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added reference to Hash CFB
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Alexandre Yamajako
Alexandre Yamajako
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It's not clear from your decryption what the algorithm is used for.

But you should be aware that while at first glance it provides privacy : it's a weird mode CFB with md5 used as a block cipher ; it doesn't provide authenticity. A simple bit flip of the ciphertext will result in the corresponding bit being flipped in the plaintext and such a bit flip won't be noticeable if it happens on the last block of input.

Addendum : I just recalled that long before your question I had read something a bit like your proposal that would enjoy both privacy and authenticity Hash CFB (see slide 5)

It's not clear from your decryption what the algorithm is used for.

But you should be aware that while at first glance it provides privacy : it's a weird mode CFB with md5 used as a block cipher ; it doesn't provide authenticity. A simple bit flip of the ciphertext will result in the corresponding bit being flipped in the plaintext and such a bit flip won't be noticeable if it happens on the last block of input.

It's not clear from your decryption what the algorithm is used for.

But you should be aware that while at first glance it provides privacy : it's a weird mode CFB with md5 used as a block cipher ; it doesn't provide authenticity. A simple bit flip of the ciphertext will result in the corresponding bit being flipped in the plaintext and such a bit flip won't be noticeable if it happens on the last block of input.

Addendum : I just recalled that long before your question I had read something a bit like your proposal that would enjoy both privacy and authenticity Hash CFB (see slide 5)

Source Link
Alexandre Yamajako
Alexandre Yamajako
  • 1.1k
  • 6
  • 6

It's not clear from your decryption what the algorithm is used for.

But you should be aware that while at first glance it provides privacy : it's a weird mode CFB with md5 used as a block cipher ; it doesn't provide authenticity. A simple bit flip of the ciphertext will result in the corresponding bit being flipped in the plaintext and such a bit flip won't be noticeable if it happens on the last block of input.