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

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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.

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package org.bouncycastle.tls;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Hashtable;

import org.bouncycastle.util.Integers;

/**
 * RFC 5764 DTLS Extension to Establish Keys for SRTP.
 */
public class TlsSRTPUtils
{
    public static final Integer EXT_use_srtp = Integers.valueOf(ExtensionType.use_srtp);

    public static void addUseSRTPExtension(Hashtable extensions, UseSRTPData useSRTPData)
        throws IOException
    {
        extensions.put(EXT_use_srtp, createUseSRTPExtension(useSRTPData));
    }

    public static UseSRTPData getUseSRTPExtension(Hashtable extensions)
        throws IOException
    {
        byte[] extensionData = TlsUtils.getExtensionData(extensions, EXT_use_srtp);
        return extensionData == null ? null : readUseSRTPExtension(extensionData);
    }

    public static byte[] createUseSRTPExtension(UseSRTPData useSRTPData)
        throws IOException
    {
        if (useSRTPData == null)
        {
            throw new IllegalArgumentException("'useSRTPData' cannot be null");
        }

        ByteArrayOutputStream buf = new ByteArrayOutputStream();

        // SRTPProtectionProfiles
        TlsUtils.writeUint16ArrayWithUint16Length(useSRTPData.getProtectionProfiles(), buf);

        // srtp_mki
        TlsUtils.writeOpaque8(useSRTPData.getMki(), buf);

        return buf.toByteArray();
    }

    public static UseSRTPData readUseSRTPExtension(byte[] extensionData)
        throws IOException
    {
        if (extensionData == null)
        {
            throw new IllegalArgumentException("'extensionData' cannot be null");
        }

        ByteArrayInputStream buf = new ByteArrayInputStream(extensionData);

        // SRTPProtectionProfiles
        int length = TlsUtils.readUint16(buf);
        if (length < 2 || (length & 1) != 0)
        {
            throw new TlsFatalAlert(AlertDescription.decode_error);
        }
        int[] protectionProfiles = TlsUtils.readUint16Array(length / 2, buf);

        // srtp_mki
        byte[] mki = TlsUtils.readOpaque8(buf);

        TlsProtocol.assertEmpty(buf);

        return new UseSRTPData(protectionProfiles, mki);
    }
}