crypto/rsa/rsa_sign.c

   1 /*
   2  * Copyright 1995-2021 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 /*
  11  * RSA low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <stdio.h>
  17 #include "internal/cryptlib.h"
  18 #include <openssl/bn.h>
  19 #include <openssl/rsa.h>
  20 #include <openssl/objects.h>
  21 #ifndef FIPS_MODULE
  22 # ifndef OPENSSL_NO_MD2
  23 #  include <openssl/md2.h> /* uses MD2_DIGEST_LENGTH */
  24 # endif
  25 # ifndef OPENSSL_NO_MD4
  26 #  include <openssl/md4.h> /* uses MD4_DIGEST_LENGTH */
  27 # endif
  28 # ifndef OPENSSL_NO_MD5
  29 #  include <openssl/md5.h> /* uses MD5_DIGEST_LENGTH */
  30 # endif
  31 # ifndef OPENSSL_NO_MDC2
  32 #  include <openssl/mdc2.h> /* uses MDC2_DIGEST_LENGTH */
  33 # endif
  34 # ifndef OPENSSL_NO_RMD160
  35 #  include <openssl/ripemd.h> /* uses RIPEMD160_DIGEST_LENGTH */
  36 # endif
  37 #endif
  38 #include <openssl/sha.h> /* uses SHA???_DIGEST_LENGTH */
  39 #include "crypto/rsa.h"
  40 #include "rsa_local.h"
  41
  42 /*
  43  * The general purpose ASN1 code is not available inside the FIPS provider.
  44  * To remove the dependency RSASSA-PKCS1-v1_5 DigestInfo encodings can be
  45  * treated as a special case by pregenerating the required ASN1 encoding.
  46  * This encoding will also be shared by the default provider.
  47  *
  48  * The EMSA-PKCS1-v1_5 encoding method includes an ASN.1 value of type
  49  * DigestInfo, where the type DigestInfo has the syntax
  50  *
  51  *     DigestInfo ::= SEQUENCE {
  52  *         digestAlgorithm DigestAlgorithm,
  53  *         digest OCTET STRING
  54  *     }
  55  *
  56  *     DigestAlgorithm ::= AlgorithmIdentifier {
  57  *         {PKCS1-v1-5DigestAlgorithms}
  58  *     }
  59  *
  60  * The AlgorithmIdentifier is a sequence containing the digest OID and
  61  * parameters (a value of type NULL).
  62  *
  63  * The ENCODE_DIGESTINFO_SHA() and ENCODE_DIGESTINFO_MD() macros define an
  64  * initialized array containing the DER encoded DigestInfo for the specified
  65  * SHA or MD digest. The content of the OCTET STRING is not included.
  66  * |name| is the digest name.
  67  * |n| is last byte in the encoded OID for the digest.
  68  * |sz| is the digest length in bytes. It must not be greater than 110.
