CSNT 181 COMPREHENSIVE 2025 REVISED QUESTIONS
AND QUESTIONS GRADED A+
Symmetric encryption - Uses a single key to encrypt and decrypt data.
Asymmetric encryption - uses two keys: a public key known to everyone and a private or secret key
known only to the recipient. A message encrypted with a public key can be decrypted only with the
same algorithm used by the public key and requires the recipient's private key, too. Anyone
intercepting the message cannot decrypt it because he or she does not have the private key.
Cryptographic hashing - Converts data into a hash, or unique signature. The hash can't be turned
back into the original data, but can be compared to the data to verify its integrity and/or
authenticity.
Caesar cipher - Simple substitution cipher
ROT13 - One type of substitution cipher in which the entire alphabet is rotated 13 steps.
Vigenere cipher - A polyalphabetic cipher, which uses a keyword to look up values in a table
composed of all possible Caesar ciphers.
one-time pad (OTP) - Combining plaintext with a random key to create ciphertext that cannot be
broken mathematically.
Transposition cipher - A cipher that rearranges the order of characters in a message.
RC4 - Stream cipher that is quick to encode or decode. (Obsolete today due to vulnerabilities)
AES - Advanced Encryption Standard. Symmetric block cipher. Variable block length up to 256-bits,
but the AES version specifies only 128-bit blocks (good enough for most purposes). It can use 128-,
192-, or 256-bit keys.
3DES or TDES - Triple DES. Symmetric block cipher that applies three different 56-bit DES keys t o the
same 64-bit block. Three different keys means total key length is 168 bits, but it's only as effective as
80-bit AES. (Obsolete today)
AND QUESTIONS GRADED A+
Symmetric encryption - Uses a single key to encrypt and decrypt data.
Asymmetric encryption - uses two keys: a public key known to everyone and a private or secret key
known only to the recipient. A message encrypted with a public key can be decrypted only with the
same algorithm used by the public key and requires the recipient's private key, too. Anyone
intercepting the message cannot decrypt it because he or she does not have the private key.
Cryptographic hashing - Converts data into a hash, or unique signature. The hash can't be turned
back into the original data, but can be compared to the data to verify its integrity and/or
authenticity.
Caesar cipher - Simple substitution cipher
ROT13 - One type of substitution cipher in which the entire alphabet is rotated 13 steps.
Vigenere cipher - A polyalphabetic cipher, which uses a keyword to look up values in a table
composed of all possible Caesar ciphers.
one-time pad (OTP) - Combining plaintext with a random key to create ciphertext that cannot be
broken mathematically.
Transposition cipher - A cipher that rearranges the order of characters in a message.
RC4 - Stream cipher that is quick to encode or decode. (Obsolete today due to vulnerabilities)
AES - Advanced Encryption Standard. Symmetric block cipher. Variable block length up to 256-bits,
but the AES version specifies only 128-bit blocks (good enough for most purposes). It can use 128-,
192-, or 256-bit keys.
3DES or TDES - Triple DES. Symmetric block cipher that applies three different 56-bit DES keys t o the
same 64-bit block. Three different keys means total key length is 168 bits, but it's only as effective as
80-bit AES. (Obsolete today)
