Simple encryption algorithms, which were invented long before first computers, are based on substitution and transposition of single plaintext characters. Meanwhile, the operations performed in modern encryption algorithms are usually similar but they affect single bits and bytes.
Substitution ciphers are about replacing each group of plaintext letters with another predefined group. For decrypting, one should use a reverse substitution.Read More
Transposition ciphers do not substitute any plaintext characters but they change positions of the letters.Read More
First electro-mechanical machines started to be used for encryption as early as at the end of the 19th century, and continued to operate until the end of World War II.Read More
This is a simple substitution cipher which operates on single bits and bytes, instead of on leters.Read More