Update AttestationVerifier api to Async (#458)

* Update AttestationVerifier api to Async

* Configure awaits

* Apply code formatting rules

Author: iamcarbon

Src/Fido2/AttestationFormat/AndroidKey.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -131,7 +132,7 @@ public static bool IsPurposeSign(byte[] attExtBytes)
         return (softwareEnforcedPurposeValue is 2 && teeEnforcedPurposeValue is 2);
     }
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 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)
@@ -220,6 +221,6 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
         if (!IsPurposeSign(attExtBytes))
             throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Found purpose field not set to KM_PURPOSE_SIGN in android key attestation certificate extension");
 
-        return (AttestationType.Basic, trustPath);
+        return new(new VerifyAttestationResult(AttestationType.Basic, trustPath));
     }
 }

Src/Fido2/AttestationFormat/AndroidSafetyNet.cs

@@ -7,6 +7,7 @@
 using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Text.Json;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -20,7 +21,7 @@ internal sealed class AndroidSafetyNet : AttestationVerifier
 {
     private const int _driftTolerance = 0;
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 1. Verify that attStmt is valid CBOR conforming to the syntax defined above and perform 
         // CBOR decoding on it to extract the contained fields
@@ -157,8 +158,7 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
             throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Nonce value not base64string in SafetyNet attestation", ex);
         }
 
-        Span<byte> dataHash = stackalloc byte[32];
-        SHA256.HashData(request.Data, dataHash);
+        byte[] dataHash = SHA256.HashData(request.Data);
 
         if (!dataHash.SequenceEqual(nonceHash))
         {
@@ -180,6 +180,6 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
         if (true != ctsProfileMatch)
             throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "SafetyNet response ctsProfileMatch false");
 
-        return (AttestationType.Basic, new X509Certificate2[] { attestationCert });
+        return new(new VerifyAttestationResult(AttestationType.Basic, new X509Certificate2[] { attestationCert }));
     }
 }

Src/Fido2/AttestationFormat/Apple.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -40,7 +41,7 @@ public static byte[] GetAppleAttestationExtensionValue(X509ExtensionCollection e
         }
     }
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 1. Verify that attStmt is valid CBOR conforming to the syntax defined above and perform CBOR decoding on it to extract the contained fields.
         if (!(request.X5c is CborArray { Length: >= 2 } x5cArray && x5cArray[0] is CborByteString { Length: > 0 }))
@@ -86,6 +87,6 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
             throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Credential public key in Apple attestation does not match subject public key of credCert");
 
         // 7. If successful, return implementation-specific values representing attestation type Anonymous CA and attestation trust path x5c.
-        return (AttestationType.Basic, trustPath);
+        return new(new VerifyAttestationResult(AttestationType.Basic, trustPath));
     }
 }

Src/Fido2/AttestationFormat/AppleAppAttest.cs

@@ -3,9 +3,9 @@
 using System.Linq;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
-using Fido2NetLib.Objects;
 
 namespace Fido2NetLib;
 
@@ -47,7 +47,7 @@ public static byte[] GetAppleAppIdFromCredCertExtValue(X509ExtensionCollection e
     // 61707061-7474-6573-7400-000000000000
     public static readonly Guid prodAaguid = new("61707061-7474-6573-7400-000000000000");
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override async ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 1. Verify that the x5c array contains the intermediate and leaf certificates for App Attest, starting from the credential certificate in the first data buffer in the array (credcert).
         if (!(request.X5c is CborArray { Length: 2 } x5cArray && x5cArray[0] is CborByteString { Length: > 0 } && x5cArray[1] is CborByteString { Length: > 0 }))
@@ -81,22 +81,20 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
         // 4. Obtain the value of the credCert extension with OID 1.2.840.113635.100.8.2, which is a DER - encoded ASN.1 sequence.Decode the sequence and extract the single octet string that it contains. Verify that the string equals nonce.
         // Steps 2 - 4 done in the "apple" format verifier
         var apple = new Apple();
-        (var attType, var trustPath) = apple.Verify(request);
+        (var attType, var trustPath) = await apple.VerifyAsync(request).ConfigureAwait(false);
 
         // 5. Create the SHA256 hash of the public key in credCert, and verify that it matches the key identifier from your app.
-        Span<byte> credCertPKHash = stackalloc byte[32];
-        SHA256.HashData(credCert.GetPublicKey(), credCertPKHash);
-        ReadOnlySpan<byte> keyIdentifier = Convert.FromHexString(credCert.GetNameInfo(X509NameType.SimpleName, false));
-        if (!credCertPKHash.SequenceEqual(keyIdentifier))
+        byte[] credCertPKHash = SHA256.HashData(credCert.GetPublicKey());
+        byte[] keyIdentifier = Convert.FromHexString(credCert.GetNameInfo(X509NameType.SimpleName, false));
+        if (!credCertPKHash.AsSpan().SequenceEqual(keyIdentifier))
         {
             throw new Fido2VerificationException("Public key hash does not match key identifier in Apple AppAttest attestation");
         }
 
         // 6. Compute the SHA256 hash of your app's App ID, and verify that it’s the same as the authenticator data's RP ID hash.
         var appId = GetAppleAppIdFromCredCertExtValue(credCert.Extensions);
-        Span<byte> appIdHash = stackalloc byte[32];
-        SHA256.HashData(appId, appIdHash);
-        if (!appIdHash.SequenceEqual(request.AuthData.RpIdHash))
+        byte[] appIdHash = SHA256.HashData(appId);
+        if (!appIdHash.AsSpan().SequenceEqual(request.AuthData.RpIdHash))
         {
             throw new Fido2VerificationException("App ID hash does not match RP ID hash in Apple AppAttest attestation");
         }
@@ -119,6 +117,6 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
             throw new Fido2VerificationException("Mismatch between credentialId and keyIdentifier in Apple AppAttest attestation");
         }
 
