CryptoAlgorithmAES_GCMMac.cpp   [plain text]

/*
 * Copyright (C) 2017 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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#include "config.h"
#include "CryptoAlgorithmAES_GCM.h"

#if ENABLE(SUBTLE_CRYPTO)

#include "CommonCryptoUtilities.h"
#include "CryptoAlgorithmAesGcmParams.h"
#include "CryptoKeyAES.h"
#include "ExceptionCode.h"
#include "ScriptExecutionContext.h"
#include <wtf/CryptographicUtilities.h>

namespace WebCore {

static ExceptionOr<Vector<uint8_t>> encryptAES_GCM(const Vector<uint8_t>& iv, const Vector<uint8_t>& key, const Vector<uint8_t>& plainText, const Vector<uint8_t>& additionalData, size_t desiredTagLengthInBytes)
{
    Vector<uint8_t> cipherText(plainText.size()); // Per section 5.2.1.2: http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
    Vector<uint8_t> tag(desiredTagLengthInBytes);
    // tagLength is actual an input <rdar://problem/30660074>
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    CCCryptorStatus status = CCCryptorGCM(kCCEncrypt, kCCAlgorithmAES, key.data(), key.size(), iv.data(), iv.size(), additionalData.data(), additionalData.size(), plainText.data(), plainText.size(), cipherText.data(), tag.data(), &desiredTagLengthInBytes);
#pragma clang diagnostic pop
    if (status)
        return Exception { OperationError };

    cipherText.append(tag.data(), desiredTagLengthInBytes);

    return WTFMove(cipherText);
}

static ExceptionOr<Vector<uint8_t>> decyptAES_GCM(const Vector<uint8_t>& iv, const Vector<uint8_t>& key, const Vector<uint8_t>& cipherText, const Vector<uint8_t>& additionalData, size_t desiredTagLengthInBytes)
{
    Vector<uint8_t> plainText(cipherText.size() - desiredTagLengthInBytes); // Per section 5.2.1.2: http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
    Vector<uint8_t> tag(desiredTagLengthInBytes);
    size_t offset = cipherText.size() - desiredTagLengthInBytes;
    // tagLength is actual an input <rdar://problem/30660074>
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    CCCryptorStatus status = CCCryptorGCM(kCCDecrypt, kCCAlgorithmAES, key.data(), key.size(), iv.data(), iv.size(), additionalData.data(), additionalData.size(), cipherText.data(), offset, plainText.data(), tag.data(), &desiredTagLengthInBytes);
#pragma clang diagnostic pop
    if (status)
        return Exception { OperationError };

    // Using a constant time comparison to prevent timing attacks.
    if (constantTimeMemcmp(tag.data(), cipherText.data() + offset, desiredTagLengthInBytes))
        return Exception { OperationError };

    return WTFMove(plainText);
}

void CryptoAlgorithmAES_GCM::platformEncrypt(std::unique_ptr<CryptoAlgorithmParameters>&& parameters, Ref<CryptoKey>&& key, Vector<uint8_t>&& plainText, VectorCallback&& callback, ExceptionCallback&& exceptionCallback, ScriptExecutionContext& context, WorkQueue& workQueue)
{
    context.ref();
    workQueue.dispatch([parameters = WTFMove(parameters), key = WTFMove(key), plainText = WTFMove(plainText), callback = WTFMove(callback), exceptionCallback = WTFMove(exceptionCallback), &context]() mutable {
        auto& aesParameters = downcast<CryptoAlgorithmAesGcmParams>(*parameters);
        auto& aesKey = downcast<CryptoKeyAES>(key.get());
        auto result = encryptAES_GCM(aesParameters.ivVector(), aesKey.key(), plainText, aesParameters.additionalDataVector(), *(aesParameters.tagLength) / 8);
        if (result.hasException()) {
            // We should only dereference callbacks after being back to the Document/Worker threads.
            context.postTask([exceptionCallback = WTFMove(exceptionCallback), ec = result.releaseException().code(), callback = WTFMove(callback)](ScriptExecutionContext& context) {
                exceptionCallback(ec);
                context.deref();
            });
            return;
        }
        // We should only dereference callbacks after being back to the Document/Worker threads.
        context.postTask([callback = WTFMove(callback), result = result.releaseReturnValue(), exceptionCallback = WTFMove(exceptionCallback)](ScriptExecutionContext& context) {
            callback(result);
            context.deref();
        });
    });
}

void CryptoAlgorithmAES_GCM::platformDecrypt(std::unique_ptr<CryptoAlgorithmParameters>&& parameters, Ref<CryptoKey>&& key, Vector<uint8_t>&& cipherText, VectorCallback&& callback, ExceptionCallback&& exceptionCallback, ScriptExecutionContext& context, WorkQueue& workQueue)
{
    context.ref();
    workQueue.dispatch([parameters = WTFMove(parameters), key = WTFMove(key), cipherText = WTFMove(cipherText), callback = WTFMove(callback), exceptionCallback = WTFMove(exceptionCallback), &context]() mutable {
        auto& aesParameters = downcast<CryptoAlgorithmAesGcmParams>(*parameters);
        auto& aesKey = downcast<CryptoKeyAES>(key.get());
        auto result = decyptAES_GCM(aesParameters.ivVector(), aesKey.key(), cipherText, aesParameters.additionalDataVector(), *(aesParameters.tagLength) / 8);
        if (result.hasException()) {
            // We should only dereference callbacks after being back to the Document/Worker threads.
            context.postTask([exceptionCallback = WTFMove(exceptionCallback), ec = result.releaseException().code(), callback = WTFMove(callback)](ScriptExecutionContext& context) {
                exceptionCallback(ec);
                context.deref();
            });
            return;
        }
        // We should only dereference callbacks after being back to the Document/Worker threads.
        context.postTask([callback = WTFMove(callback), result = result.releaseReturnValue(), exceptionCallback = WTFMove(exceptionCallback)](ScriptExecutionContext& context) {
            callback(result);
            context.deref();
        });
    });
}

} // namespace WebCore

#endif // ENABLE(SUBTLE_CRYPTO)