# Rhonabwy API documentation

Rhonabwy library is made to manage JWK, JWKS, JWS, JWE and JWT according to their respective RFCs:

- [JSON Web Keys](https://tools.ietf.org/html/rfc7517) (JWK) and JSON Web Keys Set (JWKS)
- [JSON Web Signatures](https://tools.ietf.org/html/rfc7515) (JWS)
- [JSON Web Encryption](https://tools.ietf.org/html/rfc7516) (JWE) **limited!**
- [JSON Web Token](https://tools.ietf.org/html/rfc7519) (JWT)

Rhonabwy is based on the following libraries and actively uses them:

- GnuTLS for the cryptographic functions
- Jansson for the JSON manipulation
- Yder for the logs
- Ulfius when it requires to retrieve keys from an URL

When relevant, a function can accept or return GnuTLS or Jansson data. But if you're not using those in your application and prefer raw data, you can use the more agnostic functions.

## Return values

Lots of functions in Rhonabwy library return an int value. The returned value can be one of the following:

```C
#define RHN_OK                 0
#define RHN_ERROR              1
#define RHN_ERROR_MEMORY       2
#define RHN_ERROR_PARAM        3
#define RHN_ERROR_UNSUPPORTED  4
#define RHN_ERROR_INVALID      5
```

If a function is successful, it will return `RHN_OK` (0), otherwise an error code is returned.

## Global init and close

It's **recommended** to use `r_global_init` and `r_global_close` at the beginning and at the end of your program to initialize and cleanup internal values and settings. This will make outgoing requests faster, especially if you use lots of them, and dispatch your memory allocation functions in curl and Jansson if you changed them. These functions are **NOT** thread-safe, so you must use them in a single thread context.

```C
int r_global_init();

void r_global_close();
```

## Log messages

Usually, a log message is displayed to explain more specifically what happened on error. The log manager used is [Yder](https://github.com/babelouest/yder). You can enable Yder log messages on the console with the following command at the beginning of your program:

```C

int main() {
  y_init_logs("Rhonabwy", Y_LOG_MODE_CONSOLE, Y_LOG_LEVEL_DEBUG, NULL, "Starting Rhonabwy client program");
  
  // Do your code here
  
  y_close_logs();
}
```

Example of an error log message:

```
2020-04-05T16:14:31 - Rhonabwy: r_jwk_is_valid - Invalid alg
```

Go to Yder [API Documentation](https://babelouest.github.io/yder/) for more details.

## Memory management

All typedefs managed by Rhonabwy use dedicated init and free functions. You must always use those functions to allocate or free resources manipulated by the library.

```C
int r_jwk_init(jwk_t ** jwk);

void r_jwk_free(jwk_t * jwk);

int r_jwks_init(jwks_t ** jwks);

void r_jwks_free(jwks_t * jwks);

int r_jws_init(jws_t ** jws);

void r_jws_free(jws_t * jws);

int r_jwe_init(jwe_t ** jwe);

void r_jwe_free(jwe_t * jwe);

int r_jwt_init(jwt_t ** jwt);

void r_jwt_free(jwt_t * jwt);
```

In addition, when a function return a `char *` value, this value must be freed using the function `r_free(void *)`.

And finally, all `json_t *` returned values must be de allocated using `json_decref(json_t *)`, see [Jansson Documentation](https://jansson.readthedocs.io/) for more details.

```C
void r_free(void * data);
```

## Library information

The functions `r_library_info_json_t()` and `r_library_info_json_str()` return a JSON object that represents the signature and encryption algorithms supported, as well as the library version.

Example output:

```JSON
{
  "version":"0.9.13",
  "jws":{
    "alg":[
    "none",
    "HS256",
    "HS384",
    "HS512",
    "RS256",
    "RS384",
    "RS512",
    "ES256",
    "ES384",
    "ES512",
    "EdDSA",
    "PS256",
    "PS384",
    "PS512"]
  },
  "jwe":{
    "alg":[
      "RSA1_5",
      "A128KW",
      "A256KW",
      "dir"],
    "enc":[
      "A128CBC-HS256",
      "A192CBC-HS384",
      "A256CBC-HS512",
      "A128GCM",
      "A192GCM",
      "A256GCM"]
  }
}
```

## JWK

A JWK (JSON Web Key) is a format used to store and represent a cryptographic key in a JSON object.

