Key

TEA (Tiny Encryption Algorithm) is a block cipher notable for its simplicity of description and implementation, typically a few lines of code. It was designed by David Wheeler and Roger Needham of the Cambridge Computer Laboratory; it was first presented at the Fast Software Encryption workshop in Leuven in 1994, and first published in the proceedings of that workshop.

TEA operates on two 32-bit unsigned integers (could be derived from a 64-bit data block) and uses a 128-bit key. It has a Feistel structure with a suggested 64 rounds, typically implemented in pairs termed cycles. It has an extremely simple key schedule, mixing all of the key material in exactly the same way for each cycle.

TEA Encrypt & Decrypt is a free online tool that for Tiny Encryption Algorithm Encrypt & Decrypt.

Homophonic Substitution Cipher is a substitution cipher in which single plaintext letters can be replaced by any of several different ciphertext letters. They are generally much more difficult to break than standard substitution ciphers.

Playfair Cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. It encrypts pairs of letters (bigrams or digrams), instead of single letters as in the simple substitution cipher and rather more complex Vigenère cipher systems then in use.

Polybius Square Cipher is essentially identical to the simple substitution cipher, except that each plaintext character is enciphered as 2 ciphertext characters. It can ususally be detected if there are only 5 or 6 different characters in the ciphertext.

Rail Fence Cipher is a classical type of transposition cipher. It derives its name from the manner in which encryption is performed, in analogy to a fence built with horizontal rails.