moonbitstack/mooncred/jwt does not have a README file
Refused
pub(all) suberror Refused {
Shape(String)
Algorithm(want~ : String, got~ : String)
Signature
Expired(at~ : Double)
TooEarly(at~ : Double)
Issuer(want~ : String, got~ : String)
Audience(want~ : Array[String])
Subject(want~ : String, got~ : String)
IssuedAt(at~ : Double)
Type(want~ : String, got~ : String)
Missing(claim~ : String)
} derive(Eq, Debug)Why a token was not accepted.
Each reason is separate so a caller can map it to the right answer — an
expired token deserves a different response from a forged one — and so a log
says which check failed rather than that one did.
Alg
A JOSE signature algorithm (RFC 7518 §3.1), and the one RFC 8037 adds.
none is not here and never will be. It is the algorithm that made
"verified" mean "not verified" in a dozen libraries, and a type that cannot
express it cannot be talked into accepting it.
Clock
When the time claims are measured against.
A library has no clock — reading one is a side effect and there is no reason
for a token verifier to have that power — so the instant comes in from the
caller. Ignored is the way to read a token without asking whether it has
expired: a debugging tool, an audit of tokens already collected, a migration
that has to read what was issued last year. It is spelled out at the call
site because the alternative is a verifier that quietly stopped checking.
Keyed
type KeyedA keyed MAC, standing in as both signer and verifier.
HMAC is symmetric: the same key that signs verifies. What it is not is a
signature — anyone who can check an HS256 token can mint one — so a token
verified this way says only that someone holding the shared secret issued it.
OnClash
pub(all) enum OnClash[T] {
Ignore
Panic
Handle((T, T) -> T)
}What to do when a setting is given twice.
Handle receives the base and the merged result and returns whichever it
wants, so a caller can audit, refuse, or merge some other way entirely.
There is no Warn: a library has nowhere to warn to. It arrives when
moonlog does.
Policy
What a token has to satisfy beyond its signature.
Every field is a check that is either off or told what to expect, and every
default is what the mainstream libraries do: exp and nbf are checked,
iat is not, and iss, aud, sub and the header's typ are looked at
only when the caller says what to expect. Nothing is enforced implicitly and
nothing is skipped implicitly.
One of these is assembled once for a deployment and passed to every
verification, which is what jsonwebtoken's Validation, .NET's
TokenValidationParameters and jose's options object are for.
Policy::new
Build a policy by naming the parts that differ from the default.
The same thing can be written { ..@jwt.policy, expiry: false }; this form
exists because a named argument reads better when several parts differ.
issuer, subject and typ can be set here but not cleared: the preset
leaves all three unset, so there is nothing to clear. Starting from a base of
one's own, { ..mine, issuer: None } is how a check is dropped.
Wins
Which side wins when a setting is given twice.
Every function here that takes both a base and something layered over it
says which one wins, and lets a caller say otherwise. The defaults differ by
function and each one says why: verify lets the override win, because a
per-call argument is more specific than a policy assembled once; sign lets
the base win, because the header it computes describes the signature it is
about to make.
claims_unverified
The claims of a token that has not been verified.
Whoever sent the token wrote these. Reading them before verify has
returned is reading an attacker's input; it is here because a gateway
sometimes must route on iss before it knows which key to fetch, and for no
other reason.
header
The header of a token that has not been verified.
This is for one thing: reading kid to choose which key to verify with.
Nothing else in here has been checked by anybody.
mac
Take a way of making a keyed MAC and use it as a JWT key.
It takes a factory rather than a MAC because one state cannot authenticate
two messages, and a key outlives the token it was used on.
policy
The policy a verification uses when the caller does not say otherwise.
sign
Sign a claims set as a compact JWT.
extra goes into the header beside alg and typ — kid is what it is
usually for, so a verifier can pick the right key out of a set before it
verifies anything.
typ is "JWT", which is what every library writes and what RFC 7519 §5.1
recommends. None leaves it out; another string puts that in — RFC 9068's
access tokens want "at+jwt".
extra cannot quietly rewrite alg or typ. The header describes the
signature this function is about to make; a token whose header says none
while the bytes say HS256 is not a configuration choice, it is a mistake, so
wins starts at Base and clash at Panic. A caller who means it can
say wins=Extra, clash=Ignore.
The key is whatever can sign; this package never chooses an algorithm's
implementation, so a program that issues only HS256 tokens links only HMAC.
verify
Verify a compact JWT and return its claims.
The algorithm is the caller's, not the token's. A verifier that reads
alg out of the header and then trusts it is how an RS256 public key gets
used as an HS256 shared secret, and how none gets accepted; here the header
must match what the caller already decided, or the token is refused.
The signature is checked before any claim is read, so a forged token is
never inspected for its contents.
Configuration has three layers, each overriding the one before:
@jwt.policy < the policy given here < the named arguments given here.
wins turns the last two around; clash decides whether being given a
setting twice is silent, fatal, or yours to arbitrate.
now is not configuration but data: the instant the time claims are
measured against, or Ignored to read a token without asking whether it has
expired — a debugging tool, an audit of tokens already collected, a
migration that has to read what was issued last year.
Source Files
Install
Download zipmooncred — credential formats for MoonBit: JSON Web Tokens, JWS and JWK with the JOSE algorithm set, and X.509 certificates with chain validation to the Mozilla roots, built on mooncrypt's algorithms.
jwtjwsjwkjosetokencredentialx509certificateoauth2moonbit
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