NAME    [Toc]    [Back]

       RC4_set_key, RC4 - RC4 encryption

SYNOPSIS    [Toc]    [Back]

        #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    [Toc]    [Back]

       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    [Toc]    [Back]

       RC4_set_key() and RC4() do not return values.

NOTE    [Toc]    [Back]

       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    [Toc]    [Back]

       blowfish(3), des(3), rc2(3)

HISTORY    [Toc]    [Back]

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


OpenBSD 3.6                 2000-03-19                          2