  69  */
  70
  71 #define ASN1_SEQUENCE 0x30
  72 #define ASN1_OCTET_STRING 0x04
  73 #define ASN1_NULL 0x05
  74 #define ASN1_OID 0x06
  75
  76 /* SHA OIDs are of the form: (2 16 840 1 101 3 4 2 |n|) */
  77 #define ENCODE_DIGESTINFO_SHA(name, n, sz)                                     \
  78 static const unsigned char digestinfo_##name##_der[] = {                       \
  79     ASN1_SEQUENCE, 0x11 + sz,                                                  \
  80       ASN1_SEQUENCE, 0x0d,                                                     \
  81         ASN1_OID, 0x09, 2 * 40 + 16, 0x86, 0x48, 1, 101, 3, 4, 2, n,           \
  82         ASN1_NULL, 0x00,                                                       \
  83       ASN1_OCTET_STRING, sz                                                    \
  84 };
  85
  86 /* MD2, MD4 and MD5 OIDs are of the form: (1 2 840 113549 2 |n|) */
  87 #define ENCODE_DIGESTINFO_MD(name, n, sz)                                      \
  88 static const unsigned char digestinfo_##name##_der[] = {                       \
  89     ASN1_SEQUENCE, 0x10 + sz,                                                  \
  90       ASN1_SEQUENCE, 0x0c,                                                     \
  91         ASN1_OID, 0x08, 1 * 40 + 2, 0x86, 0x48, 0x86, 0xf7, 0x0d, 2, n,        \
  92         ASN1_NULL, 0x00,                                                       \
  93       ASN1_OCTET_STRING, sz                                                    \
  94 };
  95
  96 #ifndef FIPS_MODULE
  97 # ifndef OPENSSL_NO_MD2
  98 ENCODE_DIGESTINFO_MD(md2, 0x02, MD2_DIGEST_LENGTH)
  99 # endif
 100 # ifndef OPENSSL_NO_MD4
 101 ENCODE_DIGESTINFO_MD(md4, 0x03, MD4_DIGEST_LENGTH)
 102 # endif
 103 # ifndef OPENSSL_NO_MD5
 104 ENCODE_DIGESTINFO_MD(md5, 0x05, MD5_DIGEST_LENGTH)
 105 # endif
 106 # ifndef OPENSSL_NO_MDC2
 107 /* MDC-2 (2 5 8 3 101) */
 108 static const unsigned char digestinfo_mdc2_der[] = {
 109     ASN1_SEQUENCE, 0x0c + MDC2_DIGEST_LENGTH,
 110       ASN1_SEQUENCE, 0x08,
 111         ASN1_OID, 0x04, 2 * 40 + 5, 8, 3, 101,
 112         ASN1_NULL, 0x00,
 113       ASN1_OCTET_STRING, MDC2_DIGEST_LENGTH
 114 };
 115 # endif
 116 # ifndef OPENSSL_NO_RMD160
 117 /* RIPEMD160 (1 3 36 3 2 1) */
 118 static const unsigned char digestinfo_ripemd160_der[] = {
 119     ASN1_SEQUENCE, 0x0d + RIPEMD160_DIGEST_LENGTH,
 120       ASN1_SEQUENCE, 0x09,
 121         ASN1_OID, 0x05, 1 * 40 + 3, 36, 3, 2, 1,
 122         ASN1_NULL, 0x00,
 123       ASN1_OCTET_STRING, RIPEMD160_DIGEST_LENGTH
 124 };
 125 # endif
 126 #endif /* FIPS_MODULE */
 127
 128 /* SHA-1 (1 3 14 3 2 26) */
 129 static const unsigned char digestinfo_sha1_der[] = {
 130     ASN1_SEQUENCE, 0x0d + SHA_DIGEST_LENGTH,
 131       ASN1_SEQUENCE, 0x09,
 132         ASN1_OID, 0x05, 1 * 40 + 3, 14, 3, 2, 26,
 133         ASN1_NULL, 0x00,
 134       ASN1_OCTET_STRING, SHA_DIGEST_LENGTH
 135 };
 136
 137 ENCODE_DIGESTINFO_SHA(sha256, 0x01, SHA256_DIGEST_LENGTH)
 138 ENCODE_DIGESTINFO_SHA(sha384, 0x02, SHA384_DIGEST_LENGTH)
 139 ENCODE_DIGESTINFO_SHA(sha512, 0x03, SHA512_DIGEST_LENGTH)
 140 ENCODE_DIGESTINFO_SHA(sha224, 0x04, SHA224_DIGEST_LENGTH)
 141 ENCODE_DIGESTINFO_SHA(sha512_224, 0x05, SHA224_DIGEST_LENGTH)
