Understand Key Concepts in Tink

  • Tink utilizes primitives as fundamental cryptographic building blocks for secure data operations, covering encryption, signatures, and message authentication.

  • Keysets in Tink efficiently manage multiple keys for a single purpose, enabling features like key rotation and supporting various key types within a set.

  • Keyset handles provide a secure abstraction layer, allowing users to interact with keys and perform cryptographic operations without directly exposing sensitive key material.

  • Tink offers a diverse selection of primitives and key types, accommodating varying security, performance, and storage requirements, with options like AEAD, digital signatures, and hybrid encryption.

When you start working with Tink for the first time, there are some key concepts you should understand before you begin your journey; these are described in the following sections.

Primitives

Tink uses primitives as cryptographic building blocks that manage an underlying algorithm so users can perform cryptographic tasks safely. A primitive defines the details of a cryptographic algorithm and the key type.

Key types

A key type implements a specific primitive. Most primitives have several key types to choose from depending on your requirements for security, runtime, and space. For example, AES128_GCM is an AEAD that is fast and effective for most needs. See more at Supported key types by language.

Keysets & keyset handles

Tink uses keysets for managing keys. A keyset is essentially a set of keys that facilitate key rotation. Noteworthy properties of a keyset are:

  • Each key in a keyset has a unique ID, which is unique within a keyset. This ID is usually added as a prefix to each produced ciphertext, signature or tag to indicate which key was used (see how Tink tags ciphertexts for more info).
  • Only one key at a time in a keyset is primary. A primary key in a keyset is the key "in use" at the moment.
  • All the keys in a keyset must be implementations of the same primitive (such as AEAD), but can have different key types (for example, an AES-GCM and XCHACHA20-POLY1305 key).

Each Tink implementation provides APIs to create or edit keysets. However, we recommend using Tinkey our CLI tool.

Users operate over a keyset using keyset handles. A keyset handle limits the exposure of the actual sensitive key material. It also abstracts a keyset allowing users to obtain a primitive that "wraps" the entire keyset. For example, you can get an AEAD primitive of a keyset with N keys; encryption and decryption with the obtained primitive then uses the primary key in the keyset.

For more info, see keyset design.