89 lines
2.5 KiB
C#
89 lines
2.5 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 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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namespace Org.BouncyCastle.Cms
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{
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/**
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* the RecipientInfo class for a recipient who has been sent a message
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* encrypted using a password.
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*/
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public class PasswordRecipientInformation
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: RecipientInformation
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{
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private readonly PasswordRecipientInfo _info;
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// private readonly AlgorithmIdentifier _encAlg;
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public PasswordRecipientInformation(
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PasswordRecipientInfo 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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}
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/**
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* return the object identifier for the key derivation algorithm, or null
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* if there is none present.
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*
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* @return OID for key derivation algorithm, if present.
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*/
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public virtual AlgorithmIdentifier KeyDerivationAlgorithm
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{
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get
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{
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return _info.KeyDerivationAlgorithm;
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}
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}
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/**
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* decrypt the content and return an input stream.
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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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try
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{
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AlgorithmIdentifier kekAlg = AlgorithmIdentifier.GetInstance(_info.KeyEncryptionAlgorithm);
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Asn1Sequence kekAlgParams = (Asn1Sequence)kekAlg.Parameters;
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byte[] encryptedKey = _info.EncryptedKey.GetOctets();
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string kekAlgName = DerObjectIdentifier.GetInstance(kekAlgParams[0]).Id;
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string cName = CmsEnvelopedHelper.Instance.GetRfc3211WrapperName(kekAlgName);
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IWrapper keyWrapper = WrapperUtilities.GetWrapper(cName);
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byte[] iv = Asn1OctetString.GetInstance(kekAlgParams[1]).GetOctets();
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ICipherParameters parameters = ((CmsPbeKey)key).GetEncoded(kekAlgName);
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parameters = new ParametersWithIV(parameters, iv);
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keyWrapper.Init(false, parameters);
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AlgorithmIdentifier aid = _encAlg;
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string alg = aid.ObjectID.Id;
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KeyParameter sKey = ParameterUtilities.CreateKeyParameter(
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alg, 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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}
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}
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}
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