c - AES Encryption- large files -

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i doing aes encryption using evp interface of openssl in c language in 128/192/256 cbc modes. found nice example in stackoverflow have started programming.

what know is:

  1. what default padding used while encryption?
  2. what happens if have large data. have code divide data blocks of 128 bits? or evp interface takes care of it?
  3. what should size of iv 128bit, 192bit , 256bit cbc modes(where key lengths 128, 192, 256 respectively , block size 128)

thanks

  1. there no default padding encryption. there several padding schemes. evp there encrypt final method takes incomplete block , adds padding (default pkcs padding) , encrypts it.

  2. evp take care of it.

  3. size of iv vector when cbc mode used same size block size.


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