init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Bcpg/OpenPgp/Rfc6637Utilities.cs

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+using System;
+using System.IO;
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Nist;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Math.EC;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+using Org.BouncyCastle.Utilities.Encoders;
+
+namespace Org.BouncyCastle.Bcpg.OpenPgp;
+
+public sealed class Rfc6637Utilities
+{
+	private static readonly byte[] ANONYMOUS_SENDER = Hex.Decode("416E6F6E796D6F75732053656E64657220202020");
+
+	private Rfc6637Utilities()
+	{
+	}
+
+	public static string GetAgreementAlgorithm(PublicKeyPacket pubKeyData)
+	{
+		ECDHPublicBcpgKey eCDHPublicBcpgKey = (ECDHPublicBcpgKey)pubKeyData.Key;
+		return eCDHPublicBcpgKey.HashAlgorithm switch
+		{
+			HashAlgorithmTag.Sha256 => "ECCDHwithSHA256CKDF", 
+			HashAlgorithmTag.Sha384 => "ECCDHwithSHA384CKDF", 
+			HashAlgorithmTag.Sha512 => "ECCDHwithSHA512CKDF", 
+			_ => throw new ArgumentException("Unknown hash algorithm specified: " + eCDHPublicBcpgKey.HashAlgorithm), 
+		};
+	}
+
+	public static DerObjectIdentifier GetKeyEncryptionOID(SymmetricKeyAlgorithmTag algID)
+	{
+		return algID switch
+		{
+			SymmetricKeyAlgorithmTag.Aes128 => NistObjectIdentifiers.IdAes128Wrap, 
+			SymmetricKeyAlgorithmTag.Aes192 => NistObjectIdentifiers.IdAes192Wrap, 
+			SymmetricKeyAlgorithmTag.Aes256 => NistObjectIdentifiers.IdAes256Wrap, 
+			_ => throw new PgpException("unknown symmetric algorithm ID: " + algID), 
+		};
+	}
+
+	public static int GetKeyLength(SymmetricKeyAlgorithmTag algID)
+	{
+		return algID switch
+		{
+			SymmetricKeyAlgorithmTag.Aes128 => 16, 
+			SymmetricKeyAlgorithmTag.Aes192 => 24, 
+			SymmetricKeyAlgorithmTag.Aes256 => 32, 
+			_ => throw new PgpException("unknown symmetric algorithm ID: " + algID), 
+		};
+	}
+
+	public static byte[] CreateKey(PublicKeyPacket pubKeyData, ECPoint s)
+	{
+		byte[] parameters = CreateUserKeyingMaterial(pubKeyData);
+		ECDHPublicBcpgKey eCDHPublicBcpgKey = (ECDHPublicBcpgKey)pubKeyData.Key;
+		return Kdf(eCDHPublicBcpgKey.HashAlgorithm, s, GetKeyLength(eCDHPublicBcpgKey.SymmetricKeyAlgorithm), parameters);
+	}
+
+	public static byte[] CreateUserKeyingMaterial(PublicKeyPacket pubKeyData)
+	{
+		MemoryStream memoryStream = new MemoryStream();
+		ECDHPublicBcpgKey eCDHPublicBcpgKey = (ECDHPublicBcpgKey)pubKeyData.Key;
+		byte[] encoded = eCDHPublicBcpgKey.CurveOid.GetEncoded();
+		memoryStream.Write(encoded, 1, encoded.Length - 1);
+		memoryStream.WriteByte((byte)pubKeyData.Algorithm);
+		memoryStream.WriteByte(3);
+		memoryStream.WriteByte(1);
+		memoryStream.WriteByte((byte)eCDHPublicBcpgKey.HashAlgorithm);
+		memoryStream.WriteByte((byte)eCDHPublicBcpgKey.SymmetricKeyAlgorithm);
+		memoryStream.Write(ANONYMOUS_SENDER, 0, ANONYMOUS_SENDER.Length);
+		byte[] array = PgpPublicKey.CalculateFingerprint(pubKeyData);
+		memoryStream.Write(array, 0, array.Length);
+		return memoryStream.ToArray();
+	}
+
+	private static byte[] Kdf(HashAlgorithmTag digestAlg, ECPoint s, int keyLen, byte[] parameters)
+	{
+		byte[] encoded = s.XCoord.GetEncoded();
+		string digestName = PgpUtilities.GetDigestName(digestAlg);
+		IDigest digest = DigestUtilities.GetDigest(digestName);
+		digest.Update(0);
+		digest.Update(0);
+		digest.Update(0);
+		digest.Update(1);
+		digest.BlockUpdate(encoded, 0, encoded.Length);
+		digest.BlockUpdate(parameters, 0, parameters.Length);
+		byte[] data = DigestUtilities.DoFinal(digest);
+		return Arrays.CopyOfRange(data, 0, keyLen);
+	}
+}