ywt/verify_key

Types

VerifyKey

opaque </>

A key that can verify JWT signatures.

Asymmetric verification keys contain public key material. HMAC verification keys contain the shared secret and can also be used to sign tokens.

pub opaque type VerifyKey

Values

decoder

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pub fn decoder() -> decode.Decoder(VerifyKey)

Decodes a public JWK into a verification key.

Only decode keys from trusted sources. Unknown JWK fields are ignored; key_ops, use, certificates, and key pinning are not enforced. This decoder accepts EC and RSA public keys, not HMAC shared-secret JWKs.

RSA JWKs may omit alg. In that case, JWT decoding uses the signed alg header to specialize the key. Raw signature verification with that key fails closed because there is no JWT header. For raw JSON strings, prefer parse_jwk so duplicate member handling is consistent on all targets.

json.parse(jwk_json, verify_key.decoder())

derived

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pub fn derived(sign_key: sign_key.SignKey) -> VerifyKey

Derives a verification key from a signing key.

For RSA and ECDSA this extracts public key material. For HMAC this returns the same shared secret, so treat the result as sensitive.

let verify_key = verify_key.derived(signing_key)

id

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pub fn id(key: VerifyKey) -> Result(String, Nil)

Returns the key id, if one is set.

verify_key.id(key)

parse_jwk

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pub fn parse_jwk(
  jwk: String,
) -> Result(VerifyKey, json.DecodeError)

Parses a public JWK into a verification key.

Duplicate JSON object members are handled consistently on all targets: the lexically last member value is used, matching JavaScript’s JSON.parse.

verify_key.parse_jwk(jwk_json)

parse_jwks

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pub fn parse_jwks(
  jwks: String,
) -> Result(List(VerifyKey), json.DecodeError)

Parses a JWKS into a list of verification keys.

Duplicate JSON object members are handled consistently on all targets: the lexically last member value is used, matching JavaScript’s JSON.parse.

verify_key.parse_jwks(jwks_json)

set_decoder

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pub fn set_decoder() -> decode.Decoder(List(VerifyKey))

Decodes a JWKS into a list of verification keys.

This has the same trust and validation limits as decoder. It expects a JSON object with a keys list. For raw JSON strings, prefer parse_jwks so duplicate member handling is consistent on all targets.

json.parse(jwks_json, verify_key.set_decoder())

to_jwk

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pub fn to_jwk(key: VerifyKey) -> json.Json

Encodes a verification key as a JWK.

Asymmetric keys encode only public key material. HMAC keys encode the shared secret, so do not publish HMAC JWKs.

verify_key.derived(signing_key) |> verify_key.to_jwk

to_jwks

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pub fn to_jwks(keys: List(VerifyKey)) -> json.Json

Encodes verification keys as a JWKS.

This is suitable for publishing asymmetric keys during rotation. Do not publish HMAC keys, because their JWK form contains the shared secret.

verify_key.to_jwks([current_key, previous_key])