krb5kdf.c
/*
* Copyright 2018-2023 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
*/
/*
* DES low level APIs are deprecated for public use, but still ok for internal
* use. We access the DES_set_odd_parity(3) function here.
*/
#include "internal/deprecated.h"
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <openssl/core_names.h>
#include <openssl/des.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "crypto/evp.h"
#include "internal/numbers.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/provider_util.h"
#include "prov/providercommon.h"
/* KRB5 KDF defined in RFC 3961, Section 5.1 */
static OSSL_FUNC_kdf_newctx_fn krb5kdf_new;
static OSSL_FUNC_kdf_dupctx_fn krb5kdf_dup;
static OSSL_FUNC_kdf_freectx_fn krb5kdf_free;
static OSSL_FUNC_kdf_reset_fn krb5kdf_reset;
static OSSL_FUNC_kdf_derive_fn krb5kdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn krb5kdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn krb5kdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn krb5kdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn krb5kdf_get_ctx_params;
static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
const unsigned char *key, size_t key_len,
const unsigned char *constant, size_t constant_len,
unsigned char *okey, size_t okey_len);
typedef struct {
void *provctx;
PROV_CIPHER cipher;
unsigned char *key;
size_t key_len;
unsigned char *constant;
size_t constant_len;
} KRB5KDF_CTX;
static void *krb5kdf_new(void *provctx)
{
KRB5KDF_CTX *ctx;
if (!ossl_prov_is_running())
return NULL;
if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
return NULL;
ctx->provctx = provctx;
return ctx;
}
static void krb5kdf_free(void *vctx)
{
KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
if (ctx != NULL) {
krb5kdf_reset(ctx);
OPENSSL_free(ctx);
}
}
static void krb5kdf_reset(void *vctx)
{
KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
void *provctx = ctx->provctx;
ossl_prov_cipher_reset(&ctx->cipher);
OPENSSL_clear_free(ctx->key, ctx->key_len);
OPENSSL_clear_free(ctx->constant, ctx->constant_len);
memset(ctx, 0, sizeof(*ctx));
ctx->provctx = provctx;
}
static int krb5kdf_set_membuf(unsigned char **dst, size_t *dst_len,
const OSSL_PARAM *p)
{
OPENSSL_clear_free(*dst, *dst_len);
*dst = NULL;
*dst_len = 0;
return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
}
static void *krb5kdf_dup(void *vctx)
{
const KRB5KDF_CTX *src = (const KRB5KDF_CTX *)vctx;
KRB5KDF_CTX *dest;
dest = krb5kdf_new(src->provctx);
if (dest != NULL) {
if (!ossl_prov_memdup(src->key, src->key_len,
&dest->key, &dest->key_len)
|| !ossl_prov_memdup(src->constant, src->constant_len,
&dest->constant , &dest->constant_len)
|| !ossl_prov_cipher_copy(&dest->cipher, &src->cipher))
goto err;
}
return dest;
err:
krb5kdf_free(dest);
return NULL;
}
static int krb5kdf_derive(void *vctx, unsigned char *key, size_t keylen,
const OSSL_PARAM params[])
{
KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
const EVP_CIPHER *cipher;
ENGINE *engine;
if (!ossl_prov_is_running() || !krb5kdf_set_ctx_params(ctx, params))
return 0;
cipher = ossl_prov_cipher_cipher(&ctx->cipher);
if (cipher == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);
return 0;
}
if (ctx->key == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
return 0;
}
if (ctx->constant == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CONSTANT);
return 0;
}
engine = ossl_prov_cipher_engine(&ctx->cipher);
return KRB5KDF(cipher, engine, ctx->key, ctx->key_len,
ctx->constant, ctx->constant_len,
key, keylen);
}
static int krb5kdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
const OSSL_PARAM *p;
KRB5KDF_CTX *ctx = vctx;
OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
if (params == NULL)
return 1;
if (!ossl_prov_cipher_load_from_params(&ctx->cipher, params, provctx))
return 0;
if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
if (!krb5kdf_set_membuf(&ctx->key, &ctx->key_len, p))
return 0;
