crypto/rsa/rsa_sign.c

   1 /*
   2  * Copyright 1995-2019 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 #include <openssl/x509.h>
  22 #include "crypto/x509.h"
  23 #ifndef OPENSSL_NO_MD2
  24 # include <openssl/md2.h> /* uses MD2_DIGEST_LENGTH */
  25 #endif
  26 #ifndef OPENSSL_NO_MD4
  27 # include <openssl/md4.h> /* uses MD4_DIGEST_LENGTH */
  28 #endif
  29 #ifndef OPENSSL_NO_MD5
  30 # include <openssl/md5.h> /* uses MD5_DIGEST_LENGTH */
  31 #endif
  32 #ifndef OPENSSL_NO_MDC2
  33 # include <openssl/mdc2.h> /* uses MDC2_DIGEST_LENGTH */
  34 #endif
  35 #ifndef OPENSSL_NO_RMD160
  36 # include <openssl/ripemd.h> /* uses RIPEMD160_DIGEST_LENGTH */
  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_MODE
  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 3 1 2) */
 118 static const unsigned char digestinfo_ripemd160_der[] = {
 119     ASN1_SEQUENCE, 0x0c + RIPEMD160_DIGEST_LENGTH,
 120       ASN1_SEQUENCE, 0x08,
 121         ASN1_OID, 0x04, 1 * 40 + 3, 36, 3, 3, 1, 2,
 122         ASN1_NULL, 0x00,
 123       ASN1_OCTET_STRING, RIPEMD160_DIGEST_LENGTH
 124 };
 125 # endif
 126 #endif /* FIPS_MODE */
 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 *rsa_digestinfo_encoding(int md_nid, size_t *len)
 154 {
 155     switch (md_nid) {
 156 #ifndef FIPS_MODE
 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_MODE */
 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 /* Size of an SSL signature: MD5+SHA1 */
 190 #define SSL_SIG_LENGTH  36
 191
 192 /*
 193  * Encodes a DigestInfo prefix of hash |type| and digest |m|, as
 194  * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This
 195  * encodes the DigestInfo (T and tLen) but does not add the padding.
 196  *
 197  * On success, it returns one and sets |*out| to a newly allocated buffer
 198  * containing the result and |*out_len| to its length. The caller must free
 199  * |*out| with OPENSSL_free(). Otherwise, it returns zero.
 200  */
 201 static int encode_pkcs1(unsigned char **out, size_t *out_len, int type,
 202                         const unsigned char *m, size_t m_len)
 203 {
 204     size_t di_prefix_len, dig_info_len;
 205     const unsigned char *di_prefix;
 206     unsigned char *dig_info;
 207
 208     if (type == NID_undef) {
 209         RSAerr(RSA_F_ENCODE_PKCS1, RSA_R_UNKNOWN_ALGORITHM_TYPE);
 210         return 0;
 211     }
 212     di_prefix = rsa_digestinfo_encoding(type, &di_prefix_len);
 213     if (di_prefix == NULL) {
 214         RSAerr(RSA_F_ENCODE_PKCS1,
 215                RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
 216         return 0;
 217     }
 218     dig_info_len = di_prefix_len + m_len;
 219     dig_info = OPENSSL_malloc(dig_info_len);
 220     if (dig_info == NULL) {
 221         RSAerr(RSA_F_ENCODE_PKCS1, ERR_R_MALLOC_FAILURE);
 222         return 0;
 223     }
 224     memcpy(dig_info, di_prefix, di_prefix_len);
 225     memcpy(dig_info + di_prefix_len, m, m_len);
 226
 227     *out = dig_info;
 228     *out_len = dig_info_len;
 229     return 1;
 230 }
 231
 232 int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
 233              unsigned char *sigret, unsigned int *siglen, RSA *rsa)
 234 {
 235     int encrypt_len, ret = 0;
 236     size_t encoded_len = 0;
 237     unsigned char *tmps = NULL;
 238     const unsigned char *encoded = NULL;
 239
 240     if (rsa->meth->rsa_sign != NULL)
 241         return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
 242
 243     /* Compute the encoded digest. */
 244     if (type == NID_md5_sha1) {
 245         /*
 246          * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
 247          * earlier. It has no DigestInfo wrapper but otherwise is
 248          * RSASSA-PKCS1-v1_5.
