root/content/child/webcrypto/webcrypto_util.cc

DEFINITIONS

1. Uint8VectorStart
2. ShrinkBuffer
3. CreateArrayBuffer
4. Base64DecodeUrlSafe
5. Base64EncodeUrlSafe
6. Base64EncodeUrlSafe
7. JwkKeyOpToWebCryptoUsage
8. GetWebCryptoUsagesFromJwkKeyOps
9. CreateJwkKeyOpsFromWebCryptoUsages
10. IsHashAlgorithm
11. GetInnerHashAlgorithm
12. CreateAlgorithm
13. CreateHmacImportAlgorithm
14. CreateRsaHashedImportAlgorithm
15. CreateSecretKeyAlgorithm

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/child/webcrypto/webcrypto_util.h"

#include "base/base64.h"
#include "base/logging.h"
#include "base/strings/stringprintf.h"
#include "content/child/webcrypto/status.h"
#include "third_party/WebKit/public/platform/WebCryptoAlgorithm.h"
#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
#include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"

namespace content {

namespace webcrypto {

const uint8* Uint8VectorStart(const std::vector<uint8>& data) {
  if (data.empty())
    return NULL;
  return &data[0];
}

void ShrinkBuffer(blink::WebArrayBuffer* buffer, unsigned int new_size) {
  DCHECK_LE(new_size, buffer->byteLength());

  if (new_size == buffer->byteLength())
    return;

  blink::WebArrayBuffer new_buffer = blink::WebArrayBuffer::create(new_size, 1);
  DCHECK(!new_buffer.isNull());
  memcpy(new_buffer.data(), buffer->data(), new_size);
  *buffer = new_buffer;
}

blink::WebArrayBuffer CreateArrayBuffer(const uint8* data,
                                        unsigned int data_size) {
  blink::WebArrayBuffer buffer = blink::WebArrayBuffer::create(data_size, 1);
  DCHECK(!buffer.isNull());
  if (data_size)  // data_size == 0 might mean the data pointer is invalid
    memcpy(buffer.data(), data, data_size);
  return buffer;
}

// This function decodes unpadded 'base64url' encoded data, as described in
// RFC4648 (http://www.ietf.org/rfc/rfc4648.txt) Section 5. To do this, first
// change the incoming data to 'base64' encoding by applying the appropriate
// transformation including adding padding if required, and then call a base64
// decoder.
bool Base64DecodeUrlSafe(const std::string& input, std::string* output) {
  std::string base64EncodedText(input);
  std::replace(base64EncodedText.begin(), base64EncodedText.end(), '-', '+');
  std::replace(base64EncodedText.begin(), base64EncodedText.end(), '_', '/');
  base64EncodedText.append((4 - base64EncodedText.size() % 4) % 4, '=');
  return base::Base64Decode(base64EncodedText, output);
}

// Returns an unpadded 'base64url' encoding of the input data, using the
// inverse of the process above.
std::string Base64EncodeUrlSafe(const base::StringPiece& input) {
  std::string output;
  base::Base64Encode(input, &output);
  std::replace(output.begin(), output.end(), '+', '-');
  std::replace(output.begin(), output.end(), '/', '_');
  output.erase(std::remove(output.begin(), output.end(), '='), output.end());
  return output;
}

std::string Base64EncodeUrlSafe(const std::vector<uint8>& input) {
  const base::StringPiece string_piece(
      reinterpret_cast<const char*>(Uint8VectorStart(input)), input.size());
  return Base64EncodeUrlSafe(string_piece);
}

struct JwkToWebCryptoUsage {
  const char* const jwk_key_op;
  const blink::WebCryptoKeyUsage webcrypto_usage;
};

const JwkToWebCryptoUsage kJwkWebCryptoUsageMap[] = {
    {"encrypt", blink::WebCryptoKeyUsageEncrypt},
    {"decrypt", blink::WebCryptoKeyUsageDecrypt},
    {"deriveKey", blink::WebCryptoKeyUsageDeriveKey},
    // TODO(padolph): Add 'deriveBits' once supported by Blink.
    {"sign", blink::WebCryptoKeyUsageSign},
    {"unwrapKey", blink::WebCryptoKeyUsageUnwrapKey},
    {"verify", blink::WebCryptoKeyUsageVerify},
    {"wrapKey", blink::WebCryptoKeyUsageWrapKey}};

// Modifies the input usage_mask by according to the key_op value.
bool JwkKeyOpToWebCryptoUsage(const std::string& key_op,
                              blink::WebCryptoKeyUsageMask* usage_mask) {
  for (size_t i = 0; i < arraysize(kJwkWebCryptoUsageMap); ++i) {
    if (kJwkWebCryptoUsageMap[i].jwk_key_op == key_op) {
      *usage_mask |= kJwkWebCryptoUsageMap[i].webcrypto_usage;
      return true;
    }
  }
  return false;
}

