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 summer we had a sublime experience with “Charlotte Holmes,” a story box from children’s theaters in England, about a young evacuee who solves rural crimes during World War II. Its cheerful videos taught my kids solitaire, a substitution cipher and the fundamentals of Morse code.

From New York Times

And whenever there’s a Zodiac Killer reference, a substitution cipher is never far behind.

From Slate

He methodically and religiously worked his way through each one, from the crossword to the jumble to the cryptoquip, a substitution cipher that asks solvers to decode clues and figure out the pun.

From Scientific American

Think of symmetric cryptography as a more complex version of a substitution cipher: if the message is encoded by shifting each letter of the alphabet ahead by three places, one can crack the code by simply shifting each letter back by three.

From Scientific American