Algorithms using Symmetric Encryption

Typically a symmetric encryption procedures use a sequence of steps, involving different crypto algorithms:

• Password-to-key derivation algorithm (like Scrypt or Argon2): to allow using a password instead of a key and to make password cracking hard and slow to be performed.
• Block to stream cipher transformation algorithm (block cipher mode like CBC or CTR) + message padding algorithm like PKCS7 (in some modes): to allow encrypting data of arbitrary size using a block cipher algorithm (like AES).
• Block cipher algorithm (like AES): to securely encrypt data blocks of fixed length using a secret key.
• Message authentication algorithm (like HMAC): to check whether after decryption the obtained result matches the original message before the encryption.