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esp-idf/components/wpa_supplicant/esp_supplicant/src/crypto/fastpbkdf2.c

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/*
* SPDX-FileCopyrightText: 2015 Joseph Birr-Pixton <jpixton@gmail.com>
*
* SPDX-License-Identifier: CC0-1.0
*/
/*
* fast-pbkdf2 - Optimal PBKDF2-HMAC calculation
* Written in 2015 by Joseph Birr-Pixton <jpixton@gmail.com>
*
* To the extent possible under law, the author(s) have dedicated all
* copyright and related and neighboring rights to this software to the
* public domain worldwide. This software is distributed without any
* warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication
* along with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#include "utils/common.h"
#include "fastpbkdf2.h"
#include <assert.h>
#include <string.h>
#if defined(__GNUC__)
#include <endian.h>
#endif
#include <mbedtls/sha1.h>
#include "mbedtls/esp_config.h"
#include "utils/wpa_debug.h"
/* --- MSVC doesn't support C99 --- */
#ifdef _MSC_VER
#define restrict
#define _Pragma __pragma
#endif
/* --- Common useful things --- */
#ifndef MIN
#define MIN(a, b) ((a) > (b)) ? (b) : (a)
#endif
static inline void write32_be(uint32_t n, uint8_t out[4])
{
#if defined(__GNUC__) && __GNUC__ >= 4 && __BYTE_ORDER == __LITTLE_ENDIAN
*(uint32_t *)(out) = __builtin_bswap32(n);
#else
out[0] = (n >> 24) & 0xff;
out[1] = (n >> 16) & 0xff;
out[2] = (n >> 8) & 0xff;
out[3] = n & 0xff;
#endif
}
/* Prepare block (of blocksz bytes) to contain md padding denoting a msg-size
* message (in bytes). block has a prefix of used bytes.
*
* Message length is expressed in 32 bits (so suitable for sha1, sha256, sha512). */
static inline void md_pad(uint8_t *block, size_t blocksz, size_t used, size_t msg)
{
memset(block + used, 0, blocksz - used - 4);
block[used] = 0x80;
block += blocksz - 4;
write32_be((uint32_t)(msg * 8), block);
}
/* Internal function/type names for hash-specific things. */
#define HMAC_CTX(_name) HMAC_ ## _name ## _ctx
#define HMAC_INIT(_name) HMAC_ ## _name ## _init
#define HMAC_UPDATE(_name) HMAC_ ## _name ## _update
#define HMAC_FINAL(_name) HMAC_ ## _name ## _final
#define PBKDF2_F(_name) pbkdf2_f_ ## _name
#define PBKDF2(_name) pbkdf2_ ## _name
/* This macro expands to decls for the whole implementation for a given
* hash function. Arguments are:
*
* _name like 'sha1', added to symbol names
* _blocksz block size, in bytes
* _hashsz digest output, in bytes
* _ctx hash context type
* _init hash context initialisation function
* args: (_ctx *c)
* _update hash context update function
* args: (_ctx *c, const void *data, size_t ndata)
* _final hash context finish function
* args: (_ctx *c, void *out)
* _xform hash context raw block update function
* args: (_ctx *c, const void *data)
* _xcpy hash context raw copy function (only need copy hash state)
* args: (_ctx * restrict out, const _ctx *restrict in)
* _xtract hash context state extraction
* args: args (_ctx *restrict c, uint8_t *restrict out)
* _xxor hash context xor function (only need xor hash state)
* args: (_ctx *restrict out, const _ctx *restrict in)
*
* The resulting function is named PBKDF2(_name).
*/
#define DECL_PBKDF2(_name, _blocksz, _hashsz, _ctx, \
_init, _update, _xform, _final, _xcpy, _xtract, _xxor) \
typedef struct { \
_ctx inner; \
_ctx outer; \
} HMAC_CTX(_name); \
\
static inline void HMAC_INIT(_name)(HMAC_CTX(_name) *ctx, \
const uint8_t *key, size_t nkey) \
{ \
/* Prepare key: */ \
uint8_t k[_blocksz]; \
\
/* Shorten long keys. */ \
if (nkey > _blocksz) \
{ \
_init(&ctx->inner); \
_update(&ctx->inner, key, nkey); \
_final(&ctx->inner, k); \
\
key = k; \
nkey = _hashsz; \
} \
\
/* Standard doesn't cover case where blocksz < hashsz. */ \
assert(nkey <= _blocksz); \
\
/* Right zero-pad short keys. */ \
if (k != key) \
memcpy(k, key, nkey); \
if (_blocksz > nkey) \
memset(k + nkey, 0, _blocksz - nkey); \
\
/* Start inner hash computation */ \
uint8_t blk_inner[_blocksz]; \
uint8_t blk_outer[_blocksz]; \
\
for (size_t i = 0; i < _blocksz; i++) \
{ \
blk_inner[i] = 0x36 ^ k[i]; \
blk_outer[i] = 0x5c ^ k[i]; \
} \
\
_init(&ctx->inner); \
_update(&ctx->inner, blk_inner, sizeof blk_inner); \
\
/* And outer. */ \
_init(&ctx->outer); \
_update(&ctx->outer, blk_outer, sizeof blk_outer); \
} \
\
static inline void HMAC_UPDATE(_name)(HMAC_CTX(_name) *ctx, \
const void *data, size_t ndata) \
{ \
_update(&ctx->inner, data, ndata); \
} \
\
static inline void HMAC_FINAL(_name)(HMAC_CTX(_name) *ctx, \
uint8_t out[_hashsz]) \
{ \
_final(&ctx->inner, out); \
_update(&ctx->outer, out, _hashsz); \
_final(&ctx->outer, out); \
} \
\
\
/* --- PBKDF2 --- */ \
static inline void PBKDF2_F(_name)(const HMAC_CTX(_name) *startctx, \
uint32_t counter, \
const uint8_t *salt, size_t nsalt, \
uint32_t iterations, \
uint8_t *out) \
{ \
uint8_t countbuf[4]; \
write32_be(counter, countbuf); \
\
/* Prepare loop-invariant padding block. */ \
uint8_t Ublock[_blocksz]; \
md_pad(Ublock, _blocksz, _hashsz, _blocksz + _hashsz); \
\
/* First iteration: \
* U_1 = PRF(P, S || INT_32_BE(i)) \
*/ \
HMAC_CTX(_name) ctx = *startctx; \
HMAC_UPDATE(_name)(&ctx, salt, nsalt); \
HMAC_UPDATE(_name)(&ctx, countbuf, sizeof countbuf); \
HMAC_FINAL(_name)(&ctx, Ublock); \
_ctx result = ctx.outer; \
\
/* Subsequent iterations: \
* U_c = PRF(P, U_{c-1}) \
*/ \
for (uint32_t i = 1; i < iterations; i++) \
{ \
/* Complete inner hash with previous U */ \
_xcpy(&ctx.inner, &startctx->inner); \
_xform(&ctx.inner, Ublock); \
_xtract(&ctx.inner, Ublock); \
/* Complete outer hash with inner output */ \
_xcpy(&ctx.outer, &startctx->outer); \
_xform(&ctx.outer, Ublock); \
_xtract(&ctx.outer, Ublock); \
_xxor(&result, &ctx.outer); \
} \
\
/* Reform result into output buffer. */ \
_xtract(&result, out); \
} \
\
static inline void PBKDF2(_name)(const uint8_t *pw, size_t npw, \
const uint8_t *salt, size_t nsalt, \
uint32_t iterations, \
uint8_t *out, size_t nout) \
{ \
assert(iterations); \
assert(out && nout); \
\
/* Starting point for inner loop. */ \
HMAC_CTX(_name) ctx; \
HMAC_INIT(_name)(&ctx, pw, npw); \
\
/* How many blocks do we need? */ \
uint32_t blocks_needed = (uint32_t)(nout + _hashsz - 1) / _hashsz; \
\
for (uint32_t counter = 1; counter <= blocks_needed; counter++) \
{ \
uint8_t block[_hashsz]; \
PBKDF2_F(_name)(&ctx, counter, salt, nsalt, iterations, block); \
\
size_t offset = (counter - 1) * _hashsz; \
size_t taken = MIN(nout - offset, _hashsz); \
memcpy(out + offset, block, taken); \
} \
}
static inline void sha1_extract(mbedtls_sha1_context *restrict ctx, uint8_t *restrict out)
{
#if defined(MBEDTLS_SHA1_ALT)
#if CONFIG_IDF_TARGET_ESP32
/* ESP32 stores internal SHA state in BE format similar to software */
write32_be(ctx->state[0], out);
write32_be(ctx->state[1], out + 4);
write32_be(ctx->state[2], out + 8);
write32_be(ctx->state[3], out + 12);
write32_be(ctx->state[4], out + 16);
#else
*(uint32_t *)(out) = ctx->state[0];
*(uint32_t *)(out + 4) = ctx->state[1];
*(uint32_t *)(out + 8) = ctx->state[2];
*(uint32_t *)(out + 12) = ctx->state[3];
*(uint32_t *)(out + 16) = ctx->state[4];
