oidc-token-hash

oidc-token-hash validates (and generates) ID Token _hash claims such as at_hash or c_hash

> Its [*_hash] value is the base64url encoding of the left-most half of the hash of the octets of
> the ASCII representation of the token / state / code value, where the hash algorithm used is
> the hash algorithm used in the alg Header Parameter of the ID Token's JOSE Header. For instance,
> if the alg is RS256, hash the token / state / code value with SHA-256, then take the
> left-most 128 bits and base64url encode them. The *_hash value is a case sensitive string.

Matrix

| JWS algorithm | used hash algorithm | Note |
| --- | --- | --- |
| HS256, RS256, PS256, ES256, ES256K | sha256 | |
| HS384, RS384, PS384, ES384 | sha384 | |
| HS512, RS512, PS512, ES512 | sha512 | |
| EdDSA w/ Ed25519 curve | sha512 | connect/issues#1125 |
| EdDSA w/ Ed448 curve | shake256(m, 114) | connect/issues#1125 |
| Ed25519 | sha512 | connect/issues#1125 |
| Ed448 | shake256(m, 114) | connect/issues#1125 |
| ML-DSA-44, ML-DSA-65, ML-DSA-87 | shake256(m, 64) | connect/issues#1125 |

Usage

Validating
``js
const oidcTokenHash = require('oidc-token-hash');

const access_token = 'YmJiZTAwYmYtMzgyOC00NzhkLTkyOTItNjJjNDM3MGYzOWIy9sFhvH8K_x8UIHj1osisS57f5DduL-ar_qw5jl3lthwpMjm283aVMQXDmoqqqydDSqJfbhptzw8rUVwkuQbolw';

oidcTokenHash.validate({ claim: 'at_hash', source: 'access_token' }, 'x7vk7f6BvQj0jQHYFIk4ag', access_token, 'RS256'); // => does not throw
oidcTokenHash.validate({ claim: 'at_hash', source: 'access_token' }, 'EGEAhGYyfuwDaVTifvrWSoD5MSy_5hZPy6I7Vm-7pTQ', access_token, 'EdDSA', 'Ed25519'); // => does not throw
oidcTokenHash.validate({ claim: 'at_hash', source: 'access_token' }, 'EGEAhGYyfuwDaVTifvrWSoD5MSy_5hZPy6I7Vm-7pTQ', access_token, 'Ed25519'); // => does not throw
oidcTokenHash.validate({ claim: 'at_hash', source: 'access_token' }, 'x7vk7f6BvQj0jQHYFIk4ag', 'foobar', 'RS256'); // => throws AssertionError, message: at_hash mismatch, expected w6uP8Tcg6K2QR905Rms8iQ, got: x7vk7f6BvQj0jQHYFIk4ag
`

Generating
`js
// access_token from first example
oidcTokenHash.generate(access_token, 'RS256'); // => 'x7vk7f6BvQj0jQHYFIk4ag'
oidcTokenHash.generate(access_token, 'HS384'); // => 'ups_76_7CCye_J1WIyGHKVG7AAs2olYm'
oidcTokenHash.generate(access_token, 'ES512'); // => 'EGEAhGYyfuwDaVTifvrWSoD5MSy_5hZPy6I7Vm-7pTQ'
oidcTokenHash.generate(access_token, 'Ed25519'); // => 'EGEAhGYyfuwDaVTifvrWSoD5MSy_5hZPy6I7Vm-7pTQ'
oidcTokenHash.generate(access_token, 'EdDSA', 'Ed25519'); // => 'EGEAhGYyfuwDaVTifvrWSoD5MSy_5hZPy6I7Vm-7pTQ'
oidcTokenHash.generate(access_token, 'Ed448'); // => 'jxsy68_eG9-91VnHsZ2VnCr_WqDMv4nspiSuUPRdNZnv1y5lNV3rPVYYWNiY_TbUB1JRwlgiDTzZ'
oidcTokenHash.generate(access_token, 'EdDSA', 'Ed448'); // => 'jxsy68_eG9-91VnHsZ2VnCr_WqDMv4nspiSuUPRdNZnv1y5lNV3rPVYYWNiY_TbUB1JRwlgiDTzZ'
`

Changelog


- 5.2.0 - add support ML-DSA JWS Algorithm Identifiers
- 5.1.1 - remove conditional shake256 check
- 5.1.0 - add support for Ed25519 and Ed448 JWS Algorithm Identifiers
- 5.0.2 - avoid use of deprecated String.prototype.substr
- 5.0.1 - use base64url native encoding in Node.js when available
- 5.0.0 - fixed Ed448 and shake256 to use 114 bytes output
- 4.0.0 - using sha512 for Ed25519 and shake256 for Ed448, refactored API, removed handling of none JWS alg
- 3.0.2 - removed base64url dependency
- 3.0.1 - base64url comeback
- 3.0.0 - drop lts/4 support, replace base64url dependency
- 2.0.0 - rather then assuming the alg based on the hash length #valid() now requires a third
argument with the JOSE header alg` value, resulting in strict validation
- 1.0.0 - initial release