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mycrypt.c
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mycrypt.c
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/**
* \file mycrypt.c
*
* \brief Password encryption for PennMUSH
*
* Routines for hashing passwords and comparing against them.
* Also see player.c.
*/
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <openssl/sha.h>
#include <openssl/evp.h>
#include "conf.h"
#include "mypcre.h"
#include "log.h"
#include "notify.h"
#include "strutil.h"
#include "externs.h"
#define PASSWORD_HASH "sha512"
bool decode_base64(char *encoded, int len, bool printonly, char *buff,
char **bp);
bool check_mux_password(const char *saved, const char *password);
char *mush_crypt_sha0(const char *key);
int safe_hash_byname(const char *algo, const char *plaintext, int len,
char *buff, char **bp, bool inplace_err);
char *password_hash(const char *key, const char *algo);
bool password_comp(const char *saved, const char *pass);
/** Encrypt a password and return ciphertext, using SHA0. Icky old
* style password format, used for migrating to new style.
*
* \param key plaintext to encrypt.
* \return encrypted password.
*/
char *
mush_crypt_sha0(const char *key)
{
#ifdef HAVE_SHA
static char crypt_buff[70];
uint8_t hash[SHA_DIGEST_LENGTH];
unsigned int a, b;
SHA((uint8_t *) key, strlen(key), hash);
memcpy(&a, hash, sizeof a);
memcpy(&b, hash + sizeof a, sizeof b);
if (options.reverse_shs) {
int ra, rb;
ra = (a << 16) | (a >> 16);
rb = (b << 16) | (b >> 16);
a = ((ra & 0xFF00FF00L) >> 8) | ((ra & 0x00FF00FFL) << 8);
b = ((rb & 0xFF00FF00L) >> 8) | ((rb & 0x00FF00FFL) << 8);
}
/* TODO: SHA-0 is already considered insecure, but due to the lack of
* delimiters, this matches far more than it should. For example, suppose
* a= 23 and b=456. Anything which hashed to a=1, b=23456 or a=12, b=3456
* would also erroneously match! */
sprintf(crypt_buff, "XX%u%u", a, b);
return crypt_buff;
#else
return "";
#endif
}
/** Hash a string and store it base-16 encoded in a buffer.
* \param algo the name of the hash algorithm (sha1, md5, etc.)
* \param plaintext the text to hash.
* \param len length of text to hash.
* \param buff where to store it.
* \param bp pointer into buff to store at.
* \param inplace_err true to put error messages in buff.
* \return 1 on failure, 0 on success.
*/
int
safe_hash_byname(const char *algo, const char *plaintext, int len, char *buff,
char **bp, bool inplace_err)
{
EVP_MD_CTX ctx;
const EVP_MD *md;
uint8_t hash[EVP_MAX_MD_SIZE];
unsigned int rlen = EVP_MAX_MD_SIZE;
md = EVP_get_digestbyname(algo);
if (!md) {
if (inplace_err)
safe_str(T("#-1 UNSUPPORTED DIGEST TYPE"), buff, bp);
else
do_rawlog(LT_ERR,
"safe_hash_byname: Unknown password hash function: %s", algo);
return 1;
}
EVP_DigestInit(&ctx, md);
EVP_DigestUpdate(&ctx, plaintext, len);
EVP_DigestFinal(&ctx, hash, &rlen);
return safe_hexstr(hash, rlen, buff, bp);
}
bool
check_mux_password(const char *saved, const char *password)
{
EVP_MD_CTX ctx;
const EVP_MD *md;
uint8_t hash[EVP_MAX_MD_SIZE];
unsigned int rlen = EVP_MAX_MD_SIZE;
char decoded[BUFFER_LEN];
char *dp;
char *start, *end;
start = (char *) saved;
/* MUX passwords start with a '$' */
if (*start != '$')
return 0;
start++;
/* The next '$' marks the end of the encryption algo */
end = strchr(start, '$');
if (end == NULL)
return 0;
*end++ = '\0';
md = EVP_get_digestbyname(start);
if (!md)
return 0;
start = end;
/* Up until the next '$' is the salt. After that is the password */
end = strchr(start, '$');
if (end == NULL)
return 0;
*end++ = '\0';
/* 'start' now holds the salt, 'end' the password.
