SUBSTITUTION CIPHER Definition & Meaning

substitution cipher

Cryptography.

a cipher that replaces letters of the plain text with another set of letters or symbols.

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First recorded in 1935–40

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Examples have not been reviewed.

But a simple substitution cipher is easy to crack because certain letters, such as “e,” appear much more often than others.

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The “unbreakable” Pletts Cryptograph relied in part on keyword ciphers, a type of substitution cipher.

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In a substitution cipher, each letter of the message you want to send is swapped out for a different letter.

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This is a simple substitution cipher.

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Unlike a substitution cipher, it doesn’t replace any of the letters in the original message.

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