# What is Cryptology: Definition and 11 Discussions

Cryptography, or cryptology (from Ancient Greek: κρυπτός, romanized: kryptós "hidden, secret"; and γράφειν graphein, "to write", or -λογία -logia, "study", respectively), is the practice and study of techniques for secure communication in the presence of third parties called adversaries. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, electrical engineering, communication science, and physics. Applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications.
Cryptography prior to the modern age was effectively synonymous with encryption, converting information from a readable state to unintelligible nonsense. The sender of an encrypted message shares the decoding technique only with intended recipients to preclude access from adversaries. The cryptography literature often uses the names Alice ("A") for the sender, Bob ("B") for the intended recipient, and Eve ("eavesdropper") for the adversary. Since the development of rotor cipher machines in World War I and the advent of computers in World War II, cryptography methods have become increasingly complex and its applications more varied.
Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions, making such algorithms hard to break in actual practice by any adversary. While it is theoretically possible to break into a well-designed system, it is infeasible in actual practice to do so. Such schemes, if well designed, are therefore termed "computationally secure"; theoretical advances, e.g., improvements in integer factorization algorithms, and faster computing technology require these designs to be continually reevaluated, and if necessary, adapted. There exist information-theoretically secure schemes that provably cannot be broken even with unlimited computing power, such as the one-time pad, but these schemes are much more difficult to use in practice than the best theoretically breakable but computationally secure schemes.
The growth of cryptographic technology has raised a number of legal issues in the information age. Cryptography's potential for use as a tool for espionage and sedition has led many governments to classify it as a weapon and to limit or even prohibit its use and export. In some jurisdictions where the use of cryptography is legal, laws permit investigators to compel the disclosure of encryption keys for documents relevant to an investigation. Cryptography also plays a major role in digital rights management and copyright infringement disputes in regard to digital media.

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1. ### I One-Time Pad and Frequency Analysis

My lecturer said that the cryptosystem one-time pad, has a weakness which is when it is subject to frequency analysis. But after him trying to explain why that is a weakness of this system I am still unable to see why. Because the frequency of letters is completely irrelevant to the structure of...
2. ### I Cryptology - Fast Factoring Integers by SVP Algorithms "destroys RSA"

The summary abstract (describes the method) and full paper are linked. Summary abstract https://eprint.iacr.org/2021/232.pdf
3. ### Number Theory Cryptanalysis Books: Prerequisites for Beginners

Hey guys, I just bought the book Elementary Cryptanalysis: A Mathematical Approach by Abraham Sinkov, yet before I start it, I would like to know if there are any prerequisites I should know about as I am 16 and I still haven't even taken all of high school mathematics although I am self...
4. S

### Programs Quantum Cryptology vs. Cryptology

I'm a 17 yo high school student, and my country has this system where you take a "strand" leaning towards your future career in the last two years of high school, so mine is STEM. I'm planning on taking mathematics and maybe a CS minor in college, because I want to become a cryptologist, but...
5. ### Insights Perfect Secrecy and the Unbreakable Cipher - Comments

bapowell submitted a new PF Insights post Perfect Secrecy and the Unbreakable Cipher Continue reading the Original PF Insights Post.
6. ### How to Solve a Modular Arithmetic Equation

Homework Statement compute 59x +15 \equiv 6 mod 811 Homework Equations The Attempt at a Solution 59x \equiv -9 mod 811 I really don't know hoow to do from here.
7. ### Exploring Solvability of Congruence Equations in Cryptology

Homework Statement Let n be a positive integer. Consider the congruence equation 59x + 15 congruent to 6 mod n For this equation, a solution x exits. Why? Homework Equations The Attempt at a Solution there is a k such that (59x +15) - 6 = kn (59x +15) - kn = 6 59x - kn = 6 - 15 59x - kn =...
8. ### Number Theory - Elementary Cryptology

[b]1. This is a problem involving public key cryptography [b]2. 16^31 is congruent to 081 (mod 247) [b]3. I would first evaluate 16^31 and the divided by 247 to find the remainder. I know how to work with congruences, but 16^31 is a very huge number I don't know how to evaluate it into...
9. ### Cryptology and codes vigenere code formula

http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher I have comprehended how to make a cod using this method. I understand frequency analysis for the most part. But does anyone know how the formula for decoding a vigenere code work. I have read that part of the wikipedia article many times...
10. ### Crack the Code: A Cryptography Challenge

Here's a simple code I made in math class. 46 46 48 26 34 24 05 20 24 38 12 02 11 19 20 14 28 46 26 27 34 23 26 00 34 20 22 17 24 18 24 16 46 Solve the code! Have fun!
11. ### Stuck on cryptology problem(vigenere cipher)

I was assigned to decrypt this cipher text: EWPW DRAPO MGTGT EXVAH RPSWI LSFUN RZVSE FOIWJ NYOU MHSER EFBMB VANHA LOOXI VPBIF FIFMA BFGRH GARE TLKLF NZQXQ DWGKP UWNWQ QFRZL VROOP UGBQQ HVKS CDOPW LSGTE JMFSE MLZMD TNDED VVGRO UUMLV NLHA KWASO ITAPR DTBBG CHDSH TNSFM NGWMF CASWM...