Arnika - Quantum secure VPN

Arnika is a compact, lightweight external extension for Wireguard VPN, engineered to incorporate symmetric keys as Pre-Shared Keys (PSK) into Wireguard. This integration ensures the establishment of a quantum-secure VPN (safeguarding against compromise of session keys).

It gathers a 256-bit symmetric encryption key from a Key Management System (KMS) within a Quantum Key Distribution (QKD) infrastructure, shares the associated key ID with an Arnika peer, and configures an additional Pre-Shared Key (PSK) for Wireguard using the obtained key material.

Arnika offers an additional security layer for cryptography enthusiasts. It can integrate Post-Quantum Cryptography (PQC) by leveraging a PQC key provided by a system like Rosenpass. This key is then used to create an even stronger Preshared Key (PSK) for WireGuard. This PSK benefits from both PQC and QKD, offering enhanced protection against potential security threats.

Arnika integrates with WireGuard to establish quantum-resistant VPN connections, adding a significant layer of security to your communication

Arnika has been developed in scope of EU EUROQCI / QCI-CAT research program for the Use-Case HSM BACKUP USING QKD - https://qci-cat.at/hsm-backup-using-qkd

Figure 1

Figure 2

SAE (Secure Application Entity) = Wireguard + Rosenpass + Arnika

The approach of combining symmetric keys from Quantum Key Distribution (QKD) and/or Post-Quantum Cryptography (PQC) with WireGuard as preshared key (PSK) has been used to enhance the security to achieve a post-quantum secure VPN.

The setup supports 3 operational modes, A, B, and C

• (A) ... QKD mode
• (B) ... PQC mode
• (C) ... QKD+PQC hyprid mode

Regardless of the selected mode, WireGuard always receives a single 256bit (32byte) key as PSK which is used for WireGuard internal MixKeyAndHash() using HKDF.

Figure 3 shows the key path of 2 interconnected sites for the hyprid mode (C) (QKD+PQC). In this scenario, the KEY-CONTROL function serves as a control entity, responsible for obtaining a key and transferring it to the encryption function (WireGuard).

Figure 3

The QKD key is obtained via ETSI014 from the QKDs embedded KMS and the PQC key is obtained via API or pointer/filedescriptor from a source such as Rosenpass or an alternative/already existing PQC function/implementation.

Subsequently, the KEY-CONTROL function uses the QKD key and PQC key by using a HKDF HMAC Key Derivation Function with SHA3-256 as the hash function, to derive a single key from the two input keys (QKD, PQC). The specific derivation function, whether HKDF or an alternative, is a topic open for discussion among cryptographic experts.

QKD/PQC operation on Layer 3 offers several notable advantages:

• Very low keyrate -> 1key per 120seconds (Rekey-After-Time, Rekey-After-Messages)
• PQC/QKD keys can be injected as preshared key at runtime by design
• no change in existing WireGuard setups
• L3 based VPN can go over any existing, affortable, foreign infrastructure over the internet
• Rosenpass (PQC) already implemented in netbird commercial VPN service Netbird that supports mesh functionality
• unaffected by patent "Method of integrating QKD with IPSec" (US7602919B2,CN101142779A,...)

The Secure Application Entity consists of following components running on a secure and hardened linux system:

• Wireguard
• Rosenpass
• Arnika

Version 1.22 => golang-1.22

apt install golang-1.22
export PATH=/usr/lib/go-1.22/bin/:$PATH

$ go version
go version go1.22.2 linux/amd64

$ apt install golang-go
$ go version
go version go1.18.1 linux/amd64
$ make build
/home/arnika/arnika/go.mod:3: invalid go version '1.22.1': > must match format 1.23

make build

nean@qcicat01:~/arnika$ make build
Building arnika
CGO_ENABLED=0 go build -trimpath -ldflags "-w -s -extldflags=-Wl,-Bsymbolic -X 'main.Version=v0.2.0-14-gd429061' -X 'main.APPName=arnika'" -o build/arnika .
go: downloading golang.org/x/crypto v0.8.0
go: downloading golang.zx2c4.com/wireguard/wgctrl v0.0.0-20230429144221-925a1e7659e6
go: downloading golang.zx2c4.com/wireguard v0.0.0-20230325221338-052af4a8072b
go: downloading github.com/mdlayher/genetlink v1.3.2
go: downloading github.com/mdlayher/netlink v1.7.2
go: downloading golang.org/x/sys v0.7.0
go: downloading golang.org/x/net v0.9.0
go: downloading github.com/josharian/native v1.1.0
go: downloading github.com/mdlayher/socket v0.4.1
go: downloading golang.org/x/sync v0.1.0

go run tools/mock.go

now you can use the QKD KMS mock at https://127.0.0.1:8080

http_proxy=https://127.0.0.1:8080 no_proxy=127.0.0.1 LISTEN_ADDRESS=127.0.0.1:9999 SERVER_ADDRESS=127.0.0.1:9998 INTERVAL=1m KMS_URL="https://localhost:8080/api/v1/keys/CONSA" WIREGUARD_INTERFACE=qcicat0 WIREGUARD_PEER_PUBLIC_KEY="****************" build/arnika

http_proxy=https://127.0.0.1:8080 no_proxy=127.0.0.1 LISTEN_ADDRESS=127.0.0.1:9998 SERVER_ADDRESS=127.0.0.1:9999 INTERVAL=1m KMS_URL="https://QKDServer/api/v1/keys/CONSB" WIREGUARD_INTERFACE=qcicat0 WIREGUARD_PEER_PUBLIC_KEY="****************" build/arnika

