Saya ingin mengenkripsi file atau aliran data besar

Sebaiknya gunakan primitif Streaming AEAD dengan jenis kunci AES128_GCM_HKDF_1MB untuk sebagian besar kasus penggunaan enkripsi file.

Primitive Streaming Authenticated Encryption with Associated Data (Streaming AEAD) berguna untuk mengenkripsi streaming data live atau file besar yang tidak muat dalam memori. Serupa dengan AEAD, enkripsi ini bersifat simetris, menggunakan satu kunci untuk enkripsi dan dekripsi.

Contoh berikut membantu Anda mulai menggunakan primitif Streaming AEAD:

Go

import (
	"bytes"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"

	"github.com/tink-crypto/tink-go/v2/insecurecleartextkeyset"
	"github.com/tink-crypto/tink-go/v2/keyset"
	"github.com/tink-crypto/tink-go/v2/streamingaead"
)

func Example() {
	// A keyset created with "tinkey create-keyset --key-template=AES256_CTR_HMAC_SHA256_1MB". Note
	// that this keyset has the secret key information in cleartext.
	jsonKeyset := `{
    "primaryKeyId": 1720777699,
    "key": [{
        "keyData": {
            "typeUrl": "type.googleapis.com/google.crypto.tink.AesCtrHmacStreamingKey",
            "keyMaterialType": "SYMMETRIC",
            "value": "Eg0IgCAQIBgDIgQIAxAgGiDtesd/4gCnQdTrh+AXodwpm2b6BFJkp043n+8mqx0YGw=="
        },
        "outputPrefixType": "RAW",
        "keyId": 1720777699,
        "status": "ENABLED"
    }]
	}`

	// 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 an 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 StreamingAEAD primitive we want to use from the keyset handle.
	primitive, err := streamingaead.New(keysetHandle)
	if err != nil {
		log.Fatal(err)
	}

	// Create a file with the plaintext.
	dir, err := os.MkdirTemp("", "streamingaead")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir)
	plaintextPath := filepath.Join(dir, "plaintext")
	if err := os.WriteFile(plaintextPath, []byte("this data needs to be encrypted"), 0666); err != nil {
		log.Fatal(err)
	}
	plaintextFile, err := os.Open(plaintextPath)
	if err != nil {
		log.Fatal(err)
	}

	// associatedData defines the context of the encryption. Here, we include the path of the
	// plaintext file.
	associatedData := []byte("associatedData for " + plaintextPath)

	// Encrypt the plaintext file and write the output to the ciphertext file. In this case the
	// primary key of the keyset will be used (which is also the only key in this example).
	ciphertextPath := filepath.Join(dir, "ciphertext")
	ciphertextFile, err := os.Create(ciphertextPath)
	if err != nil {
		log.Fatal(err)
	}
	w, err := primitive.NewEncryptingWriter(ciphertextFile, associatedData)
	if err != nil {
		log.Fatal(err)
	}
	if _, err := io.Copy(w, plaintextFile); err != nil {
		log.Fatal(err)
	}
	if err := w.Close(); err != nil {
		log.Fatal(err)
	}
	if err := ciphertextFile.Close(); err != nil {
		log.Fatal(err)
	}
	if err := plaintextFile.Close(); err != nil {
		log.Fatal(err)
	}

	// Decrypt the ciphertext file and write the output to the decrypted file. The
	// decryption finds the correct key in the keyset and decrypts the ciphertext.
	// If no key is found or decryption fails, it returns an error.
	ciphertextFile, err = os.Open(ciphertextPath)
	if err != nil {
		log.Fatal(err)
	}
	decryptedPath := filepath.Join(dir, "decrypted")
	decryptedFile, err := os.Create(decryptedPath)
	if err != nil {
		log.Fatal(err)
	}
	r, err := primitive.NewDecryptingReader(ciphertextFile, associatedData)
	if err != nil {
		log.Fatal(err)
	}
	if _, err := io.Copy(decryptedFile, r); err != nil {
		log.Fatal(err)
	}
	if err := decryptedFile.Close(); err != nil {
		log.Fatal(err)
	}
	if err := ciphertextFile.Close(); err != nil {
		log.Fatal(err)
	}

