1 /*
2 * Copyright 1995-2025 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 /*
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 #ifndef OPENSSL_NO_SM3
38 #include "internal/sm3.h" /* uses SM3_DIGEST_LENGTH */
39 #endif
40 #endif
41 #include <openssl/sha.h> /* uses SHA???_DIGEST_LENGTH */
42 #include "crypto/rsa.h"
43 #include "rsa_local.h"
44
45 /*
46 * The general purpose ASN1 code is not available inside the FIPS provider.
47 * To remove the dependency RSASSA-PKCS1-v1_5 DigestInfo encodings can be
48 * treated as a special case by pregenerating the required ASN1 encoding.
49 * This encoding will also be shared by the default provider.
50 *
51 * The EMSA-PKCS1-v1_5 encoding method includes an ASN.1 value of type
52 * DigestInfo, where the type DigestInfo has the syntax
53 *
54 * DigestInfo ::= SEQUENCE {
55 * digestAlgorithm DigestAlgorithm,
56 * digest OCTET STRING
57 * }
58 *
59 * DigestAlgorithm ::= AlgorithmIdentifier {
60 * {PKCS1-v1-5DigestAlgorithms}
61 * }
62 *
63 * The AlgorithmIdentifier is a sequence containing the digest OID and
64 * parameters (a value of type NULL).
65 *
66 * The ENCODE_DIGESTINFO_SHA() and ENCODE_DIGESTINFO_MD() macros define an
67 * initialized array containing the DER encoded DigestInfo for the specified
68 * SHA or MD digest. The content of the OCTET STRING is not included.
69 * |name| is the digest name.
70 * |n| is last byte in the encoded OID for the digest.
71 * |sz| is the digest length in bytes. It must not be greater than 110.
72 */
73
74 #define ASN1_SEQUENCE 0x30
75 #define ASN1_OCTET_STRING 0x04
76 #define ASN1_NULL 0x05
77 #define ASN1_OID 0x06
78
79 /* SHA OIDs are of the form: (2 16 840 1 101 3 4 2 |n|) */
80 #define ENCODE_DIGESTINFO_SHA(name, n, sz) \
81 static const unsigned char digestinfo_##name##_der[] = { \
82 ASN1_SEQUENCE, 0x11 + sz, \
83 ASN1_SEQUENCE, 0x0d, \
84 ASN1_OID, 0x09, 2 * 40 + 16, 0x86, 0x48, 1, 101, 3, 4, 2, n, \
85 ASN1_NULL, 0x00, \
86 ASN1_OCTET_STRING, sz \
87 };
88
89 /* MD2, MD4 and MD5 OIDs are of the form: (1 2 840 113549 2 |n|) */
90 #define ENCODE_DIGESTINFO_MD(name, n, sz) \
91 static const unsigned char digestinfo_##name##_der[] = { \
92 ASN1_SEQUENCE, 0x10 + sz, \
93 ASN1_SEQUENCE, 0x0c, \
94 ASN1_OID, 0x08, 1 * 40 + 2, 0x86, 0x48, 0x86, 0xf7, 0x0d, 2, n, \
95 ASN1_NULL, 0x00, \
96 ASN1_OCTET_STRING, sz \
97 };
98
99 #ifndef FIPS_MODULE
100 #ifndef OPENSSL_NO_MD2
101 ENCODE_DIGESTINFO_MD(md2, 0x02, MD2_DIGEST_LENGTH)
102 #endif
103 #ifndef OPENSSL_NO_MD4
104 ENCODE_DIGESTINFO_MD(md4, 0x03, MD4_DIGEST_LENGTH)
105 #endif
106 #ifndef OPENSSL_NO_MD5
107 ENCODE_DIGESTINFO_MD(md5, 0x05, MD5_DIGEST_LENGTH)
108 #endif
109 #ifndef OPENSSL_NO_MDC2
110 /* MDC-2 (2 5 8 3 101) */
111 static const unsigned char digestinfo_mdc2_der[] = {
112 ASN1_SEQUENCE, 0x0c + MDC2_DIGEST_LENGTH,
113 ASN1_SEQUENCE, 0x08,
114 ASN1_OID, 0x04, 2 * 40 + 5, 8, 3, 101,
115 ASN1_NULL, 0x00,
116 ASN1_OCTET_STRING, MDC2_DIGEST_LENGTH
117 };
118 #endif
119 #ifndef OPENSSL_NO_RMD160
