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openssl/crypto/kdf/x942kdf.c
Shane Lontis 1aec7716c1 Add X9.42 KDF. 
Move the KDF code for CMS DH key agreement into an EVP_KDF object.
There are 2 specifications for X9.42 KDF. This implementation uses DER for
otherinfo which embeds the KDF loop counter inside the DER object.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8898)
2019-07-09 09:33:18 +10:00

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/*
* Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2019, Oracle and/or its affiliates. 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
*/
#include "e_os.h"
#ifndef OPENSSL_NO_CMS
# include <stdlib.h>
# include <stdarg.h>
# include <string.h>
# include <openssl/hmac.h>
# include <openssl/cms.h>
# include <openssl/evp.h>
# include <openssl/kdf.h>
# include <openssl/x509.h>
# include <openssl/obj_mac.h>
# include "internal/cryptlib.h"
# include "internal/evp_int.h"
# include "kdf_local.h"
# define X942KDF_MAX_INLEN (1 << 30)
struct evp_kdf_impl_st {
const EVP_MD *md;
unsigned char *secret;
size_t secret_len;
int cek_nid;
unsigned char *ukm;
size_t ukm_len;
size_t dkm_len;
};
/* A table of allowed wrapping algorithms and the associated output lengths */
static const struct {
int nid;
size_t keklen; /* size in bytes */
} kek_algs[] = {
{ NID_id_smime_alg_CMS3DESwrap, 24 },
{ NID_id_smime_alg_CMSRC2wrap, 16 },
{ NID_id_aes128_wrap, 16 },
{ NID_id_aes192_wrap, 24 },
{ NID_id_aes256_wrap, 32 },
{ NID_id_camellia128_wrap, 16 },
{ NID_id_camellia192_wrap, 24 },
{ NID_id_camellia256_wrap, 32 }
};
/* Skip past an ASN1 structure: for OBJECT skip content octets too */
static int skip_asn1(unsigned char **pp, long *plen, int exptag)
{
int i, tag, xclass;
long tmplen;
const unsigned char *q = *pp;
i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen);
if ((i & 0x80) != 0 || tag != exptag || xclass != V_ASN1_UNIVERSAL)
return 0;
if (tag == V_ASN1_OBJECT)
q += tmplen;
*pp = (unsigned char *)q;
*plen -= q - *pp;
return 1;
}
/*
* Encode the other info structure.
*
* RFC2631 Section 2.1.2 Contains the following definition for otherinfo
*
* OtherInfo ::= SEQUENCE {
* keyInfo KeySpecificInfo,
* partyAInfo [0] OCTET STRING OPTIONAL,
* suppPubInfo [2] OCTET STRING
* }
*
* KeySpecificInfo ::= SEQUENCE {
* algorithm OBJECT IDENTIFIER,
* counter OCTET STRING SIZE (4..4)
* }
*
* |nid| is the algorithm object identifier.
* |keylen| is the length (in bytes) of the generated KEK. It is stored into
* suppPubInfo (in bits).
* |ukm| is the optional user keying material that is stored into partyAInfo. It
* can be NULL.
* |ukmlen| is the user keying material length (in bytes).
* |der| is the returned encoded data. It must be freed by the caller.
* |der_len| is the returned size of the encoded data.
* |out_ctr| returns a pointer to the counter data which is embedded inside the
* encoded data. This allows the counter bytes to be updated without re-encoding.
*
* Returns: 1 if successfully encoded, or 0 otherwise.
* Assumptions: |der|, |der_len| & |out_ctr| are not NULL.
