The "use" (public key use) parameter identifies the intended use of
the public key. The "use" parameter is employed to indicate whether
a public key is used for encrypting data or verifying the signature
on data.
Other values MAY be used. The "use" value is a case-sensitive
string. Use of the "use" member is OPTIONAL, unless the application
requires its presence.
The "use" and "key_ops" JWK members SHOULD NOT be used together;
however, if both are used, the information they convey MUST be
consistent. Applications should specify which of these members they
use, if either is to be used by the application.
When a key is used to wrap another key and a public key use
designation for the first key is desired, the "enc" (encryption) key
use value is used, since key wrapping is a kind of encryption. The
"enc" value is also to be used for public keys used for key agreement
operations.
JSON Web Key Use
The "use" (public key use) parameter identifies the intended use of the public key. The "use" parameter is employed to indicate whether a public key is used for encrypting data or verifying the signature on data.
Values defined by RFC 7517 Section 4.2 are:
Other values MAY be used. The "use" value is a case-sensitive string. Use of the "use" member is OPTIONAL, unless the application requires its presence.
The "use" and "key_ops" JWK members SHOULD NOT be used together; however, if both are used, the information they convey MUST be consistent. Applications should specify which of these members they use, if either is to be used by the application.
When a key is used to wrap another key and a public key use designation for the first key is desired, the "enc" (encryption) key use value is used, since key wrapping is a kind of encryption. The "enc" value is also to be used for public keys used for key agreement operations.