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radsecproxy/fticks_hashmac.c
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/* Copyright (c) 2011,2013, NORDUnet A/S */ | |
/* See LICENSE for licensing information. */ | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <errno.h> | |
#include <ctype.h> | |
#include <nettle/sha.h> | |
#include <nettle/hmac.h> | |
#include "fticks_hashmac.h" | |
/** \a HASH is an input buffer of length SHA256_DIGEST_SIZE bytes. | |
\a OUT_LEN is the size in bytes of \OUT. | |
\a OUT is an output buffer of length \a OUT_LEN. */ | |
static void | |
_format_hash(const uint8_t *hash, size_t out_len, uint8_t *out) | |
{ | |
int ir, iw; | |
if (out_len < 3) { | |
memset(out, 0, out_len); | |
return; | |
} | |
for (ir = 0, iw = 0; iw <= out_len - 3; ir++, iw += 2) | |
sprintf((char *) out + iw, "%02x", hash[ir % SHA256_DIGEST_SIZE]); | |
} | |
static void | |
_hash(const uint8_t *in, | |
const uint8_t *key, | |
size_t out_len, | |
uint8_t *out) | |
{ | |
if (key == NULL) { | |
struct sha256_ctx ctx; | |
uint8_t hash[SHA256_DIGEST_SIZE]; | |
sha256_init(&ctx); | |
sha256_update(&ctx, strlen((char *) in), in); | |
sha256_digest(&ctx, sizeof(hash), hash); | |
_format_hash(hash, out_len, out); | |
} | |
else { | |
struct hmac_sha256_ctx ctx; | |
uint8_t hash[SHA256_DIGEST_SIZE]; | |
hmac_sha256_set_key(&ctx, strlen((char *) key), key); | |
hmac_sha256_update(&ctx, strlen((char *) in), in); | |
hmac_sha256_digest(&ctx, sizeof(hash), hash); | |
_format_hash(hash, out_len, out); | |
} | |
} | |
/** Hash the Ethernet MAC address in \a IN, keying a HMAC with \a KEY | |
unless \a KEY is NULL. If \a KEY is null \a IN is hashed with an | |
ordinary cryptographic hash function such as SHA-2. | |
\a IN and \a KEY are NUL terminated strings. | |
\a IN is supposed to be an Ethernet MAC address and is sanitised | |
by lowercasing it, removing all but [0-9a-f] and truncating it at | |
the first ';' found. The truncation is done because RADIUS | |
supposedly has a praxis of tacking on SSID to the MAC address in | |
Calling-Station-Id. | |
The resulting hash value is written to \a OUT as a NUL terminated | |
string of numbers in two-digit hexadecimal ASCII representation. | |
Exactly \a OUT_LEN bytes are written to \a OUT, based on the first | |
(\a OUT_LEN - 1) / 2 bytes of the hash. Note that in the case when | |
\OUT_LEN - 1 is more than two times the length of the hash, the | |
output is repeated by concatinating another hex ASCII | |
representation of the hash to the output until the buffer is full. | |
\return 0 on success, -ENOMEM on out of memory. | |
*/ | |
int | |
fticks_hashmac(const uint8_t *in, | |
const uint8_t *key, | |
size_t out_len, | |
uint8_t *out) | |
{ | |
uint8_t *in_copy = NULL; | |
uint8_t *p = NULL; | |
int i; | |
in_copy = calloc(1, strlen((const char *) in) + 1); | |
if (in_copy == NULL) | |
return -ENOMEM; | |
/* Sanitise and lowercase 'in' into 'in_copy'. */ | |
for (i = 0, p = in_copy; in[i] != '\0'; i++) { | |
if (in[i] == ';') { | |
*p++ = '\0'; | |
break; | |
} | |
if (in[i] >= '0' && in[i] <= '9') { | |
*p++ = in[i]; | |
} | |
else if (tolower(in[i]) >= 'a' && tolower(in[i]) <= 'f') { | |
*p++ = tolower(in[i]); | |
} | |
} | |
_hash(in_copy, key, out_len, out); | |
free(in_copy); | |
return 0; | |
} | |
/* Local Variables: */ | |
/* c-file-style: "stroustrup" */ | |
/* End: */ |