formats.h

著名的解Unix密码的源程序

/*
 * This file is part of John the Ripper password cracker,
 * Copyright (c) 1996-98 by Solar Designer
 */

/*
 * Supported ciphertext formats management.
 */

#ifndef _JOHN_FORMATS_H
#define _JOHN_FORMATS_H

/*
 * A password to test the methods for correct operation.
 */
struct fmt_tests {
	char *ciphertext, *plaintext;
};

/*
 * Parameters of a hash function and its cracking algorithm.
 */
struct fmt_params {
/* Label to refer to this format */
	char *label;

/* Ciphertext format name */
	char *format_name;

/* Cracking algorithm name */
	char *algorithm_name;

/* Comment about the benchmark (can be empty) */
	char *benchmark_comment;

/* Maximum length of a plaintext password */
	int plaintext_length;

/* Size of binary ciphertext used for fast comparison, in bytes */
	int binary_size;

/* Size of internal salt representation, in bytes */
	int salt_size;

/* Number of plaintexts hashed by a single crypt_all() method call */
	int min_keys_per_crypt;
	int max_keys_per_crypt;

/* Some passwords to test the methods for correct operation (or NULL for no
 * self test, and no benchmark), terminated with a NULL ciphertext. */
	struct fmt_tests *tests;
};

/*
 * Functions to implement a cracking algorithm.
 *
 * When passing binary ciphertexts or salts in internal representation, these
 * should be word aligned; the functions may assume such alignment.
 */
struct fmt_methods {
/* Initializes the algorithm's internal structures, valid() is the only
 * method that is allowed to be called before a call to init(). */
	void (*init)();

/* Checks if an ASCII ciphertext is valid for this format. Returns zero for
 * invalid ciphertexts, or a number of parts the ciphertext should be split
 * into (up to 9, will usually be 1). */
	int (*valid)(char *ciphertext);

/* Splits a ciphertext into several pieces, and returns the piece with given
 * index, starting from 0 (will usually return the ciphertext unchanged). */
	char *(*split)(char *ciphertext, int index);

/* Converts an ASCII ciphertext to binary, possibly using the salt */
	void *(*binary)(char *ciphertext);

/* Converts an ASCII salt to its internal representation */
	void *(*salt)(char *ciphertext);

/* These functions calculate a hash out of a binary ciphertext. To be used
 * for hash table initialization. One of the three should be used depending
 * on the hash table size. */
	int (*binary_hash[3])(void *binary);

/* Calculates a hash out of a salt (given in internal representation). To be
 * used by the password file loader. */
	int (*salt_hash)(void *salt);

/* Sets a salt for the crypt_all() method */
	void (*set_salt)(void *salt);

/* Sets a plaintext, with index from 0 to fmt_params.max_keys_per_crypt - 1 */
	void (*set_key)(char *key, int index);

/* Returns a plaintext previously set with set_key() */
	char *(*get_key)(int index);

/* Calculates the ciphertexts for given salt and plaintexts. This may
 * always calculate at least min_keys_per_crypt ciphertexts regardless of
 * the requested count, for some formats. */
	void (*crypt_all)(int count);

/* These functions calculate a hash out of a ciphertext that has just been
 * generated with the crypt_all() method. To be used while cracking. */
	int (*get_hash[3])(int index);

/* Compares a given ciphertext against all the crypt_all() method outputs and
 * returns zero if no matches detected. A non-zero return value means that
 * there might be matches, and more checks are needed. */
	int (*cmp_all)(void *binary, int count);

/* Same as the above, except the comparison is done against only one of the
 * crypt_all() method outputs. */
	int (*cmp_one)(void *binary, int index);

/* Compares an ASCII ciphertext against a particular crypt_all() output */
	int (*cmp_exact)(char *source, int index);
};

/*
 * Private fields for formats management.
 */
struct fmt_private {
	int initialized;
};

/*
 * A structure to keep a list of supported ciphertext formats.
 */
struct fmt_main {
	struct fmt_params params;
	struct fmt_methods methods;
	struct fmt_private private;
	struct fmt_main *next;
};

/*
 * Linked list of registered formats.
 */
extern struct fmt_main *fmt_list;

/*
 * Format registration function.
 */
extern void fmt_register(struct fmt_main *format);

/*
 * Initializes the format's internal structures unless already initialized.
 */
extern void fmt_init(struct fmt_main *format);

/*
 * Tests the format's methods for correct operation. Returns a non-zero value
 * on error.
 */
extern int fmt_self_test(struct fmt_main *format);

/*
 * Default methods.
 */
extern void fmt_default_init();
extern int fmt_default_valid(char *ciphertext);
extern char *fmt_default_split(char *ciphertext, int index);
extern void *fmt_default_binary(char *ciphertext);
extern void *fmt_default_salt(char *ciphertext);
extern int fmt_default_binary_hash(void *binary);
extern int fmt_default_salt_hash(void *salt);
extern int fmt_default_get_hash(int index);

/*
 * Dummy hash function to use for salts with no hash table.
 */
#define fmt_dummy_hash fmt_default_get_hash

#endif