go-i2cp/examples/modern-crypto

Modern Cryptography Demo

This example demonstrates the modern cryptographic algorithms supported by go-i2cp.

Features Demonstrated

• Ed25519 Digital Signatures: Fast, secure signing and verification
• X25519 Key Exchange: ECDH for perfect forward secrecy
• ChaCha20-Poly1305 Encryption: Authenticated encryption with additional data (AEAD)
• Stream Serialization: I2CP protocol-compatible serialization
• Legacy DSA Support: Backward compatibility with older I2P versions

What You'll Learn

• How to generate key pairs for multiple algorithms
• Message signing and signature verification
• Diffie-Hellman key exchange (ECDH)
• Authenticated encryption and decryption
• Serialization and deserialization of cryptographic keys
• Integration with the I2CP Crypto struct

Running the Example

cd examples/modern-crypto
go run modern_crypto_demo.go

Building the Example

cd examples/modern-crypto
go build
./modern-crypto

Example Output

The demo will show:

=== I2CP Modern Cryptography Demo ===
✅ Crypto system initialized

🔑 Ed25519 Digital Signatures:
   ✅ Generated Ed25519 key pair
   ✅ Signed message (64 bytes signature)
   ✅ Signature verification successful

🔐 X25519 Key Exchange (ECDH):
   ✅ Generated Alice's X25519 key pair
   ✅ Generated Bob's X25519 key pair
   ✅ ECDH successful - shared secret established

🔒 ChaCha20-Poly1305 Authenticated Encryption:
   ✅ Created ChaCha20-Poly1305 cipher
   ✅ Encrypted message: 54 bytes → 70 bytes
   ✅ Decryption successful - message integrity verified

💾 Stream Serialization (I2CP compatibility):
   ✅ Ed25519 key pair serialized
   ✅ Ed25519 serialization/deserialization successful

🔄 Legacy DSA Support (preserved):
   ✅ Generated DSA key pair
   ✅ Legacy DSA functionality preserved

🎉 I2CP cryptography modernization complete!

Code Highlights

Ed25519 Signatures

crypto := go_i2cp.NewCrypto()
kp, _ := crypto.Ed25519SignatureKeygen()
signature, _ := kp.Sign(message)
verified := kp.Verify(message, signature)

X25519 Key Exchange

aliceKp, _ := crypto.X25519KeyExchangeKeygen()
bobKp, _ := crypto.X25519KeyExchangeKeygen()
sharedSecret, _ := aliceKp.GenerateSharedSecret(bobKp.PublicKey())

ChaCha20-Poly1305 Encryption

cipher, _ := crypto.ChaCha20Poly1305CipherKeygen()
ciphertext, _ := cipher.Encrypt(plaintext, additionalData)
decrypted, _ := cipher.Decrypt(ciphertext, additionalData)

Stream Serialization

stream := go_i2cp.NewStream(make([]byte, 0, 1024))
kp.WriteToStream(stream)
kp2, _ := go_i2cp.Ed25519KeyPairFromStream(stream)

Cryptographic Algorithms

Ed25519

• Type: Digital signature algorithm
• Security: 128-bit security level
• Key Size: 32 bytes (public), 64 bytes (private)
• Signature Size: 64 bytes
• Performance: Very fast signing and verification
• Use Case: Message authentication, identity verification

X25519

• Type: Elliptic curve Diffie-Hellman (ECDH)
• Security: 128-bit security level
• Key Size: 32 bytes (public and private)
• Shared Secret: 32 bytes
• Performance: Fast key exchange
• Use Case: Perfect forward secrecy, session key establishment

ChaCha20-Poly1305

• Type: Authenticated encryption with additional data (AEAD)
• Security: 256-bit key, 128-bit authentication
• Key Size: 32 bytes
• Nonce Size: 12 bytes
• Authentication Tag: 16 bytes
• Performance: Very fast on modern CPUs
• Use Case: Secure message encryption, tunnel encryption

Requirements

• Go 1.18 or later
• No I2P router required (this example works standalone)

Related Examples

• Context Usage - Demonstrates context-aware operations
• Examples Overview - All available examples

Further Reading

• Ed25519 Specification
• RFC 7748 - X25519
• RFC 8439 - ChaCha20-Poly1305
• I2CP Specification
• go-i