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shishi_decrypt(3)                   shishi                   shishi_decrypt(3)


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 (C) 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.

shishi                               1.0.2                   shishi_decrypt(3)

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