Example of JWK:

```JSON
{
  "kty":"EC",
  "crv":"P-256",
  "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
  "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",
  "kid":"Public key used in JWS spec Appendix A.3 example"
}
```

The standard allows to store public and private keys for RSA and ECC algorithms, it also allows to store symmetric keys. In a JWK, every raw value is encoded in Base64Url format to fit in the JSON object without any issue.

A JWK is represented in Rhonabwy library using the type `jwk_t *`.

### Import and Export JWK

Rhonabwy allows to import and export a JWK in the following formats:
- A JSON structure in a `const char *`
- A JSON structure in a `json_t *`
- A key or certificate in `PEM` or `DER` format
- A `GnuTLS` structure of the following: `gnutls_privkey_t`, `gnutls_pubkey_t` or `gnutls_x509_crt_t` (import only)

If the imported JWK contains a `x5u` property, the key or certificate will be downloaded at the given address. If so, you can give an additional parameter `x5u_flag` which values can be:
- `R_FLAG_IGNORE_SERVER_CERTIFICATE`: ignore if web server certificate is invalid
- `R_FLAG_FOLLOW_REDIRECT`: follow redirection if necessary
- `R_FLAG_IGNORE_REMOTE`: do not download remote key, but the function may return an error

The values `R_FLAG_IGNORE_SERVER_CERTIFICATE` and `R_FLAG_FOLLOW_REDIRECT` can be merged: `R_FLAG_IGNORE_SERVER_CERTIFICATE|R_FLAG_FOLLOW_REDIRECT`

### Manipulate JWK properties

You can manipulate the JWK properties directly using the dedicated functions:

```C
const char * r_jwk_get_property_str(jwk_t * jwk, const char * key);

const char * r_jwk_get_property_array(jwk_t * jwk, const char * key, size_t index);

int r_jwk_set_property_str(jwk_t * jwk, const char * key, const char * value);

int r_jwk_set_property_array(jwk_t * jwk, const char * key, size_t index, const char * value);

int r_jwk_append_property_array(jwk_t * jwk, const char * key, const char * value);

int r_jwk_delete_property_str(jwk_t * jwk, const char * key);

int r_jwk_delete_property_array_at(jwk_t * jwk, const char * key, size_t index);
```

### Validate the format of a JWK

The function `r_jwk_is_valid` will check the validity of a JWK, i.e. check if all the required properties are present and in the correct format. Note that this function is called each time an import is made.

### Generate a random key pair

You can use Rhonabwy to generate a random key pair for RSA or ECC algorithms. The `jwk_t *` parameters must be initialized first.

The `type` parameter can have one of the following values: `R_KEY_TYPE_RSA` or `R_KEY_TYPE_ECDSA`. The `bits` parameter specifies the length of the key. A RSA key must be at least 2048 bits, and the bits value allowed for an ECC key are 256, 384 or 512.

If the parameter `kid` is used, the generated key kid property will have the kid specified, otherwise a `kid` will be generated to identify the key pair.

```C
int r_jwk_generate_key_pair(jwk_t * jwk_privkey, jwk_t * jwk_pubkey, int type, unsigned int bits, const char * kid);
```

## JWKS

A JWKS (JSON Web Key Set) is a format used to store and represent a set cryptographic key in a JSON object. A JWKS is always a JSON object containing the property `"keys"` that will point to an array of JWK.

Example of JWKS:

```JSON
{
  "keys":
  [
    {
      "kty":"EC",
      "crv":"P-256",
      "x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4",
      "y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM",
      "use":"enc",
      "kid":"1"
    },
    {
      "kty":"RSA",
      "n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
      "e":"AQAB",
      "alg":"RS256",
      "kid":"2011-04-29"
    }
  ]
}
```

In Rhonabwy library, you can manipulate the JWKS inside a JWKS by iteration or get a JWK by its kid.

```C
jwk_t * r_jwks_get_at(jwks_t * jwks, size_t index);

jwk_t * r_jwks_get_by_kid(jwks_t * jwks, const char * kid);
```

You can also import a JWKS using a JSON object or an URL.

```C
int r_jwks_import_from_str(jwks_t * jwks, const char * input);

int r_jwks_import_from_json_t(jwks_t * jwks, json_t * j_input);

int r_jwks_import_from_uri(jwks_t * jwks, const char * uri, int flags);
```

## JWS

A JWS (JSON Web Signature) is a content digitally signed and serialized in a compact format that can be easily transferred in HTTP requests.

