C# MemoryBlockStream.CopyTo方法代码示例

//.........这里部分代码省略.........
		/// <para>-or-</para>
		/// <para>No recipients were specified.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The specified encryption algorithm is not supported.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The user chose to cancel the password prompt.
		/// </exception>
		/// <exception cref="System.UnauthorizedAccessException">
		/// 3 bad attempts were made to unlock the secret key.
		/// </exception>
		public MimePart SignAndEncrypt (PgpSecretKey signer, DigestAlgorithm digestAlgo, EncryptionAlgorithm cipherAlgo, IEnumerable<PgpPublicKey> recipients, Stream content)
		{
			// TODO: document the exceptions that can be thrown by BouncyCastle

			if (signer == null)
				throw new ArgumentNullException ("signer");

			if (!signer.IsSigningKey)
				throw new ArgumentException ("The specified secret key cannot be used for signing.", "signer");

			if (recipients == null)
				throw new ArgumentNullException ("recipients");

			if (content == null)
				throw new ArgumentNullException ("content");

			var encrypter = new PgpEncryptedDataGenerator (GetSymmetricKeyAlgorithm (cipherAlgo), true);
			var hashAlgorithm = GetHashAlgorithm (digestAlgo);
			int count = 0;

			foreach (var recipient in recipients) {
				if (!recipient.IsEncryptionKey)
					throw new ArgumentException ("One or more of the recipient keys cannot be used for encrypting.", "recipients");

				encrypter.AddMethod (recipient);
				count++;
			}

			if (count == 0)
				throw new ArgumentException ("No recipients specified.", "recipients");

			var compresser = new PgpCompressedDataGenerator (CompressionAlgorithmTag.ZLib);

			using (var compressed = new MemoryBlockStream ()) {
				using (var signed = compresser.Open (compressed)) {
					var signatureGenerator = new PgpSignatureGenerator (signer.PublicKey.Algorithm, hashAlgorithm);
					signatureGenerator.InitSign (PgpSignature.CanonicalTextDocument, GetPrivateKey (signer));
					var subpacket = new PgpSignatureSubpacketGenerator ();

					foreach (string userId in signer.PublicKey.GetUserIds ()) {
						subpacket.SetSignerUserId (false, userId);
						break;
					}

					signatureGenerator.SetHashedSubpackets (subpacket.Generate ());

					var onepass = signatureGenerator.GenerateOnePassVersion (false);
					onepass.Encode (signed);

					var literalGenerator = new PgpLiteralDataGenerator ();
					using (var literal = literalGenerator.Open (signed, 't', "mime.txt", content.Length, DateTime.Now)) {
						var buf = new byte[4096];
						int nread;

						while ((nread = content.Read (buf, 0, buf.Length)) > 0) {
							signatureGenerator.Update (buf, 0, nread);
							literal.Write (buf, 0, nread);
						}

						literal.Flush ();
					}

					var signature = signatureGenerator.Generate ();
					signature.Encode (signed);

					signed.Flush ();
				}

				compressed.Position = 0;

				var memory = new MemoryBlockStream ();
				using (var armored = new ArmoredOutputStream (memory)) {
					using (var encrypted = encrypter.Open (armored, compressed.Length)) {
						compressed.CopyTo (encrypted, 4096);
						encrypted.Flush ();
					}

					armored.Flush ();
				}

				memory.Position = 0;

				return new MimePart ("application", "octet-stream") {
					ContentDisposition = new ContentDisposition ("attachment"),
					ContentObject = new ContentObject (memory)
				};
			}
		}