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Carlos A. Martinez
Carlos A. Martinez

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Caesar cipher

Caesar cipher 🔒

In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.

Two alphabets 🆎

The transformation can be represented by aligning two alphabets; the cipher alphabet is the plain alphabet rotated left or right by some number of positions. For instance, here is a Caesar cipher using a left rotation of three places, equivalent to a right shift of 23 (the shift parameter is used as the key):

  • Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ
  • Cipher: XYZABCDEFGHIJKLMNOPQRSTUVW

When encrypting, a person looks up each letter of the message in the "plain" line and writes down the corresponding letter in the "cipher" line.

  • Key: 3 🔑
  • Plaintext: HELLO
  • Ciphertext: EBIIL

Repo: GitHub Caesar-cipher 🔗

source: Caesar-cipher Wikipedia 🔗

thank you for reading

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