Tink

Ubuntu	macOS

Introduction

Tink is a cryptographic library. The design goals are:

• Simplicity Tink provides APIs that are simple and easy to use correctly. Most cryptographic operations such as data encryption, digital signatures, etc. can be done with only a few lines of code.

• Security Tink reduces common cryptographic pitfalls with user-centered design, careful implementation and code reviews, and extensive testing.

• Misuse-proof Tink assumes that the attacker has complete freedom in calling methods of a high level interface; under this assumption the security is not compromised. For example, if the underlying encryption mode requires nonces and is insecure if nonces are reused then the interface does not allow to pass nonces.

• Extensibility Tink makes it easy to support new primitives, new algorithms, new ciphertext formats, new key management systems, etc.

• Agility Tink provides built-in cryptographic agility. It supports key rotation, deprecation of obsolete schemes and adaptation of new ones. For example, if an implementation of a cryptographic primitive is found broken, you can switch to a different implementation by rotating keys, without changing or recompiling code.

• Interoperability Tink produces and consumes ciphertexts that are compatible with existing cryptographic libraries. Tink supports encrypting or storing keys in Amazon KMS, Google Cloud KMS, Android Keystore, and it is easy to support other key management systems.

• Versatility No part of Tink is hard to replace or remove. All components are recombinant, and can be selected and assembled in various combinations. For example, if you need only digital signatures, you can exclude symmetric key encryption components.

• Readability Tink shows cryptographic properties (i.e., whether safe against chosen-ciphertext attacks) right in the interfaces, allowing security auditors and automated tools quickly discovering incorrect usages. Tink provides standalone static types for potential dangerous operations (e.g., loading cleartext keys from disk), allowing discovering, restricting, monitoring and logging their usages.

Tink is written by a group of cryptographers and security engineers at Google, but it is not an official Google product. In particular, it is not meant as a replacement or successor of Keyczar.

Current Status

• Tink for Java is field tested and ready for production -- it is used in several Google products such as AdMob, Android Pay, and Google Android Search App.

• Tink for C++ is catching up with Tink for Java in terms of features and stability, and the offered functionality is 100%-compatible with Java (cf. cross-language tests. We plan to make a first C++ release soon.

• Tink for Obj-C and Go are in active development.

Getting started

TIP The easiest way to get started with Tink is to install Bazel, then build, run and study the hello world samples.

Tink performs cryptographic tasks via so-called primitives, each of which is defined via a corresponding interface that specifies the functionality of the primitive. For example, symmetric key encryption is offered via an AEAD-primitive (Authenticated Encryption with Associated Data), that supports two operations:

• encrypt(plaintext, associated_data), which encrypts the given plaintext (using associated_data as additional AEAD-input) and returns the resulting ciphertext
• decrypt(ciphertext, associated_data), which decrypts the given ciphertext (using associated_data as additional AEAD-input) and returns the resulting plaintext

Before implementations of primitives can be used, they must be registered at runtime with Tink, so that Tink "knows" the desired implementations. Here's how you can register all implementations of all primitives in Tink for Java 1.0.0:

    import com.google.crypto.tink.Config;
    import com.google.crypto.tink.config.TinkConfig;

    Config.register(TinkConfig.TINK_1_0_0);

After implementations of primitives have been registered, the basic use of Tink proceeds in three steps:

1. Load or generate the cryptographic key material (a Keyset in Tink terms).
2. Use the key material to get an instance of the chosen primitive.
3. Use that primitive to accomplish the cryptographic task.

Here is how these steps would look like when encrypting or decrypting with an AEAD primitive in Java:

    import com.google.crypto.tink.Aead;
    import com.google.crypto.tink.KeysetHandle;
    import com.google.crypto.tink.aead.AeadFactory;
    import com.google.crypto.tink.aead.AeadKeyTemplates;

    // 1. Generate the key material.
    KeysetHandle keysetHandle = KeysetHandle.generateNew(
        AeadKeyTemplates.AES128_GCM);

    // 2. Get the primitive.
    Aead aead = AeadFactory.getPrimitive(keysetHandle);

    // 3. Use the primitive.
    byte[] ciphertext = aead.encrypt(plaintext, aad);

See the Java HOWTO for how to obtain and use other primitives.

Important Warnings

Do not use APIs including fields and methods marked with the @Alpha annotation. They can be modified in any way, or even removed, at any time. They are in the package, but not for official, production release, but only for testing.

Learn More

• Tink Primitives
• Key Management
• Java HOW-TO
• C++ HOW-TO
• Tinkey

Contact and mailing list

If you want to contribute, please read CONTRIBUTING and send us pull requests. You can also report bugs or request new tests.

If you'd like to talk to our developers or get notified about major new tests, you may want to subscribe to our mailing list. To join, simply send an empty email to [email protected].

Maintainers

Tink is maintained by:

• Daniel Bleichenbacher
• Thai Duong
• Quan Nguyen
• Bartosz Przydatek