if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CONSTANT))
!= NULL)
if (!krb5kdf_set_membuf(&ctx->constant, &ctx->constant_len, p))
return 0;
return 1;
}
static const OSSL_PARAM *krb5kdf_settable_ctx_params(ossl_unused void *ctx,
ossl_unused void *provctx)
{
static const OSSL_PARAM known_settable_ctx_params[] = {
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_CONSTANT, NULL, 0),
OSSL_PARAM_END
};
return known_settable_ctx_params;
}
static int krb5kdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
const EVP_CIPHER *cipher;
size_t len;
OSSL_PARAM *p;
cipher = ossl_prov_cipher_cipher(&ctx->cipher);
if (cipher)
len = EVP_CIPHER_get_key_length(cipher);
else
len = EVP_MAX_KEY_LENGTH;
if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
return OSSL_PARAM_set_size_t(p, len);
return -2;
}
static const OSSL_PARAM *krb5kdf_gettable_ctx_params(ossl_unused void *ctx,
ossl_unused void *provctx)
{
static const OSSL_PARAM known_gettable_ctx_params[] = {
OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
OSSL_PARAM_END
};
return known_gettable_ctx_params;
}
const OSSL_DISPATCH ossl_kdf_krb5kdf_functions[] = {
{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))krb5kdf_new },
{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))krb5kdf_dup },
{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))krb5kdf_free },
{ OSSL_FUNC_KDF_RESET, (void(*)(void))krb5kdf_reset },
{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))krb5kdf_derive },
{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
(void(*)(void))krb5kdf_settable_ctx_params },
{ OSSL_FUNC_KDF_SET_CTX_PARAMS,
(void(*)(void))krb5kdf_set_ctx_params },
{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
(void(*)(void))krb5kdf_gettable_ctx_params },
{ OSSL_FUNC_KDF_GET_CTX_PARAMS,
(void(*)(void))krb5kdf_get_ctx_params },
OSSL_DISPATCH_END
};
#ifndef OPENSSL_NO_DES
/*
* DES3 is a special case, it requires a random-to-key function and its
* input truncated to 21 bytes of the 24 produced by the cipher.
* See RFC3961 6.3.1
*/
static int fixup_des3_key(unsigned char *key)
{
unsigned char *cblock;
int i, j;
for (i = 2; i >= 0; i--) {
cblock = &key[i * 8];
memmove(cblock, &key[i * 7], 7);
cblock[7] = 0;
for (j = 0; j < 7; j++)
cblock[7] |= (cblock[j] & 1) << (j + 1);
DES_set_odd_parity((DES_cblock *)cblock);
}
/* fail if keys are such that triple des degrades to single des */
if (CRYPTO_memcmp(&key[0], &key[8], 8) == 0 ||
CRYPTO_memcmp(&key[8], &key[16], 8) == 0) {
return 0;
}
return 1;
}
#endif
/*
* N-fold(K) where blocksize is N, and constant_len is K
* Note: Here |= denotes concatenation
*
* L = lcm(N,K)
* R = L/K
*
* for r: 1 -> R
* s |= constant rot 13*(r-1))
*
* block = 0
* for k: 1 -> K
* block += s[N(k-1)..(N-1)k] (one's complement addition)
*
* Optimizing for space we compute:
* for each l in L-1 -> 0:
* s[l] = (constant rot 13*(l/K))[l%k]
* block[l % N] += s[l] (with carry)
* finally add carry if any
*/
static void n_fold(unsigned char *block, unsigned int blocksize,
const unsigned char *constant, size_t constant_len)
{
unsigned int tmp, gcd, remainder, lcm, carry;
int b, l;
if (constant_len == blocksize) {
memcpy(block, constant, constant_len);
return;
}
/* Least Common Multiple of lengths: LCM(a,b)*/
gcd = blocksize;
remainder = constant_len;
/* Calculate Great Common Divisor first GCD(a,b) */
while (remainder != 0) {
tmp = gcd % remainder;
gcd = remainder;
remainder = tmp;
}
/* resulting a is the GCD, LCM(a,b) = |a*b|/GCD(a,b) */
lcm = blocksize * constant_len / gcd;
/* now spread out the bits */
memset(block, 0, blocksize);
/* last to first to be able to bring carry forward */
carry = 0;
for (l = lcm - 1; l >= 0; l--) {
unsigned int rotbits, rshift, rbyte;
/* destination byte in block is l % N */
b = l % blocksize;
/* Our virtual s buffer is R = L/K long (K = constant_len) */
/* So we rotate backwards from R-1 to 0 (none) rotations */
rotbits = 13 * (l / constant_len);
/* find the byte on s where rotbits falls onto */
