NAME    [Toc]    [Back]

       acss, acss_setkey - ACSS encryption

SYNOPSIS    [Toc]    [Back]

        #include <openssl/acss.h>

        void acss_setkey(ACSS_KEY *key, const unsigned char  *data, int enc,
                int mode);

        void  acss(ACSS_KEY  *key,  unsigned  long len, const unsigned char *in,
                unsigned char *out);

DESCRIPTION    [Toc]    [Back]

       This library implements the Alleged Content Scrambling
       System.  It is believed to be interoperable with CSS of
       the DVD Copy Control Association.

       ACSS is a stream cipher with a fixed key length of 40 bit
       (5 byte).

       ACSS consists of a key setup phase and the actual encryption
 or decryption phase.

       acss_setkey() sets up the ACSS_KEY key using the 40 bit
       key at data.  If the flag enc is set to 1 key will be used
       for encryption, otherwise for decryption.  The integer
       mode denotes the mode to use.  Acceptible values are 0 to
       3.  For any other value mode 0 is used.

       acss() encrypts or decrypts the len bytes of in using key
       and places the result at out.

       Applications should use the higher level functions
       EVP_EncryptInit(3) etc.  instead of calling the acss functions
 directly.

RETURN VALUES    [Toc]    [Back]

       None of the functions presented here return any value.

NOTE    [Toc]    [Back]

       ACSS is considered as an insecure cipher.  Therefore, use
       of ACSS is discouraged.

SEE ALSO    [Toc]    [Back]

       RC4(3), arc4random(3)

History    [Toc]    [Back]

       A proprietary algorithm called CSS can be licensed from
       the DVD Copy Control Association (DVD CCA).  CSS is considered
 a trade secret and is not patented.  In October
       1999 source code for CSS was posted anonymously to the
       LiViD mailing list.  Since then, several implementations
       and mathematical descriptions of CSS are available and CSS
       has been subject to cryptanalysis.  The DVD CCA has
       repeatedly failed to sue individuals for publishing such
       information about CSS.

       ACSS is a stream cipher written from scratch and believed
       to be interoperable with CSS.


OpenBSD 3.6                 2004-01-23                          2