 142 ENCODE_DIGESTINFO_SHA(sha512_256, 0x06, SHA256_DIGEST_LENGTH)
 143 ENCODE_DIGESTINFO_SHA(sha3_224, 0x07, SHA224_DIGEST_LENGTH)
 144 ENCODE_DIGESTINFO_SHA(sha3_256, 0x08, SHA256_DIGEST_LENGTH)
 145 ENCODE_DIGESTINFO_SHA(sha3_384, 0x09, SHA384_DIGEST_LENGTH)
 146 ENCODE_DIGESTINFO_SHA(sha3_512, 0x0a, SHA512_DIGEST_LENGTH)
 147
 148 #define MD_CASE(name)                                                          \
 149     case NID_##name:                                                           \
 150         *len = sizeof(digestinfo_##name##_der);                                \
 151         return digestinfo_##name##_der;
 152
 153 const unsigned char *ossl_rsa_digestinfo_encoding(int md_nid, size_t *len)
 154 {
 155     switch (md_nid) {
 156 #ifndef FIPS_MODULE
 157 # ifndef OPENSSL_NO_MDC2
 158     MD_CASE(mdc2)
 159 # endif
 160 # ifndef OPENSSL_NO_MD2
 161     MD_CASE(md2)
 162 # endif
 163 # ifndef OPENSSL_NO_MD4
 164     MD_CASE(md4)
 165 # endif
 166 # ifndef OPENSSL_NO_MD5
 167     MD_CASE(md5)
 168 # endif
 169 # ifndef OPENSSL_NO_RMD160
 170     MD_CASE(ripemd160)
 171 # endif
 172 #endif /* FIPS_MODULE */
 173     MD_CASE(sha1)
 174     MD_CASE(sha224)
 175     MD_CASE(sha256)
 176     MD_CASE(sha384)
 177     MD_CASE(sha512)
 178     MD_CASE(sha512_224)
 179     MD_CASE(sha512_256)
 180     MD_CASE(sha3_224)
 181     MD_CASE(sha3_256)
 182     MD_CASE(sha3_384)
 183     MD_CASE(sha3_512)
 184     default:
 185         return NULL;
 186     }
 187 }
 188
 189 #define MD_NID_CASE(name, sz)                                                  \
 190     case NID_##name:                                                           \
 191         return sz;
 192
 193 static int digest_sz_from_nid(int nid)
 194 {
 195     switch (nid) {
 196 #ifndef FIPS_MODULE
 197 # ifndef OPENSSL_NO_MDC2
 198     MD_NID_CASE(mdc2, MDC2_DIGEST_LENGTH)
 199 # endif
 200 # ifndef OPENSSL_NO_MD2
 201     MD_NID_CASE(md2, MD2_DIGEST_LENGTH)
 202 # endif
 203 # ifndef OPENSSL_NO_MD4
 204     MD_NID_CASE(md4, MD4_DIGEST_LENGTH)
 205 # endif
 206 # ifndef OPENSSL_NO_MD5
 207     MD_NID_CASE(md5, MD5_DIGEST_LENGTH)
 208 # endif
 209 # ifndef OPENSSL_NO_RMD160
 210     MD_NID_CASE(ripemd160, RIPEMD160_DIGEST_LENGTH)
 211 # endif
 212 #endif /* FIPS_MODULE */
 213     MD_NID_CASE(sha1, SHA_DIGEST_LENGTH)
 214     MD_NID_CASE(sha224, SHA224_DIGEST_LENGTH)
 215     MD_NID_CASE(sha256, SHA256_DIGEST_LENGTH)
 216     MD_NID_CASE(sha384, SHA384_DIGEST_LENGTH)
 217     MD_NID_CASE(sha512, SHA512_DIGEST_LENGTH)
 218     MD_NID_CASE(sha512_224, SHA224_DIGEST_LENGTH)
 219     MD_NID_CASE(sha512_256, SHA256_DIGEST_LENGTH)
 220     MD_NID_CASE(sha3_224, SHA224_DIGEST_LENGTH)
 221     MD_NID_CASE(sha3_256, SHA256_DIGEST_LENGTH)
 222     MD_NID_CASE(sha3_384, SHA384_DIGEST_LENGTH)
 223     MD_NID_CASE(sha3_512, SHA512_DIGEST_LENGTH)
 224     default:
 225         return 0;
 226     }
 227 }
 228
 229
 230 /* Size of an SSL signature: MD5+SHA1 */
 231 #define SSL_SIG_LENGTH  36
 232
 233 /*
 234  * Encodes a DigestInfo prefix of hash |type| and digest |m|, as
 235  * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This
 236  * encodes the DigestInfo (T and tLen) but does not add the padding.
