How Does Mallory Pass Encrypted Data Without Bob Detecting It?

How Does Mallory Pass Encrypted Data Without Bob Detecting It?

Mallory and Eve are being watched by Bob the Investigator. They must now try and pass messages to each other, with Bob detecting the passing of secret messages.

If Mallory wants to trick Bob the Investigator into thinking that he is sending plain text, then he can covert the cipher text into a plain text format. In the following Mallory converts the cipher text using RFC 1751 [here]:

This converts 11 bits values to a word (where there are 2¹¹ words) [here]:

Input data (CMS): 48656c6c6f20686f772061726520796f750f0f0f0f0f0f0f0f0f0f0f0f0f0f0f

Cipher (ECB): c10c2fc11e3d73e1bc74b836b9cc8698deeae276ede8eb5a19d4f4405fda42e1

Cipher to plain: MUTT BUSS TRUE SIS SAVE TUCK MIRE KENO DEE DINT OMIT AMMO SLID BETA HYMN SIGH GOOD LENT HEM KNIT DUE MOVE JUNK DEAF

Reverse: 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

decrypt: Hello how are you

If this case we use CMS padding, and where we pad with a value that fills up to 16 bytes (128 bit block size). Here are the starting point of the 2,048 element array of strings:

The real advantage of using this human readable form, is that we can easily write down the words, and regenerate the binary value. Along with this we could easily speak the key over a telephone line.

The following is an outline of the code: