JSON Web Key Usage

Collaboration diagram for JSON Web Key Usage:

Typedefs
typedef struct jwk_item	jwk_item_t
	Object representation of a JWK.

Enumerations
enum	jwk_key_type_t {   JWK_KEY_TYPE_NONE = 0 , JWK_KEY_TYPE_EC , JWK_KEY_TYPE_RSA , JWK_KEY_TYPE_OKP ,   JWK_KEY_TYPE_OCT }
	JWK Key Types. More...
enum	jwk_pub_key_use_t { JWK_PUB_KEY_USE_NONE = 0 , JWK_PUB_KEY_USE_SIG , JWK_PUB_KEY_USE_ENC }
	Usage types for JWK public keys. More...
enum	jwk_key_op_t {   JWK_KEY_OP_NONE = 0x0000 , JWK_KEY_OP_SIGN = 0x0001 , JWK_KEY_OP_VERIFY = 0x0002 , JWK_KEY_OP_ENCRYPT = 0x0004 ,   JWK_KEY_OP_DECRYPT = 0x0008 , JWK_KEY_OP_WRAP = 0x0010 , JWK_KEY_OP_UNWRAP = 0x0020 , JWK_KEY_OP_DERIVE_KEY = 0x0040 ,   JWK_KEY_OP_DERIVE_BITS = 0x0080 , JWK_KEY_OP_INVALID = 0xffff }
	Allowed key operations for JWK private keys. More...

Functions
const jwk_item_t *	jwks_item_get (const jwk_set_t *jwk_set, size_t index)
	Return the index'th jwk_item in the jwk_set.
jwk_item_t *	jwks_find_bykid (jwk_set_t *jwk_set, const char *kid)
	Find a jwk_item_t with a specific kid (Key ID)
int	jwks_item_is_private (const jwk_item_t *item)
	Whether this key is private (or public)
int	jwks_item_error (const jwk_item_t *item)
	Check the error condition for this JWK.
const char *	jwks_item_error_msg (const jwk_item_t *item)
	Check the error message for a JWK Item.
const char *	jwks_item_curve (const jwk_item_t *item)
	A curve name, if applicable, for this key.
const char *	jwks_item_kid (const jwk_item_t *item)
	A kid (Key ID) for this JWK.
jwt_alg_t	jwks_item_alg (const jwk_item_t *item)
	The algorithm for this JWK.
jwk_key_type_t	jwks_item_kty (const jwk_item_t *item)
	The Key Type of this JWK.
jwk_pub_key_use_t	jwks_item_use (const jwk_item_t *item)
	The "use" field for this JWK.
jwk_key_op_t	jwks_item_key_ops (const jwk_item_t *item)
	The "key_ops" field for this JWK.
const char *	jwks_item_pem (const jwk_item_t *item)
	The PEM generated for the JWK.
int	jwks_item_key_oct (const jwk_item_t *item, const unsigned char **buf, size_t *len)
	Retrieve binary octet data of a key.
int	jwks_item_key_bits (const jwk_item_t *item)
	The number of bits in this JWK.
int	jwks_item_free (jwk_set_t *jwk_set, size_t index)
	Free remove and free the nth jwk_item_t in a jwk_set.
int	jwks_item_free_all (jwk_set_t *jwk_set)
	Remove and free all jwk_item_t in a jwk_set_t.
int	jwks_item_free_bad (jwk_set_t *jwk_set)
	Free all keys marked with an error in a jwk_set_t.
size_t	jwks_item_count (const jwk_set_t *jwk_set)
	Return the number of keys in a jwk_set_t.

Detailed Description

Functionality for using a JWK (represented as a jwk_item_t) to sign and validate JWT objects.

Typedef Documentation

jwk_item_t

typedef struct jwk_item jwk_item_t

Object representation of a JWK.

This object is produced by importing a JWK or JWKS into a jwk_set_t object. It represents single key and is used when generating or verifying JWT.