A JWS has 3 elements serialized in base64url format and separated by a dot (.). The 3 elements are:

- A header in JSON format
- A Payload
- A digital signature

Its representation uses the following format:

BASE64URL(UTF8(JWS Protected Header)) || '.' ||
BASE64URL(JWS Payload) || '.' ||
BASE64URL(JWS Signature)

The signature is based on the following data:

BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)

The algorithms supported by Rhonabwy are the following:
- HMAC with SHA-2 Functions: `HS256`, `HS384`, `HS512`
- Digital Signature with RSASSA-PKCS1-v1_5: `RS256`, `RS384`, `RS512`
- Digital Signature with ECDSA: `ES256`, `ES384`, `ES512`
- Digital Signature with RSASSA-PSS: `PS256`, `PS384`, `PS512`
- Digital Signature with Ed25519 Elliptic Curve: `EDdSA`
- Unsecured: `none`

### JWS example

In this example, the payload used is the following message:

```
The true sign of intelligence is not knowledge but imagination.
```

The JWS will be signed using HMAC with SHA256 algorithm, in this example, the signing process will use a key identified by the kid "1", therefore the header is the following:

```JSON
{"alg":"HS256","kid":"1"}
```

The key used to sign the data is the following:

```JSON
{
  "kty":"oct",
  "alg":"HS256",
  "k":"c2VjcmV0",
  "kid":"1"
}
```

Finally, the complete representation of the JWS is the following:

```
eyJhbGciOiJIUzI1NiIsImtpZCI6IjEifQ.VGhlIHRydWUgc2lnbiBvZiBpbnRlbGxpZ2VuY2UgaXMgbm90IGtub3dsZWRnZSBidXQgaW1hZ2luYXRpb24u.GKxWqRBFr-6X4HfflzGeGvKVsJ8v1-J39Ho2RslC-5o
```

### Serialize a JWS using Rhonabwy

The JWS above can be created with the following sample code:

```C
#include <rhonabwy.h>

jws_t * jws = NULL;
jwk_t * jwk_key_symmetric = NULL;
char * token = NULL;
const unsigned char payload[] = "The true sign of intelligence is not knowledge but imagination.";
const char jwk_key_symmetric_str[] = "{\"kty\":\"oct\",\"alg\":\"HS256\",\"k\":\"c2VjcmV0\",\"kid\":\"1\"}";

if (r_jwk_init(&jwk_key_symmetric) == RHN_OK && 
    r_jws_init(&jws) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key_symmetric, jwk_key_symmetric_str) == RHN_OK && 
    r_jws_set_alg(jws, R_JWA_ALG_HS256) == RHN_OK &&
    r_jws_set_payload(jws, payload, sizeof(payload)) == RHN_OK) {
  token = r_jws_serialize(jws, jwk_key_symmetric, 0); // token will store the signed token
}

r_free(token);
r_jws_free(jws);
r_jwk_free(jwk_key_symmetric);
```

### Parse and validate signature of a JWS using Rhonabwy

The JWS above can be parsed and verified using the following sample code:

```C
#include <rhonabwy.h>

jws_t * jws = NULL;
jwk_t * jwk_key_symmetric = NULL;
const char token[] = "eyJhbGciOiJIUzI1NiIsImtpZCI6IjEifQ."
"VGhlIHRydWUgc2lnbiBvZiBpbnRlbGxpZ2VuY2UgaXMgbm90IGtub3dsZWRnZSBidXQgaW1hZ2luYXRpb24u."
"GKxWqRBFr-6X4HfflzGeGvKVsJ8v1-J39Ho2RslC-5o";
const char jwk_key_symmetric_str[] = "{\"kty\":\"oct\",\"alg\":\"HS256\",\"k\":\"c2VjcmV0\",\"kid\":\"1\"}";
const char * payload = NULL;
size_t payload_len = 0;

if (r_jwk_init(&jwk_key_symmetric) == RHN_OK && 
    r_jws_init(&jws) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key_symmetric, jwk_key_symmetric_str) == RHN_OK && 
    r_jws_parse(jws, token, 0) == RHN_OK &&
    r_jws_verify_signature(jws, jwk_key_symmetric, 0) == RHN_OK && 
    (payload = r_jws_get_payload(jws, &payload_len)) != NULL && payload_len > 0) {
    // payload and payload_len will contain the payload data
}

r_jws_free(jws);
r_jwk_free(jwk_key_symmetric);
```

## JWE

A JWE (JSON Web Encryption) is an encrypted content serialized in a compact format that can be easily transferred in HTTP requests.

