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:
“When the cross blue lightning seemed to open
The breast of heaven, I did present myself
Even in the aim and very flash of it.”
—William Shakespeare (1564–1616)
“Then down came the lid—the day was lost, for art, at Sarajevo. World-politics stepped in, and a war was started which has not ended yet: a “war to end war.” But it merely ended art. It did not end war.”
—Wyndham Lewis (1882–1957)