1 /** 2 * Copyright 2021 Google LLC 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. 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 distributed under the License 10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 11 * or implied. See the License for the specific language governing permissions and limitations under 12 * the License. 13 */ 14 // [START cleartext-keyset-example] 15 package cleartextkeyset; 16 17 import static java.nio.charset.StandardCharsets.UTF_8; 18 19 import com.google.crypto.tink.Aead; 20 import com.google.crypto.tink.InsecureSecretKeyAccess; 21 import com.google.crypto.tink.KeysetHandle; 22 import com.google.crypto.tink.TinkJsonProtoKeysetFormat; 23 import com.google.crypto.tink.aead.AeadConfig; 24 import com.google.crypto.tink.aead.PredefinedAeadParameters; 25 import java.nio.file.Files; 26 import java.nio.file.Path; 27 import java.nio.file.Paths; 28 29 /** 30 * A command-line utility for generating, storing and using AES128_GCM keysets. 31 * 32 * <h1>WARNING: Loading a Keyset from disk is often a security problem -- hence this needs {@code 33 * InsecureSecretKeyAccess.get()}. 34 * 35 * <p>It requires the following arguments: 36 * 37 * <ul> 38 * <li>mode: Can be "generate", "encrypt" or "decrypt". If mode is "generate" it will generate, 39 * encrypt a keyset, store it in key-file. If mode is "encrypt" or "decrypt" it will read and 40 * decrypt an keyset from key-file, and use it to encrypt or decrypt input-file. 41 * <li>key-file: Read the encrypted key material from this file. 42 * <li>input-file: If mode is "encrypt" or "decrypt", read the input from this file. 43 * <li>output-file: If mode is "encrypt" or "decrypt", write the result to this file. 44 */ 45 public final class CleartextKeysetExample { 46 private static final String MODE_ENCRYPT = "encrypt"; 47 private static final String MODE_DECRYPT = "decrypt"; 48 private static final String MODE_GENERATE = "generate"; 49 private static final byte[] EMPTY_ASSOCIATED_DATA = new byte[0]; 50 main(String[] args)51 public static void main(String[] args) throws Exception { 52 if (args.length != 2 && args.length != 4) { 53 System.err.printf("Expected 2 or 4 parameters, got %d\n", args.length); 54 System.err.println( 55 "Usage: java CleartextKeysetExample generate/encrypt/decrypt key-file input-file" 56 + " output-file"); 57 System.exit(1); 58 } 59 String mode = args[0]; 60 if (!MODE_ENCRYPT.equals(mode) && !MODE_DECRYPT.equals(mode) && !MODE_GENERATE.equals(mode)) { 61 System.err.print("The first argument should be either encrypt, decrypt or generate"); 62 System.exit(1); 63 } 64 Path keyFile = Paths.get(args[1]); 65 66 // Initialise Tink: register all AEAD key types with the Tink runtime 67 AeadConfig.register(); 68 69 if (MODE_GENERATE.equals(mode)) { 70 // [START generate-a-new-keyset] 71 KeysetHandle handle = KeysetHandle.generateNew(PredefinedAeadParameters.AES128_GCM); 72 // [END generate-a-new-keyset] 73 74 // [START store-a-cleartext-keyset] 75 String serializedKeyset = 76 TinkJsonProtoKeysetFormat.serializeKeyset(handle, InsecureSecretKeyAccess.get()); 77 Files.write(keyFile, serializedKeyset.getBytes(UTF_8)); 78 // [END store-a-cleartext-keyset] 79 return; 80 } 81 82 // Use the primitive to encrypt/decrypt files 83 84 // Read the keyset from disk 85 String serializedKeyset = new String(Files.readAllBytes(keyFile), UTF_8); 86 KeysetHandle handle = 87 TinkJsonProtoKeysetFormat.parseKeyset(serializedKeyset, InsecureSecretKeyAccess.get()); 88 89 // Get the primitive 90 Aead aead = handle.getPrimitive(Aead.class); 91 92 byte[] input = Files.readAllBytes(Paths.get(args[2])); 93 Path outputFile = Paths.get(args[3]); 94 95 if (MODE_ENCRYPT.equals(mode)) { 96 byte[] ciphertext = aead.encrypt(input, EMPTY_ASSOCIATED_DATA); 97 Files.write(outputFile, ciphertext); 98 } else if (MODE_DECRYPT.equals(mode)) { 99 byte[] plaintext = aead.decrypt(input, EMPTY_ASSOCIATED_DATA); 100 Files.write(outputFile, plaintext); 101 } 102 } 103 CleartextKeysetExample()104 private CleartextKeysetExample() {} 105 } 106 // [END cleartext-keyset-example] 107