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 day, present and/or day:
“The East knew and to the present day knows only that One is Free; the Greek and the Roman world, that some are free; the German World knows that All are free. The first political form therefore which we observe in History, is Despotism, the second Democracy and Aristocracy, the third, Monarchy.”
—Georg Wilhelm Friedrich Hegel (1770–1831)
“yet when all is said
It was the dream itself enchanted me:
Character isolated by a deed
To engross the present and dominate memory.”
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—Ralph Waldo Emerson (1803–1882)