Cleanup

Src/Fido2/AttestationFormat/AndroidKey.cs

@@ -35,7 +35,7 @@ public static byte[] GetAttestationChallenge(byte[] attExtBytes)
     public static bool FindAllApplicationsField(byte[] attExtBytes)
     {
         // https://developer.android.com/training/articles/security-key-attestation#certificate_schema
-        // check both software and tee enforced AuthorizationList objects for presense of "allApplications" tag, number 600
+        // check both software and tee enforced AuthorizationList objects for presence of "allApplications" tag, number 600
 
         var keyDescription = Asn1Element.Decode(attExtBytes);
 

Src/Fido2/AttestationFormat/AttestationVerifier.cs

@@ -102,27 +102,27 @@ internal static bool IsAttnCertCACert(X509ExtensionCollection exts)
 
     internal static byte U2FTransportsFromAttnCert(X509ExtensionCollection exts)
     {
-        byte u2ftransports = 0;
+        byte u2fTransports = 0;
         var ext = exts.FirstOrDefault(e => e.Oid?.Value is "1.3.6.1.4.1.45724.2.1.1");
         if (ext != null)
         {
-            var decodedU2Ftransports = Asn1Element.Decode(ext.RawData);
-            decodedU2Ftransports.CheckPrimitive();
+            var decodedU2fTransports = Asn1Element.Decode(ext.RawData);
+            decodedU2fTransports.CheckPrimitive();
 
             // some certificates seem to have this encoded as an octet string
             // instead of a bit string, attempt to correct
-            if (decodedU2Ftransports.Tag == Asn1Tag.PrimitiveOctetString)
+            if (decodedU2fTransports.Tag == Asn1Tag.PrimitiveOctetString)
             {
                 ext.RawData[0] = (byte)UniversalTagNumber.BitString;
-                decodedU2Ftransports = Asn1Element.Decode(ext.RawData);
+                decodedU2fTransports = Asn1Element.Decode(ext.RawData);
             }
 
-            decodedU2Ftransports.CheckTag(Asn1Tag.PrimitiveBitString);
+            decodedU2fTransports.CheckTag(Asn1Tag.PrimitiveBitString);
 
-            u2ftransports = decodedU2Ftransports.GetBitString()[0];
+            u2fTransports = decodedU2fTransports.GetBitString()[0];
         }
 
-        return u2ftransports;
+        return u2fTransports;
     }
 
 #nullable disable

Src/Fido2/AttestationFormat/FidoU2f.cs

@@ -7,93 +7,92 @@
 using Fido2NetLib.Exceptions;
 using Fido2NetLib.Objects;
 
