libmar/verify/cryptox.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef XP_WIN
#  ifndef WIN32_LEAN_AND_MEAN
#    define WIN32_LEAN_AND_MEAN
#  endif
#endif

#include <stdlib.h>
#include <stdio.h>
#include "cryptox.h"

#if defined(MAR_NSS)

/**
 * Loads the public key for the specified cert name from the NSS store.
 *
 * @param certData  The DER-encoded X509 certificate to extract the key from.
 * @param certDataSize The size of certData.
 * @param publicKey Out parameter for the public key to use.
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result NSS_LoadPublicKey(const unsigned char* certData,
                                 unsigned int certDataSize,
                                 SECKEYPublicKey** publicKey) {
  CERTCertificate* cert;
  SECItem certDataItem = {siBuffer, (unsigned char*)certData, certDataSize};

  if (!certData || !publicKey) {
    return CryptoX_Error;
  }

  cert = CERT_NewTempCertificate(CERT_GetDefaultCertDB(), &certDataItem, NULL,
                                 PR_FALSE, PR_TRUE);
  /* Get the cert and embedded public key out of the database */
  if (!cert) {
    return CryptoX_Error;
  }
  *publicKey = CERT_ExtractPublicKey(cert);
  CERT_DestroyCertificate(cert);

  if (!*publicKey) {
    return CryptoX_Error;
  }
  return CryptoX_Success;
}

CryptoX_Result NSS_VerifyBegin(VFYContext** ctx,
                               SECKEYPublicKey* const* publicKey) {
  SECStatus status;
  if (!ctx || !publicKey || !*publicKey) {
    return CryptoX_Error;
  }

  /* Check that the key length is large enough for our requirements */
  if ((SECKEY_PublicKeyStrength(*publicKey) * 8) <
      XP_MIN_SIGNATURE_LEN_IN_BYTES) {
    fprintf(stderr, "ERROR: Key length must be >= %d bytes\n",
            XP_MIN_SIGNATURE_LEN_IN_BYTES);
    return CryptoX_Error;
  }

  *ctx = VFY_CreateContext(*publicKey, NULL,
                           SEC_OID_PKCS1_SHA384_WITH_RSA_ENCRYPTION, NULL);
  if (*ctx == NULL) {
    return CryptoX_Error;
  }

  status = VFY_Begin(*ctx);
  return SECSuccess == status ? CryptoX_Success : CryptoX_Error;
}

/**
 * Verifies if a verify context matches the passed in signature.
 *
 * @param ctx          The verify context that the signature should match.
 * @param signature    The signature to match.
 * @param signatureLen The length of the signature.
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result NSS_VerifySignature(VFYContext* const* ctx,
                                   const unsigned char* signature,
                                   unsigned int signatureLen) {
  SECItem signedItem;
  SECStatus status;
  if (!ctx || !signature || !*ctx) {
    return CryptoX_Error;
  }

  signedItem.len = signatureLen;
  signedItem.data = (unsigned char*)signature;
  status = VFY_EndWithSignature(*ctx, &signedItem);
  return SECSuccess == status ? CryptoX_Success : CryptoX_Error;
}

#elif defined(XP_WIN)
/**
 * Verifies if a signature + public key matches a hash context.
 *
 * @param hash      The hash context that the signature should match.
 * @param pubKey    The public key to use on the signature.
 * @param signature The signature to check.
 * @param signatureLen The length of the signature.
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result CryptoAPI_VerifySignature(HCRYPTHASH* hash, HCRYPTKEY* pubKey,
                                         const BYTE* signature,
                                         DWORD signatureLen) {
  DWORD i;
  BOOL result;
  /* Windows APIs expect the bytes in the signature to be in little-endian
   * order, but we write the signature in big-endian order.  Other APIs like
   * NSS and OpenSSL expect big-endian order.
   */
  BYTE* signatureReversed;
  if (!hash || !pubKey || !signature || signatureLen < 1) {
    return CryptoX_Error;
  }

  signatureReversed = malloc(signatureLen);
  if (!signatureReversed) {
    return CryptoX_Error;
  }

  for (i = 0; i < signatureLen; i++) {
    signatureReversed[i] = signature[signatureLen - 1 - i];
  }
  result = CryptVerifySignature(*hash, signatureReversed, signatureLen, *pubKey,
                                NULL, 0);
  free(signatureReversed);
  return result ? CryptoX_Success : CryptoX_Error;
}

