We recommend using the Deterministic AEAD primitive with the AES256_SIV key type.
Deterministic Authenticated Encryption with Associated Data (Deterministic AEAD) produces stable ciphertexts: encrypting a given plaintext always returns the same ciphertext. It is symmetric, which means it uses a single key for both encryption and decryption.
Examples
The following examples get you started using the Deterministic AEAD primitive:
C++
// A command-line utility for testing Tink Deterministic AEAD.
#include <iostream>
#include <memory>
#include <ostream>
#include <string>
#include "absl/flags/flag.h"
#include "absl/flags/parse.h"
#include "absl/log/check.h"
#include "absl/strings/string_view.h"
#include "tink/daead/deterministic_aead_config.h"
#include "tink/deterministic_aead.h"
#include "util/util.h"
#include "tink/keyset_handle.h"
#include "tink/util/status.h"
ABSL_FLAG(std::string, keyset_filename, "", "Keyset file in JSON format");
ABSL_FLAG(std::string, mode, "", "Mode of operation {encrypt|decrypt}");
ABSL_FLAG(std::string, input_filename, "", "Filename to operate on");
ABSL_FLAG(std::string, output_filename, "", "Output file name");
ABSL_FLAG(std::string, associated_data, "",
"Associated data for Deterministic AEAD (default: empty");
namespace {
using ::crypto::tink::DeterministicAead;
using ::crypto::tink::DeterministicAeadConfig;
using ::crypto::tink::KeysetHandle;
using ::crypto::tink::util::Status;
using ::crypto::tink::util::StatusOr;
constexpr absl::string_view kEncrypt = "encrypt";
constexpr absl::string_view kDecrypt = "decrypt";
void ValidateParams() {
// ...
}
} // namespace
namespace tink_cc_examples {
// Deterministic AEAD example CLI implementation.
Status DeterministicAeadCli(absl::string_view mode,
const std::string& keyset_filename,
const std::string& input_filename,
const std::string& output_filename,
absl::string_view associated_data) {
Status result = DeterministicAeadConfig::Register();
if (!result.ok()) return result;
// Read keyset from file.
StatusOr<std::unique_ptr<KeysetHandle>> keyset_handle =
ReadJsonCleartextKeyset(keyset_filename);
if (!keyset_handle.ok()) return keyset_handle.status();
// Get the primitive.
StatusOr<std::unique_ptr<DeterministicAead>> daead =
(*keyset_handle)
->GetPrimitive<crypto::tink::DeterministicAead>(
crypto::tink::ConfigGlobalRegistry());
if (!daead.ok()) return daead.status();
// Read the input.
StatusOr<std::string> input_file_content = ReadFile(input_filename);
if (!input_file_content.ok()) return input_file_content.status();
// Compute the output.
std::string output;
if (mode == kEncrypt) {
StatusOr<std::string> result = (*daead)->EncryptDeterministically(
*input_file_content, associated_data);
if (!result.ok()) return result.status();
output = *result;
} else if (mode == kDecrypt) {
StatusOr<std::string> result = (*daead)->DecryptDeterministically(
*input_file_content, associated_data);
if (!result.ok()) return result.status();
output = *result;
}
// Write output to file.
return WriteToFile(output, output_filename);
}
} // namespace tink_cc_examples
int main(int argc, char** argv) {
absl::ParseCommandLine(argc, argv);
ValidateParams();
std::string mode = absl::GetFlag(FLAGS_mode);
std::string keyset_filename = absl::GetFlag(FLAGS_keyset_filename);
std::string input_filename = absl::GetFlag(FLAGS_input_filename);
std::string output_filename = absl::GetFlag(FLAGS_output_filename);
std::string associated_data = absl::GetFlag(FLAGS_associated_data);
std::clog << "Using keyset from file " << keyset_filename
<< " to Deterministic AEAD-" << mode << " file " << input_filename
<< " with associated data '" << associated_data << "'."
<< std::endl;
std::clog << "The resulting output will be written to " << output_filename
<< "." << std::endl;
CHECK_OK(tink_cc_examples::DeterministicAeadCli(
mode, keyset_filename, input_filename, output_filename, associated_data));
return 0;
}
Go
import (
"bytes"
"fmt"
"log"
"github.com/tink-crypto/tink-go/v2/daead"
"github.com/tink-crypto/tink-go/v2/insecurecleartextkeyset"
"github.com/tink-crypto/tink-go/v2/keyset"
)
func Example() {
// A keyset created with "tinkey create-keyset --key-template=AES256_SIV". Note
// that this keyset has the secret key information in cleartext.
jsonKeyset := `{
"key": [{
"keyData": {
"keyMaterialType":
"SYMMETRIC",
"typeUrl":
"type.googleapis.com/google.crypto.tink.AesSivKey",
"value":
"EkAl9HCMmKTN1p3V186uhZpJQ+tivyc4IKyE+opg6SsEbWQ/WesWHzwCRrlgRuxdaggvgMzwWhjPnkk9gptBnGLK"
},
"keyId": 1919301694,
"outputPrefixType": "TINK",
"status": "ENABLED"
}],
"primaryKeyId": 1919301694
}`
// Create a keyset handle from the cleartext keyset in the previous
// step. The keyset handle provides abstract access to the underlying keyset to
// limit the exposure of accessing the raw key material. WARNING: In practice,
// it is unlikely you will want to use a insecurecleartextkeyset, as it implies
// that your key material is passed in cleartext, which is a security risk.
