Key Question:   23-8-1-20   9-19   5-14-3-16-25-16-20-9-15-14?

When decoded, the numbers above read What is encryption?  

What do the numbers mean?  The simple solution is 1 = A, 2 = B, 3 = C, and so on as shown below.

A    B    C    D    E    F    G    H   I    J    K     L    M         

1     2    3     4    5    6     7    8   9   10  11  12   13 

 N    O    P   Q    R    S    T    U   V    W    X    Y   Z

14  15  16  17   18   19   20  21  22  23   24   25  26

This is a simplistic form of encryption (en-CRIP-shun), which is the process of encoding information to keep it confidential, in other words to keep it from going to an adversary.  When you, the receiver, know the algorithm (AL-go-RI-them) (a problem-solving procedure, usually computer-based), decoding is easy.  If you don’t, decryption (DEE-crip-shun) or decoding is nearly impossible.

In words, the message What is encryption? is called plaintext.  The encrypted message in numbers is called ciphertext.  Actually I encoded the above Key Question twice.  The first was from a thought into written English words.  The second was encoding from the written words into numbers.  (I suppose I could have written it in some foreign language.)

In the above example, both encryption and decryption use the same keys.  This is termed a symmetric-key or private-key scheme.

With a public-key scheme, the encryption key is made available to everyone, however, only the intended message receiver(s) knows the decryption code.

The purpose of encryption is to keep information confidential, to keep it from falling into the wrong hands.  Encryption may be used with digital data "in transit,” as with an email or text  message, or with digital data in storage such as bookkeeping records, commonly called data "at rest.”  Your employer may use encryption to protect vital digital data.  Your task is to keep the encryption confidential.

This secret writing called cryptography (crip-TAH-gra-fee) has been used for millennium by warring parties, nation states, corporations, even notes passed between "lovers” in the school’s hallway (XOXOXO).   Cryptography is used to communicate with ”friends” and to keep it from "enemies.”  In today’s society, encryption is common to protect proprietary information, to withhold vital information from other nation states, and to protect against terrorism.  Ever increasingly-sophisticated encryption algorithms are continuously being developed.  A hacker assumes the task of figuring the encryption.

In situations where data must be kept confidential, encryption may not be enough.  In these cases, advanced message verification algorithms, such as Trojan Horse, may be used.

The above 1 = A, 2 = B, 3 = C scheme can be used two ways: from numbers to letters and from letters to numbers.  Here’s an encrypted message demonstrating that scheme.  What’s the message?  The solution is shown on the last page of this eText.

13-5-5-20 13-5  1-20  F-C-E  16-13