* Both are base64-encoded. */
/* decode the salt */
dp = decoded;
decode_base64(start, strlen(start), 0, decoded, &dp);
*dp = '\0';
/* Double-hash the password */
EVP_DigestInit(&ctx, md);
EVP_DigestUpdate(&ctx, start, strlen(start));
EVP_DigestUpdate(&ctx, password, strlen(password));
EVP_DigestFinal(&ctx, hash, &rlen);
/* Decode the stored password */
dp = decoded;
decode_base64(end, strlen(end), 0, decoded, &dp);
*dp = '\0';
/* Compare stored to hashed */
return (memcmp(decoded, hash, rlen) == 0);
}
/** Encrypt a password and return the formatted password
* string. Supports user-supplied algorithms. Password format:
*
* V:ALGO:HASH:TIMESTAMP
*
* V is the version number (Currently 2), ALGO is the digest algorithm
* used (Default is SHA1), HASH is the hashed password. TIMESTAMP is
* when it was set. If fields are added, the version gets bumped.
*
* HASH is salted; the first two characters of the hashed password are
* randomly chosen characters that are added to the start of the
* plaintext password before it's hashed. This way two characters with
* the same password will have different hashed ones.
*
* \param key The plaintext password to hash.
* \param algo The digest algorithm to use. If NULL, uses SHA-1.
* \return A static buffer holding the formatted password string.
*/
char *
password_hash(const char *key, const char *algo)
{
static char buff[BUFFER_LEN];
static char *salts =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
char s1, s2;
char *bp;
int len;
if (!algo)
algo = PASSWORD_HASH;
len = strlen(key);
s1 = salts[get_random32(0, 61)];
s2 = salts[get_random32(0, 61)];
bp = buff;
safe_strl("2:", 2, buff, &bp);
safe_str(algo, buff, &bp);
safe_chr(':', buff, &bp);
safe_chr(s1, buff, &bp);
safe_chr(s2, buff, &bp);
safe_hash_byname(algo, tprintf("%c%c%s", s1, s2, key), len + 2, buff, &bp, 0);
safe_chr(':', buff, &bp);
safe_time_t(time(NULL), buff, &bp);
*bp = '\0';
return buff;
}
extern const unsigned char *tables;
/** Compare a plaintext password against a hashed password.
*
* \param saved The contents of a player's password attribute.
* \param pass The plain-text password.
* \return true or false.
*/
bool
password_comp(const char *saved, const char *pass)
{
static pcre *passwd_re = NULL;
static pcre_extra *extra = NULL;
char buff[BUFFER_LEN], *bp;
const char *version = NULL, *algo = NULL, *shash = NULL;
int len, slen;
int ovec[30];
int c, r;
int retval = 0;
if (!passwd_re) {
static const char re[] = "^(\\d+):(\\w+):([0-9a-zA-Z]+):\\d+";
const char *errptr;
int erroffset = 0;
passwd_re = pcre_compile(re, 0, &errptr, &erroffset, tables);
if (!passwd_re) {
do_rawlog(LT_ERR, "Unable to compile password regexp: %s, at '%c'",
errptr, re[erroffset]);
return 0;
}
extra = pcre_study(passwd_re, pcre_study_flags, &errptr);
}
len = strlen(pass);
slen = strlen(saved);
if ((c = pcre_exec(passwd_re, extra, saved, slen, 0, 0, ovec, 30)) <= 0) {
/* Not a well-formed password string. */
return 0;
}
pcre_get_substring(saved, ovec, c, 1, &version);
pcre_get_substring(saved, ovec, c, 2, &algo);
pcre_get_substring(saved, ovec, c, 3, &shash);
/* Hash the plaintext password using the right digest */
bp = buff;
if (strcmp(version, "1") == 0) {
r = safe_hash_byname(algo, pass, len, buff, &bp, 0);
} else if (strcmp(version, "2") == 0) {
/* Salted password */
safe_chr(shash[0], buff, &bp);
safe_chr(shash[1], buff, &bp);
r =
safe_hash_byname(algo, tprintf("%c%c%s", shash[0], shash[1], pass),
len + 2, buff, &bp, 0);
} else {
/* Unknown password format version */
retval = 0;
goto cleanup;
}
if (r) {
retval = 0;
goto cleanup;
}
/* And compare against the saved one */
*bp = '\0';
retval = strcmp(shash, buff) == 0;
cleanup:
pcre_free_substring(version);
pcre_free_substring(algo);
pcre_free_substring(shash);
return retval;
}