Source/WebCore/crypto/openssl/CryptoAlgorithmECDSAOpenSSL.cpp

/*
 * Copyright (C) 2020 Sony Interactive Entertainment Inc.
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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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 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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#include "config.h"
#include "CryptoAlgorithmECDSA.h"

#if ENABLE(WEB_CRYPTO)

#include "CryptoAlgorithmEcdsaParams.h"
#include "CryptoKeyEC.h"
#include "OpenSSLUtilities.h"

namespace WebCore {

ExceptionOr<Vector<uint8_t>> CryptoAlgorithmECDSA::platformSign(const CryptoAlgorithmEcdsaParams& parameters, const CryptoKeyEC& key, const Vector<uint8_t>& data)
{
    size_t keySizeInBytes = (key.keySizeInBits() + 7) / 8;

    const EVP_MD* md = digestAlgorithm(parameters.hashIdentifier);
    if (!md)
        return Exception { NotSupportedError };

    std::optional<Vector<uint8_t>> digest = calculateDigest(md, data);
    if (!digest)
        return Exception { OperationError };

    EC_KEY* ecKey = EVP_PKEY_get0_EC_KEY(key.platformKey());
    if (!ecKey)
        return Exception { OperationError };

    // We use ECDSA_do_sign rather than EVP API because the latter handles ECDSA signature in DER format
    // while this function is supposed to return simply concatinated "r" and "s".
    auto sig = ECDSASigPtr(ECDSA_do_sign(digest->data(), digest->size(), ecKey));
    if (!sig)
        return Exception { OperationError };

    const BIGNUM* r;
    const BIGNUM* s;
    ECDSA_SIG_get0(sig.get(), &r, &s);

    // Concatenate r and s, expanding r and s to keySizeInBytes.
    Vector<uint8_t> signature = convertToBytesExpand(r, keySizeInBytes);
    signature.appendVector(convertToBytesExpand(s, keySizeInBytes));

    return signature;
}

ExceptionOr<bool> CryptoAlgorithmECDSA::platformVerify(const CryptoAlgorithmEcdsaParams& parameters, const CryptoKeyEC& key, const Vector<uint8_t>& signature, const Vector<uint8_t>& data)
{
    size_t keySizeInBytes = (key.keySizeInBits() + 7) / 8;

    // Bail if the signature size isn't double the key size (i.e. concatenated r and s components).
    if (signature.size() != keySizeInBytes * 2)
        return false;
    
    auto sig = ECDSASigPtr(ECDSA_SIG_new());
    sig->r = BN_bin2bn(signature.data(), keySizeInBytes, sig->r);
    sig->s = BN_bin2bn(signature.data() + keySizeInBytes, keySizeInBytes, sig->s);

    const EVP_MD* md = digestAlgorithm(parameters.hashIdentifier);
    if (!md)
        return Exception { NotSupportedError };

    std::optional<Vector<uint8_t>> digest = calculateDigest(md, data);
    if (!digest)
        return Exception { OperationError };

    EC_KEY* ecKey = EVP_PKEY_get0_EC_KEY(key.platformKey());
    if (!ecKey)
        return Exception { OperationError };

    int ret = ECDSA_do_verify(digest->data(), digest->size(), sig.get(), ecKey);
    return ret == 1;
}

} // namespace WebCore

#endif // ENABLE(WEB_CRYPTO)