substitution cipher

American  

noun

Cryptography.

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

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Etymology

Origin of substitution cipher

First recorded in 1935–40

Example Sentences

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

From Scientific American

This is a simple substitution cipher.

From Literature

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

From Literature

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

From Literature

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

From Literature