/**
 * Obtains the public key for the passed in cert data
 *
 * @param provider       The cyrto provider
 * @param certData       Data of the certificate to extract the public key from
 * @param sizeOfCertData The size of the certData buffer
 * @param certStore      Pointer to the handle of the certificate store to use
 * @param CryptoX_Success on success
 */
CryptoX_Result CryptoAPI_LoadPublicKey(HCRYPTPROV provider, BYTE* certData,
                                       DWORD sizeOfCertData,
                                       HCRYPTKEY* publicKey) {
  CRYPT_DATA_BLOB blob;
  CERT_CONTEXT* context;
  if (!provider || !certData || !publicKey) {
    return CryptoX_Error;
  }

  blob.cbData = sizeOfCertData;
  blob.pbData = certData;
  if (!CryptQueryObject(CERT_QUERY_OBJECT_BLOB, &blob,
                        CERT_QUERY_CONTENT_FLAG_CERT,
                        CERT_QUERY_FORMAT_FLAG_BINARY, 0, NULL, NULL, NULL,
                        NULL, NULL, (const void**)&context)) {
    return CryptoX_Error;
  }

  if (!CryptImportPublicKeyInfo(
          provider, PKCS_7_ASN_ENCODING | X509_ASN_ENCODING,
          &context->pCertInfo->SubjectPublicKeyInfo, publicKey)) {
    CertFreeCertificateContext(context);
    return CryptoX_Error;
  }

  CertFreeCertificateContext(context);
  return CryptoX_Success;
}

/* Try to acquire context in this way:
 * 1. Enhanced provider without creating a new key set
 * 2. Enhanced provider with creating a new key set
 * 3. Default provider without creating a new key set
 * 4. Default provider without creating a new key set
 * #2 and #4 should not be needed because of the CRYPT_VERIFYCONTEXT,
 * but we add it just in case.
 *
 * @param provider Out parameter containing the provider handle.
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result CryptoAPI_InitCryptoContext(HCRYPTPROV* provider) {
  if (!CryptAcquireContext(provider, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES,
                           CRYPT_VERIFYCONTEXT)) {
    if (!CryptAcquireContext(provider, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES,
                             CRYPT_NEWKEYSET | CRYPT_VERIFYCONTEXT)) {
      if (!CryptAcquireContext(provider, NULL, NULL, PROV_RSA_AES,
                               CRYPT_VERIFYCONTEXT)) {
        if (!CryptAcquireContext(provider, NULL, NULL, PROV_RSA_AES,
                                 CRYPT_NEWKEYSET | CRYPT_VERIFYCONTEXT)) {
          *provider = CryptoX_InvalidHandleValue;
          return CryptoX_Error;
        }
      }
    }
  }
  return CryptoX_Success;
}

/**
 * Begins a signature verification hash context
 *
 * @param provider The crypt provider to use
 * @param hash     Out parameter for a handle to the hash context
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result CryptoAPI_VerifyBegin(HCRYPTPROV provider, HCRYPTHASH* hash) {
  BOOL result;
  if (!provider || !hash) {
    return CryptoX_Error;
  }

  *hash = (HCRYPTHASH)NULL;
  result = CryptCreateHash(provider, CALG_SHA_384, 0, 0, hash);
  return result ? CryptoX_Success : CryptoX_Error;
}

/**
 * Updates a signature verification hash context
 *
 * @param hash The hash context to udpate
 * @param buf  The buffer to update the hash context with
 * @param len The size of the passed in buffer
 * @return CryptoX_Success on success, CryptoX_Error on error.
 */
CryptoX_Result CryptoAPI_VerifyUpdate(HCRYPTHASH* hash, BYTE* buf, DWORD len) {
  BOOL result;
  if (!hash || !buf) {
    return CryptoX_Error;
  }

  result = CryptHashData(*hash, buf, len, 0);
  return result ? CryptoX_Success : CryptoX_Error;
}

#endif