Crate hessra_cap_token 

Hessra Capability Token

Capability token implementation for the Hessra authorization system.

This crate provides functionality for creating, verifying, and attenuating capability tokens (biscuit tokens). Capability tokens follow the principle that presenting the capability IS the authorization – no subject verification is required by default.

Key Design

The authority block contains:

right(subject, resource, operation);
check if resource($res), operation($op), right($sub, $res, $op);
check if time($time), $time < expiration;

Note: subject is NOT checked by default. The right fact retains the subject for auditing purposes, but the verifier only needs to provide resource and operation.

Optional Subject Verification

When stronger guarantees are needed, the verifier can opt into subject checking:

CapabilityVerifier::new(token, public_key, "resource".into(), "read".into())
    .with_subject("alice".into())  // optional subject check
    .verify();

Structs

Biscuit

This structure represents a valid Biscuit token

CapabilityVerifier

Builder for verifying Hessra capability tokens with flexible configuration.

DesignationBuilder

Builder for adding designation blocks to capability tokens.

HessraCapability

Builder for creating Hessra capability tokens with flexible configuration.

TokenTimeConfig

TokenTimeConfig allows control over token creation times and durations This is used to create tokens with custom start times and durations for testing purposes. In the future, this can be enhanced to support variable length tokens, such as long-lived bearer tokens.

Enums

KeyPair

pair of cryptographic keys used to sign a token’s block

PublicKey

the public part of a KeyPair

TokenError

Detailed error type for hessra-token operations with specific failure information

Functions

biscuit_key_from_string

Takes a public key encoded as a string in the format “ed25519/…” or “secp256r1/…” and returns a PublicKey.

decode_token

Decode a URL-safe base64 encoded token string to binary

encode_token

Encode binary token data to URL-safe base64 string

get_capability_revocation_id

Get the revocation ID for a capability token

get_capability_revocation_id_from_bytes

Get the revocation ID from raw token bytes

parse_token

Extracts and parses a Biscuit token from a URL-safe base64 string

public_key_from_pem_file