-namespace Fido2NetLib
+namespace Fido2NetLib;
+
+internal sealed class FidoU2f : AttestationVerifier
 {
-    internal sealed class FidoU2f : AttestationVerifier
+    public override (AttestationType, X509Certificate2[]) Verify()
     {
-        public override (AttestationType, X509Certificate2[]) Verify()
+        // verify that aaguid is 16 empty bytes (note: required by fido2 conformance testing, could not find this in spec?)
+        if (AuthData.AttestedCredentialData!.AaGuid.CompareTo(Guid.Empty) != 0)
+            throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Aaguid was not empty parsing fido-u2f attestation statement");
+
+        // https://www.w3.org/TR/webauthn/#fido-u2f-attestation
+        // 1. Verify that attStmt is valid CBOR conforming to the syntax defined above and perform CBOR decoding on it to extract the contained fields.
+        // (handled in base class)
+
+        // 2a. Check that x5c has exactly one element and let attCert be that element.
+        if (!(X5c is CborArray { Length: 1 } x5cArray && x5cArray[0] is CborByteString { Length: > 0 }))
+        {
+            throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, Fido2ErrorMessages.MalformedX5c_FidoU2fAttestation);
+        }
+
+        var attCert = new X509Certificate2((byte[])x5cArray[0]);
+
+        // TODO : Check why this variable isn't used. Remove it or use it.
+        var u2fTransports = U2FTransportsFromAttnCert(attCert.Extensions);
+
+        // 2b. If certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve, terminate this algorithm and return an appropriate error
+        var pubKey = attCert.GetECDsaPublicKey()!;
+        var keyParams = pubKey.ExportParameters(false);
+
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+        {
+            if (!keyParams.Curve.Oid.FriendlyName!.Equals(ECCurve.NamedCurves.nistP256.Oid.FriendlyName, StringComparison.Ordinal))
+                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Attestation certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve");
+        }
+        else
         {
-            // verify that aaguid is 16 empty bytes (note: required by fido2 conformance testing, could not find this in spec?)
-            if (AuthData.AttestedCredentialData!.AaGuid.CompareTo(Guid.Empty) != 0)
-                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Aaguid was not empty parsing fido-u2f atttestation statement");
-
-            // https://www.w3.org/TR/webauthn/#fido-u2f-attestation
-            // 1. Verify that attStmt is valid CBOR conforming to the syntax defined above and perform CBOR decoding on it to extract the contained fields.
-            // (handled in base class)
-
-            // 2a. Check that x5c has exactly one element and let attCert be that element.
-            if (!(X5c is CborArray { Length: 1 } x5cArray && x5cArray[0] is CborByteString { Length: > 0 }))
-            {
-                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, Fido2ErrorMessages.MalformedX5c_FidoU2fAttestation);
-            }
-
-            var attCert = new X509Certificate2((byte[])x5cArray[0]);
-
-            // TODO : Check why this variable isn't used. Remove it or use it.
-            var u2ftransports = U2FTransportsFromAttnCert(attCert.Extensions);
-
-            // 2b. If certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve, terminate this algorithm and return an appropriate error
-            var pubKey = attCert.GetECDsaPublicKey()!;
-            var keyParams = pubKey.ExportParameters(false);
-
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-            {
-                if (!keyParams.Curve.Oid.FriendlyName!.Equals(ECCurve.NamedCurves.nistP256.Oid.FriendlyName, StringComparison.Ordinal))
-                    throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Attestation certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve");
-            }
-            else
-            {
-                if (!keyParams.Curve.Oid.Value!.Equals(ECCurve.NamedCurves.nistP256.Oid.Value, StringComparison.Ordinal))
-                    throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Attestation certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve");
-            }
-
-            // 3. Extract the claimed rpIdHash from authenticatorData, and the claimed credentialId and credentialPublicKey from authenticatorData
-            // see rpIdHash, credentialId, and credentialPublicKey members of base class AuthenticatorData (AuthData)
-
-            // 4. Convert the COSE_KEY formatted credentialPublicKey (see Section 7 of [RFC8152]) to CTAP1/U2F public Key format (Raw ANSI X9.62 public key format)
-            // 4a. Let x be the value corresponding to the "-2" key (representing x coordinate) in credentialPublicKey, and confirm its size to be of 32 bytes. If size differs or "-2" key is not found, terminate this algorithm and return an appropriate error
-            var x = (byte[])CredentialPublicKey[COSE.KeyTypeParameter.X];
-
