static EVP_MD_CTX *
setup(jose_cfg_t *cfg, const json_t *jwk, const json_t *sig, const char *alg,
init_t *func)
{
openssl_auto(EVP_PKEY) *key = NULL;
EVP_PKEY_CTX *epc = NULL;
const EVP_MD *md = NULL;
EVP_MD_CTX *emc = NULL;
const RSA *rsa = NULL;
int slen = 0;
int pad = 0;
switch (str2enum(alg, NAMES, NULL)) {
case 0: md = EVP_sha256(); pad = RSA_PKCS1_PADDING; break;
case 1: md = EVP_sha384(); pad = RSA_PKCS1_PADDING; break;
case 2: md = EVP_sha512(); pad = RSA_PKCS1_PADDING; break;
case 3: md = EVP_sha256(); pad = RSA_PKCS1_PSS_PADDING; slen = -1; break;
case 4: md = EVP_sha384(); pad = RSA_PKCS1_PSS_PADDING; slen = -1; break;
case 5: md = EVP_sha512(); pad = RSA_PKCS1_PSS_PADDING; slen = -1; break;
default: return NULL;
}
key = jose_openssl_jwk_to_EVP_PKEY(cfg, jwk);
if (!key || EVP_PKEY_base_id(key) != EVP_PKEY_RSA)
return NULL;
/* Don't use small keys. RFC 7518 3.3 */
rsa = EVP_PKEY_get0_RSA(key);
if (!rsa)
return NULL;
if (RSA_size(rsa) < 2048 / 8)
return NULL;
emc = EVP_MD_CTX_new();
if (!emc)
return NULL;
if (func(emc, &epc, md, NULL, key) <= 0)
goto error;
if (EVP_PKEY_CTX_set_rsa_padding(epc, pad) <= 0)
goto error;
if (slen != 0) {
if (EVP_PKEY_CTX_set_rsa_pss_saltlen(epc, slen) <= 0)
goto error;
}
return emc;
error:
EVP_MD_CTX_free(emc);
return NULL;
}
static bool
alg_wrap_wrp(const jose_hook_alg_t *alg, jose_cfg_t *cfg, json_t *jwe,
json_t *rcp, const json_t *jwk, json_t *cek)
{
openssl_auto(EVP_PKEY_CTX) *epc = NULL;
openssl_auto(EVP_PKEY) *key = NULL;
const EVP_MD *md = NULL;
const RSA *rsa = NULL;
uint8_t *pt = NULL;
uint8_t *ct = NULL;
bool ret = false;
size_t ptl = 0;
size_t ctl = 0;
int tmp = 0;
int pad = 0;
if (!json_object_get(cek, "k") && !jose_jwk_gen(cfg, cek))
return false;
switch (str2enum(alg->name, NAMES, NULL)) {
case 0: pad = RSA_PKCS1_PADDING; tmp = 11; md = EVP_sha1(); break;
case 1: pad = RSA_PKCS1_OAEP_PADDING; tmp = 41; md = EVP_sha1(); break;
case 2: pad = RSA_PKCS1_OAEP_PADDING; tmp = 41; md = EVP_sha256(); break;
default: return false;
}
key = jose_openssl_jwk_to_EVP_PKEY(cfg, jwk);
if (!key || EVP_PKEY_base_id(key) != EVP_PKEY_RSA)
return false;
ptl = jose_b64_dec(json_object_get(cek, "k"), NULL, 0);
if (ptl == SIZE_MAX)
return false;
rsa = EVP_PKEY_get0_RSA(key);
if (!rsa)
return false;
if ((int) ptl >= RSA_size(rsa) - tmp)
return false;
epc = EVP_PKEY_CTX_new(key, NULL);
if (!epc)
return false;
if (EVP_PKEY_encrypt_init(epc) <= 0)
return false;
if (EVP_PKEY_CTX_set_rsa_padding(epc, pad) <= 0)
return false;
if (pad == RSA_PKCS1_OAEP_PADDING) {
if (EVP_PKEY_CTX_set_rsa_oaep_md(epc, md) <= 0)
return false;
