INTEGER with the specified 481 * number of bits. 482 * 483 * This definition assumes that bits <= 2^19 - 9 so that the length field 484 * is at most 3 bytes. The length of the encoding is the length of the 485 * bit string padded to a whole number of bytes plus: 486 * - 1 type byte; 487 * - 1 to 3 length bytes; 488 * - 0 to 1 bytes of leading 0 due to the sign bit. 489 */ 490 #define PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(bits) \ 491 ((bits) / 8 + 5) 492 493 /* Maximum size of the export encoding of an RSA public key. 494 * Assumes that the public exponent is less than 2^32. 495 * 496 * RSAPublicKey ::= SEQUENCE { 497 * modulus INTEGER, -- n 498 * publicExponent INTEGER } -- e 499 * 500 * - 4 bytes of SEQUENCE overhead; 501 * - n : INTEGER; 502 * - 7 bytes for the public exponent. 503 */ 504 #define PSA_KEY_EXPORT_RSA_PUBLIC_KEY_MAX_SIZE(key_bits) \ 505 (PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) + 11) 506 507 /* Maximum size of the export encoding of an RSA key pair. 508 * Assumes thatthe public exponent is less than 2^32 and that the size 509 * difference between the two primes is at most 1 bit. 510 * 511 * RSAPrivateKey ::= SEQUENCE { 512 * version Version, -- 0 513 * modulus INTEGER, -- N-bit 514 * publicExponent INTEGER, -- 32-bit 515 * privateExponent INTEGER, -- N-bit 516 * prime1 INTEGER, -- N/2-bit 517 * prime2 INTEGER, -- N/2-bit 518 * exponent1 INTEGER, -- N/2-bit 519 * exponent2 INTEGER, -- N/2-bit 520 * coefficient INTEGER, -- N/2-bit 521 * } 522 * 523 * - 4 bytes of SEQUENCE overhead; 524 * - 3 bytes of version; 525 * - 7 half-size INTEGERs plus 2 full-size INTEGERs, 526 * overapproximated as 9 half-size INTEGERS; 527 * - 7 bytes for the public exponent. 528 */ 529 #define PSA_KEY_EXPORT_RSA_KEY_PAIR_MAX_SIZE(key_bits) \ 530 (9 * PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE((key_bits) / 2 + 1) + 14) 531 532 /* Maximum size of the export encoding of a DSA public key. 533 * 534 * SubjectPublicKeyInfo ::= SEQUENCE { 535 * algorithm AlgorithmIdentifier, 536 * subjectPublicKey BIT STRING } -- contains DSAPublicKey 537 * AlgorithmIdentifier ::= SEQUENCE { 538 * algorithm OBJECT IDENTIFIER, 539 * parameters Dss-Parms } -- SEQUENCE of 3 INTEGERs 540 * DSAPublicKey ::= INTEGER -- public key, Y 541 * 542 * - 3 * 4 bytes of SEQUENCE overhead; 543 * - 1 + 1 + 7 bytes of algorithm (DSA OID); 544 * - 4 bytes of BIT STRING overhead; 545 * - 3 full-size INTEGERs (p, g, y); 546 * - 1 + 1 + 32 bytes for 1 sub-size INTEGER (q <= 256 bits). 547 */ 548 #define PSA_KEY_EXPORT_DSA_PUBLIC_KEY_MAX_SIZE(key_bits) \ 549 (PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) * 3 + 59) 550 551 /* Maximum size of the export encoding of a DSA key pair. 552 * 553 * DSAPrivateKey ::= SEQUENCE { 554 * version Version, -- 0 555 * prime INTEGER, -- p 556 * subprime INTEGER, -- q 557 * generator INTEGER, -- g 558 * public INTEGER, -- y 559 * private INTEGER, -- x 560 * } 561 * 562 * - 4 bytes of SEQUENCE overhead; 563 * - 3 bytes of version; 564 * - 3 full-size INTEGERs (p, g, y); 565 * - 2 * (1 + 1 + 32) bytes for 2 sub-size INTEGERs (q, x <= 256 bits). 566 */ 567 #define PSA_KEY_EXPORT_DSA_KEY_PAIR_MAX_SIZE(key_bits) \ 568 (PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) * 3 + 75) 569 570 /* Maximum size of the export encoding of an ECC public key. 571 * 572 * The representation of an ECC public key is: 573 * - The byte 0x04; 574 * - `x_P` as a `ceiling(m/8)`-byte string, big-endian; 575 * - `y_P` as a `ceiling(m/8)`-byte string, big-endian; 576 * - where m is the bit size associated with the curve. 577 * 578 * - 1 byte + 2 * point size. 579 */ 580 #define PSA_KEY_EXPORT_ECC_PUBLIC_KEY_MAX_SIZE(key_bits) \ 581 (2 * PSA_BITS_TO_BYTES(key_bits) + 1) 582 583 /* Maximum size of the export encoding of an ECC key pair. 584 * 585 * An ECC key pair is represented by the secret value. 