Hashing algorithm
https://en.wikipedia.org/wiki/MD5
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value. Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. It remains suitable for other non-cryptographic purposes, for example for determining the partition for a particular key in a partitioned database.

Instance Deduction
https://en.wikipedia.org/wiki/Cryptanalysis
The results of cryptanalysis can also vary in usefulness. For example, cryptographer Lars Knudsen (1998) classified various types of attack on block ciphers according to the amount and quality of secret information that was discovered:
Total break - the attacker deduces the secret key.
Global deduction - the attacker discovers a functionally equivalent algorithm for encryption and decryption, but without learning the key.
Instance (local) deduction - the attacker discovers additional plaintexts (or ciphertexts) not previously known.
Information deduction - the attacker gains some Shannon information about plaintexts (or ciphertexts) not previously known.
Distinguishing algorithm - the attacker can distinguish the cipher from a random permutation.

Correct answers: Transport mode and Tunnel mode
https://en.wikipedia.org/wiki/IPsec#Modes_of_operation
The IPsec protocols AH and ESP can be implemented in a host-to-host transport mode, as well as in a network tunneling mode.

Raw Quick Pair
https://www.cs.auckland.ac.nz/courses/compsci725s2c/archive/termpapers/yy.pdf Du and Long2 (2000) introduced Raw Quick Pairs detecting method of Stego-images (the images that contain the steganographic message). The underlying principle of the method is that the number of close color pairs of Stego-images will be larger compare with the number of close color pairs of normal images. In contrast, Fridrich and Goljan (2001) pointed out that RQP method only works if the number of unique colors is relatively low; and the method can not be applied to grayscale images. However, this paper will outline the core principle of RQP method; and evaluate such critical comments in details. In addition, this paper suggests potential improvement of RQP method and provides one possible alternative.
Incorrect answers:
Chi squared analysis - https://en.wikipedia.org/wiki/Chi-squared_test
Differential Analysis - https://en.wikipedia.org/wiki/Differential_cryptanalysis Discrete Cosine Transform - https://en.wikipedia.org/wiki/Discrete_cosine_transform

Hash
https://en.wikipedia.org/wiki/Hash_function
A hash function is any function that can be used to map data of arbitrary size to fixed-size values.