Cyber Security Interview Questions Part - 5 | Cryptography Interview Questions | Simplilearn

2. 41 Define cryptography, encryption and decryption. Cryptography is used by ethical hackers to secure information. It involves converting data from a readable format to a non-readable format and vice versa

3. 41 Define cryptography, encryption and decryption. Cryptography is used by ethical hackers to secure information. It involves converting data from a readable format to a non-readable format and vice versa Consider this example: COMPUTER EQORXVGT

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5. 41 Define cryptography, encryption and decryption. Cryptography is used by ethical hackers to secure information. It involves converting data from a readable format to a non-readable format and vice versa Consider this example: COMPUTER EQORXVGT Encryption – It is the process of converting a message from a readable state to a scrambled state which makes no sense. Here, Key = Alphabet + 2

6. 41 Define cryptography, encryption and decryption. Cryptography is used by ethical hackers to secure information. It involves converting data from a readable format to a non-readable format and vice versa Consider this example: COMPUTER EQORXVGT Decryption – message is decrypted using a secret key which is known only to the recipient. Decryption = Alphabet - 2

7. 42 What is the difference between ciphertext and cleartext? Ciphertext refers to the text which is encrypted and totally undecipherable. The message received after decryption is known as cleartext. This text is comprehensible. COMPUTER EQORXVGT Ciphertext

8. 42 What is the difference between ciphertext and cleartext? Ciphertext refers to the text which is encrypted and totally undecipherable. The message received after decryption is known as cleartext. This text is comprehensible. COMPUTER EQORXVGT Cleartext

9. 43 What is a block cipher? This refers to the method of encrypting the plain message block by block. The plain message is broken down into fixed size blocks and then encrypted. Encryption Encryption = Plaintext + key Plaintext block Ex: 64 bits Ciphertext block Ex: 64 bits Key K

10. 43 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private. 

11. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Registration Authority Recipient Sender

12. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Request Registration Authority Recipient Sender

13. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Request is ok Request Registration Authority Recipient Sender

14. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Request is ok Request Certificate Private Key Registration Authority Recipient Sender

15. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Request is ok Request Certificate Private Key Registration Authority Signed data Recipient Sender

16. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Request is ok Signature Request Certificate Private Key Registration Authority Signed data Recipient Sender

17. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Certificate Public Key Request is ok Signature Request Certificate Private Key Registration Authority Signed data Recipient Sender

18. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  Certification Authority Verification Authority Certificate Public Key Request is ok Signature is ok Signature Request Certificate Private Key Registration Authority Signed data Recipient Sender

19. 44 What is Public Key Infrastructure? Public Key Infrastructure (PKI) is a set of policies which secures the communication between a server and a client. It uses two cryptographic keys, public and private.  • PKI enables trusted digital identities for people. • PKI grants secure access to digital resources • The core of PKI is a certificate authority which ensures the trustworthiness of the digital data

20. 45 What is RSA? RSA is one of the first public-key cryptosystems that is used for secure data transmission. RSA stands for Rivest, Shamir, and Adelman, who are the inventors of the technique. It is an asymmetric cryptography algorithm which works on both public and private keys. Here, the encryption key is public, and the decryption key is kept private Decryption (Using receiver’s private key) Encryption (Using receiver’s public key) - - - - - - $%&* A$J%@ - - - - - - - - - &$%@ - - - Plain Text (Sender) Cipher Text Plain Text (Receiver)

21. 46 What are a few of the alternatives to RSA? The alternatives to RSA are as follows: Google Authenticator Duo Security Okta LastPass

22. 47 What are the prime objectives of modern cryptography? • Non-repudiation • Confidentiality • Authenticity • Integrity 1 2 3 4 The prime objectives of modern cryptography are as follows: Confidentiality helps in keeping the information safe from unauthorized people

23. 47 What are the prime objectives of modern cryptography? • Non-repudiation • Confidentiality • Authenticity • Integrity 1 2 3 4 The prime objectives of modern cryptography are as follows: Non-repudiation prevents denial in an electronic transaction

24. 47 What are the prime objectives of modern cryptography? • Non-repudiation • Confidentiality • Authenticity • Integrity 1 2 3 4 The prime objectives of modern cryptography are as follows: Authenticity helps in identifying the source of the created information

25. 47 What are the prime objectives of modern cryptography? • Non-repudiation • Confidentiality • Authenticity • Integrity 1 2 3 4 The prime objectives of modern cryptography are as follows: Integrity makes sure that the data received by the receiver is not modified

26. 48 What is SAFER? Secure and Fast Encryption Routine(SAFER) is a block cipher. It has 64-bit block size and a byte-oriented algorithm SAFER’s encryption and decryption procedures are highly secure. This technology is used widely in applications like digital payment cards

27. 49 How does the Public Key Infrastructure (PKI) work? ? The working of Public Key Infrastructure (PKI) at a macro level is as follows: Firstly, the request for the Digital Certificate is sent to the appropriate CA (Certificate Authority). Once the request is processed, the Digital Certificate is issued to the person requesting it The Digital Certificate then gets signed by confirming the identity of the person  The Digital Certificate can now be used to encrypt the cleartext into ciphertext which is sent from the sending party to the other party

28. 50 What is Blowfish algorithm? It is a 64-bit symmetric encryption algorithm. The same secret key is used to encrypt and decrypt messages. Here, the operations are based on exclusive ors and additions on 32bit words The key has a maximum length of 448 bits, it is variable in nature. It is also used to generate several subkey arrays

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