Present Day
| The Enigma cipher machine |
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Modern ciphers such as Advanced Encryption Standard are not currently susceptible to known-plaintext attacks.
The PKZIP stream cipher used by older versions of the zip format specification is prone to this attack. For example, an attacker with an encrypted ZIP file needs only (part of) one unencrypted file from the archive which forms the "known-plaintext". Then using some publicly available software they can quickly calculate the key required to decrypt the entire archive. To obtain this unencrypted file the attacker could search the website for a suitable file, find it from another archive they can open, or manually try to reconstruct a plaintext file armed with the knowledge of the filename from the encrypted archive. However, the attack does not work on AES-encrypted zip files.
Read more about this topic: Known-plaintext Attack
Famous quotes containing the words present and/or day:
“There is too much sour grapes for my taste in the present American attitude. The time to denounce the bankers was when we were all feeding off their gold plate; not now! At present they have not only my sympathy but my preference. They are the last representatives of our native industries.”
—Edith Wharton (1862–1937)
“I see every day more clearly the value, necessity, and sanative qualities of the three B’s: Bench, Ballot, Barricade.”
—Aurora C. Phelps, U.S. women’s magazine contributor. The Revolution (May 21, 1868)