NAME

       shishi_decrypt - API function

SYNOPSIS

       #include <shishi.h>

       int  shishi_decrypt(Shishi  *  handle,  Shishi_key  *  key, int keyusage, const char * in,
       size_t inlen, char ** out, size_t * outlen);

ARGUMENTS

       Shishi * handle
                   shishi handle as allocated by shishi_init().

       Shishi_key * key
                   key to decrypt with.

       int keyusage
                   integer specifying what this key is decrypting.

       const char * in
                   input array with data to decrypt.

       size_t inlen
                   size of input array with data to decrypt.

       char ** out output array with newly allocated decrypted data.

       size_t * outlen
                   output variable with size of newly allocated output array.

DESCRIPTION

       Decrypts data specified key.  The key actually used is derived using the  key  usage.   If
       key  usage  is  0,  no  key derivation is used.  The OUT buffer must be deallocated by the
       caller.  The default IV is used, see shishi_decrypt_iv if you need to alter it.  The  next
       IV is lost, see shishi_decrypt_ivupdate if you need it.

       Note that DECRYPT(ENCRYPT(data)) does not necessarily yield data exactly.  Some encryption
       types add pad to make the data fit into  the  block  size  of  the  encryption  algorithm.
       Furthermore,  the  pad  is  not  guaranteed  to look in any special way, although existing
       implementations often pad with the zero byte.  This means that you  may  have  to  "frame"
       data,  so it is possible to infer the original length after decryption.  Compare ASN.1 DER
       which contains such information.

RETURN VALUE

       Returns SHISHI_OK iff successful.

REPORTING BUGS

       Report bugs to <bug-shishi@gnu.org>.

COPYRIGHT

       Copyright © 2002-2010 Simon Josefsson.
       Copying and distribution of this file, with or without modification, are permitted in  any
       medium without royalty provided the copyright notice and this notice are preserved.

SEE ALSO

       The  full  documentation  for  shishi  is maintained as a Texinfo manual.  If the info and
       shishi programs are properly installed at your site, the command

              info shishi

       should give you access to the complete manual.