Enumeration Type Documentation

jwk_key_op_t

enum jwk_key_op_t

Allowed key operations for JWK private keys.

Corresponds to the "key_ops" attribute in a JWK that represents a private key. These can be bitwise compares to the key_ops attribute of a jwk_item_t. These flags are used internally to decide if a JWK can be used for certain operations.

if (jwk_item_t.key_ops & (JWK_KEY_OP_SIGN | JWK_KEY_OP_ENCRYPT)) {
    ...
}

RFC-7517 Sec 4.3

Enumerator
JWK_KEY_OP_NONE	No key_op set
JWK_KEY_OP_SIGN	Signing
JWK_KEY_OP_VERIFY	Signature verification
JWK_KEY_OP_ENCRYPT	Used for encryption
JWK_KEY_OP_DECRYPT	Used for decrypting
JWK_KEY_OP_WRAP	For wrapping other keys
JWK_KEY_OP_UNWRAP	For unwrappng other keys
JWK_KEY_OP_DERIVE_KEY	Key derivation
JWK_KEY_OP_DERIVE_BITS	Bits derivation
JWK_KEY_OP_INVALID	Invalid key_ops in JWK

jwk_key_type_t

enum jwk_key_type_t

JWK Key Types.

Corresponds to the "kty" attribute of the JWK.

RFC-7517 Sec 4.1 RFC-7518 Sec 6.1

Enumerator
JWK_KEY_TYPE_NONE	Unused on valid keys
JWK_KEY_TYPE_EC	Elliptic Curve keys
JWK_KEY_TYPE_RSA	RSA keys (RSA and RSA-PSS)
JWK_KEY_TYPE_OKP	Octet Key Pair (e.g. EdDSA)
JWK_KEY_TYPE_OCT	Octet sequence (e.g. HS256)

jwk_pub_key_use_t

enum jwk_pub_key_use_t

Usage types for JWK public keys.

Corresponds to the "use" attribute in a JWK the represents a public key.

RFC-7517 Sec 4.2

Enumerator
JWK_PUB_KEY_USE_NONE	No usable attribute was set
JWK_PUB_KEY_USE_SIG	Signature key (JWS)
JWK_PUB_KEY_USE_ENC	Encryption key (JWE)

Function Documentation

jwks_find_bykid()

jwk_item_t * jwks_find_bykid	(	jwk_set_t *	jwk_set,
		const char *	kid )

Find a jwk_item_t with a specific kid (Key ID)

LibJWT does not ensure that kid's are unique in a given keyring, so care must be taken. This will return the first match.

Parameters

jwk_set	An existing jwk_set_t
kid	String representing a kid to find

Returns

A jwk_item_t object or NULL if none found

jwks_item_alg()

jwt_alg_t jwks_item_alg

(

const jwk_item_t *

item

)

The algorithm for this JWK.

It is perfectly valid for this to be JWT_ALG_NONE.

Parameters

item	A JWK Item

Returns

A jwt_alg_t type of this key

jwks_item_count()

size_t jwks_item_count

(

const jwk_set_t *

jwk_set

)

Return the number of keys in a jwk_set_t.

Parameters

jwk_set

Pointer to a JWKS object

Returns

The number of items in the set

jwks_item_curve()

const char * jwks_item_curve

(

const jwk_item_t *

item

)

A curve name, if applicable, for this key.

Mainly applies to EC and OKP (EdDSA) type keys.

Parameters

item	A JWK Item

Returns

A string of the curve name if one exists. NULL otherwise.

jwks_item_error()

int jwks_item_error

(

const jwk_item_t *

item

)

Check the error condition for this JWK.

Parameters

item	A JWK Item

Returns

1 for true, 0 for false

jwks_item_error_msg()

const char * jwks_item_error_msg

(

const jwk_item_t *

item

)

Check the error message for a JWK Item.

