The Random cipher is a type of substitution cipher, specifically a monoalphabetic substitution
cipher. This means that you replace a letter in the plaintext with the same letter every time.
For example, if you
replace the letter "A" with "H", you must do that for every "A" in the entire plaintext.

The random cipher is a table that maps each letter of the plaintext to a unique letter in the
ciphertext. But there's no rhyme or reason to
what letters map to. Consider the following substitution table. There's no pattern to how the
plaintext maps to the ciphertext. This is why it's called a Random substitution.

Example

Consider the following random substitution table.

Original Alphabet (Plaintext)

Substitution (Ciphertext)

Encryption

Based on the table "A" -> "S", "B" -> "B", "C" -> "X", "D" -> "E", "E" -> "M", etc. Let's use
this to encrypt the message "ATTACK AT DAWN."

Encrypting

Plaintext

A T T A C K A T D A W N

Ciphertext

S A A S X Z S A E S Q L

Decryption

To decrypt we go from the ciphertext back to the plaintext. Based on the table "S" -> "A", "B" ->
"B", "X" -> "C", "E" -> "D", "M" -> "E", etc. Let's use this to decrypt the message "QSCA LKA
FMA"

Decrypting

Ciphertext

Q S C A L K A F M A

Plaintext

W A I T N O T Y E T

Random Substitution Tool

Below is a random substitution generator. When you press "Randomize" it will shuffle the letters
of the alphabet to create a mapping from the plaintext to the ciphertext. You can use this to
encrypt/decrypt messages below the generator.

Original Alphabet (Plaintext)

Substitution (Ciphertext)

Encrypt your message

Use the tool above to set your key. When you encrypt you replace with letters in the plaintext table with the corresponding letter in the ciphertext table.

You successfully encrypted your message.

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How to decrypt?

When you decrypt you replace the letters from the ciphertext table with the corresponding letter from the plaintext table.

Decrypt your message:

Use the shift tool from above.

You completed the decryption? Were you successful?

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