IPsec downgrade protection (beta)
Cloudflare IPsec now supports IKE_SA_INIT_FULL_TRANSCRIPT_AUTH, an IKEv2 extension that protects against downgrade attacks by having both peers sign the entire handshake transcript. This prevents attackers from exploiting the original authentication design to bypass post-quantum key exchange.
Cloudflare IPsec now supports the IKE_SA_INIT_FULL_TRANSCRIPT_AUTH ↗ IKEv2 extension to protect against downgrade attacks on IPsec tunnels.
IKEv2's original authentication design has each endpoint sign only its own outbound messages, not the full handshake transcript. A quantum-capable on-path attacker ↗ can exploit this to bypass post-quantum key exchange by downgrading the connection to classical cryptography. The IKE_SA_INIT_FULL_TRANSCRIPT_AUTH extension addresses this by having both peers sign the entire handshake transcript during the authentication exchange, preventing an attacker from manipulating the negotiation without detection.
Key details:
- Available in beta for Cloudflare WAN and Magic Transit IPsec tunnels.
- Cloudflare sends the
IKE_SA_INIT_FULL_TRANSCRIPT_AUTHnotification unconditionally as a responder when the feature flag is enabled. - Both the initiator (your device) and responder (Cloudflare) must support the extension for downgrade protection to be effective.
- This feature is currently gated by a per-account feature flag. Contact your account team to turn it on.
Refer to Downgrade protection for more details.
Source: original entry ↗
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