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jwe.c
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/*!
* Copyrights
*
* Portions created or assigned to Cisco Systems, Inc. are
* Copyright (c) 2014-2016 Cisco Systems, Inc. All Rights Reserved.
*/
#include <cjose/base64.h>
#include <cjose/header.h>
#include <cjose/jwe.h>
#include <cjose/util.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#include <openssl/aes.h>
#include <openssl/hmac.h>
#include "include/concatkdf_int.h"
#include "include/header_int.h"
#include "include/jwk_int.h"
#include "include/jwe_int.h"
#include "include/util_int.h"
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_set_cek_a256gcm(cjose_jwe_t *jwe, const cjose_jwk_t *jwk, bool random, cjose_err *err);
static bool _cjose_jwe_set_cek_aes_cbc(cjose_jwe_t *jwe, const cjose_jwk_t *jwk, bool random, cjose_err *err);
static bool
_cjose_jwe_encrypt_ek_dir(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_decrypt_ek_dir(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_encrypt_ek_aes_kw(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_decrypt_ek_aes_kw(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_encrypt_ek_rsa_oaep(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_decrypt_ek_rsa_oaep(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_encrypt_ek_rsa1_5(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_decrypt_ek_rsa1_5(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_encrypt_ek_ecdh_es(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool
_cjose_jwe_decrypt_ek_ecdh_es(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err);
static bool _cjose_jwe_set_iv_a256gcm(cjose_jwe_t *jwe, cjose_err *err);
static bool _cjose_jwe_set_iv_aes_cbc(cjose_jwe_t *jwe, cjose_err *err);
static bool _cjose_jwe_encrypt_dat_a256gcm(cjose_jwe_t *jwe, const uint8_t *plaintext, size_t plaintext_len, cjose_err *err);
static bool _cjose_jwe_encrypt_dat_aes_cbc(cjose_jwe_t *jwe, const uint8_t *plaintext, size_t plaintext_len, cjose_err *err);
static bool _cjose_jwe_decrypt_dat_a256gcm(cjose_jwe_t *jwe, cjose_err *err);
static bool _cjose_jwe_decrypt_dat_aes_cbc(cjose_jwe_t *jwe, cjose_err *err);
static void _cjose_release_cek(uint8_t **cek, size_t cek_len)
{
if (NULL == *cek)
{
return;
}
memset(*cek, 0, cek_len);
cjose_get_dealloc()(*cek);
*cek = 0;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_empty_json(json_t *arg)
{
return (NULL == arg || json_is_null(arg) || (json_is_object(arg) && NULL == json_object_iter_key(arg)));
}
////////////////////////////////////////////////////////////////////////////////
static void _cjose_dealloc_part(struct _cjose_jwe_part_int *part)
{
cjose_get_dealloc()(part->raw);
cjose_get_dealloc()(part->b64u);
}
static json_t *_cjose_parse_json_object(const char *str, size_t len, cjose_err *err)
{
// unfortunately, it's not possible to tell whether the error is due
// to syntax, or memory shortage. See https://github.com/akheron/jansson/issues/352
json_error_t j_err;
json_t *json = json_loadb(str, len, 0, &j_err);
if (NULL == json || !json_is_object(json))
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
json_decref(json);
return NULL;
}
return json;
}
static inline bool _cjose_convert_part(struct _cjose_jwe_part_int *part, cjose_err *err)
{
if ((NULL == part->b64u)
&& (!cjose_base64url_encode((const uint8_t *)part->raw, part->raw_len, &part->b64u, &part->b64u_len, err)))
{
return false;
}
// dealloc the raw part, we will never need it again
cjose_get_dealloc()(part->raw);
part->raw = NULL;
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_convert_to_base64(struct _cjose_jwe_int *jwe, cjose_err *err)
{
if (!_cjose_convert_part(&jwe->enc_header, err) || !_cjose_convert_part(&jwe->enc_iv, err)
