| Caesar Cipher | Shifts letters by a fixed number down the alphabet. |
| Atbash Cipher | Maps each letter of the alphabet to its reverse, so the first letter becomes the last letter, and so on. |
| Vigenère Cipher | Uses a keyword to shift letters in a more complex pattern than the Caesar cipher. |
| Enigma Machine | A complex encryption machine used by the Germans during WWII, using rotors to encrypt messages. |
| RSA | A public-key cryptosystem for secure data transmission. |
| AES (Advanced Encryption Standard) | A symmetric block cipher chosen by the U.S. government to protect classified information. |
| DES (Data Encryption Standard) | A symmetric-key algorithm for the encryption of digital data, superseded by AES. |
| Playfair Cipher | Encrypts pairs of letters (digraphs), making it harder to break than single letter encryption. |
| Transposition Cipher | Rearranges the letters in the plaintext to encrypt the message. |
| One-Time Pad | Uses a pre-shared key of the same length as the message, making it theoretically unbreakable. |
| XOR Cipher | Applies the XOR logical operation to encrypt messages, often used in digital systems. |
| Hill Cipher | Uses linear algebra, encrypting messages by multiplying matrices. |
| Rail Fence Cipher | Writes messages in a zigzag pattern on an imaginary fence, then reads off cipher row by row. |
| ROT13 | A specific case of the Caesar cipher which shifts letters 13 positions in the alphabet. |
| Blowfish | A symmetric block cipher designed to be a fast and secure alternative to DES or IDEA. |
| Twofish | A symmetric key block cipher, a successor to Blowfish with a complex key structure. |
| IDEA (International Data Encryption Algorithm) | A symmetric-key block cipher designed as a replacement for DES. |
| RC4 (Rivest Cipher 4) | A stream cipher designed for simplicity and speed, used in protocols like WEP and WPA for Wi-Fi security. |
| Diffie-Hellman Key Exchange | A method of securely exchanging cryptographic keys over a public channel. |
| Elliptic Curve Cryptography (ECC) | Uses elliptic curves over finite fields for public key cryptography, offering smaller keys compared to RSA. |
