// Copyright 2022 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine License
// Agreement.
//
//  Reference implementation utilities of OEMCrypto APIs
//
#include "hmac.h"

#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>

#include "log.h"
#include "string_conversions.h"

namespace wvoec {
namespace util {
namespace {
constexpr bool kHmacSha256 = true;
constexpr bool kHmacSha1 = false;
const std::vector<uint8_t> kEmptyVector;

// Assumes all parameters are valid.
inline bool HmacShaInternal(const uint8_t* key, size_t key_length,
                            const uint8_t* message, size_t message_length,
                            uint8_t* signature, bool sha256) {
  return HMAC(sha256 ? EVP_sha256() : EVP_sha1(), key,
              static_cast<int>(key_length), message, message_length, signature,
              nullptr) != nullptr;
}

OEMCryptoResult GenerateSignatureInternal(const uint8_t* key, size_t key_length,
                                          const uint8_t* message,
                                          size_t message_length,
                                          uint8_t* signature,
                                          size_t* signature_length,
                                          bool sha256) {
  if (key == nullptr || key_length == 0) {
    LOGE("Input |key| is %s", key_length == 0 ? "empty" : "null");
    return OEMCrypto_ERROR_INVALID_CONTEXT;
  }
  if (message == nullptr || message_length == 0) {
    LOGE("Input |message| is %s", message_length == 0 ? "empty" : "null");
    return OEMCrypto_ERROR_INVALID_CONTEXT;
  }
  if (signature_length == nullptr) {
    LOGE("Input/output |signature_length| is null");
    return OEMCrypto_ERROR_INVALID_CONTEXT;
  }
  if (signature == nullptr && *signature_length > 0) {
    LOGE("Output |signature| is null");
    return OEMCrypto_ERROR_INVALID_CONTEXT;
  }
  const size_t required_signature_size =
      sha256 ? kHmacSha256SignatureSize : kHmacSha1SignatureSize;
  if (*signature_length < required_signature_size) {
    *signature_length = required_signature_size;
    return OEMCrypto_ERROR_SHORT_BUFFER;
  }
  if (!HmacShaInternal(key, key_length, message, message_length, signature,
                       sha256)) {
    LOGE("Failed to generate signature");
    return OEMCrypto_ERROR_UNKNOWN_FAILURE;
  }
  *signature_length = required_signature_size;
  return OEMCrypto_SUCCESS;
}

bool GenerateSignatureInternal(const uint8_t* key, size_t key_length,
                               const uint8_t* message, size_t message_length,
                               std::vector<uint8_t>* signature, bool sha256) {
  if (signature == nullptr) {
    LOGE("Output |signature| is null");
    return false;
  }
  size_t signature_length =
      sha256 ? kHmacSha256SignatureSize : kHmacSha1SignatureSize;
  signature->resize(signature_length);
  const OEMCryptoResult res =
      GenerateSignatureInternal(key, key_length, message, message_length,
                                signature->data(), &signature_length, sha256);
  if (res != OEMCrypto_SUCCESS) {
    signature->clear();
    return false;
  }
  return true;
}

// Assumes signature pointers are valid.
inline bool CompareSignatures(const uint8_t* signature_a,
                              const uint8_t* signature_b, bool sha256) {
  const size_t signature_size =
      sha256 ? kHmacSha256SignatureSize : kHmacSha1SignatureSize;
  return CRYPTO_memcmp(signature_a, signature_b, signature_size) == 0;
}

OEMCryptoResult VerifySignatureInternal(const uint8_t* key, size_t key_length,
                                        const uint8_t* message,
                                        size_t message_length,
                                        const uint8_t* signature,
                                        size_t signature_length, bool sha256) {
  if (signature == nullptr && signature_length > 0) {
    LOGE("Input |signature| is null");
    return OEMCrypto_ERROR_INVALID_CONTEXT;
  }
  size_t expected_signature_length =
      sha256 ? kHmacSha256SignatureSize : kHmacSha1SignatureSize;
  if (signature_length != expected_signature_length) {
    LOGE("Invalid signature length: expected = %zu, actual = %zu",
         expected_signature_length, signature_length);
    return OEMCrypto_ERROR_SIGNATURE_FAILURE;
  }
  // Allocate for the larger of the two.
  uint8_t expected_signature[kHmacSha256SignatureSize];
  const OEMCryptoResult res = GenerateSignatureInternal(
      key, key_length, message, message_length, expected_signature,
      &expected_signature_length, sha256);
  if (res != OEMCrypto_SUCCESS) return res;
  if (!CompareSignatures(signature, expected_signature, sha256)) {
    LOGD("Signatures do not match: type = HMAC-SHA-%s", sha256 ? "256" : "1");
    LOGD("provided = %s",
         wvutil::HexEncode(signature, signature_length).c_str());
    LOGD("expected = %s",
         wvutil::HexEncode(expected_signature, expected_signature_length)
             .c_str());
    return OEMCrypto_ERROR_SIGNATURE_FAILURE;
  }
  return OEMCrypto_SUCCESS;
}
}  // namespace

OEMCryptoResult HmacSha1(const uint8_t* key, size_t key_length,
                         const uint8_t* message, size_t message_length,
                         uint8_t* signature, size_t* signature_length) {
  return GenerateSignatureInternal(key, key_length, message, message_length,
                                   signature, signature_length, kHmacSha1);
}

