libgcrypt again: error "conflicting use" in gcry_pk_encrypt

[Claudia Reuter]

hi everybody.

so now I try to create a session key to encrypt my text files. this
seems to work. the session key must of course be encrypted with some
public key. Now an error "conflicting use" occurs in the gcry_pk_encrypt
function.

Maybe anyone could tell me what's wrong.

    gcry_md_open( &Hash , SelectedHash , 0 );
    // Retrive digest size
    HashDigestSize = gcry_md_get_algo_dlen( SelectedHash );

    Salt = (unsigned int*)gcry_random_bytes( SelectedSaltLength ,
GCRY_STRONG_RANDOM );

    // Add salt to hash
    gcry_md_write( Hash , Salt , SelectedSaltLength );

    // Fetch digest
    HashResult = gcry_md_read( Hash , SelectedHash );
   
    //HashResult = (unsigned char*)
malloc(SelectedSaltLength*sizeof(char));
    //gcry_randomize(HashResult, SelectedSaltLength, GCRY_STRONG_RANDOM);

    rc = gcry_sexp_build(&sexp, NULL, "(data (flags pkcs1) (hash sha256
%b))", HashDigestSize, HashResult);
   
    if(rc) {
        throw GeneralError( "Unable to build S-Expression. %s\n" ,
gpg_strerror( rc ) );
    }

    rc = gcry_pk_encrypt(&sexpSessionKey, sexp, pKey);
    if(rc) {
        throw GeneralError( "Unable to encrypt session key. %s\n",
gpg_strerror( rc ) );
    }

Thanks in advance.