JWS 4 (26.12.2022 3M) Flashcards
Name Registered Header Parameter Names defined by the specification.
- alg - Algorithm
- jku - JWK Set Url
- jwk - JSON Web Key
- kid - key id
- x5u - X.509 URL
- x5c - X.509 Certificate Chain
- x5t - X.509 Certificate SHA-1 Thumbprint
- x5t#S256 - X.509 Certificate SHA-256 Thumbprint
- typ - type
- cty - content type
- crit - critical
Describe “alg” Header Parameter.
The “alg” (algorithm) Header Parameter identifies the cryptographic algorithm used to secure the JWS.
This Header Parameter MUST be present and MUST be understood and processed by implementations.
The “alg” value is a case-sensitive ASCII string containing a StringOrURI value.
“alg” values should either be registered in the IANA “JSON Web Signature and Encryption Algorithms” registry established by [JWA] or be a value that contains a Collision-Resistant Name.
When JWS Signature may be stated as invalid even before applying the cryptographic algorithm to it?
If the value of “alg” header parameter is not supported. Or if there is no key associated with the party that digitally signed or MACed the content for use with the algorithm.
Describe “jku” Header Parameter.
The “jku” (JWK Set URL) Header Parameter is a URI that refers to a resource for a set of JSON-encoded public keys, one of which corresponds to the key used to digitally sign the JWS.
Use of this Header Parameter is OPTIONAL.
The keys MUST be encoded as a JWK Set.
The protocol used to acquire the resource MUST provide integrity protection and allow to verify of the server identity. The TLS with a trusted certificate is OK for this purpose.
Describe “jwk” header parameter.
The “jwk” (JSON Web Key) Header Parameter is the public key that corresponds to the key used to digitally sign the JWS. This key is represented as a JSON Web Key.
The use of this Header Parameter is OPTIONAL.
Describe “kid” header parameter
The “kid” (key ID) Header Parameter is a hint indicating which key was used to secure the JWS. This parameter allows originators to explicitly signal a change of key to recipients. The structure of the “kid” value is unspecified. Its value MUST be a case-sensitive string. The use of this Header Parameter is OPTIONAL. When used with a JWK, the “kid” value is used to match a JWK “kid” parameter value.