Arnika must be configured via environment variables, following are available:

Arnika was developed by Cancom Converged Services and the source code was released under Apache-2.0

WireGuard is an extremely simple fast and modern VPN that utilizes state-of-the-art cryptography.

WireGuard is designed as a general purpose VPN for running on embedded interfaces and super computers alike, fit for many different circumstances.

WireGuard uses state-of-the-art cryptography, like the Noise protocol framework, Curve25519, ChaCha20, Poly1305, BLAKE2, SipHash24, HKDF, and secure trusted constructions. It makes conservative and reasonable choices and has been reviewed by cryptographers.

WireGuard supports the use of an optional 256-bit (32-byte) preshared key (PSK) as an additional layer of security. The preshared key (PSK) is combined with the ephemeral keys generated during the initial handshake using the HKDF (HMAC-based Key Derivation Function). When a preshared key (PSK) is not used, the preshared key value used internally is an all-zero string of 32 bytes.

To ensure perfect forward secrecy (PFS) and minimizing the impact of key compromise WireGuard Rekeying timer is 120 seconds or 2^60 messages.

Refer to WireGuard Homepage [https://www.wireguard.com/protocol/] and Whitepaper [https://www.wireguard.com/papers/wireguard.pdf] for more technical details.

WireGuard Source Code Repositories and Official Projects

WireGuard is free and open-source software (FOSS) and licensed under GPLv2.

WireGuard and the WireGuard logo are registered trademarks of Jason A. Donenfeld.

The Rosenpass protocol provides a post-quantum-secure authenticated key exchange, based on the work Post-quantum WireGuard (PQWG) by Hülsing, Ning, Schwabe, Weber, and Zimmermann [https://eprint.iacr.org/2020/379], but also adds security against state disruption attacks CVE-2021-46873.

While Rosenpass is designed with WireGuard in mind, it can be used as a stand-alone tool to exchange keys. Using this mode, it can be employed to secure other protocols against attacks from quantum computers. Rosenpass will provide a Post-Quantum Cryptography (PQC) key every 120 seconds.

Rosenpass is using wo different Key Encapsulation Mechanisms (KEMs) Classic McEliece and Kyber

Refer to 10 – 12 Apr. 2024 Fifth NIST PQC workshop [https://classic.mceliece.org/talks/20240410.pdf]

Daniel J. Bernstein, Tung Chou, Carlos Cid, Jan Gilcher, Tanja Lange, Varun Maram, Ingo von Maurich, Rafael Misoczki, Ruben Niederhagen, Edoardo Persichetti, Christiane Peters, Nicolas Sendrier, Jakub Szefer, Cen Jung Tjhai, Martin Tomlinson, Wen Wang

Classic McEliece for long-term keys, the foundation of security for identifying and authenticating the server, as well as for encrypting data. Authenticity and Confidentiality

Kyber just for forward secrecy: a break of the lattice system does not damage security unless the attacker can also steal secret keys through, e.g., hardware theft.

Rosenpass was funded through NLnet with financial support from the European Commission’s NGI Assure program and ProtoType Fund of the Open Knowledge Foundation Germany, financed by the Federal Ministry of Education and Research (BMBF).

Refer to Rosenpass Homepage [https://rosenpass.eu/] and Whitepaper [https://rosenpass.eu/whitepaper.pdf] for more technical details.

Rosenpass is free and open-source software (FOSS) and licensed under Apache 2.0 license

Many thanks to Karo and Paul from the Rosenpass project.

Building on the long research experience of Austrian institutions in the field of quantum technologies, the project QCI-CAT aims at an adoption of modern encryption technology based on QKD for highly secure communication between public authorities.

QCI-CAT will investigate and verify new security applications for public authorities, such as secret sharing and message authentication.

Additionally, QCI-CAT will also leverage a research testbed for new technological approaches such as the combination of post-quantum encryption with QKD, long-distance QKD with secured trusted nodes and field trials of quantum repeaters.

AIT Austrian Institute of Technology (AIT) is Austria’s largest research and technology organization. The institute takes a leading position in the Austrian innovation system and a key role in Europe. With its expertise of handling large EU quantum communication projects such as OPENQKD, AIT will coordinate QCI-CAT from an administrative point, as well as act as the technical manager and project lead.