CIPHER(3) Library Functions Manual CIPHER(3)
NAME
**setkey**, **encrypt**, **des_setkey**, **des_cipher**, — DES encryption
SYNOPSIS
*int*
**setkey**(*char *key*);
*int*
**encrypt**(*char *block*, *int flag*);
*int*
**des_setkey**(*const char *key*);
*int*
**des_cipher**(*const char *in*, *char *out*, *long salt*, *int count*);
DESCRIPTION
The functions, **encrypt**(), **setkey**(), **des_setkey**() and **des_cipher**() provide
access to the DES algorithm. **setkey**() is passed a 64-byte array of
binary values (numeric 0 or 1). A 56-bit key is extracted from this
array by dividing the array into groups of 8, and ignoring the last bit
in each group. That bit is reserved for a byte parity check by DES, but
is ignored by these functions.
The *block *argument to **encrypt**() is also a 64-byte array of binary values.
If the value of *flag *is 0, *block *is encrypted otherwise it is decrypted.
The result is returned in the original array *block *after using the key
specified by **setkey**() to process it.
The argument to **des_setkey**() is a character array of length 8. The least
significant bit (the parity bit) in each character is ignored, and the
remaining bits are concatenated to form a 56-bit key. The function
**des_cipher**() encrypts (or decrypts if *count *is negative) the 64-bits
stored in the 8 characters at *in *using abs(3) of *count *iterations of DES
and stores the 64-bit result in the 8 characters at *out *(which may be the
same as *in *). The *salt *introduces disorder in the DES algorithm in one
of 16777216 or 4096 possible ways (ie. with 24 or 12 bits: if bit *i *of
the *salt *is set, then bits *i *and *i+24 *are swapped in the DES E-box
output).
The functions **setkey**(), **encrypt**(), **des_setkey**(), and **des_cipher**() return
0 on success and 1 on failure.
The **setkey**() and **des_setkey**() functions manipulate the same key space.
SEE ALSO
login(1), passwd(1), getpass(3), crypt(3), passwd(5)
HISTORY
This library (FreeSec 1.0) was developed outside the United States of
America as an unencumbered replacement for the U.S.-only NetBSD libcrypt
encryption library. Users should be aware that this code (and programs
staticly linked with it) may not be exported from the U.S., although it
apparently can be imported.
AUTHOR
David Burren <davidb@werj.com.au>
FreeSec 1.0 March 9, 1994 FreeSec 1.0