Multi-layer computer-implemented methods of encryption and decryption of English-language text messages, as well as practical systems that implement them. The first layer of encryption may be by encoding each character as a 3-digit number, or by letter-proximity-based mapping of characters to unique 1-digit, 2-digit, and 3-digit numbers. A second layer of encryption is achieved by mapping some or all of these numbers to unique cryptograms using patterns from Kaprekar Graphs for 3-digit numbers.