7.1 - History of Cryptography

Cryptography is believed to originate in Egypt, around 2000 B.C. Hieroglyphics, at the time, were used to decorate tombs which told the life story of the deceased. This practice was to portray the story in a noble and ceremonial manner than to actually hide the messages themselves.

Over time, encryption evolved from being visual representations of storytelling and into applications used to obscure information from others.

For example, substitution cipher (replacement of characters with another characters), became a cryptographic method used. A method of this could be used to require the alphabet to be flipped so each letter in the original alphabet corresponds to a different letter in the flipped alphabet. This was encryption method was called atbash, which hid the true meaning of messages.

Example:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
ZYXWVUTSRQPONMLKJIHGFEDCBA

“As an example, suppose we need to encrypt the message “Logical Security.” We take the first letter of this message, L, and shift up three locations within the alphabet. The encrypted version of this first letter is O, so we write that down. The next letter to be encrypted is O, which matches R when we shift three spaces. We continue this process for the whole message. Once the message is encrypted, a carrier takes the encrypted version to the destination, where the process is reversed.”
-CISSP Security Guide

Plaintext:
LOGICAL SECURITY

Ciphertext:
ORJLFDO VHFXULWB

Presently, this technique is rather too simplistic and ineffective; however, in the time of Julius Caesar, few people could read, so a high level of protection was provided. The Caesar cipher is an example of a monoalphabetic cipher. Once more people could read and reverse-engineer this type of encryption process, the cryptographers of that day increased the complexity by creating polyalphabetic ciphers.