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/* scrypt for Lua
* Copyright 2013 Rob Kendrick <rjek+luascrypt@rjek.com>
*
* Heavy based on Barry Steyn's code, and distributed under the same licence:
*
* Copyright (C) 2012 Barry Steyn (http://doctrina.org/Scrypt-Authentication-For-Node.html)
*
* This source code is provided 'as-is', without any express or implied
* warranty. In no event will the author be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this source code must not be misrepresented; you must not
* claim that you wrote the original source code. If you use this source code
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original source code.
*
* 3. This notice may not be removed or altered from any source distribution.
*
* Barry Steyn barry.steyn@gmail.com
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <math.h>
#include <lua.h>
#include <lauxlib.h>
#include "sha256.h"
#include "sysendian.h"
#include "crypto_scrypt.h"
#include "memlimit.h"
#include "scryptenc_cpuperf.h"
/*
* Obtains salt for password hash. This function is copied from Colin Percival's scrypt reference code
*/
static int
getsalt(uint8_t salt[32]) {
int fd;
ssize_t lenread;
uint8_t * buf = salt;
size_t buflen = 32;
/* Open /dev/urandom. */
if ((fd = open("/dev/urandom", O_RDONLY)) == -1)
goto err0;
/* Read bytes until we have filled the buffer. */
while (buflen > 0) {
if ((lenread = read(fd, buf, buflen)) == -1)
goto err1;
/* The random device should never EOF. */
if (lenread == 0)
goto err1;
/* We're partly done. */
buf += lenread;
buflen -= lenread;
}
/* Close the device. */
while (close(fd) == -1) {
if (errno != EINTR)
goto err0;
}
/* Success! */
return (0);
err1:
close(fd);
err0:
/* Failure! */
return (4);
}
static int
ls_hash_password(lua_State *L)
{
const uint8_t *passwd = (const uint8_t *)luaL_checkstring(L, 1);
size_t passwdlen = lua_objlen(L, 1);
uint64_t N = luaL_checknumber(L, 2);
uint32_t r = luaL_checknumber(L, 3);
uint32_t p = luaL_checknumber(L, 4);
uint8_t dk[64], salt[32], hbuf[32], header[96];
uint8_t *key_hmac = &dk[32];
SHA256_CTX ctx;
HMAC_SHA256_CTX hctx;
int result;
errno = 0;
if ((result = getsalt(salt)) != 0) {
lua_pushstring(L, strerror(errno));
lua_error(L);
}
errno = 0;
if (crypto_scrypt(passwd, passwdlen, salt, 32, N, r, p, dk, 64) != 0) {
lua_pushstring(L, strerror(errno));
lua_error(L);
}
memcpy(header, "scrypt", 6);
header[6] = 0;
header[7] = (int)log2(N);
be32enc(&header[8], r);
be32enc(&header[12], p);
memcpy(&header[16], salt, 32);
SHA256_Init(&ctx);
SHA256_Update(&ctx, header, 48);
SHA256_Final(hbuf, &ctx);
memcpy(&header[48], hbuf, 16);
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, header, 64);
HMAC_SHA256_Final(hbuf, &hctx);
memcpy(&header[64], hbuf, 32);
lua_pushlstring(L, (const char *)header, 96);
return 1;
}
static int
ls_verify_password(lua_State *L) {
const uint8_t *header = (uint8_t *)luaL_checkstring(L, 1);
const uint8_t *passwd = (uint8_t *)luaL_checkstring(L, 2);
size_t headerlen = lua_objlen(L, 1);
size_t passwdlen = lua_objlen(L, 2);
int N;
uint32_t r, p;
uint8_t dk[64], salt[32], hbuf[32];
uint8_t *key_hmac = &dk[32];
HMAC_SHA256_CTX hctx;
SHA256_CTX ctx;
if (headerlen != 96) {
lua_pushliteral(L, "password hash must be 96 bytes");
lua_error(L);
}
N = (uint64_t) 1 << header[7];
r = be32dec(&header[8]);
p = be32dec(&header[12]);
memcpy(salt, &header[16], 32);
SHA256_Init(&ctx);
SHA256_Update(&ctx, header, 48);
SHA256_Final(hbuf, &ctx);
if (memcmp(&header[48], hbuf, 16)) {
lua_pushnil(L);
lua_pushliteral(L, "header SHA does not verify; hash corrupt");
return 2;
}
errno = 0;
if (crypto_scrypt(passwd, passwdlen, salt, 32, N, r, p, dk, 64) != 0) {
lua_pushstring(L, strerror(errno));
lua_error(L);
}
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, header, 64);
HMAC_SHA256_Final(hbuf, &hctx);
if (memcmp(hbuf, &header[64], 32)) {
lua_pushboolean(L, 0);
} else {
lua_pushboolean(L, 1);
}
return 1;
}
static const struct luaL_Reg
ls_functions[] = {
{ "hash_password", ls_hash_password },
{ "verify_password", ls_verify_password },
{ NULL, NULL }
};
int
luaopen_scrypt(lua_State *L)
{
luaL_register(L, "scrypt", ls_functions);
return 1;
}
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