120 /* RIPEMD160 (1 3 36 3 2 1) */
121 static const unsigned char digestinfo_ripemd160_der[] = {
122 ASN1_SEQUENCE, 0x0d + RIPEMD160_DIGEST_LENGTH,
123 ASN1_SEQUENCE, 0x09,
124 ASN1_OID, 0x05, 1 * 40 + 3, 36, 3, 2, 1,
125 ASN1_NULL, 0x00,
126 ASN1_OCTET_STRING, RIPEMD160_DIGEST_LENGTH
127 };
128 #endif
129 #ifndef OPENSSL_NO_SM3
130 /* SM3 (1 2 156 10197 1 401) */
131 static const unsigned char digestinfo_sm3_der[] = {
132 ASN1_SEQUENCE, 0x10 + SM3_DIGEST_LENGTH,
133 ASN1_SEQUENCE, 0x0c,
134 ASN1_OID, 0x08, 1 * 40 + 2, 0x81, 0x1c, 0xcf, 0x55, 1, 0x83, 0x78,
135 ASN1_NULL, 0x00,
136 ASN1_OCTET_STRING, SM3_DIGEST_LENGTH
137 };
138 #endif
139 #endif /* FIPS_MODULE */
140
141 /* SHA-1 (1 3 14 3 2 26) */
142 static const unsigned char digestinfo_sha1_der[] = {
143 ASN1_SEQUENCE, 0x0d + SHA_DIGEST_LENGTH,
144 ASN1_SEQUENCE, 0x09,
145 ASN1_OID, 0x05, 1 * 40 + 3, 14, 3, 2, 26,
146 ASN1_NULL, 0x00,
147 ASN1_OCTET_STRING, SHA_DIGEST_LENGTH
148 };
149
150 ENCODE_DIGESTINFO_SHA(sha256, 0x01, SHA256_DIGEST_LENGTH)
151 ENCODE_DIGESTINFO_SHA(sha384, 0x02, SHA384_DIGEST_LENGTH)
152 ENCODE_DIGESTINFO_SHA(sha512, 0x03, SHA512_DIGEST_LENGTH)
153 ENCODE_DIGESTINFO_SHA(sha224, 0x04, SHA224_DIGEST_LENGTH)
154 ENCODE_DIGESTINFO_SHA(sha512_224, 0x05, SHA224_DIGEST_LENGTH)
155 ENCODE_DIGESTINFO_SHA(sha512_256, 0x06, SHA256_DIGEST_LENGTH)
156 ENCODE_DIGESTINFO_SHA(sha3_224, 0x07, SHA224_DIGEST_LENGTH)
157 ENCODE_DIGESTINFO_SHA(sha3_256, 0x08, SHA256_DIGEST_LENGTH)
158 ENCODE_DIGESTINFO_SHA(sha3_384, 0x09, SHA384_DIGEST_LENGTH)
159 ENCODE_DIGESTINFO_SHA(sha3_512, 0x0a, SHA512_DIGEST_LENGTH)
160
161 #define MD_CASE(name) \
162 case NID_##name: \
163 *len = sizeof(digestinfo_##name##_der); \
164 return digestinfo_##name##_der;
165
ossl_rsa_digestinfo_encoding(int md_nid,size_t * len)166 const unsigned char *ossl_rsa_digestinfo_encoding(int md_nid, size_t *len)
167 {
168 switch (md_nid) {
169 #ifndef FIPS_MODULE
170 #ifndef OPENSSL_NO_MDC2
171 MD_CASE(mdc2)
172 #endif
173 #ifndef OPENSSL_NO_MD2
174 MD_CASE(md2)
175 #endif
176 #ifndef OPENSSL_NO_MD4
177 MD_CASE(md4)
178 #endif
179 #ifndef OPENSSL_NO_MD5
180 MD_CASE(md5)
181 #endif
182 #ifndef OPENSSL_NO_RMD160
183 MD_CASE(ripemd160)
184 #endif
185 #ifndef OPENSSL_NO_SM3
186 MD_CASE(sm3)
187 #endif
188 #endif /* FIPS_MODULE */
189 MD_CASE(sha1)
190 MD_CASE(sha224)
191 MD_CASE(sha256)
192 MD_CASE(sha384)
193 MD_CASE(sha512)
194 MD_CASE(sha512_224)
195 MD_CASE(sha512_256)
196 MD_CASE(sha3_224)
197 MD_CASE(sha3_256)
198 MD_CASE(sha3_384)
199 MD_CASE(sha3_512)
200 default:
201 return NULL;
202 }
203 }
204
205 #define MD_NID_CASE(name, sz) \
206 case NID_##name: \
207 return sz;
208
digest_sz_from_nid(int nid)209 static int digest_sz_from_nid(int nid)
210 {
211 switch (nid) {
212 #ifndef FIPS_MODULE
213 #ifndef OPENSSL_NO_MDC2
214 MD_NID_CASE(mdc2, MDC2_DIGEST_LENGTH)
215 #endif
216 #ifndef OPENSSL_NO_MD2
217 MD_NID_CASE(md2, MD2_DIGEST_LENGTH)
218 #endif
219 #ifndef OPENSSL_NO_MD4
220 MD_NID_CASE(md4, MD4_DIGEST_LENGTH)
221 #endif