 237  *
 238  * On success, it returns one and sets |*out| to a newly allocated buffer
 239  * containing the result and |*out_len| to its length. The caller must free
 240  * |*out| with OPENSSL_free(). Otherwise, it returns zero.
 241  */
 242 static int encode_pkcs1(unsigned char **out, size_t *out_len, int type,
 243                         const unsigned char *m, size_t m_len)
 244 {
 245     size_t di_prefix_len, dig_info_len;
 246     const unsigned char *di_prefix;
 247     unsigned char *dig_info;
 248
 249     if (type == NID_undef) {
 250         ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_ALGORITHM_TYPE);
 251         return 0;
 252     }
 253     di_prefix = ossl_rsa_digestinfo_encoding(type, &di_prefix_len);
 254     if (di_prefix == NULL) {
 255         ERR_raise(ERR_LIB_RSA,
 256                   RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
 257         return 0;
 258     }
 259     dig_info_len = di_prefix_len + m_len;
 260     dig_info = OPENSSL_malloc(dig_info_len);
 261     if (dig_info == NULL)
 262         return 0;
 263     memcpy(dig_info, di_prefix, di_prefix_len);
 264     memcpy(dig_info + di_prefix_len, m, m_len);
 265
 266     *out = dig_info;
 267     *out_len = dig_info_len;
 268     return 1;
 269 }
 270
 271 int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
 272              unsigned char *sigret, unsigned int *siglen, RSA *rsa)
 273 {
 274     int encrypt_len, ret = 0;
 275     size_t encoded_len = 0;
 276     unsigned char *tmps = NULL;
 277     const unsigned char *encoded = NULL;
 278
 279 #ifndef FIPS_MODULE
 280     if (rsa->meth->rsa_sign != NULL)
 281         return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa) > 0;
 282 #endif /* FIPS_MODULE */
 283
 284     /* Compute the encoded digest. */
 285     if (type == NID_md5_sha1) {
 286         /*
 287          * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
 288          * earlier. It has no DigestInfo wrapper but otherwise is
 289          * RSASSA-PKCS1-v1_5.
 290          */
 291         if (m_len != SSL_SIG_LENGTH) {
 292             ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
 293             return 0;
 294         }
 295         encoded_len = SSL_SIG_LENGTH;
 296         encoded = m;
 297     } else {
 298         if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))
 299             goto err;
 300         encoded = tmps;
 301     }
 302
 303     if (encoded_len + RSA_PKCS1_PADDING_SIZE > (size_t)RSA_size(rsa)) {
 304         ERR_raise(ERR_LIB_RSA, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
 305         goto err;
 306     }
 307     encrypt_len = RSA_private_encrypt((int)encoded_len, encoded, sigret, rsa,
 308                                       RSA_PKCS1_PADDING);
 309     if (encrypt_len <= 0)
 310         goto err;
 311
 312     *siglen = encrypt_len;
 313     ret = 1;
 314
 315 err:
 316     OPENSSL_clear_free(tmps, encoded_len);
 317     return ret;
 318 }
 319
 320 /*
 321  * Verify an RSA signature in |sigbuf| using |rsa|.
 322  * |type| is the NID of the digest algorithm to use.
 323  * If |rm| is NULL, it verifies the signature for digest |m|, otherwise
 324  * it recovers the digest from the signature, writing the digest to |rm| and
 325  * the length to |*prm_len|.
