Public Key encryption

[Rüdiger Sonderfeld]

hi,
okay I don't understand the use of the gcrypt public key functions! I want to 
write a wrapper function like this

typedef GCRY_SEXP pkkey;

int pk_encrypt(pkkey pkey, unsigned char *data, unsigned char *to)
{
  /*...*/
}

but I don't know! The gcry_pk_encrypt function don't accept unsigned char* 
(only GCRY_SEXP).

What to do?