Cryptographic

Question 1

Cryptographic

Answer 1

Science of protecting information by transforming it into a
secure format. It ensures that data is kept confidential, authentic,
andsafe from tampering or theft—especially when stored or
transmitted across networks.

Question 2

Purpose of cryptographic techniques

Answer 2

To protect data at rest and in transit

Question 3

Cryptographic Techniques

Answer 3

• Ciphers
• Symmetric Encryption
• Asymmetric Encryption
• Hash Functions

Question 4

Ciphers

Answer 4

Algorithms that transform readable text (plaintext) into
unreadable text (ciphertext)

Question 5

Types of ciphers

Answer 5

• Caesar Cipher: Shifts each letter by a fixed number. Example: ‘HELLO’ →
  ‘KHOOR’ with a shift of 3.
• Vigenère Cipher: Uses a keyword to vary the shift for each letter. Example:
  Keyword ‘KEY’ encrypts ‘DATA’ to ‘NERK’.
• Polyalphabetic Cipher: Uses multiple substitution alphabets to obscure
  letter frequency. Example: Vigenère is a type of polyalphabetic cipher.

Question 6

Symmetric Encryption (AES)

Answer 6

Symmetric encryption uses the same key for both encryption and
decryption.
* AES (Advanced Encryption Standard): Encrypts data in blocks. Used in
Wi-Fi security (WPA2/WPA3), cloud storage, and banking systems.

Question 7

Pros of Symmetric Encryption

Answer 7

Fast and efficient. Suitable for large volumes of data

Question 8

Cons of Symmetric Encryption

Answer 8

Key distribution is a challenge: both sender and receiver must
securely share the same key

Question 9

Asymmetric Encryption (ECDH, ECDSA, RSA

Answer 9

Uses a pair of keys: a public key for encryption and a
private key for decryption.
* RSA: Used for secure data transmission and digital signatures. Example:
Verifying software authenticity.
* ECDH (Elliptic Curve Diffie–Hellman): Used for secure key exchange. Example:
Messaging apps like Signal use ECDH to establish secure sessions.
* ECDSA (Elliptic Curve Digital Signature Algorithm): Verifies authenticity of digital
messages. Example: Blockchain transactions use ECDSA for signature
verification.

Question 10

Pros of Asymmetric Encryption

Answer 10

Solves the key distribution problem. Enables digital signatures and
secure key exchange

Question 11

Cons of Asymmetric Encryption

Answer 11

Slower than symmetric encryption. More computationally
intensive

Question 12

Hashing Functions

Answer 12

Hashing functions convert data into a fixed-length string (hash) that
represents the original data. Hashing is one-way and cannot be reversed to the original data
* SHA-256: Common hashing algorithm used for password storage and
data integrity.