tests: add unit tests for CoseEdDsaPublicKey functionality and validation

Author: DennisDyallo

Yubico.YubiKey/tests/unit/Yubico/YubiKey/Fido2/Cose/CoseEdDsaPublicKeyTests.cs

@@ -0,0 +1,111 @@
+using System;
+using System.Buffers.Text;
+using System.Diagnostics;
+using System.Linq;
+using Xunit;
+using Xunit.Abstractions;
+using Xunit.Sdk;
+using Yubico.YubiKey.Fido2.Cbor;
+
+namespace Yubico.YubiKey.Fido2.Cose
+{
+    public class CoseEdDsaPublicKeyTests
+    {
+        private const string ValidEd25519PublicKeyPem = @"
+        -----BEGIN PUBLIC KEY-----
+        MCowBQYDK2VwAyEAGD3XimAmDGEYgGkS7BQIi6YJsm8bkJdo6rbHl2z4qao=
+        -----END PUBLIC KEY-----
+        ";
+        
+        private static byte[] ValidEd25519PublicKey => Convert
+        .FromBase64String(ValidEd25519PublicKeyPem
+            .Replace("-----BEGIN PUBLIC KEY-----", "")
+            .Replace("-----END PUBLIC KEY-----", "")
+            .Replace("\n", "")
+            .Trim()
+        ).Skip(12).ToArray(); // Skip the COSE key header and extract the public key data
+
+        [Fact]
+        public void CreateFromPublicKeyData_ValidKey_ReturnsExpectedKey()
+        {
+            // Act
+            var coseKey = CoseEdDsaPublicKey.CreateFromPublicKeyData(ValidEd25519PublicKey);
+
+            // Assert
+            Assert.Equal(CoseKeyType.Okp, coseKey.Type);
+            Assert.Equal(CoseEcCurve.Ed25519, coseKey.Curve);
+            Assert.Equal(CoseAlgorithmIdentifier.EdDSA, coseKey.Algorithm);
+            Assert.True(coseKey.PublicKey.Span.SequenceEqual(ValidEd25519PublicKey));
+        }
+
+        [Fact]
+        public void CreateFromPublicKeyData_InvalidLength_ThrowsArgumentException()
+        {
+            // Arrange
+            byte[] invalidKey = new byte[31]; // Wrong length
+
+            // Act & Assert
+            Assert.Throws<ArgumentException>(() => CoseEdDsaPublicKey.CreateFromPublicKeyData(invalidKey));
+        }
+
+        [Fact]
+        public void EncodingRoundtrip_ReturnsMatchingKey()
+        {
+            // Arrange
+            var originalKey = CoseEdDsaPublicKey.CreateFromPublicKeyData(ValidEd25519PublicKey);
+
+            // Act
+            var encodedKey = originalKey.Encode();
+            var decodedKey = CoseEdDsaPublicKey.CreateFromEncodedKey(encodedKey);
+
+            // Assert
+            Assert.Equal(originalKey.Type, decodedKey.Type);
+            Assert.Equal(originalKey.Curve, decodedKey.Curve);
+            Assert.Equal(originalKey.Algorithm, decodedKey.Algorithm);
+            Assert.True(originalKey.PublicKey.Span.SequenceEqual(decodedKey.PublicKey.Span));
+        }
+
+        [Fact]
+        public void Encode_ValidKey_ContainsRequiredMapEntries()
+        {
+            // Arrange
+            var coseKey = CoseEdDsaPublicKey.CreateFromPublicKeyData(ValidEd25519PublicKey);
+
+            // Act
+            var encoded = coseKey.Encode();
+            var map = new CborMap<int>(encoded);
+
+            var keyType = map.ReadInt32(1);
+            var algorithm = map.ReadInt32(3);
+            var curve = map.ReadInt32(-1);
+            var publicKey = map.ReadByteString(-2).Span;
+
+            // Assert
+            Assert.Equal((int)CoseKeyType.Okp, keyType); // kty
+            Assert.Equal((int)CoseAlgorithmIdentifier.EdDSA, algorithm); // alg
+            Assert.Equal((int)CoseEcCurve.Ed25519, curve); // crv
+            Assert.True(publicKey.SequenceEqual(ValidEd25519PublicKey)); // x
+        }
+
+        [Fact]
+        public void PublicKey_SetInvalidLength_ThrowsArgumentException()
+        {
+            // Arrange
+            var coseKey = CoseEdDsaPublicKey.CreateFromPublicKeyData(ValidEd25519PublicKey);
+            var invalidKey = new byte[31];
+
+            // Act & Assert
+            Assert.Throws<ArgumentException>(() => coseKey.PublicKey = invalidKey);
+        }
+
+        [Fact]
+        public void Curve_SetInvalidCurve_ThrowsArgumentException()
+        {
+            // Arrange
+            var coseKey = CoseEdDsaPublicKey.CreateFromPublicKeyData(ValidEd25519PublicKey);
+
+            // Act & Assert
+            Assert.Throws<ArgumentException>(() => coseKey.Curve = CoseEcCurve.P256);
+        }
+    }
+}