private bool VerifyS3Message(byte[] s3Message)
{
// Convert S3 message from byte array into the compatible structure
object S3MessageObj = new SigmaDataStructs.SigmaS3Message();
GeneralUtils.ByteArrayToStructure(s3Message, ref S3MessageObj);
SigmaDataStructs.SigmaS3Message S3Message = (SigmaDataStructs.SigmaS3Message)S3MessageObj;
// Locate the data index in the message
int dataInd = Marshal.SizeOf(typeof(SigmaDataStructs.SigmaS3Message)) - 1 + 32;
// Copy S3 message data from the received message into the S3 strucure data field
S3Message.data = new byte[s3Message.Length - dataInd];
Array.Copy(s3Message, dataInd, S3Message.data, 0, S3Message.data.Length);
// Prepare data for HMAC
byte[] dataForHmac = new byte[s3Message.Length - S3Message.S3Icv.Length];
Array.Copy(s3Message, S3Message.S3Icv.Length, dataForHmac, 0, dataForHmac.Length);
// Verify HMAC
CdgResult retStat = CdgResult.CdgValid;
CdgStatus status;
status = CryptoDataGenWrapper.VerifyHmac(dataForHmac, dataForHmac.Length, S3Message.S3Icv, SigmaDataStructs.SIGMA_MAC_LEN, SMK, SigmaDataStructs.SIGMA_SMK_LENGTH, ref retStat);
if (status != CdgStatus.CdgStsOk || retStat != CdgResult.CdgValid)
{
return(false);
}
// Check whether BK exists in the signed message, as a part of the S3 message validation
byte[] GaGbSig = new byte[SigmaDataStructs.EPID_SIG_LEN];
if (!SigmaUtils.DoesBKExist(S3Message, ref GaGbSig))
{
return(false);
}
// groupCert contains the SIGMA 1.0 certificate for the specific EPID group ID
byte[] groupCert = SigmaUtils.GetSpecificEpidCertificate_SIGMA_1_0(epidGroupID);
// epidParamsCert contains the mathematic parameters
byte[] epidParamsData = File.ReadAllBytes(EPIDDataStructs.PRODUCTION_SIGNED_BIN_PARAMS_CERT_FILE);
// Verify message. If a revocation list is used - the dll function will also check that the platform was not revoked.
status = CryptoDataGenWrapper.MessageVerifyPch(groupCert, groupCert.Length, epidParamsData, GaGb, GaGb.Length, null, 0, GaGbSig, GaGbSig.Length, out retStat, null);
if (status != CdgStatus.CdgStsOk || retStat != CdgResult.CdgValid)
{
return(false);
}
return(true);
}
/**
* Gets the provisioning data (including the mathematic parameters and certificate) according to the platform EPID group ID
*/
private static byte[] CreateProvisioningData(uint GroupID)
{
// Provisioning data buffer
EPIDDataStructs.ProvisioningDataSigma1_1 provisioningData = new EPIDDataStructs.ProvisioningDataSigma1_1();
// Build provisioning data
// Header
provisioningData.Header.ApiVersion = (uint)SigmaDataStructs.SIGMA_API_VERSION_1_1;
provisioningData.Header.CommandId = (uint)EPIDDataStructs.CommandId.CMD_SEND_SAFEID_PUBKEY;
provisioningData.Header.Status = 0;
// CryptoContext - contains the mathematic parameters
provisioningData.CryptoContext = File.ReadAllBytes(EPIDDataStructs.DEBUG_SIGNED_BIN_PARAMS_CERT_FILE);
// SafeIdCert - contains the SIGMA1_0 certificate for the specific EPID group ID
provisioningData.SafeIdCert = SigmaUtils.GetSpecificEpidCertificate_SIGMA_1_0(GroupID);
// tempCert contains the SIGMA 1.1 certificate for the specific EPID group ID
byte[] tempCert = SigmaUtils.GetSpecificEpidCertificate_SIGMA_1_1(GroupID);
// Calculate the needed padding length
int paddingLen = (4 - (DataStructs.VLR_HEADER_LEN + tempCert.Length) % 4) % 4;
// Pad original cert so it will be word aligned
byte[] paddedCert = new byte[tempCert.Length + paddingLen];
tempCert.CopyTo(paddedCert, 0);
tempCert = paddedCert;
// Set EPID group certificate
provisioningData.X509GroupCert = new EPIDDataStructs.X509GroupCertificate();
