1=pod 2 3=head1 NAME 4 5RC4_set_key, RC4 - RC4 encryption 6 7=head1 SYNOPSIS 8 9 #include <openssl/rc4.h> 10 11 void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data); 12 13 void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata, 14 unsigned char *outdata); 15 16=head1 DESCRIPTION 17 18This library implements the Alleged RC4 cipher, which is described for 19example in I<Applied Cryptography>. It is believed to be compatible 20with RC4[TM], a proprietary cipher of RSA Security Inc. 21 22RC4 is a stream cipher with variable key length. Typically, 128 bit 23(16 byte) keys are used for strong encryption, but shorter insecure 24key sizes have been widely used due to export restrictions. 25 26RC4 consists of a key setup phase and the actual encryption or 27decryption phase. 28 29RC4_set_key() sets up the B<RC4_KEY> B<key> using the B<len> bytes long 30key at B<data>. 31 32RC4() encrypts or decrypts the B<len> bytes of data at B<indata> using 33B<key> and places the result at B<outdata>. Repeated RC4() calls with 34the same B<key> yield a continuous key stream. 35 36Since RC4 is a stream cipher (the input is XORed with a pseudo-random 37key stream to produce the output), decryption uses the same function 38calls as encryption. 39 40Applications should use the higher level functions 41L<EVP_EncryptInit(3)|EVP_EncryptInit(3)> 42etc. instead of calling the RC4 functions directly. 43 44=head1 RETURN VALUES 45 46RC4_set_key() and RC4() do not return values. 47 48=head1 NOTE 49 50Certain conditions have to be observed to securely use stream ciphers. 51It is not permissible to perform multiple encryptions using the same 52key stream. 53 54=head1 SEE ALSO 55 56L<blowfish(3)|blowfish(3)>, L<des(3)|des(3)>, L<rc2(3)|rc2(3)> 57 58=head1 HISTORY 59 60RC4_set_key() and RC4() are available in all versions of SSLeay and OpenSSL. 61 62=cut 63