	// Print the content of the decrypted file.
	b, err := os.ReadFile(decryptedPath)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(b))
	// Output: this data needs to be encrypted
}

streamingaead_test.go

Java

package streamingaead;

import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.crypto.tink.InsecureSecretKeyAccess;
import com.google.crypto.tink.KeysetHandle;
import com.google.crypto.tink.RegistryConfiguration;
import com.google.crypto.tink.StreamingAead;
import com.google.crypto.tink.TinkJsonProtoKeysetFormat;
import com.google.crypto.tink.streamingaead.StreamingAeadConfig;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
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";
  private static final int BLOCK_SIZE_IN_BYTES = 8 * 1024;

  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];
    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);
    }

    // Initialize Tink: register all Streaming AEAD key types with the Tink runtime
    StreamingAeadConfig.register();

    // Read the keyset into a KeysetHandle
    KeysetHandle handle =
        TinkJsonProtoKeysetFormat.parseKeyset(
            new String(Files.readAllBytes(keyFile), UTF_8), InsecureSecretKeyAccess.get());

    // Get the primitive
    StreamingAead streamingAead =
        handle.getPrimitive(RegistryConfiguration.get(), StreamingAead.class);

    // Use the primitive to encrypt/decrypt files
    if (mode.equals(MODE_ENCRYPT)) {
      encryptFile(streamingAead, inputFile, outputFile, associatedData);
    } else if (mode.equals(MODE_DECRYPT)) {
      decryptFile(streamingAead, inputFile, outputFile, associatedData);
    } else {
      System.err.println(
          "The first argument must be either "
              + MODE_ENCRYPT
              + " or "
              + MODE_DECRYPT
              + ", got: "
              + mode);
      System.exit(1);
    }
  }

  private static void encryptFile(
      StreamingAead streamingAead, Path inputFile, Path outputFile, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    try (WritableByteChannel encryptingChannel =
            streamingAead.newEncryptingChannel(
                FileChannel.open(outputFile, StandardOpenOption.WRITE, StandardOpenOption.CREATE),
                associatedData);
        FileChannel inputChannel = FileChannel.open(inputFile, StandardOpenOption.READ)) {
      ByteBuffer byteBuffer = ByteBuffer.allocate(BLOCK_SIZE_IN_BYTES);
      while (true) {
        int read = inputChannel.read(byteBuffer);
        if (read <= 0) {
          return;
        }
        byteBuffer.flip();
        while (byteBuffer.hasRemaining()) {
          encryptingChannel.write(byteBuffer);
        }
        byteBuffer.clear();
      }
    }
  }

  private static void decryptFile(
      StreamingAead streamingAead, Path inputFile, Path outputFile, byte[] associatedData)
      throws GeneralSecurityException, IOException {
    try (ReadableByteChannel decryptingChannel =
            streamingAead.newDecryptingChannel(
                FileChannel.open(inputFile, StandardOpenOption.READ), associatedData);
        FileChannel outputChannel =
            FileChannel.open(outputFile, StandardOpenOption.WRITE, StandardOpenOption.CREATE)) {
      ByteBuffer byteBuffer = ByteBuffer.allocate(BLOCK_SIZE_IN_BYTES);
      while (true) {
        int read = decryptingChannel.read(byteBuffer);
        if (read <= 0) {
          return;
        }
        byteBuffer.flip();
        while (byteBuffer.hasRemaining()) {
          outputChannel.write(byteBuffer);
        }
        byteBuffer.clear();
      }
    }
  }

  private StreamingAeadExample() {}
}
StreamingAeadExample.java

Python

"""A command-line utility for using streaming AEAD for a file.

It loads cleartext keys from disk - this is not recommended!

