/*
* Argon2 reference source code package - reference C implementations
*
* Copyright 2015
* Daniel Dinu, Dmitry Khovratovich, Jean-Philippe Aumasson, and Samuel Neves
*
* You may use this work under the terms of a Creative Commons CC0 1.0
* License/Waiver or the Apache Public License 2.0, at your option. The terms of
* these licenses can be found at:
*
* - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
* - Apache 2.0 : http://www.apache.org/licenses/LICENSE-2.0
*
* You should have received a copy of both of these licenses along with this
* software. If not, they may be obtained at the above URLs.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include "encoding.h"
#include "core.h"
/*
* Example code for a decoder and encoder of "hash strings", with Argon2
* parameters.
*
* This code comprises three sections:
*
* -- The first section contains generic Base64 encoding and decoding
* functions. It is conceptually applicable to any hash function
* implementation that uses Base64 to encode and decode parameters,
* salts and outputs. It could be made into a library, provided that
* the relevant functions are made public (non-static) and be given
* reasonable names to avoid collisions with other functions.
*
* -- The second section is specific to Argon2. It encodes and decodes
* the parameters, salts and outputs. It does not compute the hash
* itself.
*
* The code was originally written by Thomas Pornin <pornin@bolet.org>,
* to whom comments and remarks may be sent. It is released under what
* should amount to Public Domain or its closest equivalent; the
* following mantra is supposed to incarnate that fact with all the
* proper legal rituals:
*
* ---------------------------------------------------------------------
* This file is provided under the terms of Creative Commons CC0 1.0
* Public Domain Dedication. To the extent possible under law, the
* author (Thomas Pornin) has waived all copyright and related or
* neighboring rights to this file. This work is published from: Canada.
* ---------------------------------------------------------------------
*
* Copyright (c) 2015 Thomas Pornin
*/
/* ==================================================================== */
/*
* Common code; could be shared between different hash functions.
*
* Note: the Base64 functions below assume that uppercase letters (resp.
* lowercase letters) have consecutive numerical codes, that fit on 8
* bits. All modern systems use ASCII-compatible charsets, where these
* properties are true. If you are stuck with a dinosaur of a system
* that still defaults to EBCDIC then you already have much bigger
* interoperability issues to deal with.
*/
/*
* Some macros for constant-time comparisons. These work over values in
* the 0..255 range. Returned value is 0x00 on "false", 0xFF on "true".
*/
#define EQ(x, y) ((((0U - ((unsigned)(x) ^ (unsigned)(y))) >> 8) & 0xFF) ^ 0xFF)
#define GT(x, y) ((((unsigned)(y) - (unsigned)(x)) >> 8) & 0xFF)
#define GE(x, y) (GT(y, x) ^ 0xFF)
#define LT(x, y) GT(y, x)
#define LE(x, y) GE(y, x)
/*
* Convert value x (0..63) to corresponding Base64 character.
*/
static int b64_byte_to_char(unsigned x) {
return (LT(x, 26) & (x + 'A')) |
(GE(x, 26) & LT(x, 52) & (x + ('a' - 26))) |
(GE(x, 52) & LT(x, 62) & (x + ('0' - 52))) | (EQ(x, 62) & '+') |
(EQ(x, 63) & '/');
}
/*
* Convert character c to the corresponding 6-bit value. If character c
* is not a Base64 character, then 0xFF (255) is returned.
*/
static unsigned b64_char_to_byte(int c) {
unsigned x;
x = (GE(c, 'A') & LE(c, 'Z') & (c - 'A')) |
(GE(c, 'a') & LE(c, 'z') & (c - ('a' - 26))) |
(GE(c, '0') & LE(c, '9') & (c - ('0' - 52))) | (EQ(c, '+') & 62) |
(EQ(c, '/') & 63);
return x | (EQ(x, 0) & (EQ(c, 'A') ^ 0xFF));
}
/*
* Convert some bytes to Base64. 'dst_len' is the length (in characters)
* of the output buffer 'dst'; if that buffer is not large enough to
* receive the result (including the terminating 0), then (size_t)-1
* is returned. Otherwise, the zero-terminated Base64 string is written
* in the buffer, and the output length (counted WITHOUT the terminating
* zero) is returned.
*/
static size_t to_base64(char *dst, size_t dst_len, const void *src,
size_t src_len) {
size_t olen;
const unsigned char *buf;
unsigned acc, acc_len;
olen = (src_len / 3) << 2;
switch (src_len % 3) {
case 2:
olen++;
/* fall through */
case 1:
olen += 2;
break;
}
if (dst_len <= olen) {
return (size_t)-1;
}
acc = 0;
acc_len = 0;
buf = (const unsigned char *)src;
while (src_len-- > 0) {
acc = (acc << 8) + (*buf++);
acc_len += 8;
while (acc_len >= 6) {
acc_len -= 6;
*dst++ = (char)b64_byte_to_char((acc >> acc_len) & 0x3F);
}
}
if (acc_len > 0) {
*dst++ = (char)b64_byte_to_char((acc << (6 - acc_len)) & 0x3F);
}
*dst++ = 0;
return olen;
}
/*
* Decode Base64 chars into bytes. The '*dst_len' value must initially
* contain the length of the output buffer '*dst'; when the decoding
* ends, the actual number of decoded bytes is written back in
* '*dst_len'.
*
* Decoding stops when a non-Base64 character is encountered, or when
* the output buffer capacity is exceeded. If an error occurred (output
* buffer is too small, invalid last characters leading to unprocessed
* buffered bits), then NULL is returned; otherwise, the returned value
* points to the first non-Base64 character in the source stream, which
* may be the terminating zero.
*/
static const char *from_base64(void *dst, size_t *dst_len, const char *src) {
size_t len;
unsigned char *buf;
unsigned acc, acc_len;
buf = (unsigned char *)dst;
len = 0;
acc = 0;
acc_len = 0;
for (;;) {
unsigned d;
d = b64_char_to_byte(*src);
if (d == 0xFF) {
break;
}
src++;
acc = (acc << 6) + d;
acc_len += 6;
if (acc_len >= 8) {
acc_len -= 8;
if ((len++) >= *dst_len) {
return NULL;
}
*buf++ = (acc >> acc_len) & 0xFF;
}
}
/*
* If the input length is equal to 1 modulo 4 (which is
* invalid), then there will remain 6 unprocessed bits;
* otherwise, only 0, 2 or 4 bits are buffered. The buffered
* bits must also all be zero.
*/
if (acc_len > 4 || (acc & (((unsigned)1 << acc_len) - 1)) != 0) {
return NULL;
}
*dst_len = len;
return src;
}
/*
* Decode decimal integer from 'str'; the value is written in '*v'.
* Returned value is a pointer to the next non-decimal character in the
* string. If there is no digit at all, or the value encoding is not
* minimal (extra leading zeros), or the value does not fit in an
* 'unsigned long', then NULL is returned.
*/
static const char *decode_decimal(const char *str, unsigned long *v) {
const char *orig;
unsigned long acc;
acc = 0;
for (orig = str;; str++) {
int c;
c = *str;
if (c < '0' || c > '9') {
break;
}
c -= '0';
if (acc > (ULONG_MAX / 10)) {
return NULL;
}
acc *= 10;
if ((unsigned long)c > (ULONG_MAX - acc)) {
return NULL;
}
acc += (unsigned long)c;
}
if (str == orig || (*orig == '0' && str != (orig + 1))) {
return NULL;
}
*v = acc;
return str;
}
/* ==================================================================== */
/*
* Code specific to Argon2.
*
* The code below applies the following format:
*
* $argon2<T>[$v=<num>]$m=<num>,t=<num>,p=<num>$<bin>$<bin>
*
* where <T> is either 'd', 'id', or 'i', <num> is a decimal integer (positive,
* fits in an 'unsigned long'), and <bin> is Base64-encoded data (no '=' padding
* characters, no newline or whitespace).
*
* The last two binary chunks (encoded in Base64) are, in that order,
* the salt and the output. Both are required. The binary salt length and the
* output length must be in the allowed ranges defined in argon2.h.
*
* The ctx struct must contain buffers large enough to hold the salt and pwd
* when it is fed into decode_string.