*/
static int x942_encode_otherinfo(int nid, size_t keylen,
const unsigned char *ukm, size_t ukmlen,
unsigned char **der, size_t *der_len,
unsigned char **out_ctr)
{
unsigned char *p, *encoded = NULL;
int ret = 0, encoded_len;
long tlen;
/* "magic" value to check offset is sane */
static unsigned char ctr[4] = { 0x00, 0x00, 0x00, 0x01 };
X509_ALGOR *ksi = NULL;
ASN1_OBJECT *alg_oid = NULL;
ASN1_OCTET_STRING *ctr_oct = NULL, *ukm_oct = NULL;
/* set the KeySpecificInfo - which contains an algorithm oid and counter */
ksi = X509_ALGOR_new();
alg_oid = OBJ_dup(OBJ_nid2obj(nid));
ctr_oct = ASN1_OCTET_STRING_new();
if (ksi == NULL
|| alg_oid == NULL
|| ctr_oct == NULL
|| !ASN1_OCTET_STRING_set(ctr_oct, ctr, sizeof(ctr))
|| !X509_ALGOR_set0(ksi, alg_oid, V_ASN1_OCTET_STRING, ctr_oct))
goto err;
/* NULL these as they now belong to ksi */
alg_oid = NULL;
ctr_oct = NULL;
/* Set the optional partyAInfo */
if (ukm != NULL) {
ukm_oct = ASN1_OCTET_STRING_new();
if (ukm_oct == NULL)
goto err;
ASN1_OCTET_STRING_set(ukm_oct, (unsigned char *)ukm, ukmlen);
}
/* Generate the OtherInfo DER data */
encoded_len = CMS_SharedInfo_encode(&encoded, ksi, ukm_oct, keylen);
if (encoded_len <= 0)
goto err;
/* Parse the encoded data to find the offset of the counter data */
p = encoded;
tlen = (long)encoded_len;
if (skip_asn1(&p, &tlen, V_ASN1_SEQUENCE)
&& skip_asn1(&p, &tlen, V_ASN1_SEQUENCE)
&& skip_asn1(&p, &tlen, V_ASN1_OBJECT)
&& skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING)
&& CRYPTO_memcmp(p, ctr, 4) == 0) {
*out_ctr = p;
*der = encoded;
*der_len = (size_t)encoded_len;
ret = 1;
}
err:
if (ret != 1)
OPENSSL_free(encoded);
ASN1_OCTET_STRING_free(ctr_oct);
ASN1_OCTET_STRING_free(ukm_oct);
ASN1_OBJECT_free(alg_oid);
X509_ALGOR_free(ksi);
return ret;
}
static int x942kdf_hash_kdm(const EVP_MD *kdf_md,
const unsigned char *z, size_t z_len,
const unsigned char *other, size_t other_len,
unsigned char *ctr,
unsigned char *derived_key, size_t derived_key_len)
{
int ret = 0, hlen;
size_t counter, out_len, len = derived_key_len;
unsigned char mac[EVP_MAX_MD_SIZE];
unsigned char *out = derived_key;
EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
if (z_len > X942KDF_MAX_INLEN || other_len > X942KDF_MAX_INLEN
|| derived_key_len > X942KDF_MAX_INLEN
|| derived_key_len == 0) {
KDFerr(KDF_F_X942KDF_HASH_KDM, KDF_R_BAD_LENGTH);
return 0;
}
hlen = EVP_MD_size(kdf_md);
if (hlen <= 0)
return 0;
out_len = (size_t)hlen;
ctx = EVP_MD_CTX_create();
ctx_init = EVP_MD_CTX_create();
if (ctx == NULL || ctx_init == NULL)
goto end;
if (!EVP_DigestInit(ctx_init, kdf_md))
goto end;
for (counter = 1;; counter++) {
/* updating the ctr modifies 4 bytes in the 'other' buffer */
ctr[0] = (unsigned char)((counter >> 24) & 0xff);
ctr[1] = (unsigned char)((counter >> 16) & 0xff);
ctr[2] = (unsigned char)((counter >> 8) & 0xff);
ctr[3] = (unsigned char)(counter & 0xff);
if (!EVP_MD_CTX_copy_ex(ctx, ctx_init)
|| !EVP_DigestUpdate(ctx, z, z_len)
|| !EVP_DigestUpdate(ctx, other, other_len))
goto end;
if (len >= out_len) {
if (!EVP_DigestFinal_ex(ctx, out, NULL))
goto end;
out += out_len;
len -= out_len;
if (len == 0)
break;
} else {
if (!EVP_DigestFinal_ex(ctx, mac, NULL))
goto end;
memcpy(out, mac, len);
break;
}
}
ret = 1;
end:
EVP_MD_CTX_free(ctx);
EVP_MD_CTX_free(ctx_init);
OPENSSL_cleanse(mac, sizeof(mac));
return ret;
}
static EVP_KDF_IMPL *x942kdf_new(void)
{
EVP_KDF_IMPL *impl;
if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL)
KDFerr(KDF_F_X942KDF_NEW, ERR_R_MALLOC_FAILURE);
return impl;
}
static void x942kdf_reset(EVP_KDF_IMPL *impl)
{
OPENSSL_clear_free(impl->secret, impl->secret_len);
OPENSSL_clear_free(impl->ukm, impl->ukm_len);
memset(impl, 0, sizeof(*impl));