586 */ 587 #define PSA_KEY_EXPORT_ECC_KEY_PAIR_MAX_SIZE(key_bits) \ 588 (PSA_BITS_TO_BYTES(key_bits)) 589 590 /** Sufficient output buffer size for psa_export_key() or psa_export_public_key(). 591 * 592 * This macro returns a compile-time constant if its arguments are 593 * compile-time constants. 594 * 595 * \warning This function may call its arguments multiple times or 596 * zero times, so you should not pass arguments that contain 597 * side effects. 598 * 599 * The following code illustrates how to allocate enough memory to export 600 * a key by querying the key type and size at runtime. 601 * \code{c} 602 * psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; 603 * psa_status_t status; 604 * status = psa_get_key_attributes(key, &attributes); 605 * if (status != PSA_SUCCESS) handle_error(...); 606 * psa_key_type_t key_type = psa_get_key_type(&attributes); 607 * size_t key_bits = psa_get_key_bits(&attributes); 608 * size_t buffer_size = PSA_KEY_EXPORT_MAX_SIZE(key_type, key_bits); 609 * psa_reset_key_attributes(&attributes); 610 * uint8_t *buffer = malloc(buffer_size); 611 * if (buffer == NULL) handle_error(...); 612 * size_t buffer_length; 613 * status = psa_export_key(key, buffer, buffer_size, &buffer_length); 614 * if (status != PSA_SUCCESS) handle_error(...); 615 * \endcode 616 * 617 * For psa_export_public_key(), calculate the buffer size from the 618 * public key type. You can use the macro #PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR 619 * to convert a key pair type to the corresponding public key type. 620 * \code{c} 621 * psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; 622 * psa_status_t status; 623 * status = psa_get_key_attributes(key, &attributes); 624 * if (status != PSA_SUCCESS) handle_error(...); 625 * psa_key_type_t key_type = psa_get_key_type(&attributes); 626 * psa_key_type_t public_key_type = PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(key_type); 627 * size_t key_bits = psa_get_key_bits(&attributes); 628 * size_t buffer_size = PSA_KEY_EXPORT_MAX_SIZE(public_key_type, key_bits); 629 * psa_reset_key_attributes(&attributes); 630 * uint8_t *buffer = malloc(buffer_size); 631 * if (buffer == NULL) handle_error(...); 632 * size_t buffer_length; 633 * status = psa_export_public_key(key, buffer, buffer_size, &buffer_length); 634 * if (status != PSA_SUCCESS) handle_error(...); 635 * \endcode 636 * 637 * \param key_type A supported key type. 638 * \param key_bits The size of the key in bits. 639 * 640 * \return If the parameters are valid and supported, return 641 * a buffer size in bytes that guarantees that 642 * psa_sign_hash() will not fail with 643 * #PSA_ERROR_BUFFER_TOO_SMALL. 644 * If the parameters are a valid combination that is not supported 645 * by the implementation, this macro shall return either a 646 * sensible size or 0. 647 * If the parameters are not valid, the 648 * return value is unspecified. 649 */ 650 #define PSA_KEY_EXPORT_MAX_SIZE(key_type, key_bits) \ 651 (PSA_KEY_TYPE_IS_UNSTRUCTURED(key_type) ? PSA_BITS_TO_BYTES(key_bits) : \ 652 (key_type) == PSA_KEY_TYPE_RSA_KEY_PAIR ? PSA_KEY_EXPORT_RSA_KEY_PAIR_MAX_SIZE(key_bits) : \ 653 (key_type) == PSA_KEY_TYPE_RSA_PUBLIC_KEY ? PSA_KEY_EXPORT_RSA_PUBLIC_KEY_MAX_SIZE(key_bits) : \ 654 (key_type) == PSA_KEY_TYPE_DSA_KEY_PAIR ? PSA_KEY_EXPORT_DSA_KEY_PAIR_MAX_SIZE(key_bits) : \ 655 (key_type) == PSA_KEY_TYPE_DSA_PUBLIC_KEY ? PSA_KEY_EXPORT_DSA_PUBLIC_KEY_MAX_SIZE(key_bits) : \ 656 PSA_KEY_TYPE_IS_ECC_KEY_PAIR(key_type) ? PSA_KEY_EXPORT_ECC_KEY_PAIR_MAX_SIZE(key_bits) : \ 657 PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY(key_type) ? PSA_KEY_EXPORT_ECC_PUBLIC_KEY_MAX_SIZE(key_bits) : \ 658 0) 659 660 /** The default nonce size for an AEAD algorithm, in bytes. 661 * 662 * This macro can be used to allocate a buffer of sufficient size to 663 * store the nonce output from #psa_aead_generate_nonce(). 