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/**
* Copyright 2021 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
// [START streaming-aead-example]
package streamingaead;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.crypto.tink.CleartextKeysetHandle;
import com.google.crypto.tink.JsonKeysetReader;
import com.google.crypto.tink.KeysetHandle;
import com.google.crypto.tink.StreamingAead;
import com.google.crypto.tink.streamingaead.StreamingAeadConfig;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
/**
* A command-line utility for encrypting files with Streaming AEAD.
*
* <p>It loads cleartext keys from disk - this is not recommended!
*
* <p>It requires the following arguments:
*
* <ul>
* <li>mode: Can be "encrypt" or "decrypt" to encrypt/decrypt the input to the output.
* <li>key-file: Read the key material from this file.
* <li>input-file: Read the input from this file.
* <li>output-file: Write the result to this file.
* <li>[optional] associated-data: Associated data used for the encryption or decryption.
*/
public final class StreamingAeadExample {
private static final String MODE_ENCRYPT = "encrypt";
private static final String MODE_DECRYPT = "decrypt";
public static void main(String[] args) throws Exception {
if (args.length != 4 && args.length != 5) {
System.err.printf("Expected 4 or 5 parameters, got %d\n", args.length);
System.err.println(
"Usage: java StreamingAeadExample encrypt/decrypt key-file input-file output-file"
+ " [associated-data]");
System.exit(1);
}
String mode = args[0];
File keyFile = new File(args[1]);
File inputFile = new File(args[2]);
File outputFile = new File(args[3]);
byte[] associatedData = new byte[0];
if (args.length == 5) {
associatedData = args[4].getBytes(UTF_8);
}
// Initalise Tink: register all Streaming AEAD key types with the Tink runtime
StreamingAeadConfig.register();
// Read the keyset into a KeysetHandle
KeysetHandle handle = null;
try {
handle = CleartextKeysetHandle.read(JsonKeysetReader.withFile(keyFile));
} catch (GeneralSecurityException | IOException ex) {
System.err.println("Cannot read keyset, got error: " + ex);
System.exit(1);
}
// Get the primitive
StreamingAead streamingAead = null;
try {
streamingAead = handle.getPrimitive(StreamingAead.class);
} catch (GeneralSecurityException ex) {
System.err.println("Cannot create primitive, got error: " + ex);
System.exit(1);
}
// Use the primitive to encrypt/decrypt files
if (MODE_ENCRYPT.equals(mode)) {
encryptFile(streamingAead, inputFile, outputFile, associatedData);
} else if (MODE_DECRYPT.equals(mode)) {
decryptFile(streamingAead, inputFile, outputFile, associatedData);
} else {
System.err.println("The first argument must be either encrypt or decrypt, got: " + mode);
System.exit(1);
}
System.exit(0);
}
private static void encryptFile(
StreamingAead streamingAead, File inputFile, File outputFile, byte[] associatedData)
throws GeneralSecurityException, IOException {
try (OutputStream ciphertextStream =
streamingAead.newEncryptingStream(new FileOutputStream(outputFile), associatedData);
InputStream plaintextStream = new FileInputStream(inputFile)) {
byte[] chunk = new byte[1024];
int chunkLen = 0;
while ((chunkLen = plaintextStream.read(chunk)) != -1) {
ciphertextStream.write(chunk, 0, chunkLen);
}
}
}
private static void decryptFile(
StreamingAead streamingAead, File inputFile, File outputFile, byte[] associatedData)
throws GeneralSecurityException, IOException {
InputStream ciphertextStream =
streamingAead.newDecryptingStream(new FileInputStream(inputFile), associatedData);
OutputStream plaintextStream = new FileOutputStream(outputFile);
byte[] chunk = new byte[1024];
int chunkLen = 0;
while ((chunkLen = ciphertextStream.read(chunk)) != -1) {
plaintextStream.write(chunk, 0, chunkLen);
}
ciphertextStream.close();
plaintextStream.close();
}
private StreamingAeadExample() {}
}
// [END streaming-aead-example]