if (EVP_PKEY_CTX_set_rsa_mgf1_md(epc, md) <= 0)
return false;
}
pt = malloc(ptl);
if (!pt)
return false;
if (jose_b64_dec(json_object_get(cek, "k"), pt, ptl) != ptl)
goto egress;
if (EVP_PKEY_encrypt(epc, NULL, &ctl, pt, ptl) <= 0)
goto egress;
ct = malloc(ctl);
if (!ct)
goto egress;
if (EVP_PKEY_encrypt(epc, ct, &ctl, pt, ptl) <= 0)
goto egress;
if (json_object_set_new(rcp, "encrypted_key", jose_b64_enc(ct, ctl)) < 0)
goto egress;
ret = add_entity(jwe, rcp, "recipients", "header", "encrypted_key", NULL);
egress:
if (pt) {
OPENSSL_cleanse(pt, ptl);
free(pt);
}
free(ct);
return ret;
}
static bool
alg_wrap_unw(const jose_hook_alg_t *alg, jose_cfg_t *cfg, const json_t *jwe,
const json_t *rcp, const json_t *jwk, json_t *cek)
{
openssl_auto(EVP_PKEY_CTX) *epc = NULL;
openssl_auto(EVP_PKEY) *key = NULL;
const uint8_t *tt = NULL;
const EVP_MD *md = NULL;
uint8_t *ct = NULL;
uint8_t *pt = NULL;
uint8_t *rt = NULL;
bool ret = false;
size_t ctl = 0;
size_t ptl = 0;
size_t rtl = 0;
size_t ttl = 0;
int pad = 0;
switch (str2enum(alg->name, NAMES, NULL)) {
case 0: pad = RSA_PKCS1_PADDING; md = EVP_sha1(); break;
case 1: pad = RSA_PKCS1_OAEP_PADDING; md = EVP_sha1(); break;
case 2: pad = RSA_PKCS1_OAEP_PADDING; md = EVP_sha256(); break;
default: return false;
}
key = jose_openssl_jwk_to_EVP_PKEY(cfg, jwk);
if (!key || EVP_PKEY_base_id(key) != EVP_PKEY_RSA)
goto egress;
ctl = jose_b64_dec(json_object_get(rcp, "encrypted_key"), NULL, 0);
if (ctl == SIZE_MAX)
goto egress;
ct = malloc(ctl);
if (!ct)
goto egress;
if (jose_b64_dec(json_object_get(rcp, "encrypted_key"), ct, ctl) != ctl)
goto egress;
ptl = ctl;
pt = malloc(ptl);
if (!pt)
goto egress;
epc = EVP_PKEY_CTX_new(key, NULL);
if (!epc)
goto egress;
if (EVP_PKEY_decrypt_init(epc) <= 0)
goto egress;
if (EVP_PKEY_CTX_set_rsa_padding(epc, pad) <= 0)
goto egress;
if (pad == RSA_PKCS1_OAEP_PADDING) {
if (EVP_PKEY_CTX_set_rsa_oaep_md(epc, md) <= 0)
return false;
if (EVP_PKEY_CTX_set_rsa_mgf1_md(epc, md) <= 0)
goto egress;
}
/* Handle MMA Attack as prescribed by RFC 3218, always generate a
* random buffer of appropriate length so that the same operations
* are performed whether decrypt succeeds or not, in an attempt to
* foil timing attacks */
rtl = ptl;
rt = malloc(rtl);
if (!rt)
goto egress;
if (RAND_bytes(rt, rtl) <= 0)
goto egress;
ret |= EVP_PKEY_decrypt(epc, pt, &ptl, ct, ctl) > 0;
ttl = ret ? ptl : rtl;
tt = ret ? pt : rt;
ret |= pad == RSA_PKCS1_PADDING;
if (json_object_set_new(cek, "k", jose_b64_enc(tt, ttl)) < 0)
ret = false;
egress:
if (pt) {
OPENSSL_cleanse(pt, ptl);
free(pt);
}
if (rt) {
OPENSSL_cleanse(rt, rtl);
free(rt);
}
free(ct);
return ret;
}