}
static void x942kdf_free(EVP_KDF_IMPL *impl)
{
x942kdf_reset(impl);
OPENSSL_free(impl);
}
static int x942kdf_set_buffer(va_list args, unsigned char **out, size_t *out_len)
{
const unsigned char *p;
size_t len;
p = va_arg(args, const unsigned char *);
len = va_arg(args, size_t);
if (len == 0 || p == NULL)
return 1;
OPENSSL_free(*out);
*out = OPENSSL_memdup(p, len);
if (*out == NULL)
return 0;
*out_len = len;
return 1;
}
static int x942kdf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
{
const EVP_MD *md;
char *alg_str = NULL;
size_t i;
switch (cmd) {
case EVP_KDF_CTRL_SET_MD:
md = va_arg(args, const EVP_MD *);
if (md == NULL)
return 0;
impl->md = md;
return 1;
case EVP_KDF_CTRL_SET_KEY:
return x942kdf_set_buffer(args, &impl->secret, &impl->secret_len);
case EVP_KDF_CTRL_SET_UKM:
return x942kdf_set_buffer(args, &impl->ukm, &impl->ukm_len);
case EVP_KDF_CTRL_SET_CEK_ALG:
alg_str = va_arg(args, char *);
if (alg_str == NULL)
return 0;
impl->cek_nid = OBJ_sn2nid(alg_str);
for (i = 0; i < (size_t)OSSL_NELEM(kek_algs); ++i) {
if (kek_algs[i].nid == impl->cek_nid) {
impl->dkm_len = kek_algs[i].keklen;
return 1;
}
}
KDFerr(KDF_F_X942KDF_CTRL, KDF_R_UNSUPPORTED_CEK_ALG);
return 0;
default:
return -2;
}
}
static int x942kdf_ctrl_str(EVP_KDF_IMPL *impl, const char *type,
const char *value)
{
if (strcmp(type, "digest") == 0)
return kdf_md2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_MD, value);
if (strcmp(type, "secret") == 0 || strcmp(type, "key") == 0)
return kdf_str2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_KEY,
value);
if (strcmp(type, "hexsecret") == 0 || strcmp(type, "hexkey") == 0)
return kdf_hex2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_KEY,
value);
if (strcmp(type, "ukm") == 0)
return kdf_str2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_UKM,
value);
if (strcmp(type, "hexukm") == 0)
return kdf_hex2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_UKM,
value);
if (strcmp(type, "cekalg") == 0)
return kdf_str2ctrl(impl, x942kdf_ctrl, EVP_KDF_CTRL_SET_CEK_ALG,
value);
return -2;
}
static size_t x942kdf_size(EVP_KDF_IMPL *impl)
{
int len;
if (impl->md == NULL) {
KDFerr(KDF_F_X942KDF_SIZE, KDF_R_MISSING_MESSAGE_DIGEST);
return 0;
}
len = EVP_MD_size(impl->md);
return (len <= 0) ? 0 : (size_t)len;
}
static int x942kdf_derive(EVP_KDF_IMPL *impl, unsigned char *key, size_t keylen)
{
int ret = 0;
unsigned char *ctr;
unsigned char *der = NULL;
size_t der_len = 0;
if (impl->secret == NULL) {
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_MISSING_SECRET);
return 0;
}
if (impl->md == NULL) {
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST);
return 0;
}
if (impl->cek_nid == NID_undef) {
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_MISSING_CEK_ALG);
return 0;
}
if (impl->ukm != NULL && impl->ukm_len >= X942KDF_MAX_INLEN) {
/*
* Note the ukm length MUST be 512 bits.
* For backwards compatibility the old check is being done.
*/
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_INAVLID_UKM_LEN);
return 0;
}
if (keylen != impl->dkm_len) {
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_MISSING_CEK_ALG);
return 0;
}
/* generate the otherinfo der */
if (!x942_encode_otherinfo(impl->cek_nid, impl->dkm_len,
impl->ukm, impl->ukm_len,
&der, &der_len, &ctr)) {
KDFerr(KDF_F_X942KDF_DERIVE, KDF_R_BAD_ENCODING);
return 0;
}
ret = x942kdf_hash_kdm(impl->md, impl->secret, impl->secret_len,
der, der_len, ctr, key, keylen);
OPENSSL_free(der);
return ret;
}
const EVP_KDF x942_kdf_meth = {
EVP_KDF_X942,
x942kdf_new,
x942kdf_free,
x942kdf_reset,
x942kdf_ctrl,
x942kdf_ctrl_str,
x942kdf_size,
x942kdf_derive
};
#endif /* OPENSSL_NO_CMS */
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