1 files changed, 85 insertions, 0 deletions
diff --git a/src/DotNetOpenId/HmacShaAssociation.cs b/src/DotNetOpenId/HmacShaAssociation.cs
new file mode 100644
index 0000000..a602909
--- /dev/null
+++ b/src/DotNetOpenId/HmacShaAssociation.cs
@@ -0,0 +1,85 @@
+using System;
+using System.Security.Cryptography;
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace DotNetOpenId {
+	internal class HmacShaAssociation : Association {
+
+		class HmacSha {
+			internal Util.Func<Protocol, string> GetAssociationType;
+			internal Util.Func<byte[], HashAlgorithm> CreateHasher;
+			internal HashAlgorithm BaseHashAlgorithm;
+			internal int SecretLength { get { return BaseHashAlgorithm.HashSize / 8; } }
+		}
+		static HmacSha[] HmacShaAssociationTypes = {
+			new HmacSha {
+				CreateHasher = secretKey => new HMACSHA1(secretKey),
+				GetAssociationType = protocol => protocol.Args.SignatureAlgorithm.HMAC_SHA1,
+				BaseHashAlgorithm = CryptUtil.Sha1,
+			},
+			new HmacSha {
+				CreateHasher = secretKey => new HMACSHA256(secretKey),
+				GetAssociationType = protocol => protocol.Args.SignatureAlgorithm.HMAC_SHA256,
+				BaseHashAlgorithm = CryptUtil.Sha256,
+			},
+			new HmacSha {
+				CreateHasher = secretKey => new HMACSHA384(secretKey),
+				GetAssociationType = protocol => protocol.Args.SignatureAlgorithm.HMAC_SHA384,
+				BaseHashAlgorithm = CryptUtil.Sha384,
+			},
+			new HmacSha {
+				CreateHasher = secretKey => new HMACSHA512(secretKey),
+				GetAssociationType = protocol => protocol.Args.SignatureAlgorithm.HMAC_SHA512,
+				BaseHashAlgorithm = CryptUtil.Sha512,
+			},
+		};
+
+		public static HmacShaAssociation Create(Protocol protocol, string associationType,
+			string handle, byte[] secret, TimeSpan totalLifeLength) {
+			foreach (HmacSha shaType in HmacShaAssociationTypes) {
+				if (String.Equals(shaType.GetAssociationType(protocol), associationType, StringComparison.Ordinal)) {
+					return new HmacShaAssociation(shaType, handle, secret, totalLifeLength);
+				}
+			}
+			throw new ArgumentOutOfRangeException("associationType");
+		}
+
+		public static HmacShaAssociation Create(int secretLength,
+			string handle, byte[] secret, TimeSpan totalLifeLength) {
+			foreach (HmacSha shaType in HmacShaAssociationTypes) {
+				if (shaType.SecretLength == secretLength) {
+					return new HmacShaAssociation(shaType, handle, secret, totalLifeLength);
+				}
+			}
+			throw new ArgumentOutOfRangeException("secretLength");
+		}
+
+		public static int GetSecretLength(Protocol protocol, string associationType) {
+			foreach (HmacSha shaType in HmacShaAssociationTypes) {
+				if (String.Equals(shaType.GetAssociationType(protocol), associationType, StringComparison.Ordinal)) {
+					return shaType.SecretLength;
+				}
+			}
+			throw new ArgumentOutOfRangeException("associationType");
+		}
+
+		HmacShaAssociation(HmacSha typeIdentity, string handle, byte[] secret, TimeSpan totalLifeLength)
+			: base(handle, secret, totalLifeLength, DateTime.UtcNow) {
+			if (typeIdentity == null) throw new ArgumentNullException("typeIdentity");
+
+			Debug.Assert(secret.Length == typeIdentity.SecretLength);
+			this.typeIdentity = typeIdentity;
+		}
+
+		HmacSha typeIdentity;
+
+		internal override string GetAssociationType(Protocol protocol) {
+			return typeIdentity.GetAssociationType(protocol);
+		}
+
+		protected override HashAlgorithm CreateHasher() {
+			return typeIdentity.CreateHasher(SecretKey);
+		}
+	}
+}
+\ No newline at end of file