Basically the payload is encrypted using AES-CBC or AES-GCM and an Initialization Vector (IV), a authentication tag is generated to validate the decryption, and the AES key used to encrypt the payload is encrypted itself using a symmetric or asymmetric encryption algorithm.

The serialized token has the following format:

BASE64URL(UTF8(JWE Protected Header)) || '.' ||
BASE64URL(JWE Encrypted Key) || '.' ||
BASE64URL(JWE Initialization Vector) || '.' ||
BASE64URL(JWE Ciphertext) || '.' ||
BASE64URL(JWE Authentication Tag)

In Rhonabwy library, the supported algorithms are the following:
- Supported Encryption Algorithm (`enc`) for JWE payload encryption: `A128CBC-HS256`, `A192CBC-HS384`, `A256CBC-HS512`, `A128GCM`, `A256GCM`
- Supported Cryptographic Algorithms for Key Management: `RSA1_5` (RSAES-PKCS1-v1_5), `dir` (Direct use of a shared symmetric key), `A128GCMKW` and `A256GCMKW`

If you don't specify a Content Encryption Key or an Initialization Vector before the serialization, Rhonabwy will automatically generate one or the other or both depending on the algorithm specified.

### JWE example

In this example, the payload used is the following message:

```
The true sign of intelligence is not knowledge but imagination.
```

The RSA private key associated to this token is:

```JSON
{
  "kty":"RSA",
  "n":"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
  "e":"AQAB",
  "d":"X4cTteJY_gn4FYPsXB8rdXix5vwsg1FLN5E3EaG6RJoVH-HLLKD9M7dx5oo7GURknchnrRweUkC7hT5fJLM0WbFAKNLWY2vv7B6NqXSzUvxT0_YSfqijwp3RTzlBaCxWp4doFk5N2o8Gy_nHNKroADIkJ46pRUohsXywbReAdYaMwFs9tv8d_cPVY3i07a3t8MN6TNwm0dSawm9v47UiCl3Sk5ZiG7xojPLu4sbg1U2jx4IBTNBznbJSzFHK66jT8bgkuqsk0GjskDJk19Z4qwjwbsnn4j2WBii3RL-Us2lGVkY8fkFzme1z0HbIkfz0Y6mqnOYtqc0X4jfcKoAC8Q",
  "p":"83i-7IvMGXoMXCskv73TKr8637FiO7Z27zv8oj6pbWUQyLPQBQxtPVnwD20R-60eTDmD2ujnMt5PoqMrm8RfmNhVWDtjjMmCMjOpSXicFHj7XOuVIYQyqVWlWEh6dN36GVZYk93N8Bc9vY41xy8B9RzzOGVQzXvNEvn7O0nVbfs","q":"3dfOR9cuYq-0S-mkFLzgItgMEfFzB2q3hWehMuG0oCuqnb3vobLyumqjVZQO1dIrdwgTnCdpYzBcOfW5r370AFXjiWft_NGEiovonizhKpo9VVS78TzFgxkIdrecRezsZ-1kYd_s1qDbxtkDEgfAITAG9LUnADun4vIcb6yelxk",
  "dp":"G4sPXkc6Ya9y8oJW9_ILj4xuppu0lzi_H7VTkS8xj5SdX3coE0oimYwxIi2emTAue0UOa5dpgFGyBJ4c8tQ2VF402XRugKDTP8akYhFo5tAA77Qe_NmtuYZc3C3m3I24G2GvR5sSDxUyAN2zq8Lfn9EUms6rY3Ob8YeiKkTiBj0","dq":"s9lAH9fggBsoFR8Oac2R_E2gw282rT2kGOAhvIllETE1efrA6huUUvMfBcMpn8lqeW6vzznYY5SSQF7pMdC_agI3nG8Ibp1BUb0JUiraRNqUfLhcQb_d9GF4Dh7e74WbRsobRonujTYN1xCaP6TO61jvWrX-L18txXw494Q_cgk",
  "qi":"GyM_p6JrXySiz1toFgKbWV-JdI3jQ4ypu9rbMWx3rQJBfmt0FoYzgUIZEVFEcOqwemRN81zoDAaa-Bk0KWNGDjJHZDdDmFhW3AN7lI-puxk_mHZGJ11rxyR8O55XLSe3SPmRfKwZI6yU24ZxvQKFYItdldUKGzO6Ia6zTKhAVRU",
  "kid":"2011-04-29"
}

