/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/crypto
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rc4(3) 25/Feb/2000 (0.9.7e) rc4(3)
NAME
RC4_set_key, RC4 - RC4 encryption
SYNOPSIS
#include <openssl/rc4.h>
void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
unsigned char *outdata);
DESCRIPTION
This library implements the Alleged RC4 cipher, which is
described for example in Applied Cryptography. It is
believed to be compatible with RC4[TM], a proprietary cipher
of RSA Security Inc.
RC4 is a stream cipher with variable key length. Typically,
128 bit (16 byte) keys are used for strong encryption, but
shorter insecure key sizes have been widely used due to
export restrictions.
RC4 consists of a key setup phase and the actual encryption
or decryption phase.
RC4_set_key() sets up the RC4_KEY key using the len bytes
long key at data.
RC4() encrypts or decrypts the len bytes of data at indata
using key and places the result at outdata. Repeated RC4()
calls with the same key yield a continuous key stream.
Since RC4 is a stream cipher (the input is XORed with a
pseudo-random key stream to produce the output), decryption
uses the same function calls as encryption.
Applications should use the higher level functions
EVP_EncryptInit(3) etc. instead of calling the RC4 functions
directly.
RETURN VALUES
RC4_set_key() and RC4() do not return values.
NOTE
Certain conditions have to be observed to securely use
stream ciphers. It is not permissible to perform multiple
encryptions using the same key stream.
SEE ALSO
blowfish(3), des(3), rc2(3)
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rc4(3) 25/Feb/2000 (0.9.7e) rc4(3)
HISTORY
RC4_set_key() and RC4() are available in all versions of
SSLeay and OpenSSL.
Page 2 (printed 10/20/05)
