/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL * project 2005. */ /* ==================================================================== * Copyright (c) 2005 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. All advertising materials mentioning features or use of this * software must display the following acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" * * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to * endorse or promote products derived from this software without * prior written permission. For written permission, please contact * licensing@OpenSSL.org. * * 5. Products derived from this software may not be called "OpenSSL" * nor may "OpenSSL" appear in their names without prior written * permission of the OpenSSL Project. * * 6. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" * * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * This product includes cryptographic software written by Eric Young * (eay@cryptsoft.com). This product includes software written by Tim * Hudson (tjh@cryptsoft.com). */ #include #include #include #include #include #include #include #include #include "internal.h" /* TODO(fork): don't the check functions have to be constant time? */ int RSA_padding_add_PKCS1_type_1(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) { unsigned j; uint8_t *p; if (tlen < RSA_PKCS1_PADDING_SIZE) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } if (flen > tlen - RSA_PKCS1_PADDING_SIZE) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); return 0; } p = (uint8_t *)to; *(p++) = 0; *(p++) = 1; /* Private Key BT (Block Type) */ /* pad out with 0xff data */ j = tlen - 3 - flen; memset(p, 0xff, j); p += j; *(p++) = 0; memcpy(p, from, (unsigned int)flen); return 1; } int RSA_padding_check_PKCS1_type_1(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) { unsigned i, j; const uint8_t *p; if (flen < 2) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL); return -1; } p = from; if ((*(p++) != 0) || (*(p++) != 1)) { OPENSSL_PUT_ERROR(RSA, RSA_R_BLOCK_TYPE_IS_NOT_01); return -1; } /* scan over padding data */ j = flen - 2; /* one for leading 00, one for type. */ for (i = 0; i < j; i++) { /* should decrypt to 0xff */ if (*p != 0xff) { if (*p == 0) { p++; break; } else { OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_FIXED_HEADER_DECRYPT); return -1; } } p++; } if (i == j) { OPENSSL_PUT_ERROR(RSA, RSA_R_NULL_BEFORE_BLOCK_MISSING); return -1; } if (i < 8) { OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_PAD_BYTE_COUNT); return -1; } i++; /* Skip over the '\0' */ j -= i; if (j > tlen) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); return -1; } memcpy(to, p, j); return j; } int RSA_padding_add_PKCS1_type_2(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) { unsigned i, j; uint8_t *p; if (tlen < RSA_PKCS1_PADDING_SIZE) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } if (flen > tlen - RSA_PKCS1_PADDING_SIZE) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); return 0; } p = (unsigned char *)to; *(p++) = 0; *(p++) = 2; /* Public Key BT (Block Type) */ /* pad out with non-zero random data */ j = tlen - 3 - flen; if (!RAND_bytes(p, j)) { return 0; } for (i = 0; i < j; i++) { while (*p == 0) { if (!RAND_bytes(p, 1)) { return 0; } } p++; } *(p++) = 0; memcpy(p, from, (unsigned int)flen); return 1; } /* constant_time_byte_eq returns 1 if |x| == |y| and 0 otherwise. */ static int constant_time_byte_eq(unsigned char a, unsigned char b) { unsigned char z = ~(a ^ b); z &= z >> 4; z &= z >> 2; z &= z >> 1; return z; } /* constant_time_select returns |x| if |v| is 1 and |y| if |v| is 0. * Its behavior is undefined if |v| takes any other value. */ static int constant_time_select(int v, int x, int y) { return ((~(v - 1)) & x) | ((v - 1) & y); } /* constant_time_le