The decryption format (e.g., AES).
The decryption key in hexadecimal format.
The initialization vector in hexadecimal format.
The ciphertext in base64 format to decrypt.
Whether to use padding (default: true).
The decrypted plaintext string, or null
if decryption fails.
Decrypts a base64-encoded ciphertext using the specified format, key, and IV.