Biblical Cryptography: The Atbash Cipher

Cryptography is the art and science of secure and private communications. Very simply put, the main idea is for a sender (call her Alice) to take a message, turn it into nonsense, and send it to a receiver (call him Bob). Upon receiving the nonsense message from Alice, Bob turns it back into the original message so that he can read it. An eavesdropper (call her Eve) who might intercept the nonsense message should be unable to turn it back into the original message. The process of turning a message into nonsense is called encryption, and the process of turning nonsense back into a message is called decryption. Thus, Alice encrypts a message and sends it to Bob, and Bob decrypts the message and reads it. Eve is (ideally) unable to decrypt the message even if she intercepts it.

Modern cryptography is heavily based on mathematical theory and is quite technically sophisticated. Classical cryptography, by contrast, was generally quite simple. It often involved simply replacing each letter of a message with a different letter from the same alphabet. Such encryption schemes are formally known as monoalphabetic substitution ciphers (a cipher is simply an encryption/decryption scheme). A simple example is the Caesar cipher, named after Julius Casaer, who is said to have used the cipher to encrypt military messages. The encryption scheme consists in replacing each letter in a message with a letter further down in the alphabet by a fixed number of spaces. Caesar himself is said to have replaced each letter with a letter three spaces down in the alphabet. In this case, 'a' would be replaced with 'd', 'b' would be replaced with 'e', 'c' would be replaced with 'f', and so on. Thus, the message "hello" would be encrypted as "khoor".

The ancient Romans were not alone in using encryption. Interestingly, the ancient Israelites also used encryption and such encryption can be found in the Bible. The Israelites used what is called the Atbash (Hebrew: אתבש) cipher. The name comes from the first, last, second, and second-to-last letters of the Hebrew alphabet: Aleph (א) – Tav (ת) – Beth (ב) – Shin (ש). (Note that Hebrew is read right-to-left). The cipher works by replacing the first letter of the alphabet with the last, the second with the second-to-last, the third with the third-to-last, and so on. For the English alphabet, 'a' would become 'z', 'b' would become 'y', 'c' would become 'x', and so on. Thus, "hello" would be encrypted as "svool".

There are three instances of the Atbash cipher being used in the book of Jeremiah. English translations not only translate from Hebrew to English, but they also generally decrypt these instances as well. As a result, the fact that encryption is being used in these passages typically passes by an English reader without notice unless said reader is attentive to footnotes. The instances are as follows (the words that are encrypted in the original Hebrew are in boldface):

• "[A]ll the kings of the north, far and near, one after another, and all the kingdoms of the world which are on the face of the earth. And after them the king of Babylon shall drink" (Jeremiah 25:26, RSV2CE, boldface added).
  
  
• "Thus says the Lord: Behold, I will stir up the spirit of a destroyer against Babylon, against the inhabitants of Chaldea" (Jeremiah 51:1, boldface added).
  
  
• "How Babylon is taken, the praise of the whole earth seized! How Babylon has become a horror among the nations!" (Jeremiah 51:41, boldface added).

In the first and third passage, the word "Babylon" (Hebrew: בבל) is actually encrypted in the original biblical text as the word "Sheshach" (Hebrew: ששך). In the second passage, the word "Chaldea" (Hebrew: כשדים) is actually encrypted in the original biblical text as the word "Leb-qamai (Hebrew: לבקמי).

So, even an inspired author of Scripture used encryption! An interesting question that I do not know the answer to is whether, in the direct quotations of God's speech, God Himself is speaking with these encrypted words or if the biblical author (Jeremiah) is encrypting parts of God's speech when he records it in writing.