 326  *
 327  * It returns one on successful verification or zero otherwise.
 328  */
 329 int ossl_rsa_verify(int type, const unsigned char *m, unsigned int m_len,
 330                     unsigned char *rm, size_t *prm_len,
 331                     const unsigned char *sigbuf, size_t siglen, RSA *rsa)
 332 {
 333     int len, ret = 0;
 334     size_t decrypt_len, encoded_len = 0;
 335     unsigned char *decrypt_buf = NULL, *encoded = NULL;
 336
 337     if (siglen != (size_t)RSA_size(rsa)) {
 338         ERR_raise(ERR_LIB_RSA, RSA_R_WRONG_SIGNATURE_LENGTH);
 339         return 0;
 340     }
 341
 342     /* Recover the encoded digest. */
 343     decrypt_buf = OPENSSL_malloc(siglen);
 344     if (decrypt_buf == NULL)
 345         goto err;
 346
 347     len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa,
 348                              RSA_PKCS1_PADDING);
 349     if (len <= 0)
 350         goto err;
 351     decrypt_len = len;
 352
 353 #ifndef FIPS_MODULE
 354     if (type == NID_md5_sha1) {
 355         /*
 356          * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
 357          * earlier. It has no DigestInfo wrapper but otherwise is
 358          * RSASSA-PKCS1-v1_5.
 359          */
 360         if (decrypt_len != SSL_SIG_LENGTH) {
 361             ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
 362             goto err;
 363         }
 364
 365         if (rm != NULL) {
 366             memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);
 367             *prm_len = SSL_SIG_LENGTH;
 368         } else {
 369             if (m_len != SSL_SIG_LENGTH) {
 370                 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
 371                 goto err;
 372             }
 373
 374             if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) {
 375                 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
 376                 goto err;
 377             }
 378         }
 379     } else if (type == NID_mdc2 && decrypt_len == 2 + 16
 380                && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) {
 381         /*
 382          * Oddball MDC2 case: signature can be OCTET STRING. check for correct
 383          * tag and length octets.
 384          */
 385         if (rm != NULL) {
 386             memcpy(rm, decrypt_buf + 2, 16);
 387             *prm_len = 16;
 388         } else {
 389             if (m_len != 16) {
 390                 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
 391                 goto err;
 392             }
 393
 394             if (memcmp(m, decrypt_buf + 2, 16) != 0) {
 395                 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
 396                 goto err;
 397             }
 398         }
 399     } else
 400 #endif /* FIPS_MODULE */
 401     {
 402         /*
 403          * If recovering the digest, extract a digest-sized output from the end
 404          * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption
 405          * output as in a standard verification.
 406          */
 407         if (rm != NULL) {
 408             len = digest_sz_from_nid(type);
 409
 410             if (len <= 0)
 411                 goto err;
 412             m_len = (unsigned int)len;
 413             if (m_len > decrypt_len) {
 414                 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_DIGEST_LENGTH);
 415                 goto err;
 416             }
 417             m = decrypt_buf + decrypt_len - m_len;
 418         }
 419
 420         /* Construct the encoded digest and ensure it matches. */
 421         if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))
 422             goto err;
 423
 424         if (encoded_len != decrypt_len
 425                 || memcmp(encoded, decrypt_buf, encoded_len) != 0) {
 426             ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
 427             goto err;
 428         }
 429
 430         /* Output the recovered digest. */
 431         if (rm != NULL) {
 432             memcpy(rm, m, m_len);
 433             *prm_len = m_len;
 434         }
 435     }
 436
 437     ret = 1;
 438
 439 err:
 440     OPENSSL_clear_free(encoded, encoded_len);
 441     OPENSSL_clear_free(decrypt_buf, siglen);
 442     return ret;
 443 }
 444
 445 int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
 446                const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
 447 {
 448
 449     if (rsa->meth->rsa_verify != NULL)
 450         return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa);
 451
 452     return ossl_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
 453 }