a field

any finite set

any arbitrary ring

 the set of integers

{0, 1}

all integers

{0, 1, 2, …, p– 1}

{1, 2, …, p}

Solving quadratic equations

Simplification of fractions

Performing divisions in modular arithmetic

Solving diophantine equations

p+q–1

p × q

(p– 1) + (q– 1)

(p– 1)(q– 1)

Tuesday

Saturday

Monday

Friday

hash function design only

symmetric-key cryptography only

steganography

public-key cryptography

Ransomware

Spyware

Adware

Rootkit

Ransomware

Logic Bomb

Spyware

Keylogger

Worm

Trojan Horse

Rootkit

Boot Sector Virus