```

The encryption algorithm used is `A128CBC-HS256` and the cryptographic algorithm to encrypt the key is `RSA1_5`

Finally, the complete representation of the JWE is the following:

```
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.0ouvmluqT8kvBCgjMw8mhBFFEI5Rua58WnnATU21RqEQ2f9M6FqGEkgYpJ81ePtTkOyW1l8V-4nxIDxy-xeTHd0v5bDEbxhWKRdOmUHACC018Gt1ZB9EHHJt7k4UYj3up2xVa8qykKbZ3WGF0Gffi6ctfLCfRCWNnXMbAylV02mf4Tfhpad_WC4EeZENNryilXbAKD_9NNje-CoXD0IQK4-z2fkzfyUislwzK7dyz--uNNAC3N6XO3Blr_z61wXWGEHBa62fyHCsQqagAzN_MqTZv6cxOpRpeWM4_SwjjvcyC77rRyVpN0lC9ukyX_pNrGLXW8zH4mH78OcKPoDLPw.o5e-xb5ZzvZA2JYD2qgFbA.YNTPRS7Hv0fqE7ReEUAS_KNM31wMPPldhBGmYuQTzUWVcX8pGqooTbwaV4o_7BBiF4apD_VCGWwQ-fDD0eDofg.uyAjCu7WSo8BeBDFmYfkLA
```

### Serialize a JWE using Rhonabwy

The JWE above can be created with the following sample code:

```C
#include <rhonabwy.h>

jwe_t * jwe = NULL;
jwk_t * jwk_key_rsa = NULL;
char * token = NULL;
const unsigned char payload[] = "The true sign of intelligence is not knowledge but imagination.";
const char jwk_pubkey_rsa_str[] = "{\"kty\":\"RSA\",\"n\":\"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRX"\
                                   "jBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6"\
                                   "qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw\""\
                                   ",\"e\":\"AQAB\",\"alg\":\"RS256\",\"kid\":\"2011-04-29\"}",

if (r_jwk_init(&jwk_key_rsa) == RHN_OK && 
    r_jwe_init(&jwe) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key_rsa, jwk_pubkey_rsa_str) == RHN_OK && 
    r_jwe_set_alg(jwe, R_JWA_ALG_RSA1_5) == RHN_OK &&
    r_jwe_set_enc(jwe, R_JWA_ENC_A128CBC) == RHN_OK &&
    r_jwe_set_payload(jwe, payload, sizeof(payload)) == RHN_OK) {
  token = r_jwe_serialize(jwe, jwk_key_rsa, 0); // token will store the encrypted token
}

r_free(token);
r_jwe_free(jwe);
r_jwk_free(jwk_key_rsa);
```

#### Compressed payload

The header value `"zip":"DEF"` is used to specify if the JWE payload is compressed using [ZIP/Deflate](https://tools.ietf.org/html/rfc7516#section-4.1.3) algorithm. Rhonabwy will automatically compress or decompress the decrypted payload during encryption or decryption process.

