org.bouncycastle.tls.TlsECCUtils Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of bctls-fips Show documentation

The Bouncy Castle Java APIs for the TLS, including a JSSE provider. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

There is a newer version: 2.0.19

Show newest version

package org.bouncycastle.tls;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.bouncycastle.tls.crypto.TlsECConfig;
import org.bouncycastle.util.Arrays;

public class TlsECCUtils
{
    public static TlsECConfig createNamedECConfig(TlsContext context, int namedGroup)
        throws IOException
    {
        if (NamedGroup.getCurveBits(namedGroup) < 1)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        return new TlsECConfig(namedGroup);
    }

    public static int getMinimumCurveBits(int cipherSuite)
    {
        /*
         * NOTE: This mechanism was added to support a minimum bit-size requirement mooted in early
         * drafts of RFC 8442. This requirement was removed in later drafts, so this mechanism is
         * currently somewhat trivial.
         */
        return isECCCipherSuite(cipherSuite) ? 1 : 0;
    }

    public static boolean isECCCipherSuite(int cipherSuite)
    {
        switch (TlsUtils.getKeyExchangeAlgorithm(cipherSuite))
        {
        case KeyExchangeAlgorithm.ECDH_anon:
        case KeyExchangeAlgorithm.ECDH_ECDSA:
        case KeyExchangeAlgorithm.ECDH_RSA:
        case KeyExchangeAlgorithm.ECDHE_ECDSA:
        case KeyExchangeAlgorithm.ECDHE_PSK:
        case KeyExchangeAlgorithm.ECDHE_RSA:
            return true;
            
        default:
            return false;
        }
    }

    public static void checkPointEncoding(int namedGroup, byte[] encoding) throws IOException
    {
        if (TlsUtils.isNullOrEmpty(encoding))
        {
            throw new TlsFatalAlert(AlertDescription.illegal_parameter);
        }

        switch (namedGroup)
        {
        case NamedGroup.x25519:
        case NamedGroup.x448:
            return;
        }

        switch (encoding[0])
        {
        case 0x04: // uncompressed
            return;

        case 0x00: // infinity
        case 0x02: // compressed
        case 0x03: // compressed
        case 0x06: // hybrid
        case 0x07: // hybrid
        default:
            throw new TlsFatalAlert(AlertDescription.illegal_parameter);
        }
    }

    public static TlsECConfig receiveECDHConfig(TlsContext context, InputStream input) throws IOException
    {
        short curveType = TlsUtils.readUint8(input);
        if (curveType != ECCurveType.named_curve)
        {
            throw new TlsFatalAlert(AlertDescription.handshake_failure);
        }

        int namedGroup = TlsUtils.readUint16(input);
        if (NamedGroup.refersToAnECDHCurve(namedGroup))
        {
            int[] clientSupportedGroups = context.getSecurityParametersHandshake().getClientSupportedGroups();
            if (null == clientSupportedGroups || Arrays.contains(clientSupportedGroups, namedGroup))
            {
                return new TlsECConfig(namedGroup);
            }
        }

        throw new TlsFatalAlert(AlertDescription.illegal_parameter);
    }

    public static void writeECConfig(TlsECConfig ecConfig, OutputStream output) throws IOException
    {
        writeNamedECParameters(ecConfig.getNamedGroup(), output);
    }

    public static void writeNamedECParameters(int namedGroup, OutputStream output) throws IOException
    {
        if (!NamedGroup.refersToASpecificCurve(namedGroup))
        {
            /*
             * RFC 4492 5.4. All those values of NamedCurve are allowed that refer to a specific
             * curve. Values of NamedCurve that indicate support for a class of explicitly defined
             * curves are not allowed here [...].
             */
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        TlsUtils.writeUint8(ECCurveType.named_curve, output);
        TlsUtils.checkUint16(namedGroup);
        TlsUtils.writeUint16(namedGroup, output);
    }
}