#### Each question is followed by 3 hints that you can use to solve the question.

### Question 1: What is the result of applying the Caesar cipher with a shift of 3 to the message "HELLO"?

- Think about shifting each letter of the alphabet by the given shift value.
- Start with the first letter of the message and apply the shift to each letter.
- Remember to wrap around the alphabet if you reach the end.

### Question 2: What is the result of XOR-ing the binary numbers 10101010 and 11001100?

- XOR compares each corresponding bit of the two numbers.
- SWrite down the binary representation of each number and compare bit by bit.
- XOR returns 1 if the bits being compared are different, and 0 if they are the same.

### Question 3: What is the result of decrypting the message "Uijt jt b nfttbhf uifsf" using a simple letter substitution cipher?

- Look for common patterns and letter frequencies in the encrypted message.
- Try to match the encrypted letters with their corresponding plain letters.
- Use trial and error to decipher the entire message.

### Question 4: What is the result of applying the Vigenère cipher to the message "HELLO" using the keyword "KEY"?

- The Vigenère cipher uses a keyword to determine the shift for each letter.
- Write down the keyword repeatedly until it matches the length of the message.
- Apply the Caesar cipher with the corresponding shift value for each letter.

### Question 5: What is the result of hashing the message "PASSWORD" using the MD5 algorithm?

- Hashing algorithms produce a fixed-length string of characters.
- MD5 is a commonly used hashing algorithm.
- The resulting hash is unique to the input message.

### Question 6: What is the next number in the sequence: 0, 1, 1, 2, 3, 5, 8, 13, ...?

- This sequence follows the Fibonacci pattern.
- Each number is the sum of the two preceding ones.
- Start with 0 and 1 and continue adding the previous two numbers.

### Question 7: What is the result of converting the hexadecimal number "1A" to decimal?

- Hexadecimal numbers use a base of 16.
- Each digit represents a multiple of a power of 16.
- "A" in hexadecimal is equivalent to 10 in decimal.

### Question 8: What is the result of applying the ROT13 cipher to the message "HELLO"?

- ROT13 is a simple letter substitution cipher with a shift of 13.
- Apply the shift to each letter of the message.
- Remember to wrap around the alphabet if you reach the end.

### Question 9: What is the result of decrypting the message "Gv1g2IjK" using a simple letter substitution cipher?

- Look for patterns and try to match the encrypted letters with their plain counterparts.
- Use frequency analysis to determine the most common letters in the English language.
- Combine the known information with trial and error to decrypt the entire message.

### Question 10: What is the result of applying the Playfair cipher with the key "CRYPTO" to the message "HELLO"?

- The Playfair cipher uses a 5x5 grid of letters based on a keyword.
- Write down the keyword in the grid, filling the remaining spaces with the alphabet.
- Encrypt the message by finding the pairs of letters in the grid and following the specific rules.

### Question 11: What is the result of converting the binary number "101011" to decimal??

- Each digit in a binary number represents a power of 2.
- Multiply each digit by the corresponding power of 2 and sum the results.
- Start from the rightmost digit and increase the power of 2 for each subsequent digit.

### Question 12: What is the result of encrypting the message "SECRET" using a rail fence cipher with a depth of 3?

- The rail fence cipher writes the message in a zigzag pattern across a set number of "rails."
- Write the message diagonally along the rails, filling each rail from top to bottom.
- Read the message off row by row to get the encrypted result.

### Question 13: What is the result of calculating the modular exponentiation of 7^4 mod 13?

- Modular exponentiation calculates the remainder when a number is raised to a power and divided by another number.
- Start by calculating the powers of 7, reducing each result modulo 13.
- Take the final result as the remainder when dividing by 13.

### Question 14: What is the result of applying the Atbash cipher to the message "HELLO"?

- The Atbash cipher substitutes each letter with its counterpart in the reverse alphabet.
- Write down the alphabet in reverse order and match each letter of the message.
- Apply the substitution to each letter of the message.

### Question 15:What is the result of decrypting the message "UIJT JT B DPOOFDUFE QSFWFOU" using a simple letter substitution cipher?

- Look for common words and patterns in the encrypted message.
- Use frequency analysis to identify frequently occurring letters and their possible plain counterparts.
- Combine known information with trial and error to decrypt the entire message.

### Question 16: What is the result of converting the decimal number 42 to binary?

- Divide the decimal number by 2 and write down the remainder.
- Repeat the process with the quotient until reaching 0.
- Read the remainders from bottom to top to get the binary representation.

### Question 17: What is the result of encrypting the message "HELLO" using a columnar transposition cipher with the keyword "KEY"?

- Columnar transposition rearranges the letters of the message based on a keyword.
- Write the message in rows under the keyword, filling any empty spaces with placeholder letters.
- Read the columns from left to right to get the encrypted result.

### Question 18:What is the result of calculating the gcd(48, 60)?

- The gcd (greatest common divisor) is the largest positive integer that divides both numbers without leaving a remainder.
- Start by finding the divisors of each number and identifying the greatest common divisor.
- Alternatively, use the Euclidean algorithm to calculate the gcd.

### Question 19:What is the result of encrypting the message "HELLO" using a transposition cipher with the permutation "32451"?

- A transposition cipher rearranges the letters of the message based on a permutation.
- Write the message in columns under the permutation, filling any empty spaces with placeholder letters.
- Read the columns from left to right and top to bottom to get the encrypted result.

### Question 20: What is the result of calculating the modular inverse of 17 mod 26?

- The modular inverse of a number is the number that, when multiplied by the original number modulo a certain value, equals 1.
- Use the extended Euclidean algorithm to find the modular inverse.
- Multiply the inverse by the original number and reduce modulo the given value to verify the result.