OEMCryptoResult HmacSha1(const std::vector<uint8_t>& key,
                         const uint8_t* message, size_t message_length,
                         uint8_t* signature, size_t* signature_length) {
  return GenerateSignatureInternal(key.data(), key.size(), message,
                                   message_length, signature, signature_length,
                                   kHmacSha1);
}

std::vector<uint8_t> HmacSha1(const std::vector<uint8_t>& key,
                              const std::vector<uint8_t>& message) {
  std::vector<uint8_t> signature;
  const bool res =
      GenerateSignatureInternal(key.data(), key.size(), message.data(),
                                message.size(), &signature, kHmacSha1);
  return res ? signature : kEmptyVector;
}

OEMCryptoResult HmacSha256(const uint8_t* key, size_t key_length,
                           const uint8_t* message, size_t message_length,
                           uint8_t* signature, size_t* signature_length) {
  return GenerateSignatureInternal(key, key_length, message, message_length,
                                   signature, signature_length, kHmacSha256);
}

OEMCryptoResult HmacSha256(const std::vector<uint8_t>& key,
                           const uint8_t* message, size_t message_length,
                           uint8_t* signature, size_t* signature_length) {
  return GenerateSignatureInternal(key.data(), key.size(), message,
                                   message_length, signature, signature_length,
                                   kHmacSha256);
}

bool HmacSha256(const std::vector<uint8_t>& key,
                const std::vector<uint8_t>& message,
                std::vector<uint8_t>* signature) {
  return GenerateSignatureInternal(key.data(), key.size(), message.data(),
                                   message.size(), signature, kHmacSha256);
}

bool HmacSha256(const std::vector<uint8_t>& key, const std::string& message,
                std::vector<uint8_t>* signature) {
  return GenerateSignatureInternal(
      key.data(), key.size(), reinterpret_cast<const uint8_t*>(message.data()),
      message.size(), signature, kHmacSha256);
}

std::vector<uint8_t> HmacSha256(const std::vector<uint8_t>& key,
                                const uint8_t* message, size_t message_length) {
  std::vector<uint8_t> signature;
  const bool res = GenerateSignatureInternal(
      key.data(), key.size(), message, message_length, &signature, kHmacSha256);
  return res ? signature : kEmptyVector;
}

std::vector<uint8_t> HmacSha256(const std::vector<uint8_t>& key,
                                const std::vector<uint8_t>& message) {
  std::vector<uint8_t> signature;
  const bool res =
      GenerateSignatureInternal(key.data(), key.size(), message.data(),
                                message.size(), &signature, kHmacSha256);
  return res ? signature : kEmptyVector;
}

std::vector<uint8_t> HmacSha256(const std::vector<uint8_t>& key,
                                const std::string& message) {
  std::vector<uint8_t> signature;
  const bool res = GenerateSignatureInternal(
      key.data(), key.size(), reinterpret_cast<const uint8_t*>(message.data()),
      message.size(), &signature, kHmacSha256);
  return res ? signature : kEmptyVector;
}

OEMCryptoResult HmacSha1Verify(const uint8_t* key, size_t key_length,
                               const uint8_t* message, size_t message_length,
                               const uint8_t* signature,
                               size_t signature_length) {
  return VerifySignatureInternal(key, key_length, message, message_length,
                                 signature, signature_length, kHmacSha1);
}

OEMCryptoResult HmacSha1Verify(const std::vector<uint8_t>& key,
                               const uint8_t* message, size_t message_length,
                               const uint8_t* signature,
                               size_t signature_length) {
  return VerifySignatureInternal(key.data(), key.size(), message,
                                 message_length, signature, signature_length,
                                 kHmacSha1);
}

OEMCryptoResult HmacSha1Verify(const std::vector<uint8_t>& key,
                               const std::vector<uint8_t>& message,
                               const std::vector<uint8_t>& signature) {
  return VerifySignatureInternal(key.data(), key.size(), message.data(),
                                 message.size(), signature.data(),
                                 signature.size(), kHmacSha1);
}

OEMCryptoResult HmacSha256Verify(const uint8_t* key, size_t key_length,
                                 const uint8_t* message, size_t message_length,
                                 const uint8_t* signature,
                                 size_t signature_length) {
  return VerifySignatureInternal(key, key_length, message, message_length,
                                 signature, signature_length, kHmacSha256);
}

OEMCryptoResult HmacSha256Verify(const std::vector<uint8_t>& key,
                                 const uint8_t* message, size_t message_length,
                                 const uint8_t* signature,
                                 size_t signature_length) {
  return VerifySignatureInternal(key.data(), key.size(), message,
                                 message_length, signature, signature_length,
                                 kHmacSha256);
}

OEMCryptoResult HmacSha256Verify(const std::vector<uint8_t>& key,
                                 const std::vector<uint8_t>& message,
                                 const std::vector<uint8_t>& signature) {
  return VerifySignatureInternal(key.data(), key.size(), message.data(),
                                 message.size(), signature.data(),
                                 signature.size(), kHmacSha256);
}

OEMCryptoResult HmacSha256Verify(const std::vector<uint8_t>& key,
                                 const std::string& message,
                                 const std::vector<uint8_t>& signature) {
  return VerifySignatureInternal(
      key.data(), key.size(), reinterpret_cast<const uint8_t*>(message.data()),
      message.size(), signature.data(), signature.size(), kHmacSha256);
}
}  // namespace util
}  // namespace wvoec