/*
* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/objects.h>
#include <openssl/x509.h>
#include "crypto/x509.h"
#include "rsa_local.h"
/* Size of an SSL signature: MD5+SHA1 */
#define SSL_SIG_LENGTH 36
/*
* encode_pkcs1 encodes a DigestInfo prefix of hash |type| and digest |m|, as
* described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This
* encodes the DigestInfo (T and tLen) but does not add the padding.
*
* On success, it returns one and sets |*out| to a newly allocated buffer
* containing the result and |*out_len| to its length. The caller must free
* |*out| with |OPENSSL_free|. Otherwise, it returns zero.
*/
static int encode_pkcs1(unsigned char **out, int *out_len, int type,
const unsigned char *m, unsigned int m_len)
{
X509_SIG sig;
X509_ALGOR algor;
ASN1_TYPE parameter;
ASN1_OCTET_STRING digest;
uint8_t *der = NULL;
int len;
sig.algor = &algor;
sig.algor->algorithm = OBJ_nid2obj(type);
if (sig.algor->algorithm == NULL) {
RSAerr(RSA_F_ENCODE_PKCS1, RSA_R_UNKNOWN_ALGORITHM_TYPE);
return 0;
}
if (OBJ_length(sig.algor->algorithm) == 0) {
RSAerr(RSA_F_ENCODE_PKCS1,
RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
return 0;
}
parameter.type = V_ASN1_NULL;
parameter.value.ptr = NULL;
sig.algor->parameter = ¶meter;
sig.digest = &digest;
sig.digest->data = (unsigned char *)m;
sig.digest->length = m_len;
len = i2d_X509_SIG(&sig, &der);
if (len < 0)
return 0;
*out = der;
*out_len = len;
return 1;
}
int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
unsigned char *sigret, unsigned int *siglen, RSA *rsa)
{
int encrypt_len, encoded_len = 0, ret = 0;
unsigned char *tmps = NULL;
const unsigned char *encoded = NULL;
#ifdef OPENSSL_FIPS
if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)
&& !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {
RSAerr(RSA_F_RSA_SIGN, RSA_R_NON_FIPS_RSA_METHOD);
return 0;
}
#endif
if (rsa->meth->rsa_sign) {
return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
}
/* Compute the encoded digest. */
if (type == NID_md5_sha1) {
/*
* NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
* earlier. It has no DigestInfo wrapper but otherwise is
* RSASSA-PKCS1-v1_5.
*/
if (m_len != SSL_SIG_LENGTH) {
RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
return 0;
}
encoded_len = SSL_SIG_LENGTH;
encoded = m;
} else {
if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))
goto err;
encoded = tmps;
}
if (encoded_len > RSA_size(rsa) - RSA_PKCS1_PADDING_SIZE) {
RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
goto err;
}
/* NB: call underlying method directly to avoid FIPS blocking */
encrypt_len = rsa->meth->rsa_priv_enc ? rsa->meth->rsa_priv_enc(encoded_len, encoded, sigret, rsa,
RSA_PKCS1_PADDING) : 0;
if (encrypt_len <= 0)
goto err;
*siglen = encrypt_len;
ret = 1;
err:
OPENSSL_clear_free(tmps, (size_t)encoded_len);
return ret;
}
/*
* int_rsa_verify verifies an RSA signature in |sigbuf| using |rsa|. It may be
* called in two modes. If |rm| is NULL, it verifies the signature for digest
* |m|. Otherwise, it recovers the digest from the signature, writing the digest
* to |rm| and the length to |*prm_len|. |type| is the NID of the digest
* algorithm to use. It returns one on successful verification and zero
* otherwise.
*/
int int_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)
{
int decrypt_len, ret = 0, encoded_len = 0;
unsigned char *decrypt_buf = NULL, *encoded = NULL;
if (siglen != (size_t)RSA_size(rsa)) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);
return 0;
}
/* Recover the encoded digest. */
decrypt_buf = OPENSSL_malloc(siglen);
if (decrypt_buf == NULL) {
RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);
goto err;
}
decrypt_len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa,
RSA_PKCS1_PADDING);
if (decrypt_len <= 0)
goto err;
if (type == NID_md5_sha1) {
/*
* NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and
* earlier. It has no DigestInfo wrapper but otherwise is
* RSASSA-PKCS1-v1_5.
*/
if (decrypt_len != SSL_SIG_LENGTH) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
goto err;
}
if (rm != NULL) {
memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);
*prm_len = SSL_SIG_LENGTH;
} else {
if (m_len != SSL_SIG_LENGTH) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
goto err;
}
if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
goto err;
}
}
} else if (type == NID_mdc2 && decrypt_len == 2 + 16
&& decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) {
/*
* Oddball MDC2 case: signature can be OCTET STRING. check for correct
* tag and length octets.
*/
if (rm != NULL) {
memcpy(rm, decrypt_buf + 2, 16);
*prm_len = 16;
} else {
if (m_len != 16) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
goto err;
}
if (memcmp(m, decrypt_buf + 2, 16) != 0) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
goto err;
}
}
} else {
/*
* If recovering the digest, extract a digest-sized output from the end
* of |decrypt_buf| for |encode_pkcs1|, then compare the decryption
* output as in a standard verification.
*/
if (rm != NULL) {
const EVP_MD *md = EVP_get_digestbynid(type);
if (md == NULL) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_UNKNOWN_ALGORITHM_TYPE);
goto err;
}
m_len = EVP_MD_size(md);
if (m_len > (size_t)decrypt_len) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);
goto err;
}
m = decrypt_buf + decrypt_len - m_len;
}
/* Construct the encoded digest and ensure it matches. */
if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))
goto err;
if (encoded_len != decrypt_len
|| memcmp(encoded, decrypt_buf, encoded_len) != 0) {
RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
goto err;
}
/* Output the recovered digest. */
if (rm != NULL) {
memcpy(rm, m, m_len);
*prm_len = m_len;
}
}
ret = 1;
err:
OPENSSL_clear_free(encoded, (size_t)encoded_len);
OPENSSL_clear_free(decrypt_buf, siglen);
return ret;
}
int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
{
if (rsa->meth->rsa_verify) {
return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa);
}
return int_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
}