|| !_cjose_convert_part(&jwe->enc_iv, err) || !_cjose_convert_part(&jwe->enc_ct, err)
|| !_cjose_convert_part(&jwe->enc_auth_tag, err))
{
return false;
}
for (int i = 0; i < jwe->to_count; i++)
{
if (!_cjose_convert_part(&jwe->to[i].enc_key, err))
{
return false;
}
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static size_t _keylen_from_enc(const char *alg)
{
size_t keylen = 0;
if (0 == strcmp(alg, CJOSE_HDR_ENC_A256GCM)) {
keylen = 256;
} else if (0 == strcmp(alg, CJOSE_HDR_ENC_A128CBC_HS256)) {
keylen = 256;
} else if (0 == strcmp(alg, CJOSE_HDR_ENC_A192CBC_HS384)) {
keylen = 384;
} else if (0 == strcmp(alg, CJOSE_HDR_ENC_A256CBC_HS512)) {
keylen = 512;
}
return keylen;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_malloc(size_t bytes, bool random, uint8_t **buffer, cjose_err *err)
{
*buffer = (uint8_t *)cjose_get_alloc()(bytes);
if (NULL == *buffer)
{
CJOSE_ERROR(err, CJOSE_ERR_NO_MEMORY);
return false;
}
if (random)
{
if (RAND_bytes((unsigned char *)*buffer, bytes) != 1)
{
cjose_get_dealloc()(*buffer);
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
}
else
{
memset(*buffer, 0, bytes);
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_build_hdr(cjose_jwe_t *jwe, cjose_err *err)
{
// serialize the header
char *hdr_str = json_dumps(jwe->hdr, JSON_ENCODE_ANY | JSON_PRESERVE_ORDER);
if (NULL == hdr_str)
{
CJOSE_ERROR(err, CJOSE_ERR_NO_MEMORY);
return false;
}
// copy the serialized header to JWE (hdr_str is owned by header object)
size_t len = strlen(hdr_str);
uint8_t *data = (uint8_t *)_cjose_strndup(hdr_str, len, err);
if (!data)
{
cjose_get_dealloc()(hdr_str);
return false;
}
jwe->enc_header.raw = data;
jwe->enc_header.raw_len = len;
cjose_get_dealloc()(hdr_str);
return true;
}
static const char *_cjose_jwe_get_from_headers(cjose_header_t *protected_header,
cjose_header_t *unprotected_header,
cjose_header_t *personal_header,
const char *key)
{
// TODO: https://github.com/cisco/cjose/issues/52
cjose_header_t *headers[] = { personal_header, unprotected_header, protected_header };
for (int i = 0; i < 3; i++)
{
if (NULL == headers[i])
{
continue;
}
json_t *obj = json_object_get((json_t *)headers[i], key);
if (NULL == obj)
{
continue;
}
const char *value = json_string_value(obj);
if (NULL == value)
{
continue;
}
return value;
}
return NULL;
}
static bool _cjose_jwe_validate_enc(cjose_jwe_t *jwe, cjose_header_t *protected_header, cjose_err *err)
{
const char *enc = cjose_header_get(protected_header, CJOSE_HDR_ENC, err);
if (NULL == enc)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
if (strcmp(enc, CJOSE_HDR_ENC_A256GCM) == 0)
{
jwe->fns.set_cek = _cjose_jwe_set_cek_a256gcm;
jwe->fns.set_iv = _cjose_jwe_set_iv_a256gcm;
jwe->fns.encrypt_dat = _cjose_jwe_encrypt_dat_a256gcm;
jwe->fns.decrypt_dat = _cjose_jwe_decrypt_dat_a256gcm;
}
if ((strcmp(enc, CJOSE_HDR_ENC_A128CBC_HS256) == 0) || (strcmp(enc, CJOSE_HDR_ENC_A192CBC_HS384) == 0)
|| (strcmp(enc, CJOSE_HDR_ENC_A256CBC_HS512) == 0))
{
jwe->fns.set_cek = _cjose_jwe_set_cek_aes_cbc;
jwe->fns.set_iv = _cjose_jwe_set_iv_aes_cbc;
jwe->fns.encrypt_dat = _cjose_jwe_encrypt_dat_aes_cbc;
jwe->fns.decrypt_dat = _cjose_jwe_decrypt_dat_aes_cbc;
}
if (NULL == jwe->fns.set_cek || NULL == jwe->fns.set_iv || NULL == jwe->fns.encrypt_dat || NULL == jwe->fns.decrypt_dat)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_validate_alg(cjose_header_t *protected_header,
cjose_header_t *unprotected_header,
bool is_multiple,
_jwe_int_recipient_t *recipient,
cjose_err *err)
{
const char *alg = _cjose_jwe_get_from_headers(protected_header, unprotected_header, (cjose_header_t *)recipient->unprotected,
CJOSE_HDR_ALG);
if (NULL == alg)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// set JWE build functions based on header contents
