1 // Copyright 2017 Google Inc. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 //////////////////////////////////////////////////////////////////////////////// 16 17 package com.google.crypto.tink.subtle; 18 19 import java.io.FilterOutputStream; 20 import java.io.IOException; 21 import java.io.OutputStream; 22 import java.nio.ByteBuffer; 23 import java.security.GeneralSecurityException; 24 25 /** 26 * An instance of {@link FilterOutputStream} that encrypts the input using a nonce based online 27 * authentication scheme. 28 */ 29 class StreamingAeadEncryptingStream extends FilterOutputStream { 30 private StreamSegmentEncrypter encrypter; 31 private int plaintextSegmentSize; 32 ByteBuffer ptBuffer; // contains plaintext that has not yet been encrypted. 33 ByteBuffer ctBuffer; // used for the ciphertext (does not buffer anything). 34 boolean open; 35 StreamingAeadEncryptingStream( NonceBasedStreamingAead streamAead, OutputStream ciphertextChannel, byte[] associatedData)36 public StreamingAeadEncryptingStream( 37 NonceBasedStreamingAead streamAead, OutputStream ciphertextChannel, byte[] associatedData) 38 throws GeneralSecurityException, IOException { 39 super(ciphertextChannel); 40 encrypter = streamAead.newStreamSegmentEncrypter(associatedData); 41 plaintextSegmentSize = streamAead.getPlaintextSegmentSize(); 42 ptBuffer = ByteBuffer.allocate(plaintextSegmentSize); 43 ctBuffer = ByteBuffer.allocate(streamAead.getCiphertextSegmentSize()); 44 ptBuffer.limit(plaintextSegmentSize - streamAead.getCiphertextOffset()); 45 ByteBuffer header = encrypter.getHeader(); 46 byte[] headerBytes = new byte[header.remaining()]; 47 header.get(headerBytes); 48 out.write(headerBytes); 49 open = true; 50 } 51 52 @Override write(int b)53 public void write(int b) throws IOException { 54 write(new byte[] {(byte) b}); 55 } 56 57 @Override write(byte[] b)58 public void write(byte[] b) throws IOException { 59 write(b, 0, b.length); 60 } 61 62 // TODO(bleichen): Mabye implement write(ByteBuffer) so that 63 // there are no surprises if the underlying class is extended. 64 65 @Override write(byte[] pt, int offset, int length)66 public synchronized void write(byte[] pt, int offset, int length) throws IOException { 67 if (!open) { 68 throw new IOException("Trying to write to closed stream"); 69 } 70 int startPosition = offset; 71 int remaining = length; 72 while (remaining > ptBuffer.remaining()) { 73 int sliceSize = ptBuffer.remaining(); 74 ByteBuffer slice = ByteBuffer.wrap(pt, startPosition, sliceSize); 75 startPosition += sliceSize; 76 remaining -= sliceSize; 77 try { 78 ptBuffer.flip(); 79 ctBuffer.clear(); 80 encrypter.encryptSegment(ptBuffer, slice, false, ctBuffer); 81 } catch (GeneralSecurityException ex) { 82 throw new IOException(ex); 83 } 84 ctBuffer.flip(); 85 out.write(ctBuffer.array(), ctBuffer.position(), ctBuffer.remaining()); 86 ptBuffer.clear(); 87 ptBuffer.limit(plaintextSegmentSize); 88 } 89 ptBuffer.put(pt, startPosition, remaining); 90 } 91 92 @Override close()93 public synchronized void close() throws IOException { 94 if (!open) { 95 return; 96 } 97 try { 98 ptBuffer.flip(); 99 ctBuffer.clear(); 100 encrypter.encryptSegment(ptBuffer, true, ctBuffer); 101 } catch (GeneralSecurityException ex) { 102 // TODO(bleichen): define the state of this. E.g. open = false; 103 throw new IOException( 104 "ptBuffer.remaining():" 105 + ptBuffer.remaining() 106 + " ctBuffer.remaining():" 107 + ctBuffer.remaining(), 108 ex); 109 } 110 ctBuffer.flip(); 111 out.write(ctBuffer.array(), ctBuffer.position(), ctBuffer.remaining()); 112 open = false; 113 super.close(); 114 } 115 } 116