/*
* Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* DH low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/params.h>
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/securitycheck.h"
#include "crypto/dh.h"
static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
static OSSL_FUNC_keyexch_init_fn dh_init;
static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
static OSSL_FUNC_keyexch_derive_fn dh_derive;
static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
/*
* This type is only really used to handle some legacy related functionality.
* If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
* here and then create and run a KDF after the key is derived.
* Note that X942 has 2 variants of key derivation:
* (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
* the counter embedded in it.
* (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
* done by creating a "X963KDF".
*/
enum kdf_type {
PROV_DH_KDF_NONE = 0,
PROV_DH_KDF_X9_42_ASN1
};
/*
* What's passed as an actual key is defined by the KEYMGMT interface.
* We happen to know that our KEYMGMT simply passes DH structures, so
* we use that here too.
*/
typedef struct {
OSSL_LIB_CTX *libctx;
DH *dh;
DH *dhpeer;
unsigned int pad : 1;
/* DH KDF */
/* KDF (if any) to use for DH */
enum kdf_type kdf_type;
/* Message digest to use for key derivation */
EVP_MD *kdf_md;
/* User key material */
unsigned char *kdf_ukm;
size_t kdf_ukmlen;
/* KDF output length */
size_t kdf_outlen;
char *kdf_cekalg;
} PROV_DH_CTX;
static void *dh_newctx(void *provctx)
{
PROV_DH_CTX *pdhctx;
if (!ossl_prov_is_running())
return NULL;
pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
if (pdhctx == NULL)
return NULL;
pdhctx->libctx = PROV_LIBCTX_OF(provctx);
pdhctx->kdf_type = PROV_DH_KDF_NONE;
return pdhctx;
}
static int dh_init(void *vpdhctx, void *vdh)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
if (!ossl_prov_is_running()
|| pdhctx == NULL
|| vdh == NULL
|| !DH_up_ref(vdh))
return 0;
DH_free(pdhctx->dh);
pdhctx->dh = vdh;
pdhctx->kdf_type = PROV_DH_KDF_NONE;
return dh_check_key(vdh);
}
static int dh_set_peer(void *vpdhctx, void *vdh)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
if (!ossl_prov_is_running()
|| pdhctx == NULL
|| vdh == NULL
|| !DH_up_ref(vdh))
return 0;
DH_free(pdhctx->dhpeer);
pdhctx->dhpeer = vdh;
return 1;
}
static int dh_plain_derive(void *vpdhctx,
unsigned char *secret, size_t *secretlen,
size_t outlen)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
int ret;
size_t dhsize;
const BIGNUM *pub_key = NULL;
/* TODO(3.0): Add errors to stack */
if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL)
return 0;
dhsize = (size_t)DH_size(pdhctx->dh);
if (secret == NULL) {
*secretlen = dhsize;
return 1;
}
if (outlen < dhsize)
return 0;
DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
if (pdhctx->pad)
ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
else
ret = DH_compute_key(secret, pub_key, pdhctx->dh);
if (ret <= 0)
return 0;
*secretlen = ret;
return 1;
}
static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
size_t *secretlen, size_t outlen)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
unsigned char *stmp = NULL;
size_t stmplen;
int ret = 0;
if (secret == NULL) {
*secretlen = pdhctx->kdf_outlen;
return 1;
}
if (pdhctx->kdf_outlen > outlen)
return 0;
if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0))
return 0;
if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen))
goto err;
/* Do KDF stuff */
if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
if (!dh_KDF_X9_42_asn1(secret, pdhctx->kdf_outlen,
stmp, stmplen,
pdhctx->kdf_cekalg,
pdhctx->kdf_ukm,
pdhctx->kdf_ukmlen,
pdhctx->kdf_md,
pdhctx->libctx, NULL))
goto err;
}
*secretlen = pdhctx->kdf_outlen;
ret = 1;
err:
OPENSSL_secure_clear_free(stmp, stmplen);
return ret;
}
static int dh_derive(void *vpdhctx, unsigned char *secret,
size_t *psecretlen, size_t outlen)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
if (!ossl_prov_is_running())
return 0;
switch (pdhctx->kdf_type) {
case PROV_DH_KDF_NONE:
return dh_plain_derive(pdhctx, secret, psecretlen, outlen);
case PROV_DH_KDF_X9_42_ASN1:
return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
default:
break;
}
return 0;
}
static void dh_freectx(void *vpdhctx)
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
OPENSSL_free(pdhctx->kdf_cekalg);
DH_free(pdhctx->dh);
DH_free(pdhctx->dhpeer);
EVP_MD_free(pdhctx->kdf_md);
OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
OPENSSL_free(pdhctx);
}
static void *dh_dupctx(void *vpdhctx)
{
PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
PROV_DH_CTX *dstctx;
if (!ossl_prov_is_running())
return NULL;
dstctx = OPENSSL_zalloc(sizeof(*srcctx));
if (dstctx == NULL)
return NULL;
*dstctx = *srcctx;
dstctx->dh = NULL;
dstctx->dhpeer = NULL;
dstctx->kdf_md = NULL;
dstctx->kdf_ukm = NULL;
dstctx->kdf_cekalg = NULL;
if (dstctx->dh != NULL && !DH_up_ref(srcctx->dh))
goto err;
else
dstctx->dh = srcctx->dh;
if (dstctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
