“Basic” is probably a misnomer here. Although the principles behind each of the most common encryption types is easy to understand, each of them relies on complicated mathematical operations and requires a lot of computing power.
Advanced Encryption Standard (AES) is a type of symmetric encryption, which means that plaintext is encrypted into ciphertext with one key, and can only be decrypted with the same key. AES uses 128-bit keys and each 16-character block of text goes through between 10 and 14 rounds of substitution.
Rivest-Shamir-Adleman (RSA) encryption is asymmetric encryption - which means that plaintext is encrypted into ciphertext with one key, and can only be decrypted with a different key.
RSA relies on the factoring of extraordinarily large prime numbers and the fact that it is very difficult to work out which prime numbers were multiplied together to produce an even bigger number. It’s simple in principle, but almost impossible to break in practice.
3DES is the most common type of encryption used by banks to secure and verify online transactions. It is based on the earlier DES, which was pioneered as a symmetric key encryption standard in the early 1970s.
3DES is now viewed as being comparatively insecure and is due to be phased out in 2023.
Twofish is the successor to Blowfish. It differs from its predecessor in that it uses a 128-bit block size instead of 64 bit, and employs key sizes of up to 256 bits.
Like Blowfish, Twofish was released into the public domain and anyone can use it, free of charge.