*/
int decode_string(argon2_context *ctx, const char *str, argon2_type type) {
/* check for prefix */
#define CC(prefix) \
do { \
size_t cc_len = strlen(prefix); \
if (strncmp(str, prefix, cc_len) != 0) { \
return ARGON2_DECODING_FAIL; \
} \
str += cc_len; \
} while ((void)0, 0)
/* optional prefix checking with supplied code */
#define CC_opt(prefix, code) \
do { \
size_t cc_len = strlen(prefix); \
if (strncmp(str, prefix, cc_len) == 0) { \
str += cc_len; \
{ code; } \
} \
} while ((void)0, 0)
/* Decoding prefix into decimal */
#define DECIMAL(x) \
do { \
unsigned long dec_x; \
str = decode_decimal(str, &dec_x); \
if (str == NULL) { \
return ARGON2_DECODING_FAIL; \
} \
(x) = dec_x; \
} while ((void)0, 0)
/* Decoding prefix into uint32_t decimal */
#define DECIMAL_U32(x) \
do { \
unsigned long dec_x; \
str = decode_decimal(str, &dec_x); \
if (str == NULL || dec_x > UINT32_MAX) { \
return ARGON2_DECODING_FAIL; \
} \
(x) = (uint32_t)dec_x; \
} while ((void)0, 0)
/* Decoding base64 into a binary buffer */
#define BIN(buf, max_len, len) \
do { \
size_t bin_len = (max_len); \
str = from_base64(buf, &bin_len, str); \
if (str == NULL || bin_len > UINT32_MAX) { \
return ARGON2_DECODING_FAIL; \
} \
(len) = (uint32_t)bin_len; \
} while ((void)0, 0)
size_t maxsaltlen = ctx->saltlen;
size_t maxoutlen = ctx->outlen;
int validation_result;
const char* type_string;
/* We should start with the argon2_type we are using */
type_string = argon2_type2string(type, 0);
if (!type_string) {
return ARGON2_INCORRECT_TYPE;
}
CC("$");
CC(type_string);
/* Reading the version number if the default is suppressed */
ctx->version = ARGON2_VERSION_10;
CC_opt("$v=", DECIMAL_U32(ctx->version));
CC("$m=");
DECIMAL_U32(ctx->m_cost);
CC(",t=");
DECIMAL_U32(ctx->t_cost);
CC(",p=");
DECIMAL_U32(ctx->lanes);
ctx->threads = ctx->lanes;
CC("$");
BIN(ctx->salt, maxsaltlen, ctx->saltlen);
CC("$");
BIN(ctx->out, maxoutlen, ctx->outlen);
/* The rest of the fields get the default values */
ctx->secret = NULL;
ctx->secretlen = 0;
ctx->ad = NULL;
ctx->adlen = 0;
ctx->allocate_cbk = NULL;
ctx->free_cbk = NULL;
ctx->flags = ARGON2_DEFAULT_FLAGS;
/* On return, must have valid context */
validation_result = validate_inputs(ctx);
if (validation_result != ARGON2_OK) {
return validation_result;
}
/* Can't have any additional characters */
if (*str == 0) {
return ARGON2_OK;
} else {
return ARGON2_DECODING_FAIL;
}
#undef CC
#undef CC_opt
#undef DECIMAL
#undef BIN
}
int encode_string(char *dst, size_t dst_len, argon2_context *ctx,
argon2_type type) {
#define SS(str) \
do { \
size_t pp_len = strlen(str); \
if (pp_len >= dst_len) { \
return ARGON2_ENCODING_FAIL; \
} \
memcpy(dst, str, pp_len + 1); \
dst += pp_len; \
dst_len -= pp_len; \
} while ((void)0, 0)
#define SX(x) \
do { \
char tmp[30]; \
sprintf(tmp, "%lu", (unsigned long)(x)); \
SS(tmp); \
} while ((void)0, 0)
#define SB(buf, len) \
do { \
size_t sb_len = to_base64(dst, dst_len, buf, len); \
if (sb_len == (size_t)-1) { \
return ARGON2_ENCODING_FAIL; \
} \
dst += sb_len; \
dst_len -= sb_len; \
} while ((void)0, 0)
const char* type_string = argon2_type2string(type, 0);
int validation_result = validate_inputs(ctx);
if (!type_string) {
return ARGON2_ENCODING_FAIL;
}
if (validation_result != ARGON2_OK) {
return validation_result;
}
SS("$");
SS(type_string);
SS("$v=");
SX(ctx->version);
SS("$m=");
SX(ctx->m_cost);
SS(",t=");
SX(ctx->t_cost);
SS(",p=");
SX(ctx->lanes);
SS("$");
SB(ctx->salt, ctx->saltlen);
SS("$");
SB(ctx->out, ctx->outlen);
return ARGON2_OK;
#undef SS
#undef SX
#undef SB
}
size_t b64len(uint32_t len) {
size_t olen = ((size_t)len / 3) << 2;
switch (len % 3) {
case 2:
olen++;
/* fall through */
case 1:
olen += 2;
break;
}
return olen;
}
size_t numlen(uint32_t num) {
size_t len = 1;
while (num >= 10) {
++len;
num = num / 10;
}
return len;
}
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