664 * 665 * See also #PSA_AEAD_NONCE_MAX_SIZE. 666 * 667 * \note This is not the maximum size of nonce supported as input to #psa_aead_set_nonce(), 668 * #psa_aead_encrypt() or #psa_aead_decrypt(), just the default size that is generated by 669 * #psa_aead_generate_nonce(). 670 * 671 * \warning This macro may evaluate its arguments multiple times or 672 * zero times, so you should not pass arguments that contain 673 * side effects. 674 * 675 * \param key_type A symmetric key type that is compatible with algorithm \p alg. 676 * 677 * \param alg An AEAD algorithm (\c PSA_ALG_XXX value such that #PSA_ALG_IS_AEAD(\p alg) is true). 678 * 679 * \return The default nonce size for the specified key type and algorithm. 680 * If the key type or AEAD algorithm is not recognized, 681 * or the parameters are incompatible, return 0. 682 * An implementation can return either 0 or a correct size for a key type 683 * and AEAD algorithm that it recognizes, but does not support. 684 */ 685 #define PSA_AEAD_NONCE_LENGTH(key_type, alg) \ 686 (PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) == 16 && \ 687 (PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH(alg) == PSA_ALG_CCM || \ 688 PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH(alg) == PSA_ALG_GCM) ? 12 : \ 689 (key_type) == PSA_KEY_TYPE_CHACHA20 && \ 690 PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH(alg) == PSA_ALG_CHACHA20_POLY1305 ? 12 : \ 691 0) 692 693 /** The maximum default nonce size among all supported pairs of key types and AEAD algorithms, in bytes. 694 * 695 * This is equal to or greater than any value that #PSA_AEAD_NONCE_LENGTH() may return. 696 * 697 * \note This is not the maximum size of nonce supported as input to #psa_aead_set_nonce(), 698 * #psa_aead_encrypt() or #psa_aead_decrypt(), just the largest size that may be generated by 699 * #psa_aead_generate_nonce(). 700 */ 701 #define PSA_AEAD_NONCE_MAX_SIZE 12 702 703 /** The default IV size for a cipher algorithm, in bytes. 704 * 705 * The IV that is generated as part of a call to #psa_cipher_encrypt() is always 706 * the default IV length for the algorithm. 707 * 708 * This macro can be used to allocate a buffer of sufficient size to 709 * store the IV output from #psa_cipher_generate_iv() when using 710 * a multi-part cipher operation. 711 * 712 * See also #PSA_CIPHER_IV_MAX_SIZE. 713 * 714 * \warning This macro may evaluate its arguments multiple times or 715 * zero times, so you should not pass arguments that contain 716 * side effects. 717 * 718 * \param key_type A symmetric key type that is compatible with algorithm \p alg. 719 * 720 * \param alg A cipher algorithm (\c PSA_ALG_XXX value such that #PSA_ALG_IS_CIPHER(\p alg) is true). 721 * 722 * \return The default IV size for the specified key type and algorithm. 723 * If the algorithm does not use an IV, return 0. 724 * If the key type or cipher algorithm is not recognized, 725 * or the parameters are incompatible, return 0. 726 * An implementation can return either 0 or a correct size for a key type 727 * and cipher algorithm that it recognizes, but does not support. 728 */ 729 #define PSA_CIPHER_IV_LENGTH(key_type, alg) \ 730 (PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) > 1 && \ 731 ((alg) == PSA_ALG_CTR || \ 732 (alg) == PSA_ALG_CFB || \ 733 (alg) == PSA_ALG_OFB || \ 734 (alg) == PSA_ALG_XTS || \ 735 (alg) == PSA_ALG_CBC_NO_PADDING || \ 736 (alg) == PSA_ALG_CBC_PKCS7) ? PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) : \ 737 (key_type) == PSA_KEY_TYPE_CHACHA20 && \ 738 (alg) == PSA_ALG_STREAM_CIPHER ? 12 : \ 739 0) 740 741 /** The maximum IV size for all supported cipher algorithms, in bytes. 742 * 743 * See also #PSA_CIPHER_IV_LENGTH(). 744 */ 745 #define PSA_CIPHER_IV_MAX_SIZE 16 746 747 #endif /* PSA_CRYPTO_SIZES_H */ 748
