diff options
| -rw-r--r-- | bigcrypt.c | 93 |
1 files changed, 26 insertions, 67 deletions
@@ -24,7 +24,7 @@ * Andy Phillips <atp@mssl.ucl.ac.uk> */ -#define _XOPEN_SOURCE +#define _XOPEN_SOURCE 700 #include <unistd.h> #include <string.h> @@ -36,80 +36,39 @@ * password). */ -#define MAX_PASS_LEN 16 +#define MAX_SEGMENTS 16 #define SEGMENT_SIZE 8 #define SALT_SIZE 2 -#define KEYBUF_SIZE ((MAX_PASS_LEN*SEGMENT_SIZE)+SALT_SIZE) #define ESEGMENT_SIZE 11 -#define CBUF_SIZE ((MAX_PASS_LEN*ESEGMENT_SIZE)+SALT_SIZE+1) -char *bigcrypt(const char *key, const char *salt) -{ - static char dec_c2_cryptbuf[CBUF_SIZE]; /* static storage area */ +char *bigcrypt(char const * key, char const * salt) { + static char outbuf[MAX_SEGMENTS * ESEGMENT_SIZE + SALT_SIZE + 1]; /* static storage area */ - unsigned long int keylen, n_seg, j; - char *cipher_ptr, *plaintext_ptr, *tmp_ptr, *salt_ptr; - char keybuf[KEYBUF_SIZE + 1]; + unsigned char n_seg, seg; + char * outptr; - /* reset arrays */ - memset(keybuf, 0, KEYBUF_SIZE + 1); - memset(dec_c2_cryptbuf, 0, CBUF_SIZE); + /* ensure NUL-termination */ + memset(outbuf, 0, sizeof(outbuf)); - /* fill KEYBUF_SIZE with key */ - strncpy(keybuf, key, KEYBUF_SIZE); - - /* deal with case that we are doing a password check for a - conventially encrypted password: the salt will be - SALT_SIZE+ESEGMENT_SIZE long. */ - if (strlen(salt) == (SALT_SIZE + ESEGMENT_SIZE)) - keybuf[SEGMENT_SIZE] = '\0'; /* terminate password early(?) */ - - keylen = strlen(keybuf); - - if (!keylen) { + if (strlen(salt) == (SALT_SIZE + ESEGMENT_SIZE)) /* conventional crypt */ n_seg = 1; - } else { - /* work out how many segments */ - n_seg = 1 + ((keylen - 1) / SEGMENT_SIZE); - } - - if (n_seg > MAX_PASS_LEN) - n_seg = MAX_PASS_LEN; /* truncate at max length */ - - /* set up some pointers */ - cipher_ptr = dec_c2_cryptbuf; - plaintext_ptr = keybuf; - - /* do the first block with supplied salt */ - tmp_ptr = crypt(plaintext_ptr, salt); /* libc crypt() */ - - /* and place in the static area */ - strncpy(cipher_ptr, tmp_ptr, 13); - cipher_ptr += ESEGMENT_SIZE + SALT_SIZE; - plaintext_ptr += SEGMENT_SIZE; /* first block of SEGMENT_SIZE */ - - /* change the salt (1st 2 chars of previous block) - this was found - by dowsing */ - - salt_ptr = cipher_ptr - ESEGMENT_SIZE; - - /* so far this is identical to "return crypt(key, salt);", if - there is more than one block encrypt them... */ - - if (n_seg > 1) { - for (j = 2; j <= n_seg; j++) { - - tmp_ptr = crypt(plaintext_ptr, salt_ptr); - - /* skip the salt for seg!=0 */ - strncpy(cipher_ptr, (tmp_ptr + SALT_SIZE), ESEGMENT_SIZE); - - cipher_ptr += ESEGMENT_SIZE; - plaintext_ptr += SEGMENT_SIZE; - salt_ptr = cipher_ptr - ESEGMENT_SIZE; - } + else if (key[0] == '\0') + n_seg = 1; + else + n_seg = (strnlen(key, MAX_SEGMENTS * SEGMENT_SIZE) + SEGMENT_SIZE - 1) / SEGMENT_SIZE; + + /* first block is special and just traditional crypt() */ + outptr = outbuf; + strncpy(outptr, crypt(key, salt), SALT_SIZE + ESEGMENT_SIZE); + + for (seg = 1, outptr += SALT_SIZE; seg < n_seg; ++seg) { + /* subsequent blocks use the previous output block for salt input */ + salt = outptr; + key += SEGMENT_SIZE; + outptr += ESEGMENT_SIZE; + /* and omit the salt on output */ + strncpy(outptr, crypt(key, salt) + SALT_SIZE, ESEGMENT_SIZE); } - /* this is the <NUL> terminated encrypted password */ - return dec_c2_cryptbuf; + return outbuf; } |