AES encryption is considered secure against attacks from both classical and quantum computers. The security of AES is based on the difficulty of performing certain mathematical operations, and no efficient attacks are known that can break it.
However, it is important to note that the advent of large-scale, fault-tolerant quantum computers could potentially pose a threat to many cryptographic algorithms, including AES. Quantum computers leverage quantum phenomena, such as superposition and entanglement, to perform certain calculations much faster than classical computers.
One particular algorithm that could pose a threat to AES and other commonly used cryptographic algorithms is Shor's algorithm. Shor's algorithm, when executed on a sufficiently powerful quantum computer, can efficiently factorize large numbers and solve the discrete logarithm problem, which are the underlying mathematical problems that many asymmetric encryption schemes, such as RSA and elliptic curve cryptography, rely on.
AES, on the other hand, is a symmetric encryption algorithm, which means that the same key is used for both encryption and decryption. Shor's algorithm does not directly apply to symmetric encryption algorithms like AES. However, quantum computers could still potentially weaken AES indirectly by breaking the asymmetric encryption algorithms used to establish secure key exchange protocols, such as Diffie-Hellman key exchange.
The exact timeline for the development of large-scale, fault-tolerant quantum computers capable of breaking AES is uncertain. It depends on the progress made in quantum technology, error correction techniques, and other factors. Researchers and cryptographic experts are actively working on developing quantum-resistant cryptographic algorithms to address the potential threat of quantum computers.
In summary, while AES is currently considered secure against attacks from both classical and quantum computers, the long-term security of AES and other cryptographic algorithms in the presence of large-scale, fault-tolerant quantum computers is a topic of ongoing research and development.