# Tag Info

1

TL;DR: This attack extends the standard chosen ciphertext attacks on RSA and ElGamal to the hybrid encryption setting, but requires some huge IFs which no longer even have a slight possibility of being fulfilled. To understand this attack, one first needs to understand how data is encrypted for PGP according to this snippet. Let's assume you have a ...

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RFC 4880, OpenPGP (superseded RFC 2440 which was up to date in 2002) contains a chapter on security considerations, which also discusses the decryption oracle attack Jallad et al described: In late summer 2002, Jallad, Katz, and Schneier published an interesting attack on the OpenPGP protocol and some of its implementations [JKS02]. In ...

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Tape is a basic concept from Turing machines. The random tape is the tape with random bits on it.

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As SEJPM said in his comment: one proceeds by contrapositive, first suppose that such an adversary with an unfair advantage exists and use that adversary to break a well known assumption, e.g.: the adversary can be used to factorise a large composite integer (as defined in RSA). As of today, we have no efficient algorithm to factorise large composite ...

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Scheme is not IND-CPA for any message longer than one block. I'll include a image of CBC mode below for reference (Source: Wikipedia). Suppose instead of block cipher encryption we have plaintext xor-ed with the key as you propose. You'll note that for message block 1, $M_1$, the ciphertext block $C_1 = M_1 \oplus IV \oplus Key$. Similarly \$C_2 = M_2 ...

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