PW security measures
Explore security requirements and innovative solutions to tackle potential threats in PW control protocols, with detailed analysis and proposed authentication and encryption methods for enhanced protection.
PW security measures
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Presentation Transcript
PWsecuritymeasures PWE3 – 65th IETF 10 November 2005 Yaakov (J) Stein
Reminder At IETF64 security threats were presented: • PWs have special features that may be exploited by hackers • PW control plane does not mandate authentication • PW user packets have no authentication/encryption options draft-stein-pwe3-sec-req-00.txt reviews security requirements here we will mention a few solution ideas …
Control Protocol Authentication Problem many of the attacks in draft-stein-pwe3-sec-req-00.txt can be avoided if it is not possible to impersonate a PE thus PWE control protocol needs a strong authentication mechanism Solution 1 – MD5 • use MD5 signature option (shared key per peer) per RFC3036 • every LDP message (even hellos) is authenticated • MD5 may be replaced by SHA-1 or any other message digest Solution 2 – authentication TLV for initialization • new optional TLV in the initialization message • use public key mechanism • reject if no authentication TLV or if authentication fails
PW Packet Authentication Problems • PW label is the only identifier in packet • CW sequence number can be used for DoS attack Solution add optional authentication field between control word and payload (becomes a control word extension) lightweight option 32 bit CW extension (must be negotiated via a new LDP TLV) computed based on limited-size input, for example: • sequence number + salt • sequence number + checksum of payload heavyweight option 64 or 128 bit CW extension (must be negotiated via a new LDP TLV) hash of sequence number + payload WARNING: if performed in SW enables DoS attack
PW Packet Encryption at IETF-64 we discussed encrypting the PW payload Problem • PW is not reliable – may lose packets (don’t even know how many bytes lost) • so, can’t use stream cipher, CBC, CFB, etc. modes Solution 1 • use ECB mode on sequence number + payload (including sequence number blocks replay attacks) Solution 2 • generate per-packet key based on secret key and sequence number • use ECB mode on payload