provisioningData.X509GroupCert.vlrHeader.ID = (byte)DataStructs.VlrIdType.X509_GROUP_CERTIFICATE_VLR_ID;
provisioningData.X509GroupCert.vlrHeader.VLRLength = (short)(DataStructs.VLR_HEADER_LEN + tempCert.Length);
provisioningData.X509GroupCert.vlrHeader.PaddedBytes = (byte)paddingLen;
provisioningData.Header.BufferLength = (uint)(Marshal.SizeOf(typeof(EPIDDataStructs.ProvisioningDataSigma1_1)) - Marshal.SizeOf(typeof(EPIDDataStructs.SessionMgrCmdHdr)) + tempCert.Length); //cert has a different length
byte[] provisioningDataArray = GeneralUtils.StructureToByteArray(provisioningData);
// The provisioning data contains the whole data: dataArray and the SIGMA 1.1 certificate for the specific EPID group ID
byte[] provisioningDataAndCert = new byte[provisioningDataArray.Length + tempCert.Length];
Array.Copy(provisioningDataArray, provisioningDataAndCert, provisioningDataArray.Length);
Array.Copy(tempCert, 0, provisioningDataAndCert, provisioningDataArray.Length, tempCert.Length);
return(provisioningDataAndCert);
}
public override void HandleClientCommunication(object client)
{
try
{
TcpClient tcpClient = (TcpClient)client;
Socket socket = tcpClient.Client;
isClientConnected = socket.Connected;
while (isClientConnected)
{
// Receive adapted message (message prepared for verification)
int dataSize = socket.ReceiveMessageAsInt();
byte[] adaptedMessage = socket.ReceiveMessage(dataSize);
// Receive signature
dataSize = socket.ReceiveMessageAsInt();
byte[] signature = socket.ReceiveMessage(dataSize);
// Receive EPID group ID
int groupID = socket.ReceiveMessageAsInt();
// groupCert contains the SIGMA 1.1 certificate for the specific EPID group ID
byte[] groupCert = SigmaUtils.GetSpecificEpidCertificate_SIGMA_1_0((uint)groupID);
// epidParamsCert contains the mathematic parameters
byte[] epidParamsCert = File.ReadAllBytes(EPIDDataStructs.DEBUG_SIGNED_BIN_PARAMS_CERT_FILE);
// taskInfoArray is a data structure defined in the DAL implementation.
// It is prepended to the message by DAL prior to signing,
// and so has to be prepended by us prior to verification
byte[] taskInfoArray = GeneralUtils.StructureToByteArray(EPIDDataStructs.GetTaskInfo());
byte[] infoNonceMessage = new byte[taskInfoArray.Length + adaptedMessage.Length]; //TaskInfo || Nonce || Message
// Concatenate the info to infoNonceMessage
taskInfoArray.CopyTo(infoNonceMessage, 0);
// Concatenate the adapted message(including the nonce) to infoNonceMessage
adaptedMessage.CopyTo(infoNonceMessage, taskInfoArray.Length);
// Verify the signature
// When we call the MessageVerifyPch function, we can send
// baseName - the basename that will be signed as part of the signature
// privateKeyRevList - a list of the platforms that were revoked based on the platform’s private key
// SignatureRevList - a list of the platforms that were revoked based on the signature generated by the platform
// GroupRevList - a list of the EPID groups that were revoked based on the group public key
// as parameters.
CdgResult retStatus;
CdgStatus status = CryptoDataGenWrapper.MessageVerifyPch(groupCert, groupCert.Length, epidParamsCert, infoNonceMessage, infoNonceMessage.Length, null, 0, signature, signature.Length, out retStatus, null, null, null);
int res = VERIFYNG_SUCCESS;
if (status != CdgStatus.CdgStsOk)
{
res = ERROR;
}
else if (retStatus != CdgResult.CdgValid)
{
res = VERIFYNG_FAILED;
}
// Send the signature verification result to the client
socket.SendInt(res);
}
Console.WriteLine("EPID Signing Sample Client disconnected.\n");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}