// Composes a Web Crypto usage mask from an array of JWK key_ops values.
Status GetWebCryptoUsagesFromJwkKeyOps(
    const base::ListValue* jwk_key_ops_value,
    blink::WebCryptoKeyUsageMask* usage_mask) {
  *usage_mask = 0;
  for (size_t i = 0; i < jwk_key_ops_value->GetSize(); ++i) {
    std::string key_op;
    if (!jwk_key_ops_value->GetString(i, &key_op)) {
      return Status::ErrorJwkPropertyWrongType(
          base::StringPrintf("key_ops[%d]", static_cast<int>(i)), "string");
    }
    if (!JwkKeyOpToWebCryptoUsage(key_op, usage_mask))
      return Status::ErrorJwkUnrecognizedKeyop();
  }
  return Status::Success();
}

// Composes a JWK key_ops List from a Web Crypto usage mask.
// Note: Caller must assume ownership of returned instance.
base::ListValue* CreateJwkKeyOpsFromWebCryptoUsages(
    blink::WebCryptoKeyUsageMask usage_mask) {
  base::ListValue* jwk_key_ops = new base::ListValue();
  for (size_t i = 0; i < arraysize(kJwkWebCryptoUsageMap); ++i) {
    if (usage_mask & kJwkWebCryptoUsageMap[i].webcrypto_usage)
      jwk_key_ops->AppendString(kJwkWebCryptoUsageMap[i].jwk_key_op);
  }
  return jwk_key_ops;
}

bool IsHashAlgorithm(blink::WebCryptoAlgorithmId alg_id) {
  return alg_id == blink::WebCryptoAlgorithmIdSha1 ||
         alg_id == blink::WebCryptoAlgorithmIdSha256 ||
         alg_id == blink::WebCryptoAlgorithmIdSha384 ||
         alg_id == blink::WebCryptoAlgorithmIdSha512;
}

blink::WebCryptoAlgorithm GetInnerHashAlgorithm(
    const blink::WebCryptoAlgorithm& algorithm) {
  DCHECK(!algorithm.isNull());
  switch (algorithm.paramsType()) {
    case blink::WebCryptoAlgorithmParamsTypeHmacImportParams:
      return algorithm.hmacImportParams()->hash();
    case blink::WebCryptoAlgorithmParamsTypeHmacKeyGenParams:
      return algorithm.hmacKeyGenParams()->hash();
    case blink::WebCryptoAlgorithmParamsTypeRsaHashedImportParams:
      return algorithm.rsaHashedImportParams()->hash();
    case blink::WebCryptoAlgorithmParamsTypeRsaHashedKeyGenParams:
      return algorithm.rsaHashedKeyGenParams()->hash();
    default:
      return blink::WebCryptoAlgorithm::createNull();
  }
}

blink::WebCryptoAlgorithm CreateAlgorithm(blink::WebCryptoAlgorithmId id) {
  return blink::WebCryptoAlgorithm::adoptParamsAndCreate(id, NULL);
}

blink::WebCryptoAlgorithm CreateHmacImportAlgorithm(
    blink::WebCryptoAlgorithmId hash_id) {
  DCHECK(IsHashAlgorithm(hash_id));
  return blink::WebCryptoAlgorithm::adoptParamsAndCreate(
      blink::WebCryptoAlgorithmIdHmac,
      new blink::WebCryptoHmacImportParams(CreateAlgorithm(hash_id)));
}

blink::WebCryptoAlgorithm CreateRsaHashedImportAlgorithm(
    blink::WebCryptoAlgorithmId id,
    blink::WebCryptoAlgorithmId hash_id) {
  DCHECK(IsHashAlgorithm(hash_id));
  DCHECK(id == blink::WebCryptoAlgorithmIdRsaSsaPkcs1v1_5 ||
         id == blink::WebCryptoAlgorithmIdRsaOaep);
  return blink::WebCryptoAlgorithm::adoptParamsAndCreate(
      id, new blink::WebCryptoRsaHashedImportParams(CreateAlgorithm(hash_id)));
}

bool CreateSecretKeyAlgorithm(const blink::WebCryptoAlgorithm& algorithm,
                              unsigned int keylen_bytes,
                              blink::WebCryptoKeyAlgorithm* key_algorithm) {
  switch (algorithm.id()) {
    case blink::WebCryptoAlgorithmIdHmac: {
      blink::WebCryptoAlgorithm hash = GetInnerHashAlgorithm(algorithm);
      if (hash.isNull())
        return false;
      if (keylen_bytes > UINT_MAX / 8)
        return false;
      *key_algorithm =
          blink::WebCryptoKeyAlgorithm::createHmac(hash.id(), keylen_bytes * 8);
      return true;
    }
    case blink::WebCryptoAlgorithmIdAesKw:
    case blink::WebCryptoAlgorithmIdAesCbc:
    case blink::WebCryptoAlgorithmIdAesCtr:
    case blink::WebCryptoAlgorithmIdAesGcm:
      *key_algorithm = blink::WebCryptoKeyAlgorithm::createAes(
          algorithm.id(), keylen_bytes * 8);
      return true;
    default:
      return false;
  }
}

}  // namespace webcrypto

}  // namespace content