cdb2a60347
SCT_verify is impossible to call through the public API (SCT_CTX_new() is not part of the public API), so rename it to SCT_CTX_verify and move it out of the public API. SCT_verify_v1 is redundant, since SCT_validate does the same verification (by calling SCT_verify) and more. The API is less confusing with a single verification function (SCT_validate). Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org>
136 lines
3.7 KiB
C
136 lines
3.7 KiB
C
/*
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* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <string.h>
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#include <openssl/ct.h>
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#include <openssl/err.h>
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#include <openssl/evp.h>
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#include <openssl/x509.h>
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#include "ct_locl.h"
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typedef enum sct_signature_type_t {
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SIGNATURE_TYPE_NOT_SET = -1,
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SIGNATURE_TYPE_CERT_TIMESTAMP,
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SIGNATURE_TYPE_TREE_HASH
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} SCT_SIGNATURE_TYPE;
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/*
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* Update encoding for SCT signature verification/generation to supplied
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* EVP_MD_CTX.
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*/
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static int sct_ctx_update(EVP_MD_CTX *ctx, const SCT_CTX *sctx, const SCT *sct)
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{
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unsigned char tmpbuf[12];
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unsigned char *p, *der;
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size_t derlen;
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/*+
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* digitally-signed struct {
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* (1 byte) Version sct_version;
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* (1 byte) SignatureType signature_type = certificate_timestamp;
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* (8 bytes) uint64 timestamp;
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* (2 bytes) LogEntryType entry_type;
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* (? bytes) select(entry_type) {
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* case x509_entry: ASN.1Cert;
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* case precert_entry: PreCert;
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* } signed_entry;
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* (2 bytes + sct->ext_len) CtExtensions extensions;
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* }
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*/
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if (sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET)
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return 0;
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if (sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)
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return 0;
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p = tmpbuf;
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*p++ = sct->version;
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*p++ = SIGNATURE_TYPE_CERT_TIMESTAMP;
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l2n8(sct->timestamp, p);
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s2n(sct->entry_type, p);
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if (!EVP_DigestUpdate(ctx, tmpbuf, p - tmpbuf))
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return 0;
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if (sct->entry_type == CT_LOG_ENTRY_TYPE_X509) {
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der = sctx->certder;
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derlen = sctx->certderlen;
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} else {
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if (!EVP_DigestUpdate(ctx, sctx->ihash, sctx->ihashlen))
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return 0;
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der = sctx->preder;
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derlen = sctx->prederlen;
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}
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/* If no encoding available, fatal error */
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if (der == NULL)
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return 0;
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/* Include length first */
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p = tmpbuf;
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l2n3(derlen, p);
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if (!EVP_DigestUpdate(ctx, tmpbuf, 3))
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return 0;
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if (!EVP_DigestUpdate(ctx, der, derlen))
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return 0;
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/* Add any extensions */
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p = tmpbuf;
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s2n(sct->ext_len, p);
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if (!EVP_DigestUpdate(ctx, tmpbuf, 2))
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return 0;
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if (sct->ext_len && !EVP_DigestUpdate(ctx, sct->ext, sct->ext_len))
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return 0;
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return 1;
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}
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int SCT_CTX_verify(const SCT_CTX *sctx, const SCT *sct)
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{
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EVP_MD_CTX *ctx = NULL;
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int ret = 0;
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if (!SCT_is_complete(sct) || sctx->pkey == NULL ||
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sct->entry_type == CT_LOG_ENTRY_TYPE_NOT_SET ||
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(sct->entry_type == CT_LOG_ENTRY_TYPE_PRECERT && sctx->ihash == NULL)) {
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CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_NOT_SET);
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return 0;
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}
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if (sct->version != SCT_VERSION_V1) {
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CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_UNSUPPORTED_VERSION);
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return 0;
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}
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if (sct->log_id_len != sctx->pkeyhashlen ||
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memcmp(sct->log_id, sctx->pkeyhash, sctx->pkeyhashlen) != 0) {
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CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_LOG_ID_MISMATCH);
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return 0;
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}
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ctx = EVP_MD_CTX_new();
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if (ctx == NULL)
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goto end;
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if (!EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, sctx->pkey))
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goto end;
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if (!sct_ctx_update(ctx, sctx, sct))
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goto end;
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/* Verify signature */
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ret = EVP_DigestVerifyFinal(ctx, sct->sig, sct->sig_len);
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/* If ret < 0 some other error: fall through without setting error */
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if (ret == 0)
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CTerr(CT_F_SCT_CTX_VERIFY, CT_R_SCT_INVALID_SIGNATURE);
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end:
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EVP_MD_CTX_free(ctx);
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return ret;
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}
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