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C839V5/D334 ADDITIONAL PRACTICE EXAM
2025 QUESTIONS AND ANSWERS.
1. What is the block size for AES?
A. 128 bits
B. 192 bits
C. 256 bits - correct answer - 128 bits
2. With the _____ block cipher mode, the encrypted version of the
IV produced in the first stage (during processing of the first
block) is fed into the second stage and encrypted.
A. OFB
B. CTR
C. CFB - correct answer - Output Feedback (OFB)
3. What is the key size for 3DES?
A. 64 bits
B. 112 bits
C. 80 bits - correct answer - 112 bits
4. AES when operating with 10 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 128 bits
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5. AES when operating with 10 rounds uses what block size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 128 bits
6. AES when operating with 14 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 256 bits
7. AES when operating with 12 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 192 bits
8. Which variation of Elliptic Curve cryptography is used to
support symmetric key exchange?
A. ECDSA
B. secp256k1
C. ECDH - correct answer - ECDH
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9. The Paillier cryptosystem supports _____ encryption.
A. homomorphic
B. active
C. passive - correct answer - homomorphic
10. PKCS #__ is a standard used for password-based
encryption.
A. 1
B. 5
C. 7 - correct answer - PKCS #5
11. PKCS #__is used to sign and/or encrypt messages for PKI.
A. 1
B. 5
C. 7 - correct answer - PKCS #7
12. AES can be susceptible to a copy-and-paste attack when
used with which block cipher mode?
A. ECB
B. OFB
C. RC4 - correct answer - ECB
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13. ____ has proven to be free from major vulnerabilities, but
poor implementation of the encryption method leaves it
susceptible to attacks such as: Brute force, use of Non-
Random Numbers, copy-and-paste and timing attacks.
A. AES
B. Ethereum
C. CTR - correct answer - AES
14. ______ measures the amount of unpredictability, and in
encryption it relates to the degree of uncertainty of the
encryption process.
A. Padding
B. Encoding
C. Entropy - correct answer - Entropy
15. For secure communications using HTTPS, the _____ is used
to prove the identity of the server for which the Web browser
connects to.
A. digital certificate
B. digital signature
C. message digest - correct answer - digital certificate
16. A digital certificate contains the _____ key of the entity the
certificate is issued to.
A. Public
C839V5/D334 ADDITIONAL PRACTICE EXAM
2025 QUESTIONS AND ANSWERS.
1. What is the block size for AES?
A. 128 bits
B. 192 bits
C. 256 bits - correct answer - 128 bits
2. With the _____ block cipher mode, the encrypted version of the
IV produced in the first stage (during processing of the first
block) is fed into the second stage and encrypted.
A. OFB
B. CTR
C. CFB - correct answer - Output Feedback (OFB)
3. What is the key size for 3DES?
A. 64 bits
B. 112 bits
C. 80 bits - correct answer - 112 bits
4. AES when operating with 10 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 128 bits
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5. AES when operating with 10 rounds uses what block size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 128 bits
6. AES when operating with 14 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 256 bits
7. AES when operating with 12 rounds uses what key size?
A. 128 bits
B. 192 Bits
C 256 bits - correct answer - 192 bits
8. Which variation of Elliptic Curve cryptography is used to
support symmetric key exchange?
A. ECDSA
B. secp256k1
C. ECDH - correct answer - ECDH
, Page | 3
9. The Paillier cryptosystem supports _____ encryption.
A. homomorphic
B. active
C. passive - correct answer - homomorphic
10. PKCS #__ is a standard used for password-based
encryption.
A. 1
B. 5
C. 7 - correct answer - PKCS #5
11. PKCS #__is used to sign and/or encrypt messages for PKI.
A. 1
B. 5
C. 7 - correct answer - PKCS #7
12. AES can be susceptible to a copy-and-paste attack when
used with which block cipher mode?
A. ECB
B. OFB
C. RC4 - correct answer - ECB
, Page | 4
13. ____ has proven to be free from major vulnerabilities, but
poor implementation of the encryption method leaves it
susceptible to attacks such as: Brute force, use of Non-
Random Numbers, copy-and-paste and timing attacks.
A. AES
B. Ethereum
C. CTR - correct answer - AES
14. ______ measures the amount of unpredictability, and in
encryption it relates to the degree of uncertainty of the
encryption process.
A. Padding
B. Encoding
C. Entropy - correct answer - Entropy
15. For secure communications using HTTPS, the _____ is used
to prove the identity of the server for which the Web browser
connects to.
A. digital certificate
B. digital signature
C. message digest - correct answer - digital certificate
16. A digital certificate contains the _____ key of the entity the
certificate is issued to.
A. Public
