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; namespace Org.BouncyCastle.Cms { /** * the RecipientInfo class for a recipient who has been sent a message * encrypted using a password. */ public class PasswordRecipientInformation : RecipientInformation { private readonly PasswordRecipientInfo info; internal PasswordRecipientInformation( PasswordRecipientInfo info, CmsSecureReadable secureReadable) : base(info.KeyEncryptionAlgorithm, secureReadable) { this.info = info; this.rid = new RecipientID(); } /** * return the object identifier for the key derivation algorithm, or null * if there is none present. * * @return OID for key derivation algorithm, if present. */ public virtual AlgorithmIdentifier KeyDerivationAlgorithm { get { return info.KeyDerivationAlgorithm; } } /** * decrypt the content and return an input stream. */ public override CmsTypedStream GetContentStream( ICipherParameters key) { try { AlgorithmIdentifier kekAlg = AlgorithmIdentifier.GetInstance(info.KeyEncryptionAlgorithm); Asn1Sequence kekAlgParams = (Asn1Sequence)kekAlg.Parameters; byte[] encryptedKey = info.EncryptedKey.GetOctets(); string kekAlgName = DerObjectIdentifier.GetInstance(kekAlgParams[0]).Id; string cName = CmsEnvelopedHelper.Instance.GetRfc3211WrapperName(kekAlgName); IWrapper keyWrapper = WrapperUtilities.GetWrapper(cName); byte[] iv = Asn1OctetString.GetInstance(kekAlgParams[1]).GetOctets(); ICipherParameters parameters = ((CmsPbeKey)key).GetEncoded(kekAlgName); parameters = new ParametersWithIV(parameters, iv); keyWrapper.Init(false, parameters); KeyParameter sKey = ParameterUtilities.CreateKeyParameter( GetContentAlgorithmName(), keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length)); return GetContentFromSessionKey(sKey); } catch (SecurityUtilityException e) { throw new CmsException("couldn't create cipher.", e); } catch (InvalidKeyException e) { throw new CmsException("key invalid in message.", e); } } } }