init commit

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

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+using System;
+using System.IO;
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Cms;
+using Org.BouncyCastle.Asn1.X509;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.X509;
+
+namespace Org.BouncyCastle.Cms;
+
+public class KeyTransRecipientInfoGenerator : RecipientInfoGenerator
+{
+	private static readonly CmsEnvelopedHelper Helper = CmsEnvelopedHelper.Instance;
+
+	private TbsCertificateStructure recipientTbsCert;
+
+	private AsymmetricKeyParameter recipientPublicKey;
+
+	private Asn1OctetString subjectKeyIdentifier;
+
+	private SubjectPublicKeyInfo info;
+
+	private IssuerAndSerialNumber issuerAndSerialNumber;
+
+	private SecureRandom random;
+
+	internal X509Certificate RecipientCert
+	{
+		set
+		{
+			recipientTbsCert = CmsUtilities.GetTbsCertificateStructure(value);
+			recipientPublicKey = value.GetPublicKey();
+			info = recipientTbsCert.SubjectPublicKeyInfo;
+		}
+	}
+
+	internal AsymmetricKeyParameter RecipientPublicKey
+	{
+		set
+		{
+			recipientPublicKey = value;
+			try
+			{
+				info = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(recipientPublicKey);
+			}
+			catch (IOException)
+			{
+				throw new ArgumentException("can't extract key algorithm from this key");
+			}
+		}
+	}
+
+	internal Asn1OctetString SubjectKeyIdentifier
+	{
+		set
+		{
+			subjectKeyIdentifier = value;
+		}
+	}
+
+	protected virtual AlgorithmIdentifier AlgorithmDetails => info.AlgorithmID;
+
+	internal KeyTransRecipientInfoGenerator()
+	{
+	}
+
+	protected KeyTransRecipientInfoGenerator(IssuerAndSerialNumber issuerAndSerialNumber)
+	{
+		this.issuerAndSerialNumber = issuerAndSerialNumber;
+	}
+
+	protected KeyTransRecipientInfoGenerator(byte[] subjectKeyIdentifier)
+	{
+		this.subjectKeyIdentifier = new DerOctetString(subjectKeyIdentifier);
+	}
+
+	public RecipientInfo Generate(KeyParameter contentEncryptionKey, SecureRandom random)
+	{
+		AlgorithmIdentifier algorithmDetails = AlgorithmDetails;
+		this.random = random;
+		byte[] str = GenerateWrappedKey(contentEncryptionKey);
+		RecipientIdentifier rid;
+		if (recipientTbsCert != null)
+		{
+			IssuerAndSerialNumber id = new IssuerAndSerialNumber(recipientTbsCert.Issuer, recipientTbsCert.SerialNumber.Value);
+			rid = new RecipientIdentifier(id);
+		}
+		else
+		{
+			rid = new RecipientIdentifier(subjectKeyIdentifier);
+		}
+		return new RecipientInfo(new KeyTransRecipientInfo(rid, algorithmDetails, new DerOctetString(str)));
+	}
+
+	protected virtual byte[] GenerateWrappedKey(KeyParameter contentEncryptionKey)
+	{
+		byte[] key = contentEncryptionKey.GetKey();
+		AlgorithmIdentifier algorithmID = info.AlgorithmID;
+		IWrapper wrapper = Helper.CreateWrapper(algorithmID.Algorithm.Id);
+		wrapper.Init(forWrapping: true, new ParametersWithRandom(recipientPublicKey, random));
+		return wrapper.Wrap(key, 0, key.Length);
+	}
+}