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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "crypto/hmac.h"
#include <stddef.h>
#include <algorithm>
#include <string>
#include "base/check.h"
#include "base/check_op.h"
#include "base/notreached.h"
#include "base/stl_util.h"
#include "crypto/openssl_util.h"
#include "crypto/secure_util.h"
#include "third_party/boringssl/src/include/openssl/hmac.h"
namespace crypto {
HMAC::HMAC(HashAlgorithm hash_alg) : hash_alg_(hash_alg), initialized_(false) {
// Only SHA-1 and SHA-256 hash algorithms are supported now.
DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
}
HMAC::~HMAC() {
// Zero out key copy.
key_.assign(key_.size(), 0);
base::STLClearObject(&key_);
}
size_t HMAC::DigestLength() const {
switch (hash_alg_) {
case SHA1:
return 20;
case SHA256:
return 32;
default:
NOTREACHED();
}
}
bool HMAC::Init(const unsigned char* key, size_t key_length) {
// Init must not be called more than once on the same HMAC object.
DCHECK(!initialized_);
initialized_ = true;
key_.assign(key, key + key_length);
return true;
}
bool HMAC::Sign(std::string_view data,
unsigned char* digest,
size_t digest_length) const {
return Sign(base::as_byte_span(data), base::span(digest, digest_length));
}
bool HMAC::Sign(base::span<const uint8_t> data,
base::span<uint8_t> digest) const {
DCHECK(initialized_);
if (digest.size() > DigestLength())
return false;
ScopedOpenSSLSafeSizeBuffer<EVP_MAX_MD_SIZE> result(digest.data(),
digest.size());
return !!::HMAC(hash_alg_ == SHA1 ? EVP_sha1() : EVP_sha256(), key_.data(),
key_.size(), data.data(), data.size(), result.safe_buffer(),
nullptr);
}
bool HMAC::Verify(std::string_view data, std::string_view digest) const {
return Verify(base::as_byte_span(data), base::as_byte_span(digest));
}
bool HMAC::Verify(base::span<const uint8_t> data,
base::span<const uint8_t> digest) const {
if (digest.size() != DigestLength())
return false;
return VerifyTruncated(data, digest);
}
bool HMAC::VerifyTruncated(std::string_view data,
std::string_view digest) const {
return VerifyTruncated(base::as_byte_span(data), base::as_byte_span(digest));
}
bool HMAC::VerifyTruncated(base::span<const uint8_t> data,
base::span<const uint8_t> digest) const {
if (digest.empty())
return false;
size_t digest_length = DigestLength();
if (digest.size() > digest_length)
return false;
std::array<uint8_t, EVP_MAX_MD_SIZE> computed_buffer;
auto computed_digest = base::span(computed_buffer).first(digest.size());
if (!Sign(data, computed_digest)) {
return false;
}
return SecureMemEqual(digest, computed_digest);
}
namespace hmac {
namespace {
const EVP_MD* EVPMDForHashKind(crypto::hash::HashKind kind) {
switch (kind) {
case crypto::hash::HashKind::kSha1:
return EVP_sha1();
case crypto::hash::HashKind::kSha256:
return EVP_sha256();
case crypto::hash::HashKind::kSha384:
return EVP_sha384();
case crypto::hash::HashKind::kSha512:
return EVP_sha512();
}
NOTREACHED();
}
} // namespace
void Sign(crypto::hash::HashKind kind,
base::span<const uint8_t> key,
base::span<const uint8_t> data,
base::span<uint8_t> hmac) {
const EVP_MD* md = EVPMDForHashKind(kind);
CHECK_EQ(hmac.size(), EVP_MD_size(md));
bssl::ScopedHMAC_CTX ctx;
CHECK(HMAC_Init_ex(ctx.get(), key.data(), key.size(), EVPMDForHashKind(kind),
nullptr));
CHECK(HMAC_Update(ctx.get(), data.data(), data.size()));
CHECK(HMAC_Final(ctx.get(), hmac.data(), nullptr));
}
bool Verify(crypto::hash::HashKind kind,
base::span<const uint8_t> key,
base::span<const uint8_t> data,
base::span<const uint8_t> hmac) {
const EVP_MD* md = EVPMDForHashKind(kind);
CHECK_EQ(hmac.size(), EVP_MD_size(md));
std::array<uint8_t, EVP_MAX_MD_SIZE> computed_buf;
base::span<uint8_t> computed =
base::span(computed_buf).first(EVP_MD_size(md));
Sign(kind, key, data, computed);
return crypto::SecureMemEqual(computed, hmac);
}
std::array<uint8_t, crypto::hash::kSha1Size> SignSha1(
base::span<const uint8_t> key,
base::span<const uint8_t> data) {
std::array<uint8_t, crypto::hash::kSha1Size> result;
Sign(crypto::hash::HashKind::kSha1, key, data, result);
return result;
}
std::array<uint8_t, crypto::hash::kSha256Size> SignSha256(
base::span<const uint8_t> key,
base::span<const uint8_t> data) {
std::array<uint8_t, crypto::hash::kSha256Size> result;
Sign(crypto::hash::HashKind::kSha256, key, data, result);
return result;
}
std::array<uint8_t, crypto::hash::kSha512Size> SignSha512(
base::span<const uint8_t> key,
base::span<const uint8_t> data) {
std::array<uint8_t, crypto::hash::kSha512Size> result;
Sign(crypto::hash::HashKind::kSha512, key, data, result);
return result;
}
bool VerifySha1(base::span<const uint8_t> key,
base::span<const uint8_t> data,
base::span<const uint8_t, 20> hmac) {
return Verify(crypto::hash::HashKind::kSha1, key, data, hmac);
}
bool VerifySha256(base::span<const uint8_t> key,
base::span<const uint8_t> data,
base::span<const uint8_t, 32> hmac) {
return Verify(crypto::hash::HashKind::kSha256, key, data, hmac);
}
bool VerifySha512(base::span<const uint8_t> key,
base::span<const uint8_t> data,
base::span<const uint8_t, 64> hmac) {
return Verify(crypto::hash::HashKind::kSha512, key, data, hmac);
}
} // namespace hmac
} // namespace crypto
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