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