Caesar cipher: Difference between revisions
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imported>Howard C. Berkowitz (New page: {{subpages}} An early and simple substitution cipher was the Caesar cipher, in which each letter in the plaintext was replaced by a letter some fixed number of positions further down t...) |
imported>Sandy Harris (rot 13 link) |
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An early and simple substitution cipher was the [[Caesar cipher]], in which each letter in the plaintext was replaced by a letter some fixed number of positions further down the alphabet. It was named after [[Julius Caesar]] who used the cipher with a shift of 3 in order to communicate with his generals during his various military campaigns. | An early and simple substitution cipher was the [[Caesar cipher]], in which each letter in the plaintext was replaced by a letter some fixed number of positions further down the alphabet. It was named after [[Julius Caesar]] who used the cipher with a shift of 3 in order to communicate with his generals during his various military campaigns. | ||
For example, with a shift of 3, "BAD DOG" would become "EDG GRJ". This type of encryption is trivial to [[cryptanalysis]] using [[frequency analysis]]. | For example, with a shift of 3, "BAD DOG" would become "EDG GRJ". This type of encryption is trivial to [[cryptanalysis | cryptanalize]] using [[frequency analysis]]. | ||
One Caesar cipher is still in use; [[rot 13]] is used to hide "spoilers" such as the ending of a movie in Internet discussions. It is not used for any serious security. | |||
Revision as of 00:32, 30 November 2008
An early and simple substitution cipher was the Caesar cipher, in which each letter in the plaintext was replaced by a letter some fixed number of positions further down the alphabet. It was named after Julius Caesar who used the cipher with a shift of 3 in order to communicate with his generals during his various military campaigns.
For example, with a shift of 3, "BAD DOG" would become "EDG GRJ". This type of encryption is trivial to cryptanalize using frequency analysis.
One Caesar cipher is still in use; rot 13 is used to hide "spoilers" such as the ending of a movie in Internet discussions. It is not used for any serious security.