Final answer:
To decrypt the Row Transposition Cipher, rearrange the letters in the ciphertext according to the key. For the Vigenere Cipher, repeat the key and assign numerical values to the letters.
Step-by-step explanation:
To decrypt the given ciphertext 'cloewoteemtpxyg' using the Row Transposition Cipher with the key 43521, we need to rearrange the letters in the ciphertext according to the key. We start by dividing the ciphertext into blocks of size equal to the key length, which is 5 in this case. The ciphertext 'cloewoteemtpxyg' can be divided into blocks as follows: 'cloew oteem tp xyg'.
Next, we rearrange the letters in each block according to the order specified by the key. The key 43521 tells us that the first letter of each block should be the 4th letter, the second letter should be the 3rd letter, and so on. Applying this to the blocks, we get: 'ceolw teemo pt gxy'.
Therefore, the decrypted message is 'ceolwteemoptgxy'.
To encrypt a sentence using the Vigenere Cipher with the key 'CODE', we start by repeating the key until it has the same length as the sentence. Let's say the sentence is 'This is a test'. The key 'CODE' repeated becomes 'CODEC ODEC ODECO DEC'.
Next, we assign numerical values to each letter of the sentence and the key, using A=0, B=1, C=2, and so on. Then we add the numerical values of the corresponding letters (mod 26) to get the ciphertext.
T: 19 + C: 2 = V: 21
I: 8 + O: 14 = A: 0
S: 18 + D: 3 = V: 21
I: 8 + E: 4 = M: 12
S: 18 + C: 2 = U: 20
A: 0 + O: 14 = O: 14
T: 19 + D: 3 = B: 1
So the encrypted sentence is 'VA V M UOOB'.