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Text Encryption - Algorithm Explaination

This document provides a detailed explanation of the encryption and decryption algorithms used in this project, which offers three levels of security: Simple, Normal, and Advanced. The core technique employed is the Caesar cipher, known for its method of alphabet shifting.

Our implementation extends the traditional Caesar cipher by introducing enhanced security features, including multiple keys (both numerical and alphanumeric) and support for Unicode Characters. Unlike standard Caesar ciphers that use a single key and are limited to ASCII Characters, our approach is designed to handle a broader range of characters, making it more robust and secure.

This advanced approach not only increases the complexity of encryption but also ensures compatibility with a wide array of characters, thus significantly improving data protection.

On Simple Level Encryption

It's using basic Caeser cipher algorithm which have only one key

1. Before Encryption

  • Original Word: "HELLO"
  • Imagine each letter is on a scale from A to Z.
H  E  L  L  O

2. Encryption Process

  • Key: 3
  • Shift each letter forward by 3 positions in the alphabet:
H → K
E → H
L → O
L → O
O → R
  • Encrypted Word: "KHOOOR"

3. After Encryption

  • The letters have shifted to their new positions:
H  E  L  L  O  →  K  H  O  O  R

4. Decryption Process

  • To decrypt, shift the letters back by the same key (3 positions):
K → H
H → E
O → L
O → L
R → O
  • Decrypted Word: "HELLO"

On Normal Level Encryption

It's a customized cipher encryption algorithm made by me, which have 2 keys (1 integer + 1 string [alpha-numeric])

1. Before Encryption

  • Original Word: Let's say the word is "HELLO".
  • Integer Key: 3
  • String Key: "abc" (repeated if needed)

2. Encryption Process

  • Each letter in "HELLO" will be shifted by a combination of the integer key and the corresponding letter in the string key.

    • For H (1st letter) and a (1st letter of string key):

      • Shift by 3 (int key) + 0 ('a' - 'a') = 3
      • H → K

    • For E (2nd letter) and b (2nd letter of string key):

      • Shift by 3 (int key) + 1 ('b' - 'a') = 4
      • E → I

    • For L (3rd letter) and c (3rd letter of string key):

      • Shift by 3 (int key) + 2 ('c' - 'a') = 5
      • L → Q

    • For L (4th letter) and a (1st letter of string key again):

      • Shift by 3 (int key) + 0 ('a' - 'a') = 3
      • L → O

    • For O (5th letter) and b (2nd letter of string key again):

      • Shift by 3 (int key) + 1 ('b' - 'a') = 4
      • O → S

  • Encrypted Word: "KIOQS"

3. After Encryption

  • The letters have been shifted to their new positions:
H  E  L  L  O  →  K  I  O  Q  S

4. Decryption Process

  • To decrypt, reverse the shift by the same keys:

    • For K (1st letter) and a (1st letter of string key):

      • Shift back by 3 (int key) + 0 ('a' - 'a') = 3
      • K → H

    • For I (2nd letter) and b (2nd letter of string key):

      • Shift back by 3 (int key) + 1 ('b' - 'a') = 4
      • I → E

    • For O (3rd letter) and c (3rd letter of string key):

      • Shift back by 3 (int key) + 2 ('c' - 'a') = 5
      • O → L

    • For Q (4th letter) and a (1st letter of string key again):

      • Shift back by 3 (int key) + 0 ('a' - 'a') = 3
      • Q → N

    • For S (5th letter) and b (2nd letter of string key again):

      • Shift back by 3 (int key) + 1 ('b' - 'a') = 4
      • S → O

  • Decrypted Word: "HELLO"

On Advanced Level Encryption

1. Deriving the Key

  • String Key: "abc"

  • Derived Key Calculation: The derived key is calculated by summing the Unicode values of the characters in the string key.

    • For "abc":
      • 'a' = 97
      • 'b' = 98
      • 'c' = 99
      • Derived Key = 97 + 98 + 99 = 294

2. Encryption Process

  • Original Text: "HELLO"
  • Integer Key: 3
  • Derived Key: 294 (from string key "abc")

To encrypt, shift each character in the text by adding the derived key and integer key:

  • For H:

    • Unicode value of 'H' = 72
    • Shifted Unicode = 72 + 294 + 3 = 369
    • Encrypted Character = chr(369) = 'ý'

  • For E:

    • Unicode value of 'E' = 69
    • Shifted Unicode = 69 + 294 + 3 = 366
    • Encrypted Character = chr(366) = 'ü'

  • Repeat this process for each character, including any Unicode characters.

  • Encrypted Text: The result will be a string of characters based on the Unicode values calculated.

3. Decryption Process

To decrypt, reverse the process by subtracting the derived key and integer key:

  • Encrypted Text: For example, "ýü..."
  • Integer Key: 3
  • Derived Key: 294 (from string key "abc")

To decrypt, shift each character in the encrypted text backward by subtracting the derived key and integer key:

  • For ý:

    • Unicode value of 'ý' = 369
    • Original Unicode = 369 - 294 - 3 = 72
    • Decrypted Character = chr(72) = 'H'

  • For ü:

    • Unicode value of 'ü' = 366
    • Original Unicode = 366 - 294 - 3 = 69
    • Decrypted Character = chr(69) = 'E'

  • Repeat this process for each character, including any Unicode characters.

  • Decrypted Text: "HELLO"

Conclusion

In this guide, we examined various methods for encrypting and decrypting text to protect information. Each technique follows the same core principle: transforming text into an unreadable format with a key and then reverting it back to its original form using the same key.

  • Basic Caesar Cipher (On Simple Level): This straightforward method shifts characters in the text by a fixed number of positions. However, it has a significant limitation—it can be easily bruteforced due to its single key and limited number of possible shifts.

  • Customized Encryption (On Normal level): To address the shortcomings of the Caesar cipher, a more advanced approach involves using multiple keys—a numerical key and a string key. This greatly reduces the likelihood of successful brute-force attacks.

  • Unicode-Compatible Encryption (On Advanced level): The most advanced method extends the concept to handle Unicode characters, which include a vast range of symbols beyond the basic alphabet. This approach enhances security significantly by using multiple keys and accommodating a much larger set of characters, making it highly resistant to brute-force attacks.

These algorithms demonstrates various ways to safeguard text using encryption keys. Understanding these techniques lays a strong foundation for further exploration into data security and privacy.

©️ 2024 Ivin Titus