It requires 4 arguments (and one optional one):
  mode: either 'encrypt' or 'decrypt'
  keyset_path: name of the file with the keyset to be used for encryption or
    decryption
  input_path: name of the file with the input data to be encrypted or decrypted
  output_path: name of the file to write the ciphertext respectively plaintext
    to
  [optional] associated_data: the associated data used for encryption/decryption
    provided as a string.
"""

from typing import BinaryIO

from absl import app
from absl import flags
from absl import logging
import tink
from tink import secret_key_access
from tink import streaming_aead

FLAGS = flags.FLAGS
BLOCK_SIZE = 1024 * 1024  # The CLI tool will read/write at most 1 MB at once.

flags.DEFINE_enum('mode', None, ['encrypt', 'decrypt'],
                  'Selects if the file should be encrypted or decrypted.')
flags.DEFINE_string('keyset_path', None,
                    'Path to the keyset used for encryption or decryption.')
flags.DEFINE_string('input_path', None, 'Path to the input file.')
flags.DEFINE_string('output_path', None, 'Path to the output file.')
flags.DEFINE_string('associated_data', None,
                    'Associated data used for the encryption or decryption.')


def read_as_blocks(file: BinaryIO):
  """Generator function to read from a file BLOCK_SIZE bytes.

  Args:
    file: The file object to read from.

  Yields:
    Returns up to BLOCK_SIZE bytes from the file.
  """
  while True:
    data = file.read(BLOCK_SIZE)
    # If file was opened in rawIO, EOF is only reached when b'' is returned.
    # pylint: disable=g-explicit-bool-comparison
    if data == b'':
      break
    # pylint: enable=g-explicit-bool-comparison
    yield data


def encrypt_file(input_file: BinaryIO, output_file: BinaryIO,
                 associated_data: bytes,
                 primitive: streaming_aead.StreamingAead):
  """Encrypts a file with the given streaming AEAD primitive.

  Args:
    input_file: File to read from.
    output_file: File to write to.
    associated_data: Associated data provided for the AEAD.
    primitive: The streaming AEAD primitive used for encryption.
  """
  with primitive.new_encrypting_stream(output_file,
                                       associated_data) as enc_stream:
    for data_block in read_as_blocks(input_file):
      enc_stream.write(data_block)


def decrypt_file(input_file: BinaryIO, output_file: BinaryIO,
                 associated_data: bytes,
                 primitive: streaming_aead.StreamingAead):
  """Decrypts a file with the given streaming AEAD primitive.

  This function will cause the program to exit with 1 if the decryption fails.

  Args:
    input_file: File to read from.
    output_file: File to write to.
    associated_data: Associated data provided for the AEAD.
    primitive: The streaming AEAD primitive used for decryption.
  """
  try:
    with primitive.new_decrypting_stream(input_file,
                                         associated_data) as dec_stream:
      for data_block in read_as_blocks(dec_stream):
        output_file.write(data_block)
  except tink.TinkError as e:
    logging.exception('Error decrypting ciphertext: %s', e)
    exit(1)


def main(argv):
  del argv

  associated_data = b'' if not FLAGS.associated_data else bytes(
      FLAGS.associated_data, 'utf-8')

  # Initialise Tink.
  try:
    streaming_aead.register()
  except tink.TinkError as e:
    logging.exception('Error initialising Tink: %s', e)
    return 1

  # Read the keyset into a keyset_handle.
  with open(FLAGS.keyset_path, 'rt') as keyset_file:
    try:
      text = keyset_file.read()
      keyset_handle = tink.json_proto_keyset_format.parse(
          text, secret_key_access.TOKEN
      )
    except tink.TinkError as e:
      logging.exception('Error reading key: %s', e)
      return 1

  # Get the primitive.
  try:
    streaming_aead_primitive = keyset_handle.primitive(
        streaming_aead.StreamingAead)
  except tink.TinkError as e:
    logging.exception('Error creating streaming AEAD primitive from keyset: %s',
                      e)
    return 1

  # Encrypt or decrypt the file.
  with open(FLAGS.input_path, 'rb') as input_file:
    with open(FLAGS.output_path, 'wb') as output_file:
      if FLAGS.mode == 'encrypt':
        encrypt_file(input_file, output_file, associated_data,
                     streaming_aead_primitive)
      elif FLAGS.mode == 'decrypt':
        decrypt_file(input_file, output_file, associated_data,
                     streaming_aead_primitive)


if __name__ == '__main__':
  flags.mark_flag_as_required('mode')
  flags.mark_flag_as_required('keyset_path')
  flags.mark_flag_as_required('input_path')
  flags.mark_flag_as_required('output_path')
  app.run(main)

streaming_aead_cli.py

Streaming AEAD

Primitive Streaming AEAD menyediakan enkripsi yang diautentikasi untuk data streaming. Fungsi ini berguna jika data yang akan dienkripsi terlalu besar untuk diproses dalam satu langkah. Kasus penggunaan umum mencakup enkripsi file besar atau streaming data live.