if (strcmp(alg, CJOSE_HDR_ALG_RSA_OAEP) == 0)
{
recipient->fns.encrypt_ek = _cjose_jwe_encrypt_ek_rsa_oaep;
recipient->fns.decrypt_ek = _cjose_jwe_decrypt_ek_rsa_oaep;
}
if (strcmp(alg, CJOSE_HDR_ALG_RSA1_5) == 0)
{
recipient->fns.encrypt_ek = _cjose_jwe_encrypt_ek_rsa1_5;
recipient->fns.decrypt_ek = _cjose_jwe_decrypt_ek_rsa1_5;
}
if (strcmp(alg, CJOSE_HDR_ALG_ECDH_ES) == 0)
{
if (is_multiple)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
recipient->fns.encrypt_ek = _cjose_jwe_encrypt_ek_ecdh_es;
recipient->fns.decrypt_ek = _cjose_jwe_decrypt_ek_ecdh_es;
}
if (strcmp(alg, CJOSE_HDR_ALG_DIR) == 0)
{
if (is_multiple)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
recipient->fns.encrypt_ek = _cjose_jwe_encrypt_ek_dir;
recipient->fns.decrypt_ek = _cjose_jwe_decrypt_ek_dir;
}
if ((strcmp(alg, CJOSE_HDR_ALG_A128KW) == 0) || (strcmp(alg, CJOSE_HDR_ALG_A192KW) == 0)
|| (strcmp(alg, CJOSE_HDR_ALG_A256KW) == 0))
{
recipient->fns.encrypt_ek = _cjose_jwe_encrypt_ek_aes_kw;
recipient->fns.decrypt_ek = _cjose_jwe_decrypt_ek_aes_kw;
}
// ensure required builders have been assigned
if (NULL == recipient->fns.encrypt_ek || NULL == recipient->fns.decrypt_ek)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_set_cek_a256gcm(cjose_jwe_t *jwe, const cjose_jwk_t *jwk, bool random, cjose_err *err)
{
// 256 bits = 32 bytes
static const size_t keysize = 32;
if (NULL != jwe->cek)
{
return true;
}
// if no JWK is provided, generate a random key
if (NULL == jwk)
{
_cjose_release_cek(&jwe->cek, jwe->cek_len);
if (!_cjose_jwe_malloc(keysize, random, &jwe->cek, err))
{
return false;
}
jwe->cek_len = keysize;
}
else
{
// if a JWK is provided, it must be a symmetric key of correct size
if (CJOSE_JWK_KTY_OCT != cjose_jwk_get_kty(jwk, err) || jwk->keysize != keysize * 8 || NULL == jwk->keydata)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// copy the key material directly from jwk to the jwe->cek
_cjose_release_cek(&jwe->cek, jwe->cek_len);
if (!_cjose_jwe_malloc(keysize, false, &jwe->cek, err))
{
return false;
}
memcpy(jwe->cek, jwk->keydata, keysize);
jwe->cek_len = keysize;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_set_cek_aes_cbc(cjose_jwe_t *jwe, const cjose_jwk_t *jwk, bool random, cjose_err *err)
{
if (NULL != jwe->cek)
{
return true;
}
// make sure we have an enc header
json_t *enc_obj = json_object_get(jwe->hdr, CJOSE_HDR_ENC);
if (NULL == enc_obj)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
const char *enc = json_string_value(enc_obj);
// determine the CEK key size based on the encryption algorithm
size_t keysize = 0;
if (strcmp(enc, CJOSE_HDR_ENC_A128CBC_HS256) == 0)
keysize = 32;
if (strcmp(enc, CJOSE_HDR_ENC_A192CBC_HS384) == 0)
keysize = 48;
if (strcmp(enc, CJOSE_HDR_ENC_A256CBC_HS512) == 0)
keysize = 64;
if (NULL == jwk)
{
// allocate memory for the CEK and fill with random bytes or 0's
_cjose_release_cek(&jwe->cek, jwe->cek_len);
if (!_cjose_jwe_malloc(keysize, !random, &jwe->cek, err))
{
return false;
}
jwe->cek_len = keysize;
}
else
{
// if a JWK is provided, it must be a symmetric key of correct size
if (CJOSE_JWK_KTY_OCT != cjose_jwk_get_kty(jwk, err) || jwk->keysize != keysize * 8 || NULL == jwk->keydata)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// copy the key material directly from jwk to the jwe->cek
_cjose_release_cek(&jwe->cek, jwe->cek_len);
if (!_cjose_jwe_malloc(keysize, false, &jwe->cek, err))
{
return false;
}
memcpy(jwe->cek, jwk->keydata, keysize);
jwe->cek_len = keysize;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_encrypt_ek_dir(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
// for direct encryption, JWE sec 5.1, step 6: let CEK be the symmetric key.