### Parse and decrypt a JWE using Rhonabwy

The JWE above can be parsed and verified using the following sample code:

```C
#include <rhonabwy.h>

jwe_t * jwe = NULL;
jwk_t * jwk_key_rsa = NULL;
const char jwk_pubkey_rsa_str[] = "{\"kty\":\"RSA\",\"n\":\"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKR"\
                                    "XjBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHz"\
                                    "u6qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKg"\
                                    "w\",\"e\":\"AQAB\",\"d\":\"X4cTteJY_gn4FYPsXB8rdXix5vwsg1FLN5E3EaG6RJoVH-HLLKD9M7dx5oo7GURknchnrRweUkC7hT5fJLM0WbFAKNLWY2v"\
                                    "v7B6NqXSzUvxT0_YSfqijwp3RTzlBaCxWp4doFk5N2o8Gy_nHNKroADIkJ46pRUohsXywbReAdYaMwFs9tv8d_cPVY3i07a3t8MN6TNwm0dSawm9v47UiCl3Sk"\
                                    "5ZiG7xojPLu4sbg1U2jx4IBTNBznbJSzFHK66jT8bgkuqsk0GjskDJk19Z4qwjwbsnn4j2WBii3RL-Us2lGVkY8fkFzme1z0HbIkfz0Y6mqnOYtqc0X4jfcKoA"\
                                    "C8Q\",\"p\":\"83i-7IvMGXoMXCskv73TKr8637FiO7Z27zv8oj6pbWUQyLPQBQxtPVnwD20R-60eTDmD2ujnMt5PoqMrm8RfmNhVWDtjjMmCMjOpSXicFHj7"\
                                    "XOuVIYQyqVWlWEh6dN36GVZYk93N8Bc9vY41xy8B9RzzOGVQzXvNEvn7O0nVbfs\",\"q\":\"3dfOR9cuYq-0S-mkFLzgItgMEfFzB2q3hWehMuG0oCuqnb3v"\
                                    "obLyumqjVZQO1dIrdwgTnCdpYzBcOfW5r370AFXjiWft_NGEiovonizhKpo9VVS78TzFgxkIdrecRezsZ-1kYd_s1qDbxtkDEgfAITAG9LUnADun4vIcb6yelx"\
                                    "k\",\"dp\":\"G4sPXkc6Ya9y8oJW9_ILj4xuppu0lzi_H7VTkS8xj5SdX3coE0oimYwxIi2emTAue0UOa5dpgFGyBJ4c8tQ2VF402XRugKDTP8akYhFo5tAA7"\
                                    "7Qe_NmtuYZc3C3m3I24G2GvR5sSDxUyAN2zq8Lfn9EUms6rY3Ob8YeiKkTiBj0\",\"dq\":\"s9lAH9fggBsoFR8Oac2R_E2gw282rT2kGOAhvIllETE1efrA"\
                                    "6huUUvMfBcMpn8lqeW6vzznYY5SSQF7pMdC_agI3nG8Ibp1BUb0JUiraRNqUfLhcQb_d9GF4Dh7e74WbRsobRonujTYN1xCaP6TO61jvWrX-L18txXw494Q_cg"\
                                    "k\",\"qi\":\"GyM_p6JrXySiz1toFgKbWV-JdI3jQ4ypu9rbMWx3rQJBfmt0FoYzgUIZEVFEcOqwemRN81zoDAaa-Bk0KWNGDjJHZDdDmFhW3AN7lI-puxk_m"\
                                    "HZGJ11rxyR8O55XLSe3SPmRfKwZI6yU24ZxvQKFYItdldUKGzO6Ia6zTKhAVRU\",\"alg\":\"RS256\",\"kid\":\"2011-04-29\"}",
token[] = "eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.0ouvmluqT8kvBCgjMw8mhBFFEI5Rua58WnnATU21RqEQ2f9M6FqGEkgYpJ81ePtTkOyW1l8V-4nxIDxy-xeTHd0v5bDEbxhWKRdOmUHACC018Gt1ZB9EHHJt7k4UYj3up2xVa8qykKbZ3WGF0Gffi6ctfLCfRCWNnXMbAylV02mf4Tfhpad_WC4EeZENNryilXbAKD_9NNje-CoXD0IQK4-z2fkzfyUislwzK7dyz--uNNAC3N6XO3Blr_z61wXWGEHBa62fyHCsQqagAzN_MqTZv6cxOpRpeWM4_SwjjvcyC77rRyVpN0lC9ukyX_pNrGLXW8zH4mH78OcKPoDLPw.o5e-xb5ZzvZA2JYD2qgFbA.YNTPRS7Hv0fqE7ReEUAS_KNM31wMPPldhBGmYuQTzUWVcX8pGqooTbwaV4o_7BBiF4apD_VCGWwQ-fDD0eDofg.uyAjCu7WSo8BeBDFmYfkLA";
const char * payload = NULL;
size_t payload_len = 0;

if (r_jwk_init(&jwk_key_rsa) == RHN_OK && 
    r_jwe_init(&jwe) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key_rsa, jwk_pubkey_rsa_str) == RHN_OK && 
    r_jwe_parse(jwe, token, 0) == RHN_OK &&
    r_jwe_decrypt(jwe, jwk_key_rsa, 0) == RHN_OK && 
    (payload = r_jwe_get_payload(jwe, &payload_len)) != NULL && payload_len > 0) {
  // payload and payload_len will contain the payload data
}

r_jwe_free(jwe);
r_jwk_free(jwk_key_rsa);
```

## JWT

Finally, a JWT (JSON Web Token) is a JSON content signed and/or encrypted and serialized in a compact format that can be easily transferred in HTTP requests. Technically, a JWT is a JWS or a JWE which payload is a stringified JSON and has the property `"type":"JWT"` in the header.

A JWT can be nested, which means signed and encrypted, in which case the payload is signed as a JWS first, then the serialized signed token is used as the payload in a JWE, or the opposite.