#endif
#else
write32_be(ctx->MBEDTLS_PRIVATE(state)[0], out);
write32_be(ctx->MBEDTLS_PRIVATE(state)[1], out + 4);
write32_be(ctx->MBEDTLS_PRIVATE(state)[2], out + 8);
write32_be(ctx->MBEDTLS_PRIVATE(state)[3], out + 12);
write32_be(ctx->MBEDTLS_PRIVATE(state)[4], out + 16);
#endif
}
static inline void sha1_cpy(mbedtls_sha1_context *restrict out, const mbedtls_sha1_context *restrict in)
{
#if defined(MBEDTLS_SHA1_ALT)
out->state[0] = in->state[0];
out->state[1] = in->state[1];
out->state[2] = in->state[2];
out->state[3] = in->state[3];
out->state[4] = in->state[4];
#else
out->MBEDTLS_PRIVATE(state)[0] = in->MBEDTLS_PRIVATE(state)[0];
out->MBEDTLS_PRIVATE(state)[1] = in->MBEDTLS_PRIVATE(state)[1];
out->MBEDTLS_PRIVATE(state)[2] = in->MBEDTLS_PRIVATE(state)[2];
out->MBEDTLS_PRIVATE(state)[3] = in->MBEDTLS_PRIVATE(state)[3];
out->MBEDTLS_PRIVATE(state)[4] = in->MBEDTLS_PRIVATE(state)[4];
#endif
}
static inline void sha1_xor(mbedtls_sha1_context *restrict out, const mbedtls_sha1_context *restrict in)
{
#if defined(MBEDTLS_SHA1_ALT)
out->state[0] ^= in->state[0];
out->state[1] ^= in->state[1];
out->state[2] ^= in->state[2];
out->state[3] ^= in->state[3];
out->state[4] ^= in->state[4];
#else
out->MBEDTLS_PRIVATE(state)[0] ^= in->MBEDTLS_PRIVATE(state)[0];
out->MBEDTLS_PRIVATE(state)[1] ^= in->MBEDTLS_PRIVATE(state)[1];
out->MBEDTLS_PRIVATE(state)[2] ^= in->MBEDTLS_PRIVATE(state)[2];
out->MBEDTLS_PRIVATE(state)[3] ^= in->MBEDTLS_PRIVATE(state)[3];
out->MBEDTLS_PRIVATE(state)[4] ^= in->MBEDTLS_PRIVATE(state)[4];
#endif
}
static int mbedtls_sha1_init_start(mbedtls_sha1_context *ctx)
{
mbedtls_sha1_init(ctx);
mbedtls_sha1_starts(ctx);
#if defined(CONFIG_IDF_TARGET_ESP32) && defined(MBEDTLS_SHA1_ALT)
/* Use software mode for esp32 since hardware can't give output more than 20 */
esp_mbedtls_set_sha1_mode(ctx, ESP_MBEDTLS_SHA1_SOFTWARE);
#endif
return 0;
}
#ifndef MBEDTLS_SHA1_ALT
static int sha1_finish(mbedtls_sha1_context *ctx,
unsigned char output[20])
{
int ret = -1;
uint32_t used;
uint32_t high, low;
/*
* Add padding: 0x80 then 0x00 until 8 bytes remain for the length
*/
used = ctx->MBEDTLS_PRIVATE(total)[0] & 0x3F;
ctx->MBEDTLS_PRIVATE(buffer)[used++] = 0x80;
if (used <= 56) {
/* Enough room for padding + length in current block */
memset(ctx->MBEDTLS_PRIVATE(buffer) + used, 0, 56 - used);
} else {
/* We'll need an extra block */
memset(ctx->MBEDTLS_PRIVATE(buffer) + used, 0, 64 - used);
if ((ret = mbedtls_internal_sha1_process(ctx, ctx->MBEDTLS_PRIVATE(buffer))) != 0) {
goto exit;
}
memset(ctx->MBEDTLS_PRIVATE(buffer), 0, 56);
}
/*
* Add message length
*/
high = (ctx->MBEDTLS_PRIVATE(total)[0] >> 29)
| (ctx->MBEDTLS_PRIVATE(total)[1] << 3);
low = (ctx->MBEDTLS_PRIVATE(total)[0] << 3);
write32_be(high, ctx->MBEDTLS_PRIVATE(buffer) + 56);
write32_be(low, ctx->MBEDTLS_PRIVATE(buffer) + 60);
if ((ret = mbedtls_internal_sha1_process(ctx, ctx->MBEDTLS_PRIVATE(buffer))) != 0) {
goto exit;
}
/*
* Output final state
*/
write32_be(ctx->MBEDTLS_PRIVATE(state)[0], output);
write32_be(ctx->MBEDTLS_PRIVATE(state)[1], output + 4);
write32_be(ctx->MBEDTLS_PRIVATE(state)[2], output + 8);
write32_be(ctx->MBEDTLS_PRIVATE(state)[3], output + 12);
write32_be(ctx->MBEDTLS_PRIVATE(state)[4], output + 16);
ret = 0;
exit:
return ret;
}
#endif
DECL_PBKDF2(sha1, // _name
64, // _blocksz
20, // _hashsz
mbedtls_sha1_context, // _ctx
mbedtls_sha1_init_start, // _init
mbedtls_sha1_update, // _update
mbedtls_internal_sha1_process, // _xform
#if defined(MBEDTLS_SHA1_ALT)
mbedtls_sha1_finish, // _final
#else
sha1_finish, // _final
#endif
sha1_cpy, // _xcpy
sha1_extract, // _xtract
sha1_xor) // _xxor
void fastpbkdf2_hmac_sha1(const uint8_t *pw, size_t npw,
const uint8_t *salt, size_t nsalt,
uint32_t iterations,
uint8_t *out, size_t nout)
{
PBKDF2(sha1)(pw, npw, salt, nsalt, iterations, out, nout);
}
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