Encryption algorithms use mathematical functions to convert plaintext into ciphertext, which is a scrambled version of the original message that is unreadable without a decryption key.

The following are some of the basic functions used in encryption algorithms:

**Substitution:**Substituting one letter, number, or symbol for another to create the ciphertext.**Transposition**: Rearranging the order of the characters in plaintext to create the ciphertext.**Modular arithmetic**: A mathematical operation used to calculate the remainder of a division between two numbers.**Bitwise operations**: Operations such as AND, OR, XOR, and NOT that manipulate binary data at the bit level.**Hashing**: A one-way function that takes an input and produces a fixed-length output, typically used in digital signatures and message authentication codes.**Key generation**: Creating a unique key to be used in the encryption and decryption process.**Block cipher algorithms**: Algorithms that encrypt data in fixed-size blocks, such as AES and DES.**Stream cipher algorithms**: Algorithms that encrypt data one bit or byte at a time, such as RC4.

These are some of the basic functions used in encryption algorithms. The specific combination and implementation of these functions can vary between different encryption algorithms, but they are all designed to provide confidentiality and security for digital information.