Enkripsi dilakukan dalam segmen, yang terikat dengan lokasinya dalam ciphertext dan tidak dapat dihapus atau diurutkan ulang. Segmen dari satu ciphertext tidak dapat disisipkan ke ciphertext lain. Untuk mengubah ciphertext yang ada, seluruh aliran data harus dienkripsi ulang.1

Dekripsi berlangsung cepat karena hanya sebagian ciphertext yang didekripsi dan diautentikasi dalam satu waktu. Teks biasa sebagian dapat diperoleh tanpa memproses seluruh ciphertext.

Implementasi AEAD streaming memenuhi definisi AEAD dan aman nOAE. Rekomendasi memiliki properti berikut:

  • Secrecy: Tidak ada yang diketahui tentang teks biasa, kecuali panjangnya.
  • Authenticity: Teks biasa terenkripsi yang mendasari ciphertext tidak dapat diubah tanpa terdeteksi.
  • Symmetric: Mengenkripsi teks biasa dan mendekripsi ciphertext dilakukan dengan kunci yang sama.
  • Pengacakan: Enkripsi dilakukan secara acak. Dua pesan dengan plaintext yang sama menghasilkan ciphertext yang berbeda. Penyerang tidak dapat mengetahui ciphertext mana yang sesuai dengan teks biasa tertentu.

Data terkait

Primitif Streaming AEAD dapat digunakan untuk mengikat ciphertext ke data terkait tertentu. Misalkan Anda memiliki database dengan kolom user-id dan encrypted-medical-history: Dalam skenario ini, user-id dapat digunakan sebagai data terkait saat mengenkripsi encrypted-medical-history. Hal ini mencegah penyerang memindahkan histori medis dari satu pengguna ke pengguna lain.

Memilih jenis kunci

Sebaiknya gunakan AES128_GCM_HKDF_1MB untuk sebagian besar penggunaan. Secara umum:

  • AES-GCM-HKDF
    • AES128_GCM_HKDF_1MB (atau AES256_GCM_HKDF_1MB) adalah opsi yang lebih cepat. File ini dapat mengenkripsi 264 file dengan masing-masing ukuran hingga 264 byte. Memori sebesar ~1 MB digunakan selama proses enkripsi dan dekripsi.
    • AES128_GCM_HKDF_4KB menggunakan memori ~4 KB dan merupakan pilihan yang baik jika sistem Anda tidak memiliki banyak memori.
  • AES-CTR HMAC
    • AES128_CTR_HMAC_SHA256_1MB (atau AES256_CTR_HMAC_SHA256_1MB) adalah opsi yang lebih konservatif.

Jaminan keamanan

Implementasi AEAD streaming menawarkan:

  • Keamanan CCA2.
  • Kekuatan autentikasi minimal 80-bit.
  • Kemampuan untuk mengenkripsi minimal 264 pesan3 dengan total 251 byte2 . Tidak ada serangan dengan hingga 232 teks biasa yang dipilih atau ciphertext yang dipilih yang memiliki probabilitas keberhasilan lebih besar dari 2-32.

  1. Alasan batasan ini adalah penggunaan cipher AES-GCM. Mengenkripsi segmen teks biasa yang berbeda di lokasi yang sama akan setara dengan menggunakan kembali IV, yang melanggar jaminan keamanan AES-GCM. Alasan lainnya adalah tindakan ini mencegah serangan rollback, saat penyerang mungkin mencoba memulihkan versi file sebelumnya tanpa terdeteksi. ↩

  2. 2 segmen 32 didukung, dengan setiap segmen berisi segment_size - tag_size byte teks biasa. Untuk segmen 1 MB, total ukuran teks biasa adalah 232 * (220-16) ~= 251 byte. ↩

  3. Streaming AEAD menjadi tidak aman saat kombinasi kunci turunan (128-bit) dan awalan nonce (nilai acak 7 byte independen) diulang. Kita memiliki resistensi tabrakan 184-bit, yang kira-kira diterjemahkan menjadi 264 pesan jika kita ingin probabilitas keberhasilan kurang dari 2-32. ↩