Description:

The tiny encryption algorithm $($TEA$)$ is a symmetric key block cipher designed for simplicity and efficiency, especially in resource$-$constraint environments. The TEA uses a $64-$bit block length and a $128-$bit key. The algorithm assumes a computing architecture with $32-$bit words, all operations are implicitly modulo $2^{32}($i$.$e$.,$ any bits beyond the $32$ nd position are automatically truncated$).$ The number of rounds is variable but must be relatively large. The conventional wisdom is that $32$ rounds are secure$.$ However, each round of TEA is more like two rounds of a Feistel cipher, such as the data encryption standard $($DES$),$ as shown in Figure $1,$ so this is roughly equivalent to $64$ rounds of DES.

Figure $1$: Cycle $i$ of TEA Encryption Algorithm $($two Feistel rounds$).$

In block cipher design, there is an inherent trade$-$off between the complexity of each round and the number of rounds required. Ciphers such as DES try to strike a balance between these two, while the advanced encryption standard $($AES$)$ reduces the number of rounds as much as possible, at the expense of having a more complex round function. In a sense, TEA can be seen as living at the opposite extreme of AES, since TEA uses a very simple round function. But as a consequence of its simple rounds, the number of rounds must be large to achieve a high level of security. TEA encryption and decryption algorithms, assuming $32$ rounds are used, are shown in Table $1$ and Table $2,$ respectively, where $""$ is a left $($non$-$cyclic$)$ shift and $">"$ is a right $($non$-$cyclic$)$ shift.

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HW #$2$: Chapters $3$ and $4$

May $27,2024$

Table $1$: TEA Encryption.

$)),],[$ delta $=09E3779B9,$

Table $2$: TEA Decryption.

$)),],[$ delta $=0x9E3779B9,$

Requirements:

Using any programming language you prefer, implement both the electronic code book $($ECB$)$ mode and the cipher block chaining $($CBC$)$ mode of TEA $($TEA$-$ECB and TEA$-$CBC$)$ with $32$ rounds for encryption and decryption. Leave the first $10$ blocks unencrypted. The implementation should be based on your own genuine effort. Additionally, your program should ask the user to enter the parameters for the TEA$-$ECB and the TEA$-$CBC $($i$.$e$.,$ key, plaintext$/$ciphertext$,$ and initialization vector $($IV$)).$ Test your implementation of both TEA$-$ECB and TEA$-$CBC by encrypting the following linked image and then decrypting the resulting ciphertext to show diagrams analogous to those in the