-            // 4b. Let y be the value corresponding to the "-3" key (representing y coordinate) in credentialPublicKey, and confirm its size to be of 32 bytes. If size differs or "-3" key is not found, terminate this algorithm and return an appropriate error
-            var y = (byte[])CredentialPublicKey[COSE.KeyTypeParameter.Y];
-
-            // 4c.Let publicKeyU2F be the concatenation 0x04 || x || y
-            var publicKeyU2F = DataHelper.Concat(stackalloc byte[1] { 0x4 }, x, y);
-
-            // 5. Let verificationData be the concatenation of (0x00 || rpIdHash || clientDataHash || credentialId || publicKeyU2F)
-            byte[] verificationData = DataHelper.Concat(
-                stackalloc byte[1] { 0x00 },
-                AuthData.RpIdHash,
-                _clientDataHash,
-                AuthData.AttestedCredentialData.CredentialID,
-                publicKeyU2F
-            );
-
-            // 6. Verify the sig using verificationData and certificate public key
-            if (!TryGetSig(out byte[]? sig))
-                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, Fido2ErrorMessages.InvalidFidoU2fAttestationSignature);
-
-            byte[] ecsig;
-            try
-            {
-                ecsig = CryptoUtils.SigFromEcDsaSig(sig, pubKey.KeySize);
-            }
-            catch (Exception ex)
-            {
-                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Failed to decode fido-u2f attestation signature from ASN.1 encoded form", ex);
-            }
-
-            var coseAlg = (COSE.Algorithm)(int)CredentialPublicKey[COSE.KeyCommonParameter.Alg];
-            var hashAlg = CryptoUtils.HashAlgFromCOSEAlg(coseAlg);
-
-            if (!pubKey.VerifyData(verificationData, ecsig, hashAlg))
-                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Invalid fido-u2f attestation signature");
-
-            // 7. Optionally, inspect x5c and consult externally provided knowledge to determine whether attStmt conveys a Basic or AttCA attestation
-
-            var trustPath = new X509Certificate2[1] { attCert };
-
-            return (AttestationType.AttCa, trustPath);
+            if (!keyParams.Curve.Oid.Value!.Equals(ECCurve.NamedCurves.nistP256.Oid.Value, StringComparison.Ordinal))
+                throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Attestation certificate public key is not an Elliptic Curve (EC) public key over the P-256 curve");
         }
+
+        // 3. Extract the claimed rpIdHash from authenticatorData, and the claimed credentialId and credentialPublicKey from authenticatorData
+        // see rpIdHash, credentialId, and credentialPublicKey members of base class AuthenticatorData (AuthData)
+
+        // 4. Convert the COSE_KEY formatted credentialPublicKey (see Section 7 of [RFC8152]) to CTAP1/U2F public Key format (Raw ANSI X9.62 public key format)
+        // 4a. Let x be the value corresponding to the "-2" key (representing x coordinate) in credentialPublicKey, and confirm its size to be of 32 bytes. If size differs or "-2" key is not found, terminate this algorithm and return an appropriate error
+        var x = (byte[])CredentialPublicKey[COSE.KeyTypeParameter.X];
+
+        // 4b. Let y be the value corresponding to the "-3" key (representing y coordinate) in credentialPublicKey, and confirm its size to be of 32 bytes. If size differs or "-3" key is not found, terminate this algorithm and return an appropriate error
+        var y = (byte[])CredentialPublicKey[COSE.KeyTypeParameter.Y];
+
+        // 4c.Let publicKeyU2F be the concatenation 0x04 || x || y
+        var publicKeyU2F = DataHelper.Concat(stackalloc byte[1] { 0x4 }, x, y);
+
+        // 5. Let verificationData be the concatenation of (0x00 || rpIdHash || clientDataHash || credentialId || publicKeyU2F)
+        byte[] verificationData = DataHelper.Concat(
+            stackalloc byte[1] { 0x00 },
+            AuthData.RpIdHash,
+            _clientDataHash,
+            AuthData.AttestedCredentialData.CredentialID,
+            publicKeyU2F
+        );
+
+        // 6. Verify the sig using verificationData and certificate public key
+        if (!TryGetSig(out byte[]? sig))
+            throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, Fido2ErrorMessages.InvalidFidoU2fAttestationSignature);
+
+        byte[] ecsig;
+        try
+        {
+            ecsig = CryptoUtils.SigFromEcDsaSig(sig, pubKey.KeySize);
+        }
+        catch (Exception ex)
+        {
+            throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Failed to decode fido-u2f attestation signature from ASN.1 encoded form", ex);
+        }
+
+        var coseAlg = (COSE.Algorithm)(int)CredentialPublicKey[COSE.KeyCommonParameter.Alg];
+        var hashAlg = CryptoUtils.HashAlgFromCOSEAlg(coseAlg);
+
+        if (!pubKey.VerifyData(verificationData, ecsig, hashAlg))
+            throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Invalid fido-u2f attestation signature");
+
+        // 7. Optionally, inspect x5c and consult externally provided knowledge to determine whether attStmt conveys a Basic or AttCA attestation
+
+        var trustPath = new X509Certificate2[1] { attCert };
+
+        return (AttestationType.AttCa, trustPath);
     }
 }

