Which encryption standard did the U.S. government adopt to replace DES in 2001?

The U.S. government adopted the Advanced Encryption Standard to replace DES in 2001.

AES was selected through a public competition run by the National Institute of Standards and Technology. The winning design was Rijndael, created by Belgian cryptographers Joan Daemen and Vincent Rijmen. NIST published AES as Federal Information Processing Standard 197 in November 2001.

AES supports 128-bit, 192-bit, and 256-bit keys, although every version uses 128-bit data blocks. Its design made it substantially more practical and secure for modern systems than the aging Data Encryption Standard, whose effective key length was only 56 bits.

AES is often confused with RSA because both are widely used in cybersecurity. AES is symmetric encryption, meaning the same secret key encrypts and decrypts data; RSA is an asymmetric public-key system. AES remains common in disk encryption, wireless security, virtual private networks, and encrypted internet connections.