Two users must encrypt and transmit large amount of data between them. Which of the following should they use to encrypt and transmit the data?

Symmetric algorithms use the same shared key for both encryption and decryption, making them extremely fast and computationally efficient for bulk data encryption. Standards like AES (Advanced Encryption Standard) are specifically designed to handle large volumes of data quickly, making symmetric encryption the industry standard for encrypting data in transit at scale.

Hash functions are one-way mathematical operations used to verify data integrity, not to encrypt and decrypt data - they cannot be reversed to recover the original plaintext.

Digital signatures use asymmetric cryptography to verify the authenticity and integrity of a message, but they do not encrypt the data payload itself for confidentiality.

Obfuscation merely makes data harder to read or understand (e.g., encoding or scrambling), but it does not provide true cryptographic security or a key-based mechanism for secure decryption.