(Which cryptographic operation has the fastest decryption process?

Symmetric cryptography generally provides the fastest encryption and decryption performance among common cryptographic operations. Algorithms like AES and ChaCha20 are designed for high throughput and efficient implementation in software and hardware (e.g., AES-NI acceleration). Symmetric decryption is computationally similar in cost to symmetric encryption, and both are far faster than asymmetric operations for equivalent security levels. Asymmetric cryptography (RSA, ECC) involves expensive mathematical operations (modular exponentiation or elliptic-curve scalar multiplication), making it much slower and unsuitable for bulk data decryption. That is why real-world secure protocols use asymmetric cryptography primarily to authenticate peers and establish keys, then switch to symmetric encryption for the actual data stream. Hashing is not decryption at all; it is one-way, and there is no “decrypt” operation for a hash. Padding is not a decryption mechanism; it is a formatting step used with block ciphers to align plaintext length. Therefore, the correct choice for the operation with the fastest decryption process is symmetric cryptography.