RC4
RC4 is a stream-cipher algorithm that generates a pseudorandom keystream from a variable-length secret key using a permutation-based internal state.
Hacking Cryptography
RC4 is a stream cipher that generates a keystream from a variable-length secret key using a permutation-based state algorithm.
- How it is used
- Uses RC4 to connect stream-cipher implementation with WEP password recovery by traffic capture.
- How deep it goes
- Works through KSA, PRGA, XOR encryption, and a byte-by-byte statistical FMS recovery procedure.
- Examples
- Demonstrates Go RC4 encryption and FMS recovery of “helloworld123” from 50,000 weak-IV packets.
- What you can do after
- Build it from scratch in Go and evaluate why weak-IV packet volume enables WEP key recovery.
Acing the CCNA Exam: Volume 2 Advanced Networking and Security
RC4 is a stream-cipher algorithm that generates a pseudorandom keystream for encrypting data.
- How it is used
- Provides WEP with stream encryption for wireless messages after client authentication and association.
- How deep it goes
- Defines RC4's WEP role and packet-level IV use, but does not explain cipher internals or implementation steps.
- Examples
- Uses a new 24-bit IV per packet and a 32-bit ICV appended before encryption as concrete WEP artifacts.
- What you can do after
- Evaluate RC4's role and security limitations when identifying legacy WEP wireless configurations.
Read how Acing the CCNA Exam: Volume 2 Advanced Networking and Security explains RC4 →
Related concepts
- WEPused by · WEP is an obsolete IEEE 802.11 wireless security protocol that used RC4 encryption and shared, weakly managed keys.
- FMS attackused by · The FMS attack is a statistical attack that exploits RC4 key-scheduling biases in WEP weak-IV traffic to recover bytes of the preshared key.
- key-scheduling algorithmhas part · The RC4 key-scheduling algorithm initializes and shuffles the cipher’s S-box using the secret key.
- pseudorandom generation algorithmhas part · RC4's pseudorandom generation algorithm updates the cipher state and produces successive keystream bytes.
- stream cipherkind of · A stream cipher is an encryption algorithm that combines plaintext sequentially with a generated keystream, typically using XOR.
- initialization vectoruses · An initialization vector is a typically nonsecret value supplied to a cryptographic operation to initialize or vary its processing across uses.
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