There are three types I guess. Symmetric, Asymmetric and Hash functions. They all have their own purposes.

Symmetric Algorithms

This is where the same key is used to encrypt and de-crypt.

• Advanced Encryption Standard (AES)
  • Key sizes: 128, 192 or 256 bits
  • Block size: 128 bits
  • Used in: WPA2, SSL/TLS, file encryption
  • Strengths: Fast, strong and widely supported
• Data Encryption Standard (DES)
  • Key size: 56 bits
  • Block size: 64
  • considered to be insecure
  • Replaces by AES
• Triple DES(3DES)
  • Key size: 112 or 168 bits
  • Just works as DES 3 times over
  • More secure than DES but slower and depreciated
• Blowfish
  • Key size: up to 256 bits
  • Block size: 64 bits
  • Fast and good for software encryption
• Twofish
  • Key size: up to 256 bits
  • Block size: 128 bits
  • Successor to blowfish, secure and flexible
• Rivest Cipher 4 (RC4)
  • Stream cipher (not a block cipher)
  • considered to be insecure
  • Used in WEP and early versions of TLS
• RC5/RC6
  • Variable key and block size
  • RC6 was almost used as AES
• ChaCha20
  • Stream cipher
  • Modern and secure alternative to RC4
  • Used in TLS and mobile encryption

Asymmetric Algorithms

This is where a public key is used to encrypt and a private key is used to decrypt. The private key is derived from the public key.

• Rivest-Shamir-Adleman (RSA)
  • Keysize: 1024-4096 bits
  • Based on factoring large intergers
  • Used for SSL/TLS, digital signatures
• Elliptic Curve Cryptography (ECC)
  • Smaller key sizes than RSA for same security level
  • Used in mobile devices, bitcoin and modern SSL
  • Popular curves: secp265k1, P-256
• ElGamal
  • Based on Diffie-Hellman key exchange
  • Used for digital signatures and encryption
  • Slower than RSA
• Digitial Signature Algorithm (DSA)
  • Used for digital signatures only
  • Often combined with SHA-1 and SHA-2

Hashing Algorithms

These are one way and non-reversible. These are used for data integrity and password storage

• Message Digest 5 (MD5)
  • Output size: 128 bits
  • Fast but broken with collisions
  • Do not use for security
• Secure Hash Algorithm 1 (SHA-1)
  • Output size: 160 bits
  • Broken- proven to have collisions
  • Depreciated by most standards
• SHA-2 Family
  • SHA-224, SHA-256, SHA-384 and SHA-512
  • Secure and widely used everywhere
  • Used in digital signatures, TLS and bitcoin
• SHA-3
  • Newer, built on Keccak
  • Resistant to attacks different from SHA-2
  • Slower in software but highly secure
• BLAKE2 / BLAKE 3
  • Fast and secure
  • Modern alternative to MD5 and SHA-2
  • Good for embedded devices and cryptographic use

Key Derivation and Password Hashing Functions

• Password Based Key Derivation Function 2 (PBKDF2)
  • Used for hashing passwords
  • Includes salts and iterations
  • supported in many libraries
• bcrypt
  • Good for password hashing
  • Includes salt and cost factor
  • Slower by design to resist brute force attacks
• scrypt
  • Designed to be memory intensive
  • Even better protection against hardware attacks
• Argon2
  • Winner of Password Hashing Competition
  • Highly recommended for newer systems
  • Has variants: Argon2i, Argon2d, Argon2id

Protocols and Algorithm Standards