AES (Advanced Encryption Standard)

AES is a symmetric block cipher standardized by NIST in FIPS 197 (2001) after Vincent Rijmen and Joan Daemen's Rijndael design won an open competition to replace DES. It encrypts data in 128-bit blocks with key sizes of 128, 192, or 256 bits, running 10, 12, or 14 rounds of substitution, permutation, mixing, and key addition. AES is used either in confidentiality-only modes (CTR, CBC) or — preferably — authenticated modes such as AES-GCM, AES-CCM, or AES-GCM-SIV that also provide integrity. After more than two decades of public cryptanalysis, no practical attack reduces effective security below brute force; AES is widely hardware-accelerated (AES-NI, ARMv8 crypto) and is considered the modern gold standard for symmetric encryption.