code: 9ferno

ref: 44ce0097b612a1fefd754065bdf8d9d2e5ef60c8
dir: /man/2/crypt-rc4/

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.TH CRYPT-RC4 2
.SH NAME
crypt: rc4setup, rc4, rc4skip, rc4back \- RC4 encryption
.SH SYNOPSIS
.EX
include "ipints.m";
ipints := load IPints IPints->PATH;
IPint: import ipints;

include "crypt.m";
crypt := load Crypt Crypt->PATH;

rc4setup: fn(seed: array of byte): ref RC4state;
rc4:      fn(state: ref RC4state, buf: array of byte, n: int);
rc4skip:  fn(state: ref RC4state, n: int);
rc4back:  fn(state: ref RC4state, n: int);
.EE
.SH DESCRIPTION
These functions implement the stream encryption algorithm that is claimed to
be equivalent to RSA Security's RC4.
It is a pseudo-random number generator with a 256
byte state and a long cycle.
.PP
.B Rc4setup
sets the initial
.IR seed ,
which can be any non-zero length, and
returns a representation of the initial state of the algorithm,
which is used in subsequent calls.
.PP
.B Rc4
runs the generator starting with the given
.IR state ,
and XORs the output of the generator with
the first
.I n
bytes of
.IR buf ,
updating the
.IR state .
.B Rc4
is symmetric and is used both to encrypt and decrypt.
.B Rc4skip
skips over bytes (eg, to account for lost transmissions);
.B rc4back
runs the generator backwards (eg, to account for retransmissions).
.SH SEE ALSO
.IR crypt-intro (2),
.IR crypt-crypt (2)