History of Cryptography: From Ancient Egypt to Modern Encryption, Slides of Cryptography and System Security

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HISTORY OF CRYPTOGRAPHY

NAME-AKASH KUMAR SWAIN

ROLL NO-15101FT

WHAT IS CRYPTOGRAPHY?

Cryptography is technique of securing information and communications from unauthorized access and tampering. It

involves converting messages into secret codes to prevent unauthorized people from reading or tampering with them. It

involves processes like encryption (turning plain information into secret code) and decryption (turning the secret code

back into readable information). The word 'cryptography' is combination of two Greek words, 'Krypto' meaning hidden

and 'graphene' meaning writing.

THE PURPOSE OF CRYPTOGRAPHY :-

Protect Privacy: Keep personal and sensitive information secret from unauthorized individuals or groups.

Ensure Data Integrity: Make sure that data has not been altered or tampered with during transmission or storage.

Secure Communication

Prevent Unauthorized Access

Greek and Roman Use Of Cryptography :-

The Greeks and Romans employed cryptography primarily for military and secret communication.

GREEK CRYPTOGRAPHY:

1. Scytale Cipher: Used by the Spartan military, it involved wrapping a strip of parchment around a cylindrical rod

(scytale). The letters on the strip would form a meaningful message only when wrapped around a rod of the same

diameter.

2. Polybius Square: Invented by the Greek historian Polybius, this method uses a 5x5 grid to encode letters into pairs

of numbers representing their coordinates. For example, "BAT" would be encoded as "12 11 44". It was particularly

useful in signaling with pairs of torches or other devices, allowing for discrete and efficient communication over

distance.

1 A B C D E

2 F G H I K

3 L M N O P

4 Q R S T U

5 V W X Y Z

Caesar Cipher: Later, the scholars moved on to using simple mono-alphabetic substitution ciphers during 500 to 600 BC.

This involved replacing alphabets of message with other alphabets with some secret rule. This rule became a key to

retrieve the message back from the garbled message.

the Caesar cipher , was used by Julius Caesar to secure military communications.

The ancient Greeks were well known for the use of Ciphers. The Caesar Cipher or Shift Cipher is one of the earliest and

simplest well-known cryptographic techniques. It is a form of Substitution Cipher where each character in a word is

replaced by a fixed number of positions. For example with a shift of 3, A is replaced by D, B by E, and so on.

ROMAN CRYPTOGRAPHY:

Vigenère Cipher :-

• Invented : 16th century, polyalphabetic cipher.

How it Works : Uses a keyword to encrypt the message, making it harder to break than the Caesar Cipher.

Example : Encrypting "HELLO" with the key "KEY" changes the letters based on their positions.

2. IMPACT ON MATHEMATICS AND CRYPTOLOGY:

Al-Kindi’s contributions to mathematics, especially in introducing Arabic numerals, were instrumental in advancing both

Islamic and Western knowledge.

His methods in cryptanalysis influenced not just the Muslim world but eventually also Western Europe, where his ideas

were integrated centuries later.

3. Medical Applications:

Beyond cryptography, Al-Kindi applied his analytical skills to medicine, developing a scale for quantifying the potency of

medications. This shows the breadth of his intellectual pursuits, linking cryptography, mathematics, and medical

science.

Cryptography from 1800 to World War II :-

• Cryptography (the practice of creating and solving codes) became more organized in the 19th century. Before that,

methods were often improvised. By the late 1800s, cryptographers, like Auguste Kerckhoffs, began to formalize the

field.

In the 1840s, famous writer Edgar Allan Poe used systematic techniques to crack ciphers. He even invited people to

send him codes through a Philadelphia newspaper, which he solved almost entirely, gaining public attention. Poe

later wrote an essay on cryptography, which became helpful for British codebreakers during World War I.

In World War I, a British group called "Room 40" played a key role by breaking German naval codes. This allowed

them to intercept German fleets, leading to important battles like Dogger Bank and Jutland in the North Sea.

Cryptography was critical to military success during this time.

ELECTRO MECHANICAL :-

In 1917, Gilbert Vernam proposed a teletype cipher in which a previously-prepared key, kept on paper tape, is

combined character by character with the plaintext message to produce the cyphertext. This led to the

development of electromechanical devices as cipher machines.

ENGIMA AND SIGABA :-

In the 1840s, Edgar Allan Poe showcased his cryptographic skills by advertising in a Philadelphia newspaper, inviting

people to submit ciphers. He successfully solved nearly all the ciphers he received.

ADVANCED ENCRYPTION STANDARD :-

There was suspicion that government organizations even then had sufficient computing power to break DES messages,

clearly others have achieved this capability.

The aging DES was officially replaced by the Advanced Encryption Standard (AES) in 2001

PUBLIC KEY :-

The publication of the paper New Directions in Cryptography by Whitfield Diffie and Martin Hellman.

It introduced a radically new method of distributing cryptographic keys, which went far toward solving one of the

fundamental problems of cryptography, key distribution, and has become known as Diffie- Hellman key exchange.

• The second development, in 1976, was perhaps even more important, for it fundamentally changed the way

cryptosystems might work. This was the publication of the paper New Directions in Cryptography by Whitfield Diffie and

Martin Hellman.

It introduced a radically new method of distributing cryptographic keys, which went far toward solving one of the

fundamental problems of cryptography, key distribution, and has become known as Diffie-Hellman key exchange. The

article also stimulated the almost immediate public development of a new class of enciphering algorithms, the

asymmetric key algorithms.

Conclusion :-

Cryptography has evolved significantly over time, from basic techniques like the Caesar Cipher to advanced algorithms

like AES. It plays a crucial role in securing modern communication, ensuring privacy and protecting sensitive data in

the digital age. As technology advances, especially with the potential of quantum computing, cryptography will

continue to adapt, shaping the future of secure communication.