Why should you study this page:   In a SHTF situation... Communications will be critical to your survival...
and The Vigenere Cipher is a simple, practical and effective type of encryption... to be used for secured communications.

Can the The Vigenere Cipher be be broken?

Of course it can... but it would be very difficult without the aid of a computer or a cryptologist.  For three centuries it resisted all attempts to break it. Today, there are numerous ciphers available and each one can have many variations. You can't learn them all... but you can and need to learn at least one.

The Vigenere Cipher employs a private Key Word or Phrase similar to our Ghost Mark.   The Key Word is used to encrypt and decrypt the message by using a scrambled letter polyalphabetic substitution method.   Guarding and protecting the Key Word is critical... and of course the Key Word should be changed on a set basis.

The longer the Key Word... the safer it will be as you repeat it below the letters of the plain text.   In the text... Numbers will cross to numbers... So you should spell out numbers and also avoid pronunciation marks.   Also try to avoid common identifies like the word "the".   Spaces will cross to spaces... So some people chose to block the message or apply letter grouping at a set interval (Ex: space after every nth letter). However, Do not be so creative that the decoder has problems ciphering the plain text.

Modern computer encryption methods now use 64 bit encrption or the newest 128 bit encryptions... which employ a public key along with a computer generated private key from the two endpoints.   It would take a super computer years to crack the code... but of course nothing is ever 100% secure.   Somebody wrote the code and somebody may be recording keys.

IMHO... In a SHTF situation, The Vigenere Cipher offers a secure, yet simple method to communicate secured data.   Every prepper group needs a comms man to receive and transmit data and information.   Ham radios are usually recommended. Although usually associated with manual physical/field delivery... The Vigenere Cipher can also be communicated over Ham radio using Morse Code.

You can use The Vigenere Cipher within our Ghost Mark private dropbox.   It will not be 100% secure, but it will suffice unless someone in the IC (Intelligence Community) has really targeted you. Do not use the Private Key as the Ghost Mark in case the DB is hacked... Best to have 2 separate keys.

For prepping purposes... Your group should go ahead and print multiple copies of The Vigenere Cipher and seal them in plastic. I would also do the same for copies of the Morse Code.

The Vigenere Cipher... Print it and learn how to use it.

Steps to Prepare Msg:
1. Compose Plaintext Msg.  
2. Determine the Key Word or Phrase.
3. Transpose Plaintext letters with Key Word letters... Repeat the Key Word as needed to match Msg Length.
4. For ea Plaintext Msg line... You now have a Key Word Msg Line.  

Steps to Encrypt using The Vigenere Table:
1. Encrypt letter by letter to form the Ciphertext Line
2. Use/find Plaintext letters across the Top Row.
3. Use/find Key Word letters down the Left Side Column.
4. Follow the vertical column for the Plaintext letter and the horizonal row for the Key letter to determine the intersecting cell/letter.
5. Apply the intersecting letter to the ciphertext line.

Steps to Decrypt using The Vigenere Table:
1. Still Decrypt letter by letter to form the Plaintext Line
2. Still Use/find Key Word letters down the Left Side Column.
3. On the Key Letter Row... Locate the Ciphertext letter
4. Then follow the vertical column up to the Top Row to determine the Plaintext letter.
5. Apply the Top Row letter to the Plaintext line.

Steps to Cipher using Math:
1. Prepare the Msg as shown above
2. Use/find Plaintext or Ciphertext letter and find the corresponding numeric value.
3. Use/find Key Word letter and find the corresponding numeric value.
4. To Encrypt... Add the math value for the 2 cipher letters...  If < 26... Simply find the corresponding letter value.  If > 26... then subtract 26... before finding the corresponding letter value.
5. To Decrypt... Subtract the math value for the 2 cipher letters...  If > 0... Simply find the corresponding letter value.  If < 0 (negative)... then add 26... before finding the corresponding letter value.

For some, Using the Math Modulus 26 table will be faster and simpler once they fully understand the concept.

Study and learn the preceding intructions for a SHTF case... A computer assisted mode is provided below:
Note: No Key Words or Data entered here are saved or stored in our Database... You can use copy/paste to post a private Q & A or paste it in an encoded email.

Encrypt or Decrypt:   
Key Word or Phrase:

Message Text... (Plain text or Encoded):

Cipher Reset

This is your encoded or decoded text:

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