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)
HISTORY
RC4_set_key() and RC4() are available in all versions of SSLeay
and OpenSSL.
