What does AES stand for?
AES stands for Advanced Encryption Standard. The symmetric block cipher that encrypts most data today, with 128-, 192- or 256-bit keys. It secures Wi-Fi under WPA2 and WPA3 (replacing the broken RC4 of WEP and TKIP), BitLocker, FileVault and TLS.
AES is the symmetric block cipher used almost everywhere data is encrypted today: Wi-Fi with WPA2 and WPA3, full-disk encryption, VPNs, TLS. Symmetric means the same key encrypts and decrypts. It works on blocks of 128 bits with a key of 128, 192 or 256 bits. It is fast, especially on processors with built-in AES instructions, which is why it is used for bulk data while slower asymmetric algorithms are used to exchange the key.
AES in practice: an example
A technician configures a wireless router. The security options offer WPA with TKIP or WPA2 with AES. He selects WPA2 with AES, because TKIP was a stopgap for old hardware and is no longer considered secure, and newer wireless standards will not run at full speed with it.
What AES is confused with
AES vs RSA: what is the difference?
AES is symmetric: one shared key, fast, used for the data itself. RSA is asymmetric: a public and a private key, slow, used for key exchange and signatures.
AES vs TKIP: what is the difference?
TKIP is the older encryption protocol introduced with the first WPA to patch WEP on existing hardware. AES, in the form of CCMP, replaced it in WPA2.
Which exams cover AES?
AES is on the official CompTIA acronym list for one of the four exams covered here.
- A+ 220-1201 and 220-1202: 220-1202 2.0 (Security).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. Which key sizes does AES support?
- 56 and 112 bits
- 128, 192 and 256 bits
- 1024 and 2048 bits
- 512 bits only
Show the answer
B. 128, 192 and 256 bits. The standard defines three key lengths: 128, 192 and 256 bits. The larger numbers in the other options belong to asymmetric algorithms and the smaller ones to DES.
2. Which statement about AES is correct?
- It uses a public key to encrypt and a private key to decrypt
- It uses the same key to encrypt and to decrypt
- It is a hashing algorithm
- It is used only for digital signatures
Show the answer
B. It uses the same key to encrypt and to decrypt. AES is a symmetric cipher. Public and private key pairs belong to asymmetric algorithms, and a hash cannot be reversed at all.
Sources: NIST FIPS 197, Advanced Encryption Standard (AES); NIST glossary: Advanced Encryption Standard; Wi-Fi Alliance: Wi-Fi security. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.