// Consider encrypting it with a remote key in Cloud KMS, AWS KMS or HashiCorp Vault.
// See https://github.com/google/tink/blob/master/docs/GOLANG-HOWTO.md#storing-and-loading-existing-keysets.
keysetHandle, err := insecurecleartextkeyset.Read(
keyset.NewJSONReader(bytes.NewBufferString(jsonKeyset)))
if err != nil {
log.Fatal(err)
}
// Retrieve the DAEAD primitive we want to use from the keyset handle.
primitive, err := daead.New(keysetHandle)
if err != nil {
log.Fatal(err)
}
// Use the primitive to encrypt a message. In this case the primary key of the
// keyset will be used (which is also the only key in this example).
plaintext := []byte("message")
associatedData := []byte("associated data")
ciphertext, err := primitive.EncryptDeterministically(plaintext, associatedData)
if err != nil {
log.Fatal(err)
}
// Use the primitive to decrypt the message. Decrypt finds the correct key in
// the keyset and decrypts the ciphertext. If no key is found or decryption
// fails, it returns an error.
decrypted, err := primitive.DecryptDeterministically(ciphertext, associatedData)
if err != nil {
log.Fatal(err)
}
fmt.Println(ciphertext)
fmt.Println(string(decrypted))
// Output:
// [1 114 102 56 62 150 98 146 84 99 211 36 127 214 229 231 157 56 143 192 250 132 32 153 124 244 238 112]
// message
}
Java
package deterministicaead;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.crypto.tink.DeterministicAead;
import com.google.crypto.tink.InsecureSecretKeyAccess;
import com.google.crypto.tink.KeysetHandle;
import com.google.crypto.tink.TinkJsonProtoKeysetFormat;
import com.google.crypto.tink.daead.DeterministicAeadConfig;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
* A command-line utility for encrypting small files with Deterministic 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 DeterministicAeadExample {
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 DeterministicAeadExample encrypt/decrypt key-file input-file output-file"
+ " [associated-data]");
System.exit(1);
}
String mode = args[0];
Path keyFile = Paths.get(args[1]);
Path inputFile = Paths.get(args[2]);
Path outputFile = Paths.get(args[3]);
byte[] associatedData = new byte[0];
if (args.length == 5) {
associatedData = args[4].getBytes(UTF_8);
}
// Initialise Tink: register all Deterministic AEAD key types with the Tink runtime
DeterministicAeadConfig.register();
// Read the keyset into a KeysetHandle
KeysetHandle handle =
TinkJsonProtoKeysetFormat.parseKeyset(
new String(Files.readAllBytes(keyFile), UTF_8), InsecureSecretKeyAccess.get());
// Get the primitive
DeterministicAead daead = handle.getPrimitive(DeterministicAead.class);
// Use the primitive to encrypt/decrypt files.
if (MODE_ENCRYPT.equals(mode)) {
byte[] plaintext = Files.readAllBytes(inputFile);
byte[] ciphertext = daead.encryptDeterministically(plaintext, associatedData);
Files.write(outputFile, ciphertext);
} else if (MODE_DECRYPT.equals(mode)) {
byte[] ciphertext = Files.readAllBytes(inputFile);
byte[] plaintext = daead.decryptDeterministically(ciphertext, associatedData);
Files.write(outputFile, plaintext);
} else {
System.err.println("The first argument must be either encrypt or decrypt, got: " + mode);
System.exit(1);
}
System.exit(0);
}
private DeterministicAeadExample() {}
}
Python
import tink
from tink import daead
from tink import secret_key_access
def example():
"""Encrypt and decrypt using deterministic AEAD."""
# Register the deterministic AEAD key manager. This is needed to create a
# DeterministicAead primitive later.
daead.register()
# A keyset created with "tinkey create-keyset --key-template=AES256_SIV". Note
# that this keyset has the secret key information in cleartext.
keyset = r"""{
"key": [{
"keyData": {
"keyMaterialType":
"SYMMETRIC",
"typeUrl":
"type.googleapis.com/google.crypto.tink.AesSivKey",
"value":
"EkAl9HCMmKTN1p3V186uhZpJQ+tivyc4IKyE+opg6SsEbWQ/WesWHzwCRrlgRuxdaggvgMzwWhjPnkk9gptBnGLK"
},
"keyId": 1919301694,
"outputPrefixType": "TINK",
"status": "ENABLED"
}],
"primaryKeyId": 1919301694
}"""
# Create a keyset handle from the cleartext keyset in the previous
# step. The keyset handle provides abstract access to the underlying keyset to
# limit the exposure of accessing the raw key material. WARNING: In practice,
# it is unlikely you will want to use a cleartext_keyset_handle, as it implies
# that your key material is passed in cleartext which is a security risk.
keyset_handle = tink.json_proto_keyset_format.parse(
keyset, secret_key_access.TOKEN
)
# Retrieve the DeterministicAead primitive we want to use from the keyset
# handle.
primitive = keyset_handle.primitive(daead.DeterministicAead)
# Use the primitive to encrypt a message. In this case the primary key of the
# keyset will be used (which is also the only key in this example).
ciphertext = primitive.encrypt_deterministically(b'msg', b'associated_data')
# Use the primitive to decrypt the message. Decrypt finds the correct key in
# the keyset and decrypts the ciphertext. If no key is found or decryption
# fails, it raises an error.
output = primitive.decrypt_deterministically(ciphertext, b'associated_data')