-        return (attType, trustPath);
+        return new VerifyAttestationResult(attType, trustPath);
     }
 }

Src/Fido2/AttestationFormat/AttestationVerifier.cs

@@ -1,6 +1,7 @@
 using System.Formats.Asn1;
 using System.Linq;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -10,12 +11,12 @@ namespace Fido2NetLib;
 
 public abstract class AttestationVerifier
 {
-    public (AttestationType, X509Certificate2[]) Verify(CborMap attStmt, AuthenticatorData authenticatorData, byte[] clientDataHash)
+    public ValueTask<VerifyAttestationResult> VerifyAsync(CborMap attStmt, AuthenticatorData authenticatorData, byte[] clientDataHash)
     {
-        return Verify(new VerifyAttestationRequest(attStmt, authenticatorData, clientDataHash));
+        return VerifyAsync(new VerifyAttestationRequest(attStmt, authenticatorData, clientDataHash));
     }
 
-    public abstract (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request);
+    public abstract ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request);
 
     public static AttestationVerifier Create(string formatIdentifier)
     {

Src/Fido2/AttestationFormat/FidoU2f.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -10,7 +11,7 @@ namespace Fido2NetLib;
 
 internal sealed class FidoU2f : AttestationVerifier
 {
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // verify that aaguid is 16 empty bytes (note: required by fido2 conformance testing, could not find this in spec?)
         if (request.AuthData.AttestedCredentialData!.AaGuid.CompareTo(Guid.Empty) != 0)
@@ -86,6 +87,6 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
 
         var trustPath = new X509Certificate2[1] { attCert };
 
-        return (AttestationType.AttCa, trustPath);
+        return new(new VerifyAttestationResult(AttestationType.AttCa, trustPath));
     }
 }

Src/Fido2/AttestationFormat/None.cs

@@ -1,4 +1,4 @@
-using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Exceptions;
 using Fido2NetLib.Objects;
@@ -7,11 +7,11 @@ namespace Fido2NetLib;
 
 public sealed class None : AttestationVerifier
 {
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         if (request.AttStmt.Count != 0)
             throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Attestation format none should have no attestation statement");
 
-        return (AttestationType.None, null!);
+        return new(new VerifyAttestationResult(AttestationType.None, null!));
     }
 }

Src/Fido2/AttestationFormat/Packed.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -36,7 +37,7 @@ public static bool IsValidPackedAttnCertSubject(string attnCertSubj)
             && subjectMap.TryGetValue("CN", out var cn) && cn.Length > 0;
     }
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 1. Verify that attStmt is valid CBOR conforming to the syntax defined above and 
         // perform CBOR decoding on it to extract the contained fields.
@@ -117,7 +118,7 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
 
             // 2d. Optionally, inspect x5c and consult externally provided knowledge to determine whether attStmt conveys a Basic or AttCA attestation
 
-            return (AttestationType.AttCa, trustPath);
+            return new(new VerifyAttestationResult(AttestationType.AttCa, trustPath));
         }
 
         // 3. If ecdaaKeyId is present, then the attestation type is ECDAA
@@ -145,7 +146,7 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
             if (!request.AuthData.AttestedCredentialData.CredentialPublicKey.Verify(request.Data, sig))
                 throw new Fido2VerificationException(Fido2ErrorCode.InvalidAttestation, "Failed to validate signature");
 
-            return (AttestationType.Self, null!);
+            return new(new VerifyAttestationResult(AttestationType.Self, null!));
         }
     }
 }

Src/Fido2/AttestationFormat/Tpm.cs

@@ -5,6 +5,7 @@
 using System.Linq;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 using Fido2NetLib.Cbor;
 using Fido2NetLib.Exceptions;
@@ -43,7 +44,7 @@ internal sealed class Tpm : AttestationVerifier
         "id:474F4F47", // 'GOOG' Google
     };
 
-    public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRequest request)
+    public override ValueTask<VerifyAttestationResult> VerifyAsync(VerifyAttestationRequest request)
     {
         // 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)
@@ -202,7 +203,7 @@ public override (AttestationType, X509Certificate2[]) Verify(VerifyAttestationRe
                 throw new Fido2VerificationException($"aaguid malformed, expected {request.AuthData.AttestedCredentialData.AaGuid}, got {new Guid(aaguid)}");
             }
 
-            return (AttestationType.AttCa, trustPath);
+            return new(new VerifyAttestationResult(AttestationType.AttCa, trustPath));
         }
         // If ecdaaKeyId is present, then the attestation type is ECDAA
         else if (request.EcdaaKeyId != null)

Src/Fido2/AttestationFormat/VerifyAttestationResult.cs

@@ -0,0 +1,23 @@
+using System.Security.Cryptography.X509Certificates;
+
+using Fido2NetLib.Objects;
+
+namespace Fido2NetLib;
+
+public sealed class VerifyAttestationResult
+{
+    public VerifyAttestationResult(AttestationType type, X509Certificate2[] certificates)
+    {
+        Type = type;
+        Certificates = certificates;
+    }
+
+    public AttestationType Type { get; }
+
+    public X509Certificate2[] Certificates { get; }
+
+    public void Deconstruct(out AttestationType type, out X509Certificate2[] certificates)
+    {
+        (type, certificates) = (Type, Certificates);
+    }
+}