Src/Fido2/AttestationFormat/Packed.cs

@@ -113,7 +113,7 @@ public override (AttestationType, X509Certificate2[]?) Verify()
             }
 
             // id-fido-u2f-ce-transports 
-            byte u2ftransports = U2FTransportsFromAttnCert(attestnCert.Extensions);
+            byte u2fTransports = U2FTransportsFromAttnCert(attestnCert.Extensions);
 
             // 2d. Optionally, inspect x5c and consult externally provided knowledge to determine whether attStmt conveys a Basic or AttCA attestation
 

Src/Fido2/AttestationFormat/Tpm.cs

@@ -229,15 +229,15 @@ public override (AttestationType, X509Certificate2[]) Verify()
         { 3, TpmEccCurve.TPM_ECC_NIST_P521}
     };
 
-    private static (string?, string?, string?) SANFromAttnCertExts(X509ExtensionCollection extensions)
+    private static (string?, string?, string?) SANFromAttnCertExts(X509ExtensionCollection exts)
     {
         string? tpmManufacturer = null;
         string? tpmModel = null;
         string? tpmVersion = null;
 
         var foundSAN = false;
 
-        foreach (var extension in extensions)
+        foreach (var extension in exts)
         {
             if (extension.Oid!.Value is "2.5.29.17") // subject alternative name
             {
@@ -433,7 +433,7 @@ public enum TpmAlg : ushort
 // TPMS_ATTEST, TPMv2-Part2, section 10.12.8
 public class CertInfo
 {
-    private static readonly Dictionary<TpmAlg, ushort> tpmAlgToDigestSizeMap = new()
+    private static readonly Dictionary<TpmAlg, ushort> s_tpmAlgToDigestSizeMap = new()
     {
         { TpmAlg.TPM_ALG_SHA1,   (160/8) },
         { TpmAlg.TPM_ALG_SHA256, (256/8) },
@@ -472,7 +472,7 @@ public static (ushort size, byte[] name) NameFromTPM2BName(ReadOnlySpan<byte> ab
         if (Enum.IsDefined(typeof(TpmAlg), size))
         {
             var tpmalg = (TpmAlg)size;
-            if (tpmAlgToDigestSizeMap.TryGetValue(tpmalg, out ushort tplAlgDigestSize))
+            if (s_tpmAlgToDigestSizeMap.TryGetValue(tpmalg, out ushort tplAlgDigestSize))
             {
                 name = AuthDataHelper.GetSizedByteArray(ab, ref offset, tplAlgDigestSize);
             }
@@ -529,19 +529,19 @@ public CertInfo(byte[] certInfo)
         if (certInfo.Length != offset)
             throw new Fido2VerificationException("Leftover bits decoding certInfo");
     }
-    public byte[] Raw { get; private set; }
-    public byte[] Magic { get; private set; }
-    public byte[] Type { get; private set; }
-    public byte[] QualifiedSigner { get; private set; }
-    public byte[] ExtraData { get; private set; }
-    public byte[] Clock { get; private set; }
-    public byte[] ResetCount { get; private set; }
-    public byte[] RestartCount { get; private set; }
-    public byte[] Safe { get; private set; }
-    public byte[] FirmwareVersion { get; private set; }
-    public ushort Alg { get; private set; }
-    public byte[] AttestedName { get; private set; }
-    public byte[] AttestedQualifiedNameBuffer { get; private set; }
+    public byte[] Raw { get; }
+    public byte[] Magic { get; }
+    public byte[] Type { get; }
+    public byte[] QualifiedSigner { get; }
+    public byte[] ExtraData { get; }
+    public byte[] Clock { get; }
+    public byte[] ResetCount { get; }
+    public byte[] RestartCount { get;  }
+    public byte[] Safe { get; }
+    public byte[] FirmwareVersion { get;  }
+    public ushort Alg { get; }
+    public byte[] AttestedName { get; }
+    public byte[] AttestedQualifiedNameBuffer { get; }
 }
 
 // TPMT_PUBLIC, TPMv2-Part2, section 12.2.4
@@ -635,18 +635,18 @@ public PubArea(byte[] pubArea)
             throw new Fido2VerificationException("Leftover bytes decoding pubArea");
     }
 
-    public byte[] Raw { get; private set; }
-    public byte[] Type { get; private set; }
-    public byte[] Alg { get; private set; }
-    public byte[] Attributes { get; private set; }
-    public byte[] Policy { get; private set; }
-    public byte[]? Symmetric { get; private set; }
-    public byte[]? Scheme { get; private set; }
-    public byte[]? KeyBits { get; private set; }
-    public uint Exponent { get; private set; }
-    public byte[]? CurveID { get; private set; }
-    public byte[]? KDF { get; private set; }
-    public byte[]? Unique { get; private set; }
+    public byte[] Raw { get; }
+    public byte[] Type { get; }
+    public byte[] Alg { get; }
+    public byte[] Attributes { get; }
+    public byte[] Policy { get;  }
+    public byte[]? Symmetric { get; }
+    public byte[]? Scheme { get; }
+    public byte[]? KeyBits { get; }
+    public uint Exponent { get; }
+    public byte[]? CurveID { get; }
+    public byte[]? KDF { get;}
+    public byte[]? Unique { get; }
     public TpmEccCurve EccCurve => (TpmEccCurve)Enum.ToObject(typeof(TpmEccCurve), BinaryPrimitives.ReadUInt16BigEndian(CurveID));
-    public ECPoint ECPoint { get; private set; }
+    public ECPoint ECPoint { get; }
 }