init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Cms/KekRecipientInfoGenerator.cs

@@ -0,0 +1,102 @@
+using System;
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Cms;
+using Org.BouncyCastle.Asn1.Kisa;
+using Org.BouncyCastle.Asn1.Nist;
+using Org.BouncyCastle.Asn1.Ntt;
+using Org.BouncyCastle.Asn1.Pkcs;
+using Org.BouncyCastle.Asn1.X509;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Cms;
+
+internal class KekRecipientInfoGenerator : RecipientInfoGenerator
+{
+	private static readonly CmsEnvelopedHelper Helper = CmsEnvelopedHelper.Instance;
+
+	private KeyParameter keyEncryptionKey;
+
+	private string keyEncryptionKeyOID;
+
+	private KekIdentifier kekIdentifier;
+
+	private AlgorithmIdentifier keyEncryptionAlgorithm;
+
+	internal KekIdentifier KekIdentifier
+	{
+		set
+		{
+			kekIdentifier = value;
+		}
+	}
+
+	internal KeyParameter KeyEncryptionKey
+	{
+		set
+		{
+			keyEncryptionKey = value;
+			keyEncryptionAlgorithm = DetermineKeyEncAlg(keyEncryptionKeyOID, keyEncryptionKey);
+		}
+	}
+
+	internal string KeyEncryptionKeyOID
+	{
+		set
+		{
+			keyEncryptionKeyOID = value;
+		}
+	}
+
+	internal KekRecipientInfoGenerator()
+	{
+	}
+
+	public RecipientInfo Generate(KeyParameter contentEncryptionKey, SecureRandom random)
+	{
+		byte[] key = contentEncryptionKey.GetKey();
+		IWrapper wrapper = Helper.CreateWrapper(keyEncryptionAlgorithm.Algorithm.Id);
+		wrapper.Init(forWrapping: true, new ParametersWithRandom(keyEncryptionKey, random));
+		Asn1OctetString encryptedKey = new DerOctetString(wrapper.Wrap(key, 0, key.Length));
+		return new RecipientInfo(new KekRecipientInfo(kekIdentifier, keyEncryptionAlgorithm, encryptedKey));
+	}
+
+	private static AlgorithmIdentifier DetermineKeyEncAlg(string algorithm, KeyParameter key)
+	{
+		if (Platform.StartsWith(algorithm, "DES"))
+		{
+			return new AlgorithmIdentifier(PkcsObjectIdentifiers.IdAlgCms3DesWrap, DerNull.Instance);
+		}
+		if (Platform.StartsWith(algorithm, "RC2"))
+		{
+			return new AlgorithmIdentifier(PkcsObjectIdentifiers.IdAlgCmsRC2Wrap, new DerInteger(58));
+		}
+		if (Platform.StartsWith(algorithm, "AES"))
+		{
+			return new AlgorithmIdentifier((key.GetKey().Length * 8) switch
+			{
+				128 => NistObjectIdentifiers.IdAes128Wrap, 
+				192 => NistObjectIdentifiers.IdAes192Wrap, 
+				256 => NistObjectIdentifiers.IdAes256Wrap, 
+				_ => throw new ArgumentException("illegal keysize in AES"), 
+			});
+		}
+		if (Platform.StartsWith(algorithm, "SEED"))
+		{
+			return new AlgorithmIdentifier(KisaObjectIdentifiers.IdNpkiAppCmsSeedWrap);
+		}
+		if (Platform.StartsWith(algorithm, "CAMELLIA"))
+		{
+			return new AlgorithmIdentifier((key.GetKey().Length * 8) switch
+			{
+				128 => NttObjectIdentifiers.IdCamellia128Wrap, 
+				192 => NttObjectIdentifiers.IdCamellia192Wrap, 
+				256 => NttObjectIdentifiers.IdCamellia256Wrap, 
+				_ => throw new ArgumentException("illegal keysize in Camellia"), 
+			});
+		}
+		throw new ArgumentException("unknown algorithm");
+	}
+}