# Affine Cipher

## Dublin Core

### Title

Affine Cipher

### Subject

Affine Cipher

### Description

The Affine Cipher is a form of substitution cipher that involves math. The shift of the alphabet- while transpositioning plaintext into ciphertext is determined by a mathematical equation. This equation is:

E(x) = (ax+b) mod m

E(x) = The number equaling the letter to be used in the cipher text

a, b = Any given number

x = the number correlating to the plaintext letter

mod m = A mathematical way (subtraction, division, etc.) to bring (ax+b) back within range of 26 for all answers.

To decrypt, the equation is c(x-b) mod m.

c = the modular multiplicative inverse of a

E(x) = (ax+b) mod m

E(x) = The number equaling the letter to be used in the cipher text

a, b = Any given number

x = the number correlating to the plaintext letter

mod m = A mathematical way (subtraction, division, etc.) to bring (ax+b) back within range of 26 for all answers.

To decrypt, the equation is c(x-b) mod m.

c = the modular multiplicative inverse of a

### Creator

Unknown

### Source

https://crypto.interactive-maths.com/affine-cipher.html

### Publisher

Crypto Corner

### Contributor

Daniel Rodriguez-Clark

### Format

.JPEG

### Language

English

## Still Image Item Type Metadata

### Original Format

Cipher

### Collection

### Citation

Unknown, “Affine Cipher,”

*Ciphers and Encryption*, accessed September 25, 2022, https://crypto.omeka.net/items/show/23.