On Jun 1, 1:52 am, Paul Subramanian <[email protected]> wrote: > Hi, > I am new to cryptography and I inherited the code from someone else. > We are doing AES-CBC encryption in pieces and after each piece I was > told that IV vector needs to change. > > Initially the code was > e_CBC.SetKeyWithIV( m_crypto_encryption_packet_h.encr_key, key_size / > 8, m_crypto_encryption_packet_h.encr_cntr_iv ); > > StringSource( m_crypto_encryption_packet_h.encr_data_in, > crypto_encr_seg_size, true, new StreamTransformationFilter( e_CBC, new > ArraySink( m_crypto_encryption_packet_h.encr_data_out, > crypto_encr_seg_size), StreamTransformationFilter::NO_PADDING)); > > I tried to the add the following lines for IV vector update > e_CBC.GetNextIV(NullRNG(), m_crypto_encryption_packet_h.encr_cntr_iv); > This doesn't change the IV vector > > e_CBC.GetNextIV(RandomPool(), > m_crypto_encryption_packet_h.encr_cntr_iv); > This changes the vector but the encryption output is not what I expect > > Can someone provide me a sample code on what I should be doing. The library handles IV updates internally. There is no need to do it yourself. See http://www.cryptopp.com/wiki/Cbc for a couple of examples.
To see how to put in a few bytes at a time (and extract bytes in block size chunks), see the paragraph that starts with "To manually insert bytes into the filter...". Be sure to call MessageEnd() so the encryptor will add padding and finish encrypting the data. Jeff -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [email protected]. More information about Crypto++ and this group is available at http://www.cryptopp.com.
