When we designed PASETO, our goal was to provide an easy-to-use, secure-by-default, and simple protocol that solves the same sort of problems as JSON Web Tokens (except actually secure).

This resulted in two types of PASETO token being defined for each version of the protocol:

1. Local tokens: Symmetric authenticated encryption
2. Public tokens: Asymmetric digital signatures

This solved the majority of use cases, but not all: If you wanted to use public-key encryption instead of symmetric-key encryption, you couldn't accomplish that with PASETO. Put flatly, there was no JWK-equivalent for PASETO.

With that in mind, today we'd like to announce the first PASETO extension:

Platform-Agnostic SERializd Keys (PASERK)

PASERK provides the key-wrapping and serialization features missing from PASETO (which we excluded from PASETO to keep code sizes and complexity small; nobody wants to implement a standard that includes everything including the kitchen sink).

Serialized PASETO keys are always in the format

k[version_number].[type].[payload]

The version number in a PASERK must match the protocol version number of the corresponding PASETO token. Additionally, each PASERK type encodes a key that can only be used with a specific PASETO purpose.

Although we haven't declared the PASERK specification final yet, we do have a reference implementation in PHP available. Don't deploy PASERK in production until we tag v1.0.0.

Key Serialization

The most obvious feature of PASERK is the ability to unambiguously encode PASETO keys.

Key Serialization Examples

k4.local.cHFyc3R1dnd4eXp7fH1-f4CBgoOEhYaHiImKi4yNjo8

k4.public.cHFyc3R1dnd4eXp7fH1-f4CBgoOEhYaHiImKi4yNjpA

k4.secret.cHFyc3R1dnd4eXp7fH1-f4CBgoOEhYaHiImKi4yNjo8c5WpIyC_5kWKhS8VEYSZ05dYfuTF-ZdQFV4D9vLTcNQ

Key Wrapping

PASERK allows you to wrap symmetric keys (for local tokens) and asymmetric secret keys (for public tokens) with a symmetric key.

PASERK key-wrapping is intentionally designed to allow vendors to specify their own key-wrapping procedures, provided they reserve a unique identifier in the PASERK specification (to ensure interoperability).

We hope this makes PASERK useful for integrating with cryptographic material management services.

However, we also provide a standard implementation out-of-the-box.

Key-Wrapping Examples

k4.secret-wrap.pie.7W3QNfBlWJOv-ZpAj21_-zL_FoeF_7fLxMyZWEFM2wluA0at6zhGosy0wYnXIXVtvODGO78dT3-fyKUPxYEpVMFoL9oX8dBtOzMxnfdC7e4hQPw_si8sMLlMjeQvgixK6y9ObKbFzPpaeA3NiJ3_c5PmkS2Kg6SYdeSvlAaJXY0

k4.secret-wrap.pie.jLhVAJYWaOcKiFvnKv6kFEQxSGV9BQuW1Qt4jRwr6yHiNeQf2h1GQ0czBJZpveX5T0R0YZv2OEenf8uyLqwamDJUbtS-GdYp_TXT1OJCwGJb2UpEHvcSOciH2PVCEiTrLM9n_mAI4SWXDfw4xYenmINDhi8EiPaPKvsOU64YBvY

Public-Key Encryption

PASERK allows you to use public-key encryption to wrap ephemeral symmetric keys, which you can in turn use with local PASETO tokens.

Public-Key Encryption Example

k4.seal.OPFn-AEUsKUWtAUZrutVvd9YaZ4CmV4_lk6ii8N72l5gTnl8RlL_zRFqWTZZV9gSnPzARQ_QklrZ2Qs6cJGKOENNOnsDXL5haXcr-QbTXgoLVBvT4ruJ8MdjWXGRTVc9

Password-Based Key-Wrapping

Want to protect a PASETO key with a password? PASERK lets you do that too.

Password-Based Key Wrapping Examples

k4.local-pw._bru5tnkPSFXOtKhBTmW4gAAAAAEAAAAAAAAAgAAAAGKI3PyFS2vyQ9o5qowCR_GUXskLmdV1bjjc3vqnbwN7hVG1lAUCGjElTGIoH-K6lnkHnP4uaFBKWEtB3xFEGzAjzBSnl_JBmwLYK5jstjAV6LnJm_NOt0j

k4.secret-pw.P9TfOO2cQALHf6zR_ztWLQAAAAAEAAAAAAAAAgAAAAEXfZr9S7Fv_j6onvrpEEyynt83OiH-q9pgT0eW9vgvUFevooP7dP13g51HQmNMT_5y9-sJCw5VCqfMnXHoOppw5Zu98ZQxEZXuIbbqQdc4MWS99uA3J63k2vSsy8_gUUQV1sStrO4fxVs-OWsl4oxVdRGFfF0bhLI

Universally Unique Key Identifiers

Finally, PASETO offers a unique and unambiguous way to calculate Key IDs from a given PASETO key.

Key Identification Examples

k4.lid.iVtYQDjr5gEijCSjJC3fQaJm7nCeQSeaty0Jixy8dbsk

k4.pid.9ShR3xc8-qVJ_di0tc9nx0IDIqbatdeM2mqLFBJsKRHs

k4.sid.gHYyx8y5YzqKEZeYoMDqUOKejdSnY_AWhYZiSCMjR1V5