RC4

rc4(3)                              OpenSSL                             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 decryp-
       tion 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.



0.9.7a                            2000-02-25                            rc4(3)