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/*
This file is part of GNUnet
Copyright (C) 2010-2015 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file reclaim/jwt.c
* @brief helper library for JSON-Web-Tokens
* @author Martin Schanzenbach
*/
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_signatures.h"
#include "gnunet_reclaim_attribute_lib.h"
#include <jansson.h>
#define JWT_ALG "alg"
/* Use 512bit HMAC */
#define JWT_ALG_VALUE "HS512"
#define JWT_TYP "typ"
#define JWT_TYP_VALUE "jwt"
#define SERVER_ADDRESS "https://reclaim.id/api/openid/userinfo"
static char*
create_jwt_header(void)
{
json_t *root;
char *json_str;
root = json_object ();
json_object_set_new (root, JWT_ALG, json_string (JWT_ALG_VALUE));
json_object_set_new (root, JWT_TYP, json_string (JWT_TYP_VALUE));
json_str = json_dumps (root, JSON_INDENT(0) | JSON_COMPACT);
json_decref (root);
return json_str;
}
static void
replace_char(char* str, char find, char replace){
char *current_pos = strchr(str,find);
while (current_pos){
*current_pos = replace;
current_pos = strchr(current_pos,find);
}
}
//RFC4648
static void
fix_base64(char* str) {
char *padding;
//First, remove trailing padding '='
padding = strtok(str, "=");
while (NULL != padding)
padding = strtok(NULL, "=");
//Replace + with -
replace_char (str, '+', '-');
//Replace / with _
replace_char (str, '/', '_');
}
/**
* Create a JWT from attributes
*
* @param aud_key the public of the audience
* @param sub_key the public key of the subject
* @param attrs the attribute list
* @param expiration_time the validity of the token
* @param secret_key the key used to sign the JWT
* @return a new base64-encoded JWT string.
*/
char*
jwt_create_from_list (const struct GNUNET_CRYPTO_EcdsaPublicKey *aud_key,
const struct GNUNET_CRYPTO_EcdsaPublicKey *sub_key,
const struct GNUNET_RECLAIM_ATTRIBUTE_ClaimList *attrs,
const struct GNUNET_TIME_Relative *expiration_time,
const char *nonce,
const char *secret_key)
{
struct GNUNET_RECLAIM_ATTRIBUTE_ClaimListEntry *le;
struct GNUNET_HashCode signature;
struct GNUNET_TIME_Absolute exp_time;
struct GNUNET_TIME_Absolute time_now;
char* audience;
char* subject;
char* header;
char* body_str;
char* result;
char* header_base64;
char* body_base64;
char* signature_target;
char* signature_base64;
char* attr_val_str;
json_t* body;
//iat REQUIRED time now
time_now = GNUNET_TIME_absolute_get();
//exp REQUIRED time expired from config
exp_time = GNUNET_TIME_absolute_add (time_now, *expiration_time);
//auth_time only if max_age
//nonce only if nonce
// OPTIONAL acr,amr,azp
subject = GNUNET_STRINGS_data_to_string_alloc (&sub_key,
sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey));
audience = GNUNET_STRINGS_data_to_string_alloc (aud_key,
sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey));
header = create_jwt_header ();
body = json_object ();
//iss REQUIRED case sensitive server uri with https
//The issuer is the local reclaim instance (e.g. https://reclaim.id/api/openid)
json_object_set_new (body,
"iss", json_string (SERVER_ADDRESS));
//sub REQUIRED public key identity, not exceed 255 ASCII length
json_object_set_new (body,
"sub", json_string (subject));
//aud REQUIRED public key client_id must be there
json_object_set_new (body,
"aud", json_string (audience));
//iat
json_object_set_new (body,
"iat", json_integer (time_now.abs_value_us));
//exp
json_object_set_new (body,
"exp", json_integer (exp_time.abs_value_us));
//nbf
json_object_set_new (body,
"nbf", json_integer (time_now.abs_value_us));
//nonce
if (NULL != nonce)
json_object_set_new (body,
"nonce", json_string (nonce));
for (le = attrs->list_head; NULL != le; le = le->next)
{
attr_val_str = GNUNET_RECLAIM_ATTRIBUTE_value_to_string (le->claim->type,
le->claim->data,
le->claim->data_size);
json_object_set_new (body,
le->claim->name,
json_string (attr_val_str));
GNUNET_free (attr_val_str);
}
body_str = json_dumps (body, JSON_INDENT(0) | JSON_COMPACT);
json_decref (body);
GNUNET_STRINGS_base64_encode (header,
strlen (header),
&header_base64);
fix_base64(header_base64);
GNUNET_STRINGS_base64_encode (body_str,
strlen (body_str),
&body_base64);
fix_base64(body_base64);
GNUNET_free (subject);
GNUNET_free (audience);
/**
* Creating the JWT signature. This might not be
* standards compliant, check.
*/
GNUNET_asprintf (&signature_target, "%s.%s", header_base64, body_base64);
GNUNET_CRYPTO_hmac_raw (secret_key, strlen (secret_key), signature_target, strlen (signature_target), &signature);
GNUNET_STRINGS_base64_encode ((const char*)&signature,
sizeof (struct GNUNET_HashCode),
&signature_base64);
fix_base64(signature_base64);
GNUNET_asprintf (&result, "%s.%s.%s",
header_base64, body_base64, signature_base64);
GNUNET_free (signature_target);
GNUNET_free (header);
GNUNET_free (body_str);
GNUNET_free (signature_base64);
GNUNET_free (body_base64);
GNUNET_free (header_base64);
return result;
}
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