Parameters

item	A JWK Item

Returns

A string message. Empty string if no error.

jwks_item_free()

int jwks_item_free	(	jwk_set_t *	jwk_set,
		size_t	index )

Free remove and free the nth jwk_item_t in a jwk_set.

Parameters

jwk_set	Pointer to a JWKS object
index	the position of the item in the index

Returns

0 if no item was was deleted (found), 1 if it was

jwks_item_free_all()

int jwks_item_free_all

(

jwk_set_t *

jwk_set

)

Remove and free all jwk_item_t in a jwk_set_t.

The jwk_set_t becomes an empty set.

Parameters

jwk_set

Pointer to a JWKS object

Returns

The number of items deleted

jwks_item_free_bad()

int jwks_item_free_bad

(

jwk_set_t *

jwk_set

)

Free all keys marked with an error in a jwk_set_t.

The jwk_set_t becomes an empty set.

Parameters

jwk_set

Pointer to a JWKS object

Returns

The number of items with an error that were deleted

jwks_item_get()

const jwk_item_t * jwks_item_get	(	const jwk_set_t *	jwk_set,
		size_t	index )

Return the index'th jwk_item in the jwk_set.

Allows you to obtain the raw jwk_item. NOTE, this is not a copy of the item, which means if the jwk_set is freed, then this data is freed and cannot be used.

Parameters

jwk_set	An existing jwk_set_t
index	Index of the jwk_set

Returns

A valid jwk_item_t or NULL if it doesn't exist

Warning

The index of an item in a keyring can change if items are deleted. Effort is made to add new JWK to the end of the set, so this should not affect the index of previous items.

jwks_item_is_private()

int jwks_item_is_private

(

const jwk_item_t *

item

)

Whether this key is private (or public)

Parameters

item	A JWK Item

Returns

1 for true, 0 for false

jwks_item_key_bits()

int jwks_item_key_bits

(

const jwk_item_t *

item

)

The number of bits in this JWK.

This is relevant to the key type (kty). E.g. an RSA key would have at least 2048 bits, and an EC key would be 256, 384, or 521 bits, etc.

Parameters

item	A JWK Item

Returns

The number of bits for the key

jwks_item_key_oct()

int jwks_item_key_oct	(	const jwk_item_t *	item,
		const unsigned char **	buf,
		size_t *	len )

Retrieve binary octet data of a key.

Only valid for JWT_KEY_TYPE_OCT.

Parameters

item	A JWK Item
buf	Pointer to a pointer buffer
len	Pointer to a length

Returns

0 on success. buf will point to data of len length. Non-zero on error.

jwks_item_key_ops()

jwk_key_op_t jwks_item_key_ops

(

const jwk_item_t *

item

)

The "key_ops" field for this JWK.

Parameters

item	A JWK Item

Returns

A jwk_key_op_t type for this key which represents all of the "key_ops" supported as a bit field.

jwks_item_kid()

const char * jwks_item_kid

(

const jwk_item_t *

item

)

A kid (Key ID) for this JWK.

Parameters

item	A JWK Item

Returns

A string of the kid if one exists. NULL otherwise.

jwks_item_kty()

jwk_key_type_t jwks_item_kty

(

const jwk_item_t *

item

)

The Key Type of this JWK.

Parameters

item	A JWK Item

Returns

A jwk_key_type_t type for this key

jwks_item_pem()

const char * jwks_item_pem

(

const jwk_item_t *

item

)

The PEM generated for the JWK.

This is an optional field that may or may not be supported depending on which crypto backend is in use. It is provided as a courtesy.

Parameters

item	A JWK Item

Returns

A string of the PEM file for this key or NULL if none exists

jwks_item_use()

jwk_pub_key_use_t jwks_item_use

(

const jwk_item_t *

item

)

The "use" field for this JWK.

Parameters

item	A JWK Item

Returns

A jwk_pub_key_use_t type for this key