Annexure B – Application Layer Security – JWS Signature

Illustrative Process Flow of Generating the Detached JWS Signature

Cryptographic Standard algorithms: JSON Web Signature (JWS)

JWS Protected Header

Description: Produce JWS header parameters which define how the signature is created

Claims	Mandatory(M)/ Optional(O)	Description
"b64":" false	M	Determines whether payload data is b64 encoded or not.
“kid”: "…."	M	Determine the signer certificate to verify the signature
"x5t#S256": "…."	O	Hash of signing certificate. It means digest of the X.509 signing certificate using SHA 256.
"crit":["b64"]	O	Non-standard (i.e., not defined in RFC 7515) JWS header parameters which are critical
"alg": "RS256"	M	Signature algorithm

Note: This is shown below in a pretty print layout. It will be sent as a single string without line brakes or extra spaces. Escape characters are not used.

Disclaimer: These examples should not be taken as reference point for implementations of the AA JWS profile. They are based on a single implementation and have not been tested for correctness against other implementations.

JSON Web Signature Standard Algorithm

Note: RS256 is the currently adopted algorithm by all AAs for interoperability purpose.

"alg" Param	Digital Signature or MAC Algorithm	Implementation Requirements
HS256	HMAC using SHA-256	Required
HS384	HMAC using SHA-384	Optional
HS512	MAC using SHA-512	Optional
RS256	RSASSA-PKCS1-v1_5 using SHA 256	Recommended
RS384	RSASSA-PKCS1-v1_5 using SHA 384	Optional
RS512	RSASSA-PKCS1-v1_5 using SHA 512	Optional
ES256	ECDSA using P-256 and SHA-256	Recommended
ES384	ECDSA using P-256 and SHA-384	Optional
ES512	ECDSA using P-256 and SHA-512	Optional