 249          */
 250         if (m_len != SSL_SIG_LENGTH) {
 251             RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
 252             return 0;
 253         }
 254         encoded_len = SSL_SIG_LENGTH;
 255         encoded = m;
 256     } else {
 257         if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))
 258             goto err;
 259         encoded = tmps;
 260     }
 261
 262     if (encoded_len + RSA_PKCS1_PADDING_SIZE > (size_t)RSA_size(rsa)) {
 263         RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
 264         goto err;
 265     }
 266     encrypt_len = RSA_private_encrypt((int)encoded_len, encoded, sigret, rsa,
 267                                       RSA_PKCS1_PADDING);
 268     if (encrypt_len <= 0)
 269         goto err;
 270
 271     *siglen = encrypt_len;
 272     ret = 1;
 273
 274 err:
 275     OPENSSL_clear_free(tmps, encoded_len);
 276     return ret;
 277 }
 278
 279 /*
 280  * Verify an RSA signature in |sigbuf| using |rsa|.
 281  * |type| is the NID of the digest algorithm to use.
 282  * If |rm| is NULL, it verifies the signature for digest |m|, otherwise
 283  * it recovers the digest from the signature, writing the digest to |rm| and
 284  * the length to |*prm_len|.
 285  *
 286  * It returns one on successful verification or zero otherwise.
 287  */
 288 int int_rsa_verify(int type, const unsigned char *m, unsigned int m_len,
 289                    unsigned char *rm, size_t *prm_len,
 290                    const unsigned char *sigbuf, size_t siglen, RSA *rsa)
 291 {
 292     int len, ret = 0;
 293     size_t decrypt_len, encoded_len = 0;
 294     unsigned char *decrypt_buf = NULL, *encoded = NULL;
 295
 296     if (siglen != (size_t)RSA_size(rsa)) {
 297         RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);
 298         return 0;
 299     }
 300
 301     /* Recover the encoded digest. */
 302     decrypt_buf = OPENSSL_malloc(siglen);
 303     if (decrypt_buf == NULL) {
 304         RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);
 305         goto err;
 306     }
 307
 308     len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa,
 309                              RSA_PKCS1_PADDING);
 310     if (len <= 0)
 311         goto err;
 312     decrypt_len = len;
 313
 314     if (type == NID_md5_sha1) {
 315         /*
 316          * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
 317          * earlier. It has no DigestInfo wrapper but otherwise is
 318          * RSASSA-PKCS1-v1_5.
 319          */
 320         if (decrypt_len != SSL_SIG_LENGTH) {
 321             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 322             goto err;
 323         }
 324
 325         if (rm != NULL) {
 326             memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);
 327             *prm_len = SSL_SIG_LENGTH;
 328         } else {
 329             if (m_len != SSL_SIG_LENGTH) {
 330                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
 331                 goto err;
 332             }
 333
 334             if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) {
 335                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 336                 goto err;
 337             }
 338         }
 339     } else if (type == NID_mdc2 && decrypt_len == 2 + 16
 340                && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) {
 341         /*
 342          * Oddball MDC2 case: signature can be OCTET STRING. check for correct
 343          * tag and length octets.
 344          */
 345         if (rm != NULL) {
 346             memcpy(rm, decrypt_buf + 2, 16);
 347             *prm_len = 16;
 348         } else {
 349             if (m_len != 16) {
 350                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
 351                 goto err;
 352             }
 353
 354             if (memcmp(m, decrypt_buf + 2, 16) != 0) {
 355                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 356                 goto err;
 357             }
 358         }
 359     } else {
 360         /*
 361          * If recovering the digest, extract a digest-sized output from the end
 362          * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption
 363          * output as in a standard verification.
 364          */
 365         if (rm != NULL) {
 366             const EVP_MD *md = EVP_get_digestbynid(type);
 367             if (md == NULL) {
 368                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_UNKNOWN_ALGORITHM_TYPE);
 369                 goto err;
 370             }
 371
 372             len = EVP_MD_size(md);
 373             if (len <= 0)
 374                 goto err;
 375             m_len = (unsigned int)len;
 376             if (m_len > decrypt_len) {
 377                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);
 378                 goto err;
 379             }
 380             m = decrypt_buf + decrypt_len - m_len;
 381         }
 382
 383         /* Construct the encoded digest and ensure it matches. */
 384         if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))
 385             goto err;
 386
 387         if (encoded_len != decrypt_len
 388                 || memcmp(encoded, decrypt_buf, encoded_len) != 0) {
 389             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 390             goto err;
 391         }
 392
 393         /* Output the recovered digest. */
 394         if (rm != NULL) {
 395             memcpy(rm, m, m_len);
 396             *prm_len = m_len;
 397         }
 398     }
 399
 400     ret = 1;
 401
 402 err:
 403     OPENSSL_clear_free(encoded, encoded_len);
 404     OPENSSL_clear_free(decrypt_buf, siglen);
 405     return ret;
 406 }
 407
 408 int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
 409                const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
 410 {
 411
 412     if (rsa->meth->rsa_verify != NULL)
 413         return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa);
 414
 415     return int_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
 416 }