if (!jwe->fns.set_cek(jwe, jwk, false, err))
{
return false;
}
// for direct encryption, JWE sec 5.1, step 5: let EK be empty octet seq.
recipient->enc_key.raw = NULL;
recipient->enc_key.raw_len = 0;
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_decrypt_ek_dir(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
// do not try and decrypt the ek. that's impossible.
// instead... only try to realize the truth. there is no ek.
return jwe->fns.set_cek(jwe, jwk, false, err);
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_encrypt_ek_aes_kw(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
if (NULL == jwe || NULL == jwk)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// jwk must be OCT
if (jwk->kty != CJOSE_JWK_KTY_OCT)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// generate random CEK
if (!jwe->fns.set_cek(jwe, NULL, true, err))
{
return false;
}
// create the AES encryption key from the shared key
AES_KEY akey;
if (AES_set_encrypt_key(jwk->keydata, jwk->keysize, &akey) < 0)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
// allocate buffer for encrypted CEK (=cek_len + 8)
if (!_cjose_jwe_malloc(jwe->cek_len + 8, false, &recipient->enc_key.raw, err))
{
return false;
}
// AES wrap the CEK
int len = AES_wrap_key(&akey, NULL, recipient->enc_key.raw, jwe->cek, jwe->cek_len);
if (len <= 0)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
recipient->enc_key.raw_len = len;
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_decrypt_ek_aes_kw(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
if (NULL == jwe || NULL == jwk)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// jwk must be OCT
if (jwk->kty != CJOSE_JWK_KTY_OCT)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// create the AES decryption key from the shared key
AES_KEY akey;
if (AES_set_decrypt_key(jwk->keydata, jwk->keysize, &akey) < 0)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
if (!jwe->fns.set_cek(jwe, NULL, false, err))
{
return false;
}
// AES unwrap the CEK in to jwe->cek
int len = AES_unwrap_key(&akey, (const unsigned char *)NULL, jwe->cek, (const unsigned char *)recipient->enc_key.raw,
recipient->enc_key.raw_len);
if (len <= 0)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
jwe->cek_len = len;
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_encrypt_ek_rsa_padding(
_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, int padding, cjose_err *err)
{
// jwk must be RSA
if (jwk->kty != CJOSE_JWK_KTY_RSA || NULL == jwk->keydata)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// jwk must have the necessary public parts set
BIGNUM *rsa_n = NULL, *rsa_e = NULL, *rsa_d = NULL;
_cjose_jwk_rsa_get((RSA *)jwk->keydata, &rsa_n, &rsa_e, &rsa_d);
if (NULL == rsa_e || NULL == rsa_n)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// generate random cek
if (!jwe->fns.set_cek(jwe, NULL, true, err))
{
return false;
}
// the size of the ek will match the size of the RSA key
recipient->enc_key.raw_len = RSA_size((RSA *)jwk->keydata);
// for OAEP padding - the RSA size - 41 must be greater than input
if (jwe->cek_len >= recipient->enc_key.raw_len - 41)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// allocate memory for RSA encryption
cjose_get_dealloc()(recipient->enc_key.raw);
