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As far as I know, in IGE mode (infinite garble extension) each block depends on the previous one.

In that case, can the encryption be parallelized? Is there some way to do it?

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  • $\begingroup$ Any reason why you'd use IGE? $\endgroup$ – CodesInChaos Mar 7 '15 at 22:40
  • $\begingroup$ Hi, welcome to cryptography Stack Exchange. Your message was migrated here from Security Stack Exchange, because it is about a mode of operation, and better answered here. Please create an account here using the same Mail address as you used as Security SE, to be able to claim your question, possibly edit it, and accept an answer. $\endgroup$ – Paŭlo Ebermann Mar 8 '15 at 17:33
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No, the IGE encryption cannot be parallelized. Also the decryption of IGE/ABC is serial.

The input to the block cipher for encryption is the ciphertext of the previous block xor'd with the plaintext (and the result is then xor'd with the previous block plaintext).

For decryption, you have to XOR the ciphertext with the plaintext of the previous block before decrypting (and then XOR the result with the previous ciphertext).

If either ciphertext or plaintext is not available, you cannot processes the next block, or any future block.

IGE encryption image

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  • $\begingroup$ @TildalWave the reason was in the question, the input to the next block depends on the ciphertext of the previous one, i will edit the answer with more detail $\endgroup$ – Richie Frame Mar 7 '15 at 21:51

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