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/*
* Copyright (C) 2017 Apple Inc. All rights reserved.
* Copyright (C) 2017 Metrological Group B.V.
* Copyright (C) 2017 Igalia S.L.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "CryptoAlgorithmECDH.h"
#include "CryptoKeyEC.h"
#include "GCryptUtilities.h"
#include <pal/crypto/gcrypt/Handle.h>
#include <pal/crypto/gcrypt/Utilities.h>
namespace WebCore {
static std::optional<Vector<uint8_t>> gcryptDerive(gcry_sexp_t baseKeySexp, gcry_sexp_t publicKeySexp, size_t keySizeInBytes)
{
// First, retrieve private key data, which is roughly of the following form:
// (private-key
// (ecc
// ...
// (d ...)))
PAL::GCrypt::Handle<gcry_sexp_t> dataSexp;
{
PAL::GCrypt::Handle<gcry_sexp_t> dSexp(gcry_sexp_find_token(baseKeySexp, "d", 0));
if (!dSexp)
return std::nullopt;
auto data = mpiData(dSexp);
if (!data)
return std::nullopt;
gcry_sexp_build(&dataSexp, nullptr, "(data(flags raw)(value %b))", data->size(), data->data());
if (!dataSexp)
return std::nullopt;
}
// Encrypt the data s-expression with the public key.
PAL::GCrypt::Handle<gcry_sexp_t> cipherSexp;
gcry_error_t error = gcry_pk_encrypt(&cipherSexp, dataSexp, publicKeySexp);
if (error != GPG_ERR_NO_ERROR) {
PAL::GCrypt::logError(error);
return std::nullopt;
}
// Retrieve the shared point value from the generated s-expression, which is of the following form:
// (enc-val
// (ecdh
// (s ...)
// (e ...)))
PAL::GCrypt::Handle<gcry_mpi_t> xMPI(gcry_mpi_new(0));
if (!xMPI)
return std::nullopt;
{
PAL::GCrypt::Handle<gcry_sexp_t> sSexp(gcry_sexp_find_token(cipherSexp, "s", 0));
if (!sSexp)
return std::nullopt;
PAL::GCrypt::Handle<gcry_mpi_t> sMPI(gcry_sexp_nth_mpi(sSexp, 1, GCRYMPI_FMT_USG));
if (!sMPI)
return std::nullopt;
PAL::GCrypt::Handle<gcry_mpi_point_t> point(gcry_mpi_point_new(0));
if (!point)
return std::nullopt;
error = gcry_mpi_ec_decode_point(point, sMPI, nullptr);
if (error != GPG_ERR_NO_ERROR)
return std::nullopt;
// We're only interested in the x-coordinate.
gcry_mpi_point_snatch_get(xMPI, nullptr, nullptr, point.release());
}
return mpiZeroPrefixedData(xMPI, keySizeInBytes);
}
std::optional<Vector<uint8_t>> CryptoAlgorithmECDH::platformDeriveBits(const CryptoKeyEC& baseKey, const CryptoKeyEC& publicKey)
{
return gcryptDerive(baseKey.platformKey().get(), publicKey.platformKey().get(), (baseKey.keySizeInBits() + 7) / 8);
}
} // namespace WebCore
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