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I'm trying to understand RSA encryption (as a beginner in cryptography).

  1. go on this wiki page http://en.wikipedia.org/wiki/Optimal_asymmetric_encryption_padding
  2. scroll down to the 2 numbered points: "OAEP satisfies the following two goals:"
  3. The 2nd point says "Prevent partial decryption of ciphertexts".

Say that an attacker attacks a an RSA crypto system that does not prevent the partial decryption of ciphertexts.

What happens if an attacker can decrypt a small part of a string (e.g. 2bits out of 10) using the public key? What information can the attacker retrieve from the decrypted?

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  • $\begingroup$ Note: I've substantially edited the question above to make it at least legible. If anything is not clear, please take a look at the initial question by clicking on the time of the last edit. $\endgroup$ – Maarten Bodewes Nov 26 '14 at 15:37
  • $\begingroup$ Quick hint: contrast to the scheme attacked in this reference, and its reference 2. $\endgroup$ – fgrieu Nov 26 '14 at 18:09

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