#StackBounty: #encryption #aes #cbc Does reusing IV in AES-CBC weaken it?

Bounty: 50

Rsynccrypto allegedly uses AES-CBC with a twist: If the last few bytes of plaintext meet a condition*, then stop, pad the current block and start encrypting new block from the current position in file while reusing the IV.
Better example might be in pseudocode:

if (trigger(buffer, i)) {
  encrypt_next_block(buffer, i);
  init_encryption(iv);
} else if(is_block_boundary(i)) {
  encrypt_next_block(buffer, i)
}

You can check the code here

Does that weaken the encryption somehow? If so, how?

* The exact condition is sum of the last 8196 bytes mod 4096 equals 0.


Get this bounty!!!

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