rbyte = l - (rotbits / 8);
/* calculate how much shift on that byte */
rshift = rotbits & 0x07;
/* rbyte % constant_len gives us the unrotated byte in the
* constant buffer, get also the previous byte then
* appropriately shift them to get the rotated byte we need */
tmp = (constant[(rbyte-1) % constant_len] << (8 - rshift)
| constant[rbyte % constant_len] >> rshift)
& 0xff;
/* add with carry to any value placed by previous passes */
tmp += carry + block[b];
block[b] = tmp & 0xff;
/* save any carry that may be left */
carry = tmp >> 8;
}
/* if any carry is left at the end, add it through the number */
for (b = blocksize - 1; b >= 0 && carry != 0; b--) {
carry += block[b];
block[b] = carry & 0xff;
carry >>= 8;
}
}
static int cipher_init(EVP_CIPHER_CTX *ctx,
const EVP_CIPHER *cipher, ENGINE *engine,
const unsigned char *key, size_t key_len)
{
int klen, ret;
ret = EVP_EncryptInit_ex(ctx, cipher, engine, key, NULL);
if (!ret)
goto out;
/* set the key len for the odd variable key len cipher */
klen = EVP_CIPHER_CTX_get_key_length(ctx);
if (key_len != (size_t)klen) {
ret = EVP_CIPHER_CTX_set_key_length(ctx, key_len);
if (ret <= 0) {
ret = 0;
goto out;
}
}
/* we never want padding, either the length requested is a multiple of
* the cipher block size or we are passed a cipher that can cope with
* partial blocks via techniques like cipher text stealing */
ret = EVP_CIPHER_CTX_set_padding(ctx, 0);
if (!ret)
goto out;
out:
return ret;
}
static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
const unsigned char *key, size_t key_len,
const unsigned char *constant, size_t constant_len,
unsigned char *okey, size_t okey_len)
{
EVP_CIPHER_CTX *ctx = NULL;
unsigned char block[EVP_MAX_BLOCK_LENGTH * 2];
unsigned char *plainblock, *cipherblock;
size_t blocksize;
size_t cipherlen;
size_t osize;
#ifndef OPENSSL_NO_DES
int des3_no_fixup = 0;
#endif
int ret;
if (key_len != okey_len) {
#ifndef OPENSSL_NO_DES
/* special case for 3des, where the caller may be requesting
* the random raw key, instead of the fixed up key */
if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc &&
key_len == 24 && okey_len == 21) {
des3_no_fixup = 1;
} else {
#endif
ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
return 0;
#ifndef OPENSSL_NO_DES
}
#endif
}
ctx = EVP_CIPHER_CTX_new();
if (ctx == NULL)
return 0;
ret = cipher_init(ctx, cipher, engine, key, key_len);
if (!ret)
goto out;
/* Initialize input block */
blocksize = EVP_CIPHER_CTX_get_block_size(ctx);
if (constant_len > blocksize) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CONSTANT_LENGTH);
ret = 0;
goto out;
}
n_fold(block, blocksize, constant, constant_len);
plainblock = block;
cipherblock = block + EVP_MAX_BLOCK_LENGTH;
for (osize = 0; osize < okey_len; osize += cipherlen) {
int olen;
ret = EVP_EncryptUpdate(ctx, cipherblock, &olen,
plainblock, blocksize);
if (!ret)
goto out;
cipherlen = olen;
ret = EVP_EncryptFinal_ex(ctx, cipherblock, &olen);
if (!ret)
goto out;
if (olen != 0) {
ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
ret = 0;
goto out;
}
/* write cipherblock out */
if (cipherlen > okey_len - osize)
cipherlen = okey_len - osize;
memcpy(okey + osize, cipherblock, cipherlen);
if (okey_len > osize + cipherlen) {
/* we need to reinitialize cipher context per spec */
ret = EVP_CIPHER_CTX_reset(ctx);
if (!ret)
goto out;
ret = cipher_init(ctx, cipher, engine, key, key_len);
if (!ret)
goto out;
/* also swap block offsets so last ciphertext becomes new
* plaintext */
plainblock = cipherblock;
if (cipherblock == block) {
cipherblock += EVP_MAX_BLOCK_LENGTH;
} else {
cipherblock = block;
}
}
}
#ifndef OPENSSL_NO_DES
if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc && !des3_no_fixup) {
ret = fixup_des3_key(okey);
if (!ret) {
ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GENERATE_KEY);
goto out;
}
}
#endif
ret = 1;
out:
EVP_CIPHER_CTX_free(ctx);
OPENSSL_cleanse(block, EVP_MAX_BLOCK_LENGTH * 2);
return ret;
}
