CAESAR CIPHER…
CAESAR CIPHER
Caesar Cipher என்பது ஒரு classical substitution cipher. இதில் plaintext-ல் உள்ள ஒவ்வொரு letter-யும் alphabet-ல் ஒரு fixed number of positions shift செய்து ciphertext உருவாக்கப்படுகிறது. Simple definition: Caesar Cipher = Each plaintext let…
Premium — locked
Advanced
17 min
74 cards
3 programs 10 MCQs v3
This is a premium lesson. You can see the shape of every card — unlock to read them.
Unlock
Definition
Caesar Cipher என்பது ஒரு classical substitution cipher. இதில் plaintext-ல் உள்ள ஒவ்வொரு letter-யும் alphabet-……
Simple Explanation
Suppose: Key = 3 அதாவது ஒவ்வொரு letter-யும் 3 positions forward shift செய்ய வேண்டும். A → D B → E C →……
Explanation
Why name caesar cipher?
இந்த cipher-க்கு Julius Caesar பெயர் வந்துள்ளது. Historical accounts-ல் Julius Caesar தனத……
Explanation
Type of cipher
Caesar Cipher ஒரு: Substitution Cipher மேலும் specifically: Monoalphabetic Substitution Cipher ஏன்?……
Flow
Plaintext ↓ Choose Shift Key ↓ Shift Each Letter ↓ C……
Explanation
Key
Caesar Cipher-ல் Key என்பது எத்தனை positi……
Program
Example
Explanation
means: 3 positions forward Encryption……
Explanation
Alphabet mapping
Key = 3 என்று எடுத்துக்கொள்வோம். Plain : A B C D E F G H I J K L M Cipher: D E F G H I J K L M N O P Continue……
Explanation
Letter number representation
Mathematical calculation செய்ய letters-ஐ numbers-ஆக repr……
Explanation
Why a = 0?
Caesar cipher formula: mod 26 பயன்படுத்துகிறது. 26 letters-……
Formula
Encryption formula
Caesar Cipher encryption formula: C = (P + K) m……
Formula
Decryption formula
P = (C - K) mod 26 Where: P = Plaintext C = C……
Real Life Example
Example 1
Plaintext: HELLO Key: 3 Step ……
Real Life Example
Therefore: HELLO → KHOOR…
Dry Run
Dry run: h
Formula
C = (P + K) mod 26 Substitute: C = (……
Dry Run
Dry run: e
Real Life Example
Wrap around example
Suppose plaintext: X Key: 3 X value: X = 23 Encrypt……
Real Life Example
Another wrap example
Plaintext: Z Key: 3 Z = 25. C = (……
Real Life Example
Example 2
Plaintext: CAT Key: 3 Calcula……
Real Life Example
Example 3
Plaintext: ATTACK Key: 3 Letter conver……
Explanation
Decryption
Suppose ciphertext: KHOOR Key: 3 We need original p……
Real Life Example
Decryption mathematical example
Cipher letter: K K value: 10 ……
Formula
P = (C - K) mod 26 Substitute: P = (……
Real Life Example
Negative mod example
Suppose ciphertext: B Key: 3 B = 1. Decryption: P = (1 - 3) mod 26 = ……
Explanation
General form
If: P = Plaintext C = Ciphertext K = Key The……
Explanation
Shift direction
Usually: Encryption = Right / Forward Shift and:……
Explanation
Key space
English alphabet: 26 letters Possible shifts: 0 to 25 But: Ke……
Explanation
Why caesar cipher is weak
Caesar cipher has only: 25 useful keys Attacker can try all possible shifts. Ciphertext: ……
Explanation
Brute force attack
Brute Force என்பது: Possible keys அனைத்தையும் ஒன்றன்பின் ஒன்றாக try ச……
Explanation
Frequency analysis
Caesar Cipher monoalphabetic cipher என்பதால்: Same plaintext letter ↓ Same ciphertext letter E → H Every E be……
Explanation
Why frequency is preserved
Suppose plaintext: EEEE Key 3: HHHH Plaintext-ல் E 4 times. Ciphertext-ல……
Comparison
Caesar cipher vs monoalphabetic
Caesar cipher actually monoalphabetic substitution cipher-ன் special case. ……
Explanation
Example
Caesar Key 3: ABCDEFGHIJKLMNOPQRSTUVWXYZ DEFGHIJKLMNOPQRS……
Comparison
Caesar vs vigenère
Explanation
Example
Caesar: A → D A → D A → D Vigen……
Algorithm
Encryption Algorithm Step 1: Read plaintext. Step 2: Choose shift key K. Step 3: Conver……
Algorithm
Decryption algorithm
Step 1: Read ciphertext. Step 2: Use same key K. Step 3: Convert cipher le……
Explanation
Pseudocode
Encryption: For each character P: C = (P + K) mod 26 Print C……
Explanation
Line explanation
text = "HELLO" Plaintext store செய்கிறது. key = 3 Shift amount. for ch in text: ஒவ்வொரு character-யும் எடுத்த……
Explanation
Advantages
Caesar Cipher-ன் advantages: Very simple. Easy to understan……
Explanation
Disadvantages
Very small key space. Brute-force attack easy. Frequency analysis……
Explanation
Security
Caesar cipher: Historical / Educational Cipher மட்டுமே. Modern sensitive in……
Important
Caesar Cipher-ஐ: Shift Cipher என்றும் அழைக்கிறார்கள். It is: Substituti……
Common Mistake
Common error 1
Wrong: Caesar Cipher changes letter positions. Correct: Caesar C……
Common Mistake
Common error 2
Wrong: Caesar cipher is polyalp……
Common Mistake
Common error 3
Wrong: Caesar encryption uses……
Common Mistake
Common error 4
Wrong: A = 1, B = 2 ... Z = 26 Caesar mathematical form……
Common Mistake
Common error 5
Encryption formula: C = P + K என்று மட்டும்……
Memory Trick
Caesar: C = Change by Constant…
Remember
Encryption → + Decryption → - Alphabet →……
TRB Point
TRB / NET / SET exam-க்கு முக்கியமான facts: Caesar cipher is a substitution cipher. It is a monoalphabetic ci……
MCQ
Caesar Cipher is a:…
MCQ
Caesar Cipher is classified a……
MCQ
Caesar Cipher is also called:…
MCQ
Caesar encryption formula is:…
MCQ
Caesar decryption formula is:…
MCQ
If key = 3, A becomes:…
MCQ
If key = 3, X becomes:…
MCQ
If plaintext is HELLO and key……
MCQ
Caesar cipher has how many us……
MCQ
Caesar Cipher is vulnerable t……
Practice
Question 1
Encrypt: DATA using: Key = 3 Try: D → ? A……
Practice
Question 2
Encrypt: XYZ using Key = 3. A……
Practice
Question 3
Decrypt: FDW using Key = 3. F……
TRB Point
Exam short answer
Caesar Cipher என்பது ஒரு classical monoalphabetic substitution cipher. இதில் plaintext-ல் உள்ள ஒவ்வொரு letter……
Summary
CAESAR CIPHER | ├── Classical Cipher | ├── Substitution Cipher | ├── Monoalphabetic | ├── Fixed Shift | ├── E……
Text size
Theme
Contents
Print / PDF