public bool Validate(Recipient recipientReceiver)
{
byte[] rgbKey = null;
int cbitKey;
CBORObject alg = FindAttribute(HeaderKeys.Algorithm);
if (alg.Type == CBORType.TextString)
{
switch (alg.AsString())
{
case "AES-CMAC-128/64":
cbitKey = 128;
break;
case "AES-CMAC-256/64":
cbitKey = 256;
break;
default:
throw new CoseException("Unknown Algorithm Specified");
}
}
else if (alg.Type == CBORType.Integer)
{
switch ((AlgorithmValuesInt)alg.AsInt32())
{
case AlgorithmValuesInt.HMAC_SHA_256_64:
case AlgorithmValuesInt.HMAC_SHA_256:
cbitKey = 256;
break;
case AlgorithmValuesInt.HMAC_SHA_384: cbitKey = 384; break;
case AlgorithmValuesInt.HMAC_SHA_512: cbitKey = 512; break;
case AlgorithmValuesInt.AES_CBC_MAC_128_64:
case AlgorithmValuesInt.AES_CBC_MAC_128_128:
cbitKey = 128;
break;
case AlgorithmValuesInt.AES_CBC_MAC_256_64:
case AlgorithmValuesInt.AES_CBC_MAC_256_128:
cbitKey = 256;
break;
default:
throw new CoseException("MAC algorithm not recognized " + alg.AsInt32());
}
}
else
{
throw new CoseException("Algorithm incorrectly encoded");
}
foreach (Recipient msgRecpient in _recipientList)
{
if (recipientReceiver == msgRecpient)
{
try {
rgbKey = msgRecpient.Decrypt(cbitKey, alg);
}
catch (CoseException) { }
}
else if (recipientReceiver.RecipientList.Count > 0)
{
try {
rgbKey = recipientReceiver.Decrypt(cbitKey, alg, recipientReceiver);
}
catch (CoseException) {
}
}
if (rgbKey != null)
{
break;
}
}
if (rgbKey == null)
{
throw new CoseException("Recipient not found");
}
byte[] rgbCheck;
if (alg.Type == CBORType.TextString)
{
switch (alg.AsString())
{
case "AES-CMAC-128/64":
case "AES-CMAC-256/64":
rgbCheck = AES_CMAC(alg, rgbKey);
break;
default:
throw new CoseException("Unknown Algorithm Specified");
}
}
else if (alg.Type == CBORType.Integer)
{
switch ((AlgorithmValuesInt)alg.AsInt32())
{
case AlgorithmValuesInt.HMAC_SHA_256:
case AlgorithmValuesInt.HMAC_SHA_384:
case AlgorithmValuesInt.HMAC_SHA_512:
case AlgorithmValuesInt.HMAC_SHA_256_64:
rgbCheck = HMAC(alg, rgbKey);
break;
case AlgorithmValuesInt.AES_CBC_MAC_128_64:
case AlgorithmValuesInt.AES_CBC_MAC_128_128:
case AlgorithmValuesInt.AES_CBC_MAC_256_64:
case AlgorithmValuesInt.AES_CBC_MAC_256_128:
rgbCheck = AES_CBC_MAC(alg, rgbKey);
break;
default:
throw new CoseException("MAC algorithm not recognized " + alg.AsInt32());
}
}
else
{
throw new CoseException("Algorithm incorrectly encoded");
}
bool fReturn = true;
for (int i = 0; i < rgbCheck.Length; i++)
{
fReturn &= (RgbTag[i] == rgbCheck[i]);
}
return(fReturn);
}