if (!_cjose_jwe_malloc(recipient->enc_key.raw_len, false, &recipient->enc_key.raw, err))
{
return false;
}
// encrypt the CEK using RSA v1.5 or OAEP padding
if (RSA_public_encrypt(jwe->cek_len, jwe->cek, recipient->enc_key.raw, (RSA *)jwk->keydata, padding)
!= recipient->enc_key.raw_len)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_decrypt_ek_rsa_padding(
_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, int padding, cjose_err *err)
{
if (NULL == jwe || NULL == jwk)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// jwk must be RSA
if (jwk->kty != CJOSE_JWK_KTY_RSA)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// we don't know the size of the key to expect, but must be < RSA_size
_cjose_release_cek(&jwe->cek, jwe->cek_len);
size_t buflen = RSA_size((RSA *)jwk->keydata);
if (!_cjose_jwe_malloc(buflen, false, &jwe->cek, err))
{
return false;
}
// decrypt the CEK using RSA v1.5 or OAEP padding
jwe->cek_len = RSA_private_decrypt(recipient->enc_key.raw_len, recipient->enc_key.raw, jwe->cek, (RSA *)jwk->keydata, padding);
if (-1 == jwe->cek_len)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_encrypt_ek_rsa_oaep(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
return _cjose_jwe_encrypt_ek_rsa_padding(recipient, jwe, jwk, RSA_PKCS1_OAEP_PADDING, err);
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_decrypt_ek_rsa_oaep(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
return _cjose_jwe_decrypt_ek_rsa_padding(recipient, jwe, jwk, RSA_PKCS1_OAEP_PADDING, err);
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_encrypt_ek_rsa1_5(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
return _cjose_jwe_encrypt_ek_rsa_padding(recipient, jwe, jwk, RSA_PKCS1_PADDING, err);
}
////////////////////////////////////////////////////////////////////////////////
static bool
_cjose_jwe_decrypt_ek_rsa1_5(_jwe_int_recipient_t *recipient, cjose_jwe_t *jwe, const cjose_jwk_t *jwk, cjose_err *err)
{
return _cjose_jwe_decrypt_ek_rsa_padding(recipient, jwe, jwk, RSA_PKCS1_PADDING, err);
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_encrypt_ek_ecdh_es(_jwe_int_recipient_t *recipient,
cjose_jwe_t *jwe,
const cjose_jwk_t *jwk,
cjose_err *err)
{
cjose_jwk_t *epk_jwk = NULL;
char *epk_json = NULL;
uint8_t *secret = NULL;
size_t secret_len = 0;
uint8_t *otherinfo = NULL;
size_t otherinfo_len = 0;
uint8_t *derived = NULL;
bool result = false;
// generate and export random EPK
epk_jwk = cjose_jwk_create_EC_random(cjose_jwk_EC_get_curve(jwk, err), err);
if (NULL == epk_jwk)
{
// error details already set
goto cjose_encrypt_ek_ecdh_es_finish;
}
epk_json = cjose_jwk_to_json(epk_jwk, false, err);
if (NULL == epk_json)
{
goto cjose_encrypt_ek_ecdh_es_finish;
}
if (!cjose_header_set_raw(jwe->hdr, CJOSE_HDR_EPK, epk_json, err))
{
goto cjose_encrypt_ek_ecdh_es_finish;
}
// perform ECDH (private=epk_jwk, public=jwk)
if (!cjose_jwk_derive_ecdh_bits(epk_jwk, jwk, &secret, &secret_len, err))
{
goto cjose_encrypt_ek_ecdh_es_finish;
}
// perform label, ConcatKDF
// - assemble otherInfo from:
// * alg (== {enc})
// * apu (default = "")
// * apv (default = "")
// * keylen (determined from {enc})
cjose_header_t *hdr = jwe->hdr;
const char *algId = cjose_header_get(hdr, CJOSE_HDR_ENC, err);