### Verify a list of claims in the JWT

The function int `int r_jwt_validate_claims(jwt_t * jwt, ...)` will help you verify the validity of some claims in the JWT.

Claim types available
- `R_JWT_CLAIM_ISS`: claim `"iss"`, values expected a string or `NULL` to validate the presence of the claim
- `R_JWT_CLAIM_SUB`: claim `"sub"`, values expected a string or `NULL` to validate the presence of the claim
- `R_JWT_CLAIM_AUD`: claim `"aud"`, values expected a string or `NULL` to validate the presence of the claim
- `R_JWT_CLAIM_EXP`: claim `"exp"`, value expected `R_JWT_CLAIM_NOW` or an positive integer value or `R_JWT_CLAIM_PRESENT` to validate the presence of the claim
- `R_JWT_CLAIM_NBF`: claim `"nbf"`, value expected `R_JWT_CLAIM_NOW` or an positive integer value or `R_JWT_CLAIM_PRESENT` to validate the presence of the claim
- `R_JWT_CLAIM_IAT`: claim `"iat"`, value expected `R_JWT_CLAIM_NOW` or an positive integer value or `R_JWT_CLAIM_PRESENT` to validate the presence of the claim
- `R_JWT_CLAIM_JTI`: claim `"jti"`, values expected a string or `NULL` to validate the presence of the claim
- `R_JWT_CLAIM_STR`: the claim name specified must have the string value expected or `NULL` to validate the presence of the claim
- `R_JWT_CLAIM_INT`: the claim name specified must have the integer value expected
- `R_JWT_CLAIM_JSN`: the claim name specified must have the json_t * value expected or `NULL` to validate the presence of the claim

For example, the following code will check the jwt against the claim `iss` has the value `"https://example.com"`, the claim `sub` has the value `"client_1"`, the presence of the claim `aud`, the claim `exp` is after now, the claim `nbf` is before now, the claim `scope` has the value `"scope1"`, the claim `age` has the value `42` and the claim `verified` has the JSON value `true`:

```C
if (r_jwt_validate_claims(jwt, R_JWT_CLAIM_ISS, "https://example.com", 
                               R_JWT_CLAIM_SUB, "client_1", 
                               R_JWT_CLAIM_AUD, NULL, 
                               R_JWT_CLAIM_EXP, R_JWT_CLAIM_NOW, 
                               R_JWT_CLAIM_NBF, R_JWT_CLAIM_NOW, 
                               R_JWT_CLAIM_STR, "scope", "scope1",
                               R_JWT_CLAIM_INT, "age", 42,
                               R_JWT_CLAIM_JSN, "verified", json_true(),
                               R_JWT_CLAIM_NOP) == RHN_OK)
```

### Serialize a JWT using Rhonabwy

Let's use the following JSON object in a JWT:

```JSON
{
  "iss":"joe",
  "exp":1300819380,
  "http://example.com/is_root":true
}
```

The JWT can be signed using the algorithm `HS256` and the following key:

```JSON
{
  "kty":"oct",
  "k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
}
```

The signed JWT serialized will be the following:

```
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
```

#### Signed JWT

The signed JWT above can be created with the following sample code:

```C
#include <rhonabwy.h>

jwt_t * jwt = NULL;
jwk_t * jwk_key = NULL;
const char payload[] = "{\"iss\":\"joe\",\"exp\":1300819380,\"http://example.com/is_root\":true}",
           jwk_key_str[] = "{\"kty\":\"oct\",\"k\":\"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow\"}";
char * token = NULL;

if (r_jwk_init(&jwk_key) == RHN_OK && 
    r_jwt_init(&jwt) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key, jwk_key_str) == RHN_OK && 
    r_jwt_set_sign_alg(jwt, R_JWA_ALG_HS256) == RHN_OK &&
    r_jwt_set_full_claims_json_str(jwt, payload) == RHN_OK) {
  token = r_jwt_serialize_signed(jwt, jwk_key, 0); // token will store the signed token
}

r_free(token);
r_jwt_free(jwt);
r_jwk_free(jwk_key);
```

The same payload can be encrypted and serialized in an encrypted JWT using `RSA1_5` as key encryption algorithm and `A128CBC-HS256` as content encryption algorithm.

