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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.