Monoalfabeetilise

Monoalfabeetilise is a term that refers to a type of cipher or cryptographic system where a simple substitution is applied to each letter of the alphabet. In a monoalphabetic substitution cipher, each letter in the plaintext is consistently replaced by a different letter or symbol in the ciphertext. For example, if 'A' is always replaced by 'Q', then every instance of 'A' in the original message will appear as 'Q' in the encrypted message. The key to this cipher is the specific mapping or substitution alphabet used.

These types of ciphers are considered "monoalphabetic" because only one substitution alphabet is used for the entire message. This is in contrast to polyalphabetic ciphers, which employ multiple substitution alphabets, making them more complex and generally more secure. Examples of simple monoalphabetic ciphers include the Caesar cipher, where each letter is shifted by a fixed number of positions in the alphabet, and more general substitution ciphers where the mapping is arbitrary.

While easy to implement and understand, monoalphabetic ciphers are relatively weak and susceptible to cryptanalysis. Frequency analysis, which examines the patterns of letter occurrences in the ciphertext, can often be used to deduce the substitution alphabet, especially for longer messages. Despite their security limitations, monoalphabetic ciphers have historical significance and serve as a foundational concept in the study of cryptography.