Hill Cipher

Alphabet
Key

Hill Cipher is a polygraphic substitution cipher based on linear algebra. Invented by Lester S. Hill in 1929, it was the first polygraphic cipher in which it was practical (though barely) to operate on more than three symbols at once. It used matrices and matrix multiplication to mix up the plaintext. [Wikipedia]

Bifid Cipher is a cipher which combines the Polybius square with transposition, and uses fractionation to achieve diffusion.

Bifid Cipher

Bifid Cipher is a cipher which combines the Polybius square with transposition, and uses fractionation to achieve diffusion.
Four-Square Cipher encrypts pairs of letters (like playfair), which makes it significantly stronger than substitution ciphers etc. since frequency analysis becomes much more difficult.

Four-Square Cipher

Four-Square Cipher encrypts pairs of letters (like playfair), which makes it significantly stronger than substitution ciphers etc. since frequency analysis becomes much more difficult.
Vernam Cipher (also known as the one-time pad (OTP)) is an encryption technique that cannot be cracked, but requires the use of a one-time pre-shared key the same size as, or longer than, the message being sent.

Vernam Cipher

Vernam Cipher (also known as the one-time pad (OTP)) is an encryption technique that cannot be cracked, but requires the use of a one-time pre-shared key the same size as, or longer than, the message being sent.
XOR Cipher is a type of additive cipher.

XOR Cipher

XOR Cipher is a type of additive cipher.