222 #ifndef OPENSSL_NO_MD5
223 MD_NID_CASE(md5, MD5_DIGEST_LENGTH)
224 #endif
225 #ifndef OPENSSL_NO_RMD160
226 MD_NID_CASE(ripemd160, RIPEMD160_DIGEST_LENGTH)
227 #endif
228 #endif /* FIPS_MODULE */
229 MD_NID_CASE(sha1, SHA_DIGEST_LENGTH)
230 MD_NID_CASE(sha224, SHA224_DIGEST_LENGTH)
231 MD_NID_CASE(sha256, SHA256_DIGEST_LENGTH)
232 MD_NID_CASE(sha384, SHA384_DIGEST_LENGTH)
233 MD_NID_CASE(sha512, SHA512_DIGEST_LENGTH)
234 MD_NID_CASE(sha512_224, SHA224_DIGEST_LENGTH)
235 MD_NID_CASE(sha512_256, SHA256_DIGEST_LENGTH)
236 MD_NID_CASE(sha3_224, SHA224_DIGEST_LENGTH)
237 MD_NID_CASE(sha3_256, SHA256_DIGEST_LENGTH)
238 MD_NID_CASE(sha3_384, SHA384_DIGEST_LENGTH)
239 MD_NID_CASE(sha3_512, SHA512_DIGEST_LENGTH)
240 default:
241 return 0;
242 }
243 }
244
245 /* Size of an SSL signature: MD5+SHA1 */
246 #define SSL_SIG_LENGTH 36
247
248 /*
249 * Encodes a DigestInfo prefix of hash |type| and digest |m|, as
250 * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This
251 * encodes the DigestInfo (T and tLen) but does not add the padding.
252 *
253 * On success, it returns one and sets |*out| to a newly allocated buffer
254 * containing the result and |*out_len| to its length. The caller must free
255 * |*out| with OPENSSL_free(). Otherwise, it returns zero.
256 */
encode_pkcs1(unsigned char ** out,size_t * out_len,int type,const unsigned char * m,size_t m_len)257 static int encode_pkcs1(unsigned char **out, size_t *out_len, int type,
258 const unsigned char *m, size_t m_len)
259 {
260 size_t di_prefix_len, dig_info_len;
261 const unsigned char *di_prefix;
262 unsigned char *dig_info;
263
264 if (type == NID_undef) {
265 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_ALGORITHM_TYPE);
266 return 0;
267 }
268 di_prefix = ossl_rsa_digestinfo_encoding(type, &di_prefix_len);
269 if (di_prefix == NULL) {
270 ERR_raise(ERR_LIB_RSA,
271 RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
272 return 0;
273 }
274 dig_info_len = di_prefix_len + m_len;
275 dig_info = OPENSSL_malloc(dig_info_len);
276 if (dig_info == NULL)
277 return 0;
278 memcpy(dig_info, di_prefix, di_prefix_len);
279 memcpy(dig_info + di_prefix_len, m, m_len);
280
281 *out = dig_info;
282 *out_len = dig_info_len;
283 return 1;
284 }
285
RSA_sign(int type,const unsigned char * m,unsigned int m_len,unsigned char * sigret,unsigned int * siglen,RSA * rsa)286 int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
287 unsigned char *sigret, unsigned int *siglen, RSA *rsa)
288 {
289 int encrypt_len, ret = 0;
290 size_t encoded_len = 0;
291 unsigned char *tmps = NULL;
292 const unsigned char *encoded = NULL;
293
294 #ifndef FIPS_MODULE
295 if (rsa->meth->rsa_sign != NULL)
296 return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa) > 0;
297 #endif /* FIPS_MODULE */
298
299 /* Compute the encoded digest. */
300 if (type == NID_md5_sha1) {
301 /*
302 * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
303 * earlier. It has no DigestInfo wrapper but otherwise is
304 * RSASSA-PKCS1-v1_5.
