private void OnExecute()
{
Fido2Settings.Flags = FidoFlags.Debug;
var ext = HMACSalt != null ? FidoExtensions.HmacSecret : FidoExtensions.None;
using (var assert = new FidoAssertion()) {
using (var dev = new FidoDevice()) {
dev.Open(Device);
if (ForceU2F)
{
dev.ForceU2F();
}
if (CredentialId != null)
{
var credId = File.ReadAllBytes(CredentialId);
assert.AllowCredential(credId);
}
assert.ClientDataHash = Cdh;
assert.Rp = "localhost";
assert.SetExtensions(ext);
assert.SetOptions(UserPresenceRequired, UserVerificationRequired);
dev.GetAssert(assert, Pin);
dev.Close();
}
if (assert.Count != 1)
{
throw new Exception($"{assert.Count} signatures required");
}
VerifyAssert(assert[0].AuthData, assert[0].Signature, ext);
if (HMACSecret != null)
{
File.WriteAllBytes(HMACSecret, assert[0].HmacSecret.ToArray());
}
}
}
private void VerifyAssert(ReadOnlySpan <byte> authData, ReadOnlySpan <byte> signature, FidoExtensions extensions)
{
var ext = HMACSalt != null ? FidoExtensions.HmacSecret : FidoExtensions.None;
byte[] keyBytes = null;
using (var fin = new StreamReader(File.OpenRead(PublicKey))) {
var reader = new PemReader(fin);
if (Type == KeyType.ECDSA)
{
ECPublicKeyParameters parameters = (ECPublicKeyParameters)reader.ReadObject();
var x = parameters.Q.XCoord.ToBigInteger().ToByteArray();
var y = parameters.Q.YCoord.ToBigInteger().ToByteArray();
keyBytes = new byte[x.Length + y.Length - 1];
x.CopyTo(keyBytes, 0);
// Why? There seems to be an extra byte at the beginning
Array.Copy(y, 1, keyBytes, x.Length, y.Length - 1);
}
else
{
RsaKeyParameters parameters = (RsaKeyParameters)reader.ReadObject();
var mod = parameters.Modulus.ToByteArray();
var e = parameters.Exponent.ToByteArray();
keyBytes = new byte[mod.Length + e.Length];
mod.CopyTo(keyBytes, 0);
e.CopyTo(keyBytes, mod.Length);
}
}
using (var assert = new FidoAssertion()) {
assert.ClientDataHash = Cdh;
assert.Rp = "localhost";
assert.Count = 1;
assert.SetAuthData(authData, 0);
assert.SetExtensions(ext);
assert.SetOptions(UserPresenceRequired, UserVerificationRequired);
assert.SetSignature(signature, 0);
assert.Verify(0, FromKeyType(Type), keyBytes);
}
}
//View the c# versions of the c examples from Yubico here:
//https://github.com/borrrden/Fido2Net/blob/master/Examples/assert/Assert/Program.cs
//This will help explain how to eg retrieve hmac secrets
private static AssertionResult DoAssertion(string devicePath, bool useHmacExtension, string rp, FidoCose algorithmType, string pin, MakeCredentialResult credential, MakeCredentialResult credential2, byte[] salt, byte[] salt2, bool requireUp, bool requireUv)
{
var ext = useHmacExtension ? FidoExtensions.HmacSecret : FidoExtensions.None;
using (var assert = new FidoAssertion())
{
using (var dev = new FidoDevice())
{
dev.Open(devicePath);
if (credential.CredentialId != null)
{
assert.AllowCredential(Convert.FromBase64String(credential.CredentialId));
}
if (credential2.CredentialId != null)
{
assert.AllowCredential(Convert.FromBase64String(credential2.CredentialId));
}
assert.ClientDataHash = Cdh;
assert.Rp = rp;
assert.SetExtensions(ext);
if (useHmacExtension)
{
assert.SetHmacSalt(salt, 0);
if (credential2.CredentialId != null)
{
assert.SetHmacSalt(salt2, 1);
}
}
if (requireUv)
{
assert.SetOptions(requireUp, requireUv);
}
dev.GetAssert(assert, pin);
dev.Close();
}
if (assert.Count != 1)
{
throw new Exception($"{assert.Count} signatures required");
}
var authData = assert[0].AuthData;
var signature = assert[0].Signature;
var credentialId = Convert.ToBase64String(assert[0].Id.ToArray());
var verifiedKey = "";
using (var verify = new FidoAssertion())
{
verify.ClientDataHash = Cdh;
verify.Rp = rp;
verify.Count = 1;
verify.SetAuthData(authData, 0);
verify.SetExtensions(ext);
if (requireUv)
{
verify.SetOptions(requireUp, requireUv);
}
verify.SetSignature(signature, 0);
//Get the correct public id
string publicKey = string.Empty;
if (credential.CredentialId == credentialId)
{
publicKey = credential.PublicKey;
}
else if (credential2.CredentialId == credentialId)
{
publicKey = credential2.PublicKey;
}
if (string.IsNullOrEmpty(publicKey))
{
throw new ApplicationException("Credential not found in assertion.");
}
//Now verify with the public key
verify.Verify(0, algorithmType, Convert.FromBase64String(publicKey));
verifiedKey = credential.PublicKey;
}
AssertionResult result;
result.HmacSecret = (useHmacExtension) ? assert[0].HmacSecret.ToArray() : new Byte[] { };
result.Valid = !String.IsNullOrEmpty(verifiedKey);
result.PublicKey = verifiedKey;
return(result);
}
}
//View the c# versions of the c examples from Yubico here:
//https://github.com/borrrden/Fido2Net/blob/master/Examples/assert/Assert/Program.cs
//This will help explain how to eg retrieve hmac secrets
private static AssertionResult DoAssertion(string devicePath, bool useHmacExtension, string rp, FidoCose algorithmType, string pin, string credentialId, string publicKey, bool requireUp, bool requireUv)
{
var ext = useHmacExtension ? FidoExtensions.HmacSecret : FidoExtensions.None;
using (var assert = new FidoAssertion())
{
using (var dev = new FidoDevice())
{
dev.Open(devicePath);
if (credentialId != null)
{
assert.AllowCredential(Convert.FromBase64String(credentialId));
}
assert.ClientDataHash = Cdh;
assert.Rp = rp;
assert.SetExtensions(ext);
if (useHmacExtension)
{
assert.SetHmacSalt(Salt, 0);
}
if (requireUv)
{
assert.SetOptions(requireUp, requireUv);
}
dev.GetAssert(assert, pin);
//Find the generated secret (somehow)
dev.Close();
}
if (assert.Count != 1)
{
throw new Exception($"{assert.Count} signatures required");
}
var authData = assert[0].AuthData;
var signature = assert[0].Signature;
using (var verify = new FidoAssertion())
{
verify.ClientDataHash = Cdh;
verify.Rp = rp;
verify.Count = 1;
verify.SetAuthData(authData, 0);
verify.SetExtensions(ext);
if (requireUv)
{
verify.SetOptions(requireUp, requireUv);
}
verify.SetSignature(signature, 0);
verify.Verify(0, algorithmType, Convert.FromBase64String(publicKey));
}
AssertionResult result;
result.HmacSecret = (useHmacExtension) ? assert[0].HmacSecret.ToArray() : new Byte[] { };
result.Valid = true;
return(result);
}
}