public override void ProcessServerExtensions(IDictionary clientExtensions)
{
base.ProcessServerExtensions(clientExtensions);
// set to some reasonable default value
int chosenProfile = SrtpProtectionProfile.SRTP_AES128_CM_HMAC_SHA1_80;
UseSrtpData clientSrtpData = TlsSRTPUtils.GetUseSrtpExtension(clientExtensions);
foreach (int profile in clientSrtpData.ProtectionProfiles)
{
switch (profile)
{
case SrtpProtectionProfile.SRTP_AES128_CM_HMAC_SHA1_32:
case SrtpProtectionProfile.SRTP_AES128_CM_HMAC_SHA1_80:
case SrtpProtectionProfile.SRTP_NULL_HMAC_SHA1_32:
case SrtpProtectionProfile.SRTP_NULL_HMAC_SHA1_80:
chosenProfile = profile;
break;
}
}
// server chooses a mutually supported SRTP protection profile
// http://tools.ietf.org/html/draft-ietf-avt-dtls-srtp-07#section-4.1.2
int[] protectionProfiles = { chosenProfile };
// server agrees to use the MKI offered by the client
clientSrtpData = new UseSrtpData(protectionProfiles, clientSrtpData.Mki);
}
public DtlsSrtpClient(Certificate certificateChain, AsymmetricKeyParameter privateKey,
UseSrtpData clientSrtpData)
{
if (certificateChain == null && privateKey == null)
{
(certificateChain, privateKey) = DtlsUtils.CreateSelfSignedTlsCert();
}
if (clientSrtpData == null)
{
SecureRandom random = new SecureRandom();
int[] protectionProfiles = { SrtpProtectionProfile.SRTP_AES128_CM_HMAC_SHA1_80 };
byte[] mki = new byte[(SrtpParameters.SRTP_AES128_CM_HMAC_SHA1_80.GetCipherKeyLength() +
SrtpParameters.SRTP_AES128_CM_HMAC_SHA1_80.GetCipherSaltLength()) / 8];
random.NextBytes(mki); // Reusing our secure random for generating the key.
this.clientSrtpData = new UseSrtpData(protectionProfiles, mki);
}
else
{
this.clientSrtpData = clientSrtpData;
}
this.mPrivateKey = privateKey;
mCertificateChain = certificateChain;
//Generate FingerPrint
var certificate = mCertificateChain.GetCertificateAt(0);
Fingerprint = certificate != null?DtlsUtils.Fingerprint(certificate) : null;
}
public DtlsSrtpClient(UseSrtpData clientSrtpData) : this(null, null, clientSrtpData)
{
}
public DtlsSrtpClient(UseSrtpData clientSrtpData) : this(DtlsUtils.CreateSelfSignedCert())
{
this.clientSrtpData = clientSrtpData;
}