Ancient Egypt (1900 B.C.)

• Example: Hieroglyphs covered at the wall of Old Kingdom
• Some known characters/words substituted with unknown symbols
• It is unknown if it was used as cryptography

Atbash Ciphers (600-500 B.C.)

• Used by Hebrew scholars to encrypt alphabet.
• It is an example of simple monoalphabetic substitution cipher
• Encryption: map alphabet with its reverse

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• Example: Apple → Zkkov
• Decryption: encrypt again
• There is no security for this scheme because there is no key
• Can be considered a special case of Affine Cipher (will be studied later)

Note : lookup extended atbash

Spartan Scytale (500 B.C.)

• Used by the Greek for military communication (confidentiality) and to prevent spies from sending false messages (authentication)
• Encryption:
  • wrap a leather strip (or parchment) around the rod.
  • Write left-to-right then top-bottom
  • Unwrap the strip
• Decryption:
  • Wrap on a rod of same diameter.
  • Read message left-to-right then top-bottom
• It is a type of transposition cipher

We can model the Spartan scheme using the following: