libgrypt and symmetric block cipher

[backus]

i have a program which have to encrypt data by using a symmetric block cipher with cbc encryption mode . it seems, that the IN data length must be a multiple of the cipher block length. is there a possibility to advice libgrypt to do the padding of the IN buffer automatically or must i do this manually?

in case of manual padding: what is the recommended strategy to perform high security? fill with zeros or random numbers or ...?

language: c
library: libgcrypt

[Kloschüssel]

*hm*

Since the previous cyphers are propagated to the latter, I would doubt if it would significantly degrade the algorithm by using zeros. And this doesn't mean I would encourage someone to use this encryption method.