305 */
306 if (m_len != SSL_SIG_LENGTH) {
307 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
308 return 0;
309 }
310 encoded_len = SSL_SIG_LENGTH;
311 encoded = m;
312 } else {
313 if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))
314 goto err;
315 encoded = tmps;
316 }
317
318 if (encoded_len + RSA_PKCS1_PADDING_SIZE > (size_t)RSA_size(rsa)) {
319 ERR_raise(ERR_LIB_RSA, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
320 goto err;
321 }
322 encrypt_len = RSA_private_encrypt((int)encoded_len, encoded, sigret, rsa,
323 RSA_PKCS1_PADDING);
324 if (encrypt_len <= 0)
325 goto err;
326
327 *siglen = encrypt_len;
328 ret = 1;
329
330 err:
331 OPENSSL_clear_free(tmps, encoded_len);
332 return ret;
333 }
334
335 /*
336 * Verify an RSA signature in |sigbuf| using |rsa|.
337 * |type| is the NID of the digest algorithm to use.
338 * If |rm| is NULL, it verifies the signature for digest |m|, otherwise
339 * it recovers the digest from the signature, writing the digest to |rm| and
340 * the length to |*prm_len|.
341 *
342 * It returns one on successful verification or zero otherwise.
343 */
ossl_rsa_verify(int type,const unsigned char * m,unsigned int m_len,unsigned char * rm,size_t * prm_len,const unsigned char * sigbuf,size_t siglen,RSA * rsa)344 int ossl_rsa_verify(int type, const unsigned char *m, unsigned int m_len,
345 unsigned char *rm, size_t *prm_len,
346 const unsigned char *sigbuf, size_t siglen, RSA *rsa)
347 {
348 int len, ret = 0;
349 size_t decrypt_len, encoded_len = 0;
350 unsigned char *decrypt_buf = NULL, *encoded = NULL;
351
352 if (siglen != (size_t)RSA_size(rsa)) {
353 ERR_raise(ERR_LIB_RSA, RSA_R_WRONG_SIGNATURE_LENGTH);
354 return 0;
355 }
356
357 /* Recover the encoded digest. */
358 decrypt_buf = OPENSSL_malloc(siglen);
359 if (decrypt_buf == NULL)
360 goto err;
361
362 len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa,
363 RSA_PKCS1_PADDING);
364 if (len <= 0)
365 goto err;
366 decrypt_len = len;
367
368 #ifndef FIPS_MODULE
369 if (type == NID_md5_sha1) {
370 /*
371 * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
372 * earlier. It has no DigestInfo wrapper but otherwise is
373 * RSASSA-PKCS1-v1_5.
374 */
375 if (decrypt_len != SSL_SIG_LENGTH) {
376 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
377 goto err;
378 }
379
380 if (rm != NULL) {
381 memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);
382 *prm_len = SSL_SIG_LENGTH;
383 } else {
384 if (m_len != SSL_SIG_LENGTH) {
385 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
386 goto err;
387 }
388
389 if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) {
390 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
391 goto err;
392 }
393 }
394 } else if (type == NID_mdc2 && decrypt_len == 2 + 16
395 && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) {
396 /*
397 * Oddball MDC2 case: signature can be OCTET STRING. check for correct
398 * tag and length octets.
399 */
400 if (rm != NULL) {
401 memcpy(rm, decrypt_buf + 2, 16);
402 *prm_len = 16;
403 } else {
404 if (m_len != 16) {
405 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);
406 goto err;
407 }
408
409 if (memcmp(m, decrypt_buf + 2, 16) != 0) {
410 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
411 goto err;
412 }
413 }
414 } else
415 #endif /* FIPS_MODULE */
416 {
417 /*
418 * If recovering the digest, extract a digest-sized output from the end
419 * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption
420 * output as in a standard verification.
421 */
422 if (rm != NULL) {
423 len = digest_sz_from_nid(type);
424
425 if (len <= 0)
426 goto err;
427 m_len = (unsigned int)len;
428 if (m_len > decrypt_len) {
429 ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_DIGEST_LENGTH);
430 goto err;
431 }
432 m = decrypt_buf + decrypt_len - m_len;
433 }
434
435 /* Construct the encoded digest and ensure it matches. */
436 if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))
437 goto err;
438
439 if (encoded_len != decrypt_len
440 || memcmp(encoded, decrypt_buf, encoded_len) != 0) {
441 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);
442 goto err;
443 }
444
445 /* Output the recovered digest. */
446 if (rm != NULL) {
447 memcpy(rm, m, m_len);
448 *prm_len = m_len;
449 }
450 }
451
452 ret = 1;
453
454 err:
455 OPENSSL_clear_free(encoded, encoded_len);
456 OPENSSL_clear_free(decrypt_buf, siglen);
457 return ret;
458 }
459
RSA_verify(int type,const unsigned char * m,unsigned int m_len,const unsigned char * sigbuf,unsigned int siglen,RSA * rsa)460 int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
461 const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
462 {
463
464 if (rsa->meth->rsa_verify != NULL)
465 return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa);
466
467 return ossl_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
468 }
469