const size_t keylen = _keylen_from_enc(algId) / 8;
if (!cjose_concatkdf_create_otherinfo(algId, keylen * 8, hdr, &otherinfo, &otherinfo_len, err))
{
goto cjose_encrypt_ek_ecdh_es_finish;
}
derived = cjose_concatkdf_derive(keylen, secret, secret_len, otherinfo, otherinfo_len, err);
if (NULL == derived)
{
goto cjose_encrypt_ek_ecdh_es_finish;
}
jwe->cek = derived;
jwe->cek_len = keylen;
recipient->enc_key.raw = NULL;
recipient->enc_key.raw_len = 0;
result = true;
cjose_encrypt_ek_ecdh_es_finish:
cjose_jwk_release(epk_jwk);
cjose_get_dealloc()(epk_json);
cjose_get_dealloc()(secret);
cjose_get_dealloc()(otherinfo);
return result;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_decrypt_ek_ecdh_es(_jwe_int_recipient_t *recipient,
cjose_jwe_t *jwe,
const cjose_jwk_t *jwk,
cjose_err *err)
{
cjose_jwk_t *epk_jwk = NULL;
uint8_t *secret = NULL;
size_t secret_len = 0;
uint8_t *otherinfo = NULL;
size_t otherinfo_len = 0;
uint8_t *derived = NULL;
bool result = false;
memset(err, 0, sizeof(cjose_err));
char *epk_json = cjose_header_get_raw(jwe->hdr, CJOSE_HDR_EPK, err);
if (NULL != epk_json)
{
epk_jwk = cjose_jwk_import(epk_json, strlen(epk_json), err);
}
else if (CJOSE_ERR_NONE == err->code)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
goto cjose_decrypt_ek_ecdh_es_finish;
}
if (NULL == epk_jwk)
{
// error details already set
goto cjose_decrypt_ek_ecdh_es_finish;
}
// perform ECDH (private=jwk, public=epk_jwk)
if (!cjose_jwk_derive_ecdh_bits(jwk, epk_jwk, &secret, &secret_len, err))
{
goto cjose_decrypt_ek_ecdh_es_finish;
}
// perform label, ConcatKDF
// - assemble otherInfo from:
// * alg (== {enc})
// * apu (default = "")
// * apv (default = "")
// * keylen (determined from {enc})
cjose_header_t *hdr = jwe->hdr;
const char *algId = cjose_header_get(hdr, CJOSE_HDR_ENC, err);
const size_t keylen = _keylen_from_enc(algId) / 8;
if (!cjose_concatkdf_create_otherinfo(algId, keylen * 8, hdr, &otherinfo, &otherinfo_len, err))
{
goto cjose_decrypt_ek_ecdh_es_finish;
}
derived = cjose_concatkdf_derive(keylen, secret, secret_len, otherinfo, otherinfo_len, err);
if (NULL == derived)
{
goto cjose_decrypt_ek_ecdh_es_finish;
}
jwe->cek = derived;
jwe->cek_len = keylen;
recipient->enc_key.raw = NULL;
recipient->enc_key.raw_len = 0;
result = true;
cjose_decrypt_ek_ecdh_es_finish:
cjose_jwk_release(epk_jwk);
cjose_get_dealloc()(epk_json);
cjose_get_dealloc()(secret);
cjose_get_dealloc()(otherinfo);
return result;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_set_iv_a256gcm(cjose_jwe_t *jwe, cjose_err *err)
{
// generate IV as random 96 bit value
cjose_get_dealloc()(jwe->enc_iv.raw);
jwe->enc_iv.raw_len = 12;
if (!_cjose_jwe_malloc(jwe->enc_iv.raw_len, true, &jwe->enc_iv.raw, err))
{
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_set_iv_aes_cbc(cjose_jwe_t *jwe, cjose_err *err)
{
// make sure we have an enc header
json_t *enc_obj = json_object_get(jwe->hdr, CJOSE_HDR_ENC);
if (NULL == enc_obj)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
const char *enc = json_string_value(enc_obj);
cjose_get_dealloc()(jwe->enc_iv.raw);
jwe->enc_iv.raw_len = 0;
if (strcmp(enc, CJOSE_HDR_ENC_A128CBC_HS256) == 0)
jwe->enc_iv.raw_len = 16;
if (strcmp(enc, CJOSE_HDR_ENC_A192CBC_HS384) == 0)
