WEP, WPA/TKIP, and WPS: Why Legacy Wireless Security Fails

WEP (Wired Equivalent Privacy) is insecure because its RC4-based encryption reuses short initialization vectors, letting an attacker who captures enough traffic recover the network key in minutes with free tools. WPA with TKIP (Temporal Key Integrity Protocol) was only ever a stopgap patch on that same broken foundation and is likewise deprecated. WPS (Wi-Fi Protected Setup) fails differently — its 8-digit PIN can be brute-forced in hours because of a design flaw in how the PIN is validated. On any network you touch as a technician, all three should be off or absent, replaced by WPA2-AES at minimum and WPA3 where supported.

WEP: broken encryption you can crack in minutes

WEP was the original 802.11 security scheme, and its name states its ambition: privacy roughly equivalent to a wired connection. It missed. WEP encrypts with the RC4 stream cipher using a static key shared by every device, combined with a 24-bit initialization vector (IV) that changes per packet. The problems compound:

• The IV is too short. With only about 16.7 million possible values, IVs repeat quickly on a busy network. Repeated IVs with the same static key produce related keystreams, and related keystreams leak the key.
• The key is static. Every device uses the same key indefinitely; there is no per-session rekeying, so every captured packet contributes to the same attack.
• The keys themselves are small. 64-bit and 128-bit WEP actually provide 40 and 104 bits of secret key after the IV is subtracted.

The practical result: a passive attacker who collects enough packets — accelerated by injection techniques that generate traffic on demand — recovers the WEP key with automated tools, typically in under ten minutes. This is not a theoretical weakness that requires a nation-state; it is a solved, scripted attack. That is why WEP is unsuitable for any modern network and why it has been formally deprecated for well over a decade. If you audit a customer site and find WEP anywhere, that finding outranks nearly everything else on your report.

WPA with TKIP: the stopgap that expired

When WEP collapsed, hardware in the field could not run AES (Advanced Encryption Standard) — the chips lacked the processing capability. WPA with TKIP was engineered as a firmware-upgradeable bridge: it kept the RC4 cipher those chips could handle but wrapped it with per-packet key mixing, a longer 48-bit IV, sequence counters to stop replay attacks, and an integrity check called Michael.

Those patches bought time, not safety. TKIP still rests on RC4, and published attacks can decrypt individual packets and inject forged traffic on TKIP networks. The Wi-Fi Alliance formally deprecated TKIP, and modern Wi-Fi standards refuse to negotiate high data rates over it. So when you find an older router running “WPA/TKIP,” the most significant concern is that it relies on a deprecated protocol with known cryptographic weaknesses — it is not merely “older,” it is attackable. The fix is to reconfigure for WPA2 with AES-CCMP or, better, WPA3 — the differences are covered in WPA2 vs WPA3. If the hardware cannot do that, the hardware gets replaced.

On the exam’s “choose two deprecated technologies” pattern, WEP and WPA (TKIP) are the pair. WPA2 remains acceptable with AES; WPA3 is current.

WPS: convenience with a brute-forceable back door

WPS attacks a different layer. It never encrypts anything — it is an onboarding convenience that lets a device join a WPA/WPA2-protected network without the user typing the passphrase, either by pressing a physical button on the router (push-button connect) or by entering an 8-digit PIN printed on the router’s label.

The PIN method is the disaster. Eight digits sounds like 100 million combinations, but the protocol validates the PIN in two halves: the router’s response reveals whether the first four digits were correct before the rest is even checked, and the eighth digit is a checksum. That collapses the search space to roughly 10,000 guesses for the first half plus about 1,000 for the second — around 11,000 total attempts. An attacker in radio range runs an automated tool against the router and typically recovers the PIN within hours; the tool then extracts the actual Wi-Fi passphrase, no matter how long and random the owner made it. Many routers, especially older ones, never lock out repeated PIN attempts.

This is why disabling WPS PIN entry is a standard hardening step: it removes an always-on external attack surface that bypasses the passphrase entirely. A 63-character random passphrase protects nothing if the router will hand it over to anyone who grinds through 11,000 PINs. Push-button mode is less dangerous (it requires physical access during a short window), but on routers that only offer a global WPS on/off switch, turn the whole feature off. Disabling WPS belongs on the same checklist as the other steps in SOHO router hardening.

The legacy lineup at a glance

Technology	What it is	Fatal flaw	Status
WEP	Original 802.11 encryption (RC4, static key)	Short repeating IVs let attackers recover the key in minutes	Deprecated — never use
WPA (TKIP)	RC4 stopgap with per-packet key mixing	Still RC4-based; packet decryption and injection attacks exist	Deprecated — never use
WPS (PIN)	Passphrase-free onboarding via 8-digit PIN	PIN validated in halves ≈ 11,000 guesses reveals the passphrase	Disable on every router
WPA2 (AES-CCMP)	AES-based successor	Offline dictionary attacks on weak passphrases	Acceptable minimum
WPA3 (SAE)	Current generation	—	Preferred

How the 220-1202 exam tests this

• An audit scenario: a technician inspects an older router configured for WPA/TKIP or WEP and must identify the most significant concern — the deprecated, cryptographically broken protocol, not cosmetic issues like the SSID name or channel selection. (For why SSID tweaks are cosmetic in the first place, see SSID hiding and MAC filtering.)
• A “why is this a best practice” question: the technician disables WPS PIN entry during hardening, and you must explain that the PIN is brute-forceable and exposes the passphrase regardless of passphrase strength.
• A pick-the-deprecated-pair question: from a list including WEP, WPA (TKIP), WPA2, and WPA3, identify the two that must not be used on a modern network.
• A trait-matching drag-and-drop: pair each protocol with its signature characteristic — WEP with crackable RC4/IV reuse, TKIP with the deprecated RC4 stopgap, WPA2 with AES-CCMP, WPA3 with SAE, WPS with the brute-forceable PIN — the same pairing drills you’ll meet in A+ Core 2 practice questions.

Wireless security is one slice of the Security domain — the full 220-1202 study guide maps every domain, the exam format, and how to plan your prep.

Quick reference

• WEP uses RC4 with a static key and 24-bit IVs; IV reuse lets attackers recover the key in minutes.
• WPA/TKIP kept RC4 to run on WEP-era hardware; it is deprecated and vulnerable to packet decryption and injection.
• The deprecated pair to eliminate on any network: WEP and WPA (TKIP).
• WPS PIN validation leaks each half separately — about 11,000 guesses defeats it and reveals the full passphrase.
• Disable WPS (at minimum the PIN method) on every SOHO router you configure.
• A strong passphrase cannot compensate for WEP, TKIP, or an enabled WPS PIN.
• Remediation path: WPA2 with AES-CCMP as the floor, WPA3 wherever client devices support it.