goto err;
else
dstctx->dhpeer = srcctx->dhpeer;
if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
goto err;
else
dstctx->kdf_md = srcctx->kdf_md;
/* Duplicate UKM data if present */
if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
srcctx->kdf_ukmlen);
if (dstctx->kdf_ukm == NULL)
goto err;
}
dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
return dstctx;
err:
dh_freectx(dstctx);
return NULL;
}
static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
const OSSL_PARAM *p;
unsigned int pad;
char name[80] = { '\0' }; /* should be big enough */
char *str = NULL;
if (pdhctx == NULL || params == NULL)
return 0;
p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
if (p != NULL) {
str = name;
if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
return 0;
if (name[0] == '\0')
pdhctx->kdf_type = PROV_DH_KDF_NONE;
else if (strcmp(name, OSSL_KDF_NAME_X942KDF) == 0)
pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
else
return 0;
}
p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
if (p != NULL) {
char mdprops[80] = { '\0' }; /* should be big enough */
str = name;
if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
return 0;
str = mdprops;
p = OSSL_PARAM_locate_const(params,
OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
if (p != NULL) {
if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
return 0;
}
EVP_MD_free(pdhctx->kdf_md);
pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
if (!digest_is_allowed(pdhctx->kdf_md)) {
EVP_MD_free(pdhctx->kdf_md);
pdhctx->kdf_md = NULL;
}
if (pdhctx->kdf_md == NULL)
return 0;
}
p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
if (p != NULL) {
size_t outlen;
if (!OSSL_PARAM_get_size_t(p, &outlen))
return 0;
pdhctx->kdf_outlen = outlen;
}
p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
if (p != NULL) {
void *tmp_ukm = NULL;
size_t tmp_ukmlen;
OPENSSL_free(pdhctx->kdf_ukm);
pdhctx->kdf_ukm = NULL;
pdhctx->kdf_ukmlen = 0;
/* ukm is an optional field so it can be NULL */
if (p->data != NULL && p->data_size != 0) {
if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
return 0;
pdhctx->kdf_ukm = tmp_ukm;
pdhctx->kdf_ukmlen = tmp_ukmlen;
}
}
p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
if (p != NULL) {
if (!OSSL_PARAM_get_uint(p, &pad))
return 0;
pdhctx->pad = pad ? 1 : 0;
}
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
if (p != NULL) {
str = name;
if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
return 0;
pdhctx->kdf_cekalg = OPENSSL_strdup(name);
}
return 1;
}
static const OSSL_PARAM known_settable_ctx_params[] = {
OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
OSSL_PARAM_END
};
static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *provctx)
{
return known_settable_ctx_params;
}
static const OSSL_PARAM known_gettable_ctx_params[] = {
OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
NULL, 0),
OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_UKM_LEN, NULL),
OSSL_PARAM_END
};
static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *provctx)
{
return known_gettable_ctx_params;
}
static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
{
PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
OSSL_PARAM *p;
if (pdhctx == NULL || params == NULL)
return 0;
p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
if (p != NULL) {
const char *kdf_type = NULL;
switch (pdhctx->kdf_type) {
case PROV_DH_KDF_NONE:
kdf_type = "";
break;
case PROV_DH_KDF_X9_42_ASN1:
kdf_type = OSSL_KDF_NAME_X942KDF;
break;
default:
return 0;
}
if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
return 0;
}
p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
if (p != NULL
&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
? ""
: EVP_MD_name(pdhctx->kdf_md))){
return 0;
}
p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
return 0;
p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
if (p != NULL && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, 0))
return 0;
p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM_LEN);
if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_ukmlen))
return 0;
p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
if (p != NULL
&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
? "" : pdhctx->kdf_cekalg))
return 0;
return 1;
}
const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
{ OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
{ OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
{ OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
{ OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
{ OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
{ OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
{ OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
{ OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
(void (*)(void))dh_settable_ctx_params },
{ OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
{ OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
(void (*)(void))dh_gettable_ctx_params },
{ 0, NULL }
};