The encrypted JWT of the payload above can be the following:

```
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.QR1Owv2ug2WyPBnbQrRARTeEk9kDO2w8qDcjiHnSJflSdv1iNqhWXaKH4MqAkQtMoNfABIPJaZm0HaA415sv3aeuBWnD8J-Ui7Ah6cWafs3ZwwFKDFUUsWHSK-IPKxLGTkND09XyjORj_CHAgOPJ-Sd8ONQRnJvWn_hXV1BNMHzUjPyYwEsRhDhzjAD26imasOTsgruobpYGoQcXUwFDn7moXPRfDE8-NoQX7N7ZYMmpUDkR-Cx9obNGwJQ3nM52YCitxoQVPzjbl7WBuB7AohdBoZOdZ24WlN1lVIeh8v1K4krB8xgKvRU8kgFrEn_a1rZgN5TiysnmzTROF869lQ.AxY8DCtDaGlsbGljb3RoZQ.MKOle7UQrG6nSxTLX6Mqwt0orbHvAKeWnDYvpIAeZ72deHxz3roJDXQyhxx0wKaMHDjUEOKIwrtkHthpqEanSBNYHZgmNOV7sln1Eu9g3J8.fiK51VwhsxJ-siBMR-YFiA
```

#### Encrypted JWT

An encrypted JWT can be created with Rhonabwy using the following sample code:

```C
#include <rhonabwy.h>

jwt_t * jwt = NULL;
jwk_t * jwk_key = NULL;
const char payload[] = "{\"iss\":\"joe\",\"exp\":1300819380,\"http://example.com/is_root\":true}",
jwk_pubkey_rsa_str[] = "{\"kty\":\"RSA\",\"n\":\"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRX"\
                      "jBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6"\
                      "qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw\""\
                      ",\"e\":\"AQAB\",\"alg\":\"RS256\",\"kid\":\"2011-04-29\"}";
char * token = NULL;

if (r_jwk_init(&jwk_key) == RHN_OK && 
    r_jwt_init(&jwt) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key, jwk_pubkey_rsa_str) == RHN_OK && 
    r_jwt_set_enc_alg(jwt, R_JWA_ALG_RSA1_5) == RHN_OK &&
    r_jwt_set_enc(jwt, R_JWA_ENC_A128CBC) == RHN_OK &&
    r_jwt_set_full_claims_json_str(jwt, payload) == RHN_OK) {
  token = r_jwt_serialize_encrypted(jwt, jwk_key, 0); // token will store the encrypted token
}

r_free(token);
r_jwt_free(jwt);
r_jwk_free(jwk_key);
```

#### Nested JWT

A nested JWT can be created with Rhonabwy using the following sample code:

```C
#include <rhonabwy.h>

jwt_t * jwt = NULL;
jwk_t * jwk_key = NULL, * jwk_key_sign = NULL;
const char payload[] = "{\"iss\":\"joe\",\"exp\":1300819380,\"http://example.com/is_root\":true}",
jwk_pubkey_rsa_str[] = "{\"kty\":\"RSA\",\"n\":\"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRX"\
                      "jBZCiFV4n3oknjhMstn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6"\
                      "qMQvRL5hajrn1n91CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw\""\
                      ",\"e\":\"AQAB\",\"alg\":\"RS256\",\"kid\":\"2011-04-29\"}",
jwk_key_str[] = "{\"kty\":\"oct\",\"k\":\"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow\"}";
char * token = NULL;

if (r_jwk_init(&jwk_key) == RHN_OK && 
    r_jwk_init(&jwk_key_sign) == RHN_OK &&
    r_jwt_init(&jwt) == RHN_OK &&
    r_jwk_import_from_json_str(jwk_key, jwk_pubkey_rsa_str) == RHN_OK && 
    r_jwk_import_from_json_str(jwk_key_sign, jwk_key_str) == RHN_OK && 
    r_jwt_set_enc_alg(jwt, R_JWA_ALG_RSA1_5) == RHN_OK &&
    r_jwt_set_enc(jwt, R_JWA_ENC_A128CBC) == RHN_OK &&
    r_jwt_set_sign_alg(jwt, R_JWA_ALG_HS256) == RHN_OK &&
    r_jwt_set_sign_alg(jwt, R_JWA_ALG_HS256) == RHN_OK &&
    r_jwt_set_full_claims_json_str(jwt, payload) == RHN_OK) {
  token = r_jwt_serialize_nested(jwt, R_JWT_TYPE_NESTED_SIGN_THEN_ENCRYPT, jwk_key_sign, 0, jwk_key, 0); // token will store the nested token
}

r_free(token);
r_jwt_free(jwt);
r_jwk_free(jwk_key);
```