Pre-shared key
A pre-shared key is secret keying material provisioned in advance to communicating parties for authentication or cryptographic operations.
Real-World Cryptography
A secret key provisioned to communicating parties before a protocol session begins and shared for use in cryptographic operations.
- How it is used
- Uses a shared secret to avoid public-key infrastructure and key exchange between known communicating machines.
- How deep it goes
- Defines PSKs and sketches TLS 1.3 negotiation, but stops short of key-derivation internals and provisioning guidance.
- Examples
- Uses two machines that connect only to each other and a ClientHello/ServerHello PSK exchange.
- What you can do after
- Evaluate TLS 1.3 PSK use when avoiding a public-key exchange is appropriate.
Hacking Cryptography
Secret keying material configured in advance and shared by the communicating parties.
- How it is used
- Uses a preconfigured secret with public initialization vectors to derive per-packet RC4 keys in WEP.
- How deep it goes
- Traces key construction, RC4 scheduling bias, weak-IV selection, statistical recovery, and failure from insufficient message volume.
- Examples
- Uses WEP packets, the key helloworld123, weak-IV Go code, and 50,000-versus-500-message recovery tests.
- What you can do after
- Evaluate how WEP’s PSK construction enables practical key recovery through weak IVs and RC4 statistical bias.
Acing the CCNA Exam: Volume 2 Advanced Networking and Security
A pre-shared key is a secret value configured in advance on wireless clients and access points for shared-key authentication.
- How it is used
- Deploys shared wireless authentication primarily in SOHO networks and within CCNA WPA2-PSK configuration tasks.
- How deep it goes
- Explains PSK formats, authentication sequencing, handshake purposes, WPA3 SAE, and WLC security choices without providing CLI commands.
- Examples
- Uses WLC Layer 2 settings, ASCII passphrases, hexadecimal keys, WPA2 Policy, AES Encryption, and handshake figures.
- What you can do after
- Configure WPA2-PSK authentication on a WLAN and distinguish its WPA, WPA3 SAE, and WPA-Enterprise alternatives.
Read how Acing the CCNA Exam: Volume 2 Advanced Networking and Security explains pre-shared key →
Related concepts
- WPA-Personalused by · WPA-Personal is a wireless security mode that authenticates clients with a shared passphrase or pre-shared key.
- four-way handshakeused by · A four-way handshake is a protocol exchange consisting of four messages for terminating a TCP connection or establishing WPA encryption keys.
- password authenticationproduced by · Password authentication is an authentication method that verifies a claimed identity or access by checking a supplied secret password or passphrase.
- 802.1xalternative to · IEEE 802.1X is a port-based network access-control standard that requires device or user authentication before network access is granted.
- key exchangealternative to · Key exchange is a cryptographic protocol by which communicating parties establish a shared secret over a communication channel without directly transmitting that secret.
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