ct_vfy.c
/*
* Written by Rob Stradling (rob@comodo.com) and Stephen Henson
* (steve@openssl.org) for the OpenSSL project 2014.
*/
/* ====================================================================
* Copyright (c) 2014 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* licensing@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#include <string.h>
#include <openssl/ct.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include "ct_locl.h"
typedef enum sct_signature_type_t {
SIGNATURE_TYPE_NOT_SET = -1,
SIGNATURE_TYPE_CERT_TIMESTAMP,
SIGNATURE_TYPE_TREE_HASH
} SCT_SIGNATURE_TYPE;
/*
* Update encoding for SCT signature verification/generation to supplied
* EVP_MD_CTX.
*/
static int sct_ctx_update(EVP_MD_CTX *ctx, const SCT_CTX *sctx, const SCT *sct)
{
unsigned char tmpbuf[12];
unsigned char *p, *der;
size_t derlen;
/*+
* digitally-signed struct {
* (1 byte) Version sct_version;
* (1 byte) SignatureType signature_type = certificate_timestamp;
* (8 bytes) uint64 timestamp;
* (2 bytes) LogEntryType entry_type;
* (? bytes) select(entry_type) {
* case x509_entry: ASN.1Cert;
* case precert_entry: PreCert;
* } signed_entry;
* (2 bytes + sct->ext_len) CtExtensions extensions;
* }
*/
if (sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET)
return 0;
if (sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)
return 0;
p = tmpbuf;
*p++ = sct->version;
*p++ = SIGNATURE_TYPE_CERT_TIMESTAMP;
l2n8(sct->timestamp, p);
s2n(sct->entry_type, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, p - tmpbuf))
return 0;
if (sct->entry_type == CT_LOG_ENTRY_TYPE_X509) {
der = sctx->certder;
derlen = sctx->certderlen;
} else {
if (!EVP_DigestUpdate(ctx, sctx->ihash, sctx->ihashlen))
return 0;
der = sctx->preder;
derlen = sctx->prederlen;
}
/* If no encoding available, fatal error */
if (der == NULL)
return 0;
/* Include length first */
p = tmpbuf;
l2n3(derlen, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, 3))
return 0;
if (!EVP_DigestUpdate(ctx, der, derlen))
return 0;
/* Add any extensions */
p = tmpbuf;
s2n(sct->ext_len, p);
if (!EVP_DigestUpdate(ctx, tmpbuf, 2))
return 0;
if (sct->ext_len && !EVP_DigestUpdate(ctx, sct->ext, sct->ext_len))
return 0;
return 1;
}
int SCT_verify(const SCT_CTX *sctx, const SCT *sct)
{
EVP_MD_CTX *ctx = NULL;
int ret = 0;
if (!SCT_is_complete(sct) || sctx->pkey == NULL ||
sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET ||
(sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)) {
CTerr(CT_F_SCT_VERIFY, CT_R_SCT_NOT_SET);
return 0;
}
if (sct->version != SCT_VERSION_V1) {
CTerr(CT_F_SCT_VERIFY, CT_R_SCT_UNSUPPORTED_VERSION);
return 0;
}
if (sct->log_id_len != sctx->pkeyhashlen ||
memcmp(sct->log_id, sctx->pkeyhash, sctx->pkeyhashlen) != 0) {
CTerr(CT_F_SCT_VERIFY, CT_R_SCT_LOG_ID_MISMATCH);
return 0;
}
ctx = EVP_MD_CTX_new();
if (ctx == NULL)
goto end;
if (!EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, sctx->pkey))
goto end;
if (!sct_ctx_update(ctx, sctx, sct))
goto end;
/* Verify signature */
ret = EVP_DigestVerifyFinal(ctx, sct->sig, sct->sig_len);
/* If ret < 0 some other error: fall through without setting error */
if (ret == 0)
CTerr(CT_F_SCT_VERIFY, CT_R_SCT_INVALID_SIGNATURE);
end:
EVP_MD_CTX_free(ctx);
return ret;
}
int SCT_verify_v1(SCT *sct, X509 *cert, X509 *preissuer,
X509_PUBKEY *log_pubkey, X509 *issuer_cert)
{
int ret = 0;
SCT_CTX *sctx = NULL;
if (!SCT_is_complete(sct)) {
CTerr(CT_F_SCT_VERIFY_V1, CT_R_SCT_NOT_SET);
return 0;
}
if (sct->version != 0) {
CTerr(CT_F_SCT_VERIFY_V1, CT_R_SCT_UNSUPPORTED_VERSION);
return 0;
}
sctx = SCT_CTX_new();
if (sctx == NULL)
goto done;
if (!SCT_CTX_set1_pubkey(sctx, log_pubkey))
goto done;
if (!SCT_CTX_set1_cert(sctx, cert, preissuer))
goto done;
if (sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT &&
!SCT_CTX_set1_issuer(sctx, issuer_cert))
goto done;
ret = SCT_verify(sctx, sct);
done:
SCT_CTX_free(sctx);
return ret;
}
