277 lines
8.9 KiB
C
Executable File
277 lines
8.9 KiB
C
Executable File
/* $OpenBSD: rsa_sign.c,v 1.31 2018/09/05 00:55:33 djm Exp $ */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include <stdio.h>
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#include <string.h>
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#include <openssl/bn.h>
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#include <openssl/err.h>
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#include <openssl/objects.h>
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#include <openssl/rsa.h>
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#include <openssl/x509.h>
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#include "rsa_locl.h"
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/* Size of an SSL signature: MD5+SHA1 */
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#define SSL_SIG_LENGTH 36
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static int encode_pkcs1(unsigned char **, int *, int , const unsigned char *,
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unsigned int);
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/*
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* encode_pkcs1 encodes a DigestInfo prefix of hash `type' and digest `m', as
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* described in EMSA-PKCS-v1_5-ENCODE, RFC 8017 section 9. step 2. This
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* encodes the DigestInfo (T and tLen) but does not add the padding.
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*
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* On success, it returns one and sets `*out' to a newly allocated buffer
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* containing the result and `*out_len' to its length. Freeing `*out' is
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* the caller's responsibility. Failure is indicated by zero.
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*/
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static int
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encode_pkcs1(unsigned char **out, int *out_len, int type,
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const unsigned char *m, unsigned int m_len)
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{
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X509_SIG sig;
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X509_ALGOR algor;
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ASN1_TYPE parameter;
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ASN1_OCTET_STRING digest;
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uint8_t *der = NULL;
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int len;
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sig.algor = &algor;
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if ((sig.algor->algorithm = OBJ_nid2obj(type)) == NULL) {
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RSAerror(RSA_R_UNKNOWN_ALGORITHM_TYPE);
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return 0;
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}
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if (sig.algor->algorithm->length == 0) {
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RSAerror(
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RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
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return 0;
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}
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parameter.type = V_ASN1_NULL;
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parameter.value.ptr = NULL;
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sig.algor->parameter = ¶meter;
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sig.digest = &digest;
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sig.digest->data = (unsigned char*)m; /* TMP UGLY CAST */
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sig.digest->length = m_len;
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if ((len = i2d_X509_SIG(&sig, &der)) < 0)
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return 0;
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*out = der;
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*out_len = len;
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return 1;
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}
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int
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RSA_sign(int type, const unsigned char *m, unsigned int m_len,
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unsigned char *sigret, unsigned int *siglen, RSA *rsa)
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{
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const unsigned char *encoded = NULL;
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unsigned char *tmps = NULL;
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int encrypt_len, encoded_len = 0, ret = 0;
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if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_sign != NULL)
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return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
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/* Compute the encoded digest. */
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if (type == NID_md5_sha1) {
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/*
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* NID_md5_sha1 corresponds to the MD5/SHA1 combination in
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* TLS 1.1 and earlier. It has no DigestInfo wrapper but
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* otherwise is RSASSA-PKCS-v1.5.
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*/
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if (m_len != SSL_SIG_LENGTH) {
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RSAerror(RSA_R_INVALID_DIGEST_LENGTH);
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return 0;
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}
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encoded_len = SSL_SIG_LENGTH;
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encoded = m;
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} else {
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if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))
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goto err;
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encoded = tmps;
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}
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if (encoded_len > RSA_size(rsa) - RSA_PKCS1_PADDING_SIZE) {
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RSAerror(RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
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goto err;
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}
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if ((encrypt_len = RSA_private_encrypt(encoded_len, encoded, sigret,
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rsa, RSA_PKCS1_PADDING)) <= 0)
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goto err;
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*siglen = encrypt_len;
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ret = 1;
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err:
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freezero(tmps, (size_t)encoded_len);
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return (ret);
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}
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/*
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* int_rsa_verify verifies an RSA signature in `sigbuf' using `rsa'. It may be
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* called in two modes. If `rm' is NULL, it verifies the signature for the
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* digest `m'. Otherwise, it recovers the digest from the signature, writing the
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* digest to `rm' and the length to `*prm_len'. `type' is the NID of the digest
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* algorithm to use. It returns one on successful verification and zero
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* otherwise.
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*/
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int
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int_rsa_verify(int type, const unsigned char *m, unsigned int m_len,
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unsigned char *rm, size_t *prm_len, const unsigned char *sigbuf,
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size_t siglen, RSA *rsa)
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{
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unsigned char *decrypt_buf, *encoded = NULL;
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int decrypt_len, encoded_len = 0, ret = 0;
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if (siglen != (size_t)RSA_size(rsa)) {
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RSAerror(RSA_R_WRONG_SIGNATURE_LENGTH);
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return 0;
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}
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/* Recover the encoded digest. */
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if ((decrypt_buf = malloc(siglen)) == NULL) {
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RSAerror(ERR_R_MALLOC_FAILURE);
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goto err;
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}
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if ((decrypt_len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf,
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rsa, RSA_PKCS1_PADDING)) <= 0)
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goto err;
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if (type == NID_md5_sha1) {
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/*
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* NID_md5_sha1 corresponds to the MD5/SHA1 combination in
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* TLS 1.1 and earlier. It has no DigestInfo wrapper but
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* otherwise is RSASSA-PKCS1-v1_5.
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*/
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if (decrypt_len != SSL_SIG_LENGTH) {
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RSAerror(RSA_R_INVALID_DIGEST_LENGTH);
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goto err;
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}
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if (rm != NULL) {
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memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);
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*prm_len = SSL_SIG_LENGTH;
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} else {
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if (m_len != SSL_SIG_LENGTH) {
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RSAerror(RSA_R_INVALID_MESSAGE_LENGTH);
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goto err;
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}
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if (timingsafe_bcmp(decrypt_buf,
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m, SSL_SIG_LENGTH) != 0) {
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RSAerror(RSA_R_BAD_SIGNATURE);
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goto err;
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}
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}
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} else {
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/*
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* If recovering the digest, extract a digest-sized output from
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* the end of `decrypt_buf' for `encode_pkcs1', then compare the
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* decryption output as in a standard verification.
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*/
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if (rm != NULL) {
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const EVP_MD *md;
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if ((md = EVP_get_digestbynid(type)) == NULL) {
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RSAerror(RSA_R_UNKNOWN_ALGORITHM_TYPE);
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goto err;
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}
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if ((m_len = EVP_MD_size(md)) > (size_t)decrypt_len) {
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RSAerror(RSA_R_INVALID_DIGEST_LENGTH);
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goto err;
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}
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m = decrypt_buf + decrypt_len - m_len;
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}
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/* Construct the encoded digest and ensure it matches */
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if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))
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goto err;
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if (encoded_len != decrypt_len ||
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timingsafe_bcmp(encoded, decrypt_buf, encoded_len) != 0) {
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RSAerror(RSA_R_BAD_SIGNATURE);
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goto err;
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}
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/* Output the recovered digest. */
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if (rm != NULL) {
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memcpy(rm, m, m_len);
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*prm_len = m_len;
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}
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}
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ret = 1;
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err:
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freezero(encoded, (size_t)encoded_len);
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freezero(decrypt_buf, siglen);
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return ret;
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}
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int
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RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,
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const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
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{
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if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify)
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return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen,
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rsa);
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return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
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}
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