jwe->enc_iv.raw_len = 24;
if (strcmp(enc, CJOSE_HDR_ENC_A256CBC_HS512) == 0)
jwe->enc_iv.raw_len = 32;
if (jwe->enc_iv.raw_len == 0)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
return false;
}
// generate IV as random iv_size * 8 bit value
if (!_cjose_jwe_malloc(jwe->enc_iv.raw_len, true, &jwe->enc_iv.raw, err))
{
return false;
}
return true;
}
#if defined(CJOSE_OPENSSL_11X)
#define CJOSE_EVP_CTRL_GCM_GET_TAG EVP_CTRL_AEAD_GET_TAG
#define CJOSE_EVP_CTRL_GCM_SET_TAG EVP_CTRL_AEAD_SET_TAG
#else
#define CJOSE_EVP_CTRL_GCM_GET_TAG EVP_CTRL_GCM_GET_TAG
#define CJOSE_EVP_CTRL_GCM_SET_TAG EVP_CTRL_GCM_SET_TAG
#endif
////////////////////////////////////////////////////////////////////////////////
static bool _cjose_jwe_encrypt_dat_a256gcm(cjose_jwe_t *jwe, const uint8_t *plaintext, size_t plaintext_len, cjose_err *err)
{
EVP_CIPHER_CTX *ctx = NULL;
if (NULL == plaintext)
{
CJOSE_ERROR(err, CJOSE_ERR_INVALID_ARG);
goto _cjose_jwe_encrypt_dat_fail;
}
// get A256GCM cipher
const EVP_CIPHER *cipher = EVP_aes_256_gcm();
if (NULL == cipher)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
// instantiate and initialize a new openssl cipher context
ctx = EVP_CIPHER_CTX_new();
if (NULL == ctx)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
EVP_CIPHER_CTX_init(ctx);
// initialize context for encryption using A256GCM cipher and CEK and IV
if (EVP_EncryptInit_ex(ctx, cipher, NULL, jwe->cek, jwe->enc_iv.raw) != 1)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
// we need the header in base64url encoding as input for encryption
if ((NULL == jwe->enc_header.b64u) && (!cjose_base64url_encode((const uint8_t *)jwe->enc_header.raw, jwe->enc_header.raw_len,
&jwe->enc_header.b64u, &jwe->enc_header.b64u_len, err)))
{
goto _cjose_jwe_encrypt_dat_fail;
}
// set GCM mode AAD data (hdr_b64u) by setting "out" to NULL
int bytes_encrypted = 0;
if (EVP_EncryptUpdate(ctx, NULL, &bytes_encrypted, (unsigned char *)jwe->enc_header.b64u, jwe->enc_header.b64u_len) != 1
|| bytes_encrypted != jwe->enc_header.b64u_len)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
// allocate buffer for the ciphertext
cjose_get_dealloc()(jwe->enc_ct.raw);
jwe->enc_ct.raw_len = plaintext_len;
if (!_cjose_jwe_malloc(jwe->enc_ct.raw_len, false, &jwe->enc_ct.raw, err))
{
goto _cjose_jwe_encrypt_dat_fail;
}
// encrypt entire plaintext to ciphertext buffer
if (EVP_EncryptUpdate(ctx, jwe->enc_ct.raw, &bytes_encrypted, plaintext, plaintext_len) != 1)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
jwe->enc_ct.raw_len = bytes_encrypted;
// finalize the encryption and set the ciphertext length to correct value
if (EVP_EncryptFinal_ex(ctx, NULL, &bytes_encrypted) != 1)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
// allocate buffer for the authentication tag
cjose_get_dealloc()(jwe->enc_auth_tag.raw);
jwe->enc_auth_tag.raw_len = 16;
if (!_cjose_jwe_malloc(jwe->enc_auth_tag.raw_len, false, &jwe->enc_auth_tag.raw, err))
{
goto _cjose_jwe_encrypt_dat_fail;
}
// get the GCM-mode authentication tag
if (EVP_CIPHER_CTX_ctrl(ctx, CJOSE_EVP_CTRL_GCM_GET_TAG, jwe->enc_auth_tag.raw_len, jwe->enc_auth_tag.raw) != 1)
{
CJOSE_ERROR(err, CJOSE_ERR_CRYPTO);
goto _cjose_jwe_encrypt_dat_fail;
}
EVP_CIPHER_CTX_free(ctx);
return true;