🎇Encryption Standards & Cryptographic Protocols

Overview of the Cryptographic Stack

Anon VPN uses a hybrid cryptographic model, where:

• Symmetric encryption is used for high-speed data transfer after the tunnel is established.

• Asymmetric encryption is used for secure key exchanges and authentication.

• Hash functions verify data integrity and ensure secure message authentication.

Key Protocols and Libraries Used:

Layer	Technology / Protocol	Library / Standard
Symmetric	AES-256-GCM	OpenSSL / Libsodium
Asymmetric	ECDHE, RSA-4096	OpenSSL / BoringSSL
Key Exchange	ECDH / Curve25519	NaCl / Libsodium
Hashing	SHA-512, BLAKE2, SHA-2	FIPS 180-4
Authentication	HMAC, ChaCha20-Poly1305	RFC 8439, RFC 7634
Handshake	TLS 1.3, Noise Protocol	WireGuard, OpenVPN

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2. Symmetric Encryption

AES-256-GCM (Galois/Counter Mode)

• Purpose: Encrypts the payload of VPN traffic after session key establishment.

• Block Size: 128 bits

• Key Size: 256 bits

• Mode: GCM ensures authenticated encryption with associated data (AEAD).

• Advantages: High throughput, resistance to timing attacks, and secure even on untrusted hardware.

All OpenVPN-based connections in Anon VPN are encrypted using AES-256-GCM unless the client explicitly requests an alternative.

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ChaCha20-Poly1305

• Used in: WireGuard and fallback modes on mobile.

• Advantages: Fast on low-power devices (e.g., ARM), constant-time operations.

• Nonce Size: 96 bits

• Key Size: 256 bits

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3. Key Exchange Protocols

ECDHE (Elliptic-Curve Diffie–Hellman Ephemeral)

• Purpose: Establishes shared secrets between clients and servers without transmitting private keys.

• Curve Used: secp384r1 or Curve25519 depending on protocol.

• Ephemeral Keys: Regenerated per session to enable Perfect Forward Secrecy (PFS).

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X25519 (WireGuard’s Key Exchange)

• Advantages:

  • Highly performant

  • Small key sizes

  • Resistant to several known attacks

• Library: Libsodium’s implementation of ECDH over Curve25519

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4. Message Authentication

HMAC (Hash-based Message Authentication Code)

• Used in: OpenVPN and TLS 1.2/1.3

• Hash Function: SHA-2 (SHA-256 or SHA-512)

• Purpose: Ensures the authenticity and integrity of each packet and handshake message.

Poly1305 MAC

• Used in combination with ChaCha20 for authenticated encryption in WireGuard.

• Provides integrity and authenticity guarantees with minimal overhead.

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5. Hash Functions

Anon VPN uses strong cryptographic hash functions for message integrity and pseudo-random key derivation:

Algorithm	Usage
SHA-512	HMAC, integrity checks, signature schemes
BLAKE2s	Lightweight hashing for embedded platforms
SHA-256	TLS/SSL negotiation, key derivation

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6. TLS and Handshake Protocols

TLS 1.3 (Transport Layer Security)

• Usage: Utilized during OpenVPN session negotiation.

• Benefits:

  • Reduced handshake round trips

  • Eliminates weak cipher suites

  • Supports only AEAD (authenticated encryption)

TLS 1.3 handshakes are further hardened by:

• Enforcing minimum key sizes (2048-bit RSA, 256-bit ECDSA)

• Enabling certificate pinning for internal servers

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7. Forward Secrecy (PFS)

Perfect Forward Secrecy ensures that even if a long-term key is compromised, previous session keys remain secure.

How Anon VPN enforces PFS:

• All key exchanges are ephemeral (ECDHE / X25519)

• Session keys are regenerated every 15–30 minutes

• Key material is never written to disk

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8. Post-Quantum Cryptography (PQC) Readiness

Anon VPN is actively testing integration of quantum-resistant algorithms, particularly:

Algorithm	Type	Status
Kyber-768	KEM (Key Encapsulation Mechanism)	Under test
Dilithium	Digital Signatures	Planned

These will be deployed in hybrid mode with current algorithms to future-proof communications while maintaining backward compatibility.

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9. Encrypted Metadata & Obfuscation

While VPN protocols often expose metadata (e.g., handshake sizes, timing), Anon VPN addresses this via:

• TLS Record Padding: Prevents fingerprinting of handshake packets.

• Pluggable Transports (future): Will use obfs4, Shadowsocks, and meek to disguise traffic as normal HTTPS.

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10. Protocol-Specific Security Summary

Protocol	Encryption	Handshake	Auth & Integrity	Forward Secrecy
OpenVPN	AES-256-GCM	TLS 1.3 + ECDHE	HMAC-SHA-512	Yes
WireGuard	ChaCha20-Poly1305	Noise Protocol (IKpsk2)	Poly1305, Curve25519	Yes
IKEv2/IPSec	AES-256-CBC or GCM	Diffie–Hellman Groups	HMAC-SHA2	Yes

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Conclusion

Anon VPN employs cutting-edge cryptographic standards rooted in proven mathematical rigor and industry-recognized protocols. From ephemeral key exchanges and authenticated encryption to PQC-readiness, every cryptographic component in Anon VPN is optimized for:

• High performance

• Strong privacy guarantees

• Resilience against present and future adversaries

This foundation enables Anon VPN to meet the demands of privacy-conscious users, developers, enterprises, and censorship-resilient applications.