112 lines
3.1 KiB
C#
112 lines
3.1 KiB
C#
using System;
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using System.IO;
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using Org.BouncyCastle.Asn1;
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using Org.BouncyCastle.Asn1.Cms;
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using Asn1Pkcs = Org.BouncyCastle.Asn1.Pkcs;
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using Org.BouncyCastle.Asn1.X509;
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using Org.BouncyCastle.Crypto;
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using Org.BouncyCastle.Crypto.Parameters;
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using Org.BouncyCastle.Security;
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using Org.BouncyCastle.X509;
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namespace Org.BouncyCastle.Cms
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{
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/**
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* the KeyTransRecipientInformation class for a recipient who has been sent a secret
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* key encrypted using their public key that needs to be used to
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* extract the message.
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*/
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public class KeyTransRecipientInformation
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: RecipientInformation
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{
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private KeyTransRecipientInfo _info;
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// private new AlgorithmIdentifier _encAlg;
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public KeyTransRecipientInformation(
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KeyTransRecipientInfo info,
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AlgorithmIdentifier encAlg,
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Stream data)
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: base(encAlg, AlgorithmIdentifier.GetInstance(info.KeyEncryptionAlgorithm), data)
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{
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this._info = info;
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// this._encAlg = encAlg;
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this._rid = new RecipientID();
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RecipientIdentifier r = info.RecipientIdentifier;
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try
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{
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if (r.IsTagged)
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{
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Asn1OctetString octs = Asn1OctetString.GetInstance(r.ID);
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_rid.SubjectKeyIdentifier = octs.GetOctets();
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}
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else
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{
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IssuerAndSerialNumber iAnds = IssuerAndSerialNumber.GetInstance(r.ID);
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_rid.Issuer = iAnds.Name;
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_rid.SerialNumber = iAnds.SerialNumber.Value;
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}
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}
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catch (IOException)
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{
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throw new ArgumentException("invalid rid in KeyTransRecipientInformation");
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}
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}
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private string GetExchangeEncryptionAlgorithmName(
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DerObjectIdentifier oid)
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{
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if (Asn1Pkcs.PkcsObjectIdentifiers.RsaEncryption.Equals(oid))
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{
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return "RSA//PKCS1Padding";
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}
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return oid.Id;
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}
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/**
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* decrypt the content and return it as a byte array.
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*/
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public override CmsTypedStream GetContentStream(
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ICipherParameters key)
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{
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byte[] encryptedKey = _info.EncryptedKey.GetOctets();
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string keyExchangeAlgorithm = GetExchangeEncryptionAlgorithmName(_keyEncAlg.ObjectID);
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try
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{
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IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyExchangeAlgorithm);
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keyWrapper.Init(false, key);
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KeyParameter sKey = ParameterUtilities.CreateKeyParameter(
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_encAlg.ObjectID, keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length));
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return GetContentFromSessionKey(sKey);
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}
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catch (SecurityUtilityException e)
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{
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throw new CmsException("couldn't create cipher.", e);
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}
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catch (InvalidKeyException e)
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{
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throw new CmsException("key invalid in message.", e);
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}
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// catch (IllegalBlockSizeException e)
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catch (DataLengthException e)
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{
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throw new CmsException("illegal blocksize in message.", e);
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}
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// catch (BadPaddingException e)
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catch (InvalidCipherTextException e)
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{
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throw new CmsException("bad padding in message.", e);
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}
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}
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}
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}
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