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:
“To think the world therefore a general Bedlam, or place of madmen, and oneself a physician, is the most necessary point of present wisdom: an important imagination, and the way to happiness.”
—Thomas Traherne (1636–1674)
“Tomorrow, and tomorrow, and tomorrow
Creeps in this petty pace from day to day
To the last syllable of recorded time,
And all our yesterdays have lighted fools
The way to dusty death.”
—William Shakespeare (1564–1616)