Source/WebCore/crypto/gcrypt/CryptoAlgorithmRSAES_PKCS1_v1_5GCrypt.cpp

/*
 * Copyright (C) 2014 Igalia S.L. All rights reserved.
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 * modification, are permitted provided that the following conditions
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#include "config.h"
#include "CryptoAlgorithmRSAES_PKCS1_v1_5.h"

#if ENABLE(WEB_CRYPTO)

#include "CryptoKeyRSA.h"
#include "GCryptUtilities.h"

namespace WebCore {

static std::optional<Vector<uint8_t>> gcryptEncrypt(gcry_sexp_t keySexp, const Vector<uint8_t>& plainText, size_t keySizeInBytes)
{
    // Embed the plain-text data in a `data` s-expression using PKCS#1 padding.
    PAL::GCrypt::Handle<gcry_sexp_t> dataSexp;
    gcry_error_t error = gcry_sexp_build(&dataSexp, nullptr, "(data(flags pkcs1)(value %b))",
        plainText.size(), plainText.data());
    if (error != GPG_ERR_NO_ERROR) {
        PAL::GCrypt::logError(error);
        return std::nullopt;
    }

    // Encrypt data with the provided key. The returned s-expression is of this form:
    // (enc-val
    //   (rsa
    //     (a a-mpi)))
    PAL::GCrypt::Handle<gcry_sexp_t> cipherSexp;
    error = gcry_pk_encrypt(&cipherSexp, dataSexp, keySexp);
    if (error != GPG_ERR_NO_ERROR) {
        PAL::GCrypt::logError(error);
        return std::nullopt;
    }

    // Return MPI data of the embedded `a` integer.
    PAL::GCrypt::Handle<gcry_sexp_t> aSexp(gcry_sexp_find_token(cipherSexp, "a", 0));
    if (!aSexp)
        return std::nullopt;

    return mpiZeroPrefixedData(aSexp, keySizeInBytes);
}

static std::optional<Vector<uint8_t>> gcryptDecrypt(gcry_sexp_t keySexp, const Vector<uint8_t>& cipherText)
{
    // Embed the cipher-text data in an `enc-val` s-expression using PKCS#1 padding.
    PAL::GCrypt::Handle<gcry_sexp_t> encValSexp;
    gcry_error_t error = gcry_sexp_build(&encValSexp, nullptr, "(enc-val(flags pkcs1)(rsa(a %b)))",
        cipherText.size(), cipherText.data());
    if (error != GPG_ERR_NO_ERROR) {
        PAL::GCrypt::logError(error);
        return std::nullopt;
    }

    // Decrypt data with the provided key. The returned s-expression is of this form:
    // (data
    //   (flags pkcs1)
    //   (value block))
    PAL::GCrypt::Handle<gcry_sexp_t> plainSexp;
    error = gcry_pk_decrypt(&plainSexp, encValSexp, keySexp);
    if (error != GPG_ERR_NO_ERROR) {
        PAL::GCrypt::logError(error);
        return std::nullopt;
    }

    // Return MPI data of the embedded `value` integer.
    PAL::GCrypt::Handle<gcry_sexp_t> valueSexp(gcry_sexp_find_token(plainSexp, "value", 0));
    if (!valueSexp)
        return std::nullopt;

    return mpiData(valueSexp);
}

ExceptionOr<Vector<uint8_t>> CryptoAlgorithmRSAES_PKCS1_v1_5::platformEncrypt(const CryptoKeyRSA& key, const Vector<uint8_t>& plainText)
{
    RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!(key.keySizeInBits() % 8));
    auto output = gcryptEncrypt(key.platformKey(), plainText, key.keySizeInBits() / 8);
    if (!output)
        return Exception { OperationError };
    return WTFMove(*output);
}

ExceptionOr<Vector<uint8_t>> CryptoAlgorithmRSAES_PKCS1_v1_5::platformDecrypt(const CryptoKeyRSA& key, const Vector<uint8_t>& cipherText)
{
    auto output = gcryptDecrypt(key.platformKey(), cipherText);
    if (!output)
        return Exception { OperationError };
    return WTFMove(*output);
}

} // namespace WebCore

#endif // ENABLE(WEB_CRYPTO)