returns 1 if |x| <= |y| and 0 otherwise. * |x| and |y| must be positive. */ static int constant_time_le(int x, int y) { return ((x - y - 1) >> (sizeof(int) * 8 - 1)) & 1; } int RSA_message_index_PKCS1_type_2(const uint8_t *from, size_t from_len, size_t *out_index) { size_t i; int first_byte_is_zero, second_byte_is_two, looking_for_index; int valid_index, zero_index = 0; /* PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography * Standard", section 7.2.2. */ if (from_len < RSA_PKCS1_PADDING_SIZE) { /* |from| is zero-padded to the size of the RSA modulus, a public value, so * this can be rejected in non-constant time. */ *out_index = 0; return 0; } first_byte_is_zero = constant_time_byte_eq(from[0], 0); second_byte_is_two = constant_time_byte_eq(from[1], 2); looking_for_index = 1; for (i = 2; i < from_len; i++) { int equals0 = constant_time_byte_eq(from[i], 0); zero_index = constant_time_select(looking_for_index & equals0, i, zero_index); looking_for_index = constant_time_select(equals0, 0, looking_for_index); } /* The input must begin with 00 02. */ valid_index = first_byte_is_zero; valid_index &= second_byte_is_two; /* We must have found the end of PS. */ valid_index &= ~looking_for_index; /* PS must be at least 8 bytes long, and it starts two bytes into |from|. */ valid_index &= constant_time_le(2 + 8, zero_index); /* Skip the zero byte. */ zero_index++; *out_index = constant_time_select(valid_index, zero_index, 0); return valid_index; } int RSA_padding_check_PKCS1_type_2(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) { size_t msg_index, msg_len; if (flen == 0) { OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY); return -1; } /* NOTE: Although |RSA_message_index_PKCS1_type_2| itself is constant time, * the API contracts of this function and |RSA_decrypt| with * |RSA_PKCS1_PADDING| make it impossible to completely avoid Bleichenbacher's * attack. */ if (!RSA_message_index_PKCS1_type_2(from, flen, &msg_index)) { OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR); return -1; } msg_len = flen - msg_index; if (msg_len > tlen) { /* This shouldn't happen because this function is always called with |tlen| * the key size and |flen| is bounded by the key size. */ OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR); return -1; } memcpy(to, &from[msg_index], msg_len); return msg_len; } int RSA_padding_add_none(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) { if (flen > tlen) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); return 0; } if (flen < tlen) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL_FOR_KEY_SIZE); return 0; } memcpy(to, from, (unsigned int)flen); return 1; } int PKCS1_MGF1(uint8_t *mask, unsigned len, const uint8_t *seed, unsigned seedlen, const EVP_MD *dgst) { unsigned outlen = 0; uint32_t i; uint8_t cnt[4]; EVP_MD_CTX c; uint8_t md[EVP_MAX_MD_SIZE]; unsigned mdlen; int ret = -1; EVP_MD_CTX_init(&c); mdlen = EVP_MD_size(dgst); for (i = 0; outlen < len; i++) { cnt[0] = (uint8_t)((i >> 24) & 255); cnt[1] = (uint8_t)((i >> 16) & 255); cnt[2] = (uint8_t)((i >> 8)) & 255; cnt[3] = (uint8_t)(i & 255); if (!EVP_DigestInit_ex(&c, dgst, NULL) || !EVP_DigestUpdate(&c, seed, seedlen) || !EVP_DigestUpdate(&c, cnt, 4)) { goto err; } if (outlen + mdlen <= len) { if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL)) { goto err; } outlen += mdlen; } else { if (!EVP_DigestFinal_ex(&c, md, NULL)) { goto err; } memcpy(mask + outlen, md, len - outlen); outlen = len; } } ret = 0; err: EVP_MD_CTX_cleanup(&c); return ret; } int RSA_padding_add_PKCS1_OAEP_mgf1(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen, const uint8_t *param, unsigned plen, const EVP_MD *md, const EVP_MD *mgf1md) { unsigned i, emlen, mdlen; uint8_t *db, *seed; uint8_t *dbmask = NULL, seedmask[EVP_MAX_MD_SIZE]; int ret = 0; if (md == NULL) { md = EVP_sha1(); } if (mgf1md == NULL) { mgf1md = md; } mdlen = EVP_MD_size(md); if (tlen < 2 * mdlen + 2) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } emlen = tlen - 1; if (flen > emlen - 2 * mdlen - 1) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); return 0; } if (emlen < 2 * mdlen + 1) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } to[0] = 0; seed = to + 1; db = to + mdlen + 1; if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL)) { return 0; } memset(db + mdlen, 0, emlen - flen - 2 * mdlen - 1); db[emlen - flen - mdlen - 1] = 0x01; memcpy(db + emlen - flen - mdlen, from, flen); if (!RAND_bytes(seed, mdlen)) { return 0; } dbmask = OPENSSL_malloc(emlen - mdlen); if (dbmask == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); return 0; } if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0) { goto out; } for (i = 0; i < emlen - mdlen; i++) { db[i] ^= dbmask[i]; } if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0) { goto out; } for (i = 0; i < mdlen; i++) { seed[i] ^= seedmask[i]; } ret = 1; out: OPENSSL_free(dbmask); return ret; } int RSA_padding_check_PKCS1_OAEP_mgf1(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen, const uint8_t *param, unsigned plen, const EVP_MD *md, const EVP_MD *mgf1md) { unsigned i, dblen, mlen = -1, mdlen; const uint8_t *maskeddb, *maskedseed; uint8_t *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE]; int bad, looking_for_one_byte, one_index = 0; if (md == NULL) { md = EVP_sha1(); } if (mgf1md == NULL) { mgf1md = md; } mdlen = EVP_MD_size(md); /* The encoded message is one byte smaller than the modulus to ensure that it * doesn't end up greater than the modulus. Thus there's an extra "+1" here * compared to https://tools.ietf.org/html/rfc2437#section-9.1.1.2. */ if (flen < 1 + 2*mdlen + 1) { /* 'flen' is the length of the modulus, i.e. does not depend on the * particular ciphertext. */ goto decoding_err; } dblen = flen - mdlen - 1; db = OPENSSL_malloc(dblen); if (db == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } maskedseed = from + 1; maskeddb = from + 1 + mdlen; if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) { goto err; } for (i = 0; i < mdlen; i++) { seed[i] ^= maskedseed[i]; } if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md)) { goto err; } for (i = 0; i < dblen; i++) { db[i] ^= maskeddb[i]; } if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL)) { goto err; } bad = CRYPTO_memcmp(db, phash, mdlen); bad |= from[0]; looking_for_one_byte = 1; for (i = mdlen; i < dblen; i++) { int equals1 = constant_time_byte_eq(db[i], 1); int equals0 = constant_time_byte_eq(db[i], 0); one_index = constant_time_select(looking_for_one_byte & equals1, i, one_index); looking_for_one_byte = constant_time_select(equals1, 0, looking_for_one_byte); bad |= looking_for_one_byte & ~equals0; } bad |= looking_for_one_byte; if (bad) { goto decoding_err; } one_index++; mlen = dblen - one_index; if (tlen < mlen) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); mlen = -1; } else { memcpy(to, db + one_index, mlen); } OPENSSL_free(db); return mlen; decoding_err: /* to avoid chosen ciphertext attacks, the error message should not reveal * which kind of decoding error happened */ OPENSSL_PUT_ERROR(RSA, RSA_R_OAEP_DECODING_ERROR); err: OPENSSL_free(db); return -1; } static const unsigned char zeroes[] = {0,0,0,0,0,0,0,0}; int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const uint8_t *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, const uint8_t *EM, int sLen) { int i; int ret = 0; int maskedDBLen, MSBits, emLen; size_t hLen; const uint8_t *H; uint8_t *DB = NULL; EVP_MD_CTX ctx; uint8_t H_[EVP_MAX_MD_SIZE]; EVP_MD_CTX_init(&ctx); if (mgf1Hash == NULL) { mgf1Hash = Hash; } hLen = EVP_MD_size(Hash); /* Negative sLen has special meanings: * -1 sLen == hLen * -2 salt length is autorecovered from signature * -N reserved */ if (sLen == -1) { sLen = hLen; } else if (sLen == -2) { sLen = -2; } else if (sLen < -2) { OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED); goto err; } MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; emLen = RSA_size(rsa); if (EM[0] & (0xFF << MSBits)) { OPENSSL_PUT_ERROR(RSA, RSA_R_FIRST_OCTET_INVALID); goto err; } if (MSBits == 0) { EM++; emLen--; } if (emLen < ((int)hLen + sLen + 2)) { /* sLen can be small negative */ OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); goto err; } if (EM[emLen - 1] != 0xbc) { OPENSSL_PUT_ERROR(RSA, RSA_R_LAST_OCTET_INVALID); goto err; } maskedDBLen = emLen - hLen - 1; H = EM + maskedDBLen; DB = OPENSSL_malloc(maskedDBLen); if (!DB) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) { goto err; } for (i = 0; i < maskedDBLen; i++) { DB[i] ^= EM[i]; } if (MSBits) { DB[0] &= 0xFF >> (8 - MSBits); } for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) { ; } if (DB[i++] != 0x1) { OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_RECOVERY_FAILED); goto err; } if (sLen >= 0 && (maskedDBLen - i) != sLen) { OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED); goto err; } if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || !EVP_DigestUpdate(&ctx, mHash, hLen)) { goto err; } if (maskedDBLen - i) { if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) { goto err; } } if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) { goto err; } if (memcmp(H_, H, hLen)) { OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_SIGNATURE); ret = 0; } else { ret = 1; } err: OPENSSL_free(DB); EVP_MD_CTX_cleanup(&ctx); return ret; } int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, int sLen) { int i; int ret = 0; size_t maskedDBLen, MSBits, emLen; size_t hLen; unsigned char *H, *salt = NULL, *p; EVP_MD_CTX ctx; if (mgf1Hash == NULL) { mgf1Hash = Hash; } hLen = EVP_MD_size(Hash); /* Negative sLen has special meanings: * -1 sLen == hLen * -2 salt length is maximized * -N reserved */ if (sLen == -1) { sLen = hLen; } else if (sLen == -2) { sLen = -2; } else if (sLen < -2) { OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED); goto err; } if (BN_is_zero(rsa->n)) { OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY); goto err; } MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; emLen = RSA_size(rsa); if (MSBits == 0) { assert(emLen >= 1); *EM++ = 0; emLen--; } if (sLen == -2) { if (emLen < hLen + 2) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); goto err; } sLen = emLen - hLen - 2; } else if (emLen < hLen + sLen + 2) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); goto err; } if (sLen > 0) { salt = OPENSSL_malloc(sLen); if (!salt) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } if (!RAND_bytes(salt, sLen)) { goto err; } } maskedDBLen = emLen - hLen - 1; H = EM + maskedDBLen; EVP_MD_CTX_init(&ctx); if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || !EVP_DigestUpdate(&ctx, mHash, hLen)) { goto err; } if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) { goto err; } if (!EVP_DigestFinal_ex(&ctx, H, NULL)) { goto err; } EVP_MD_CTX_cleanup(&ctx); /* Generate dbMask in place then perform XOR on it */ if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) { goto err; } p = EM; /* Initial PS XORs with all zeroes which is a NOP so just update * pointer. Note from a test above this value is guaranteed to * be non-negative. */ p += emLen - sLen - hLen - 2; *p++ ^= 0x1; if (sLen > 0) { for (i = 0; i < sLen; i++) { *p++ ^= salt[i]; } } if (MSBits) { EM[0] &= 0xFF >> (8 - MSBits); } /* H is already in place so just set final 0xbc */ EM[emLen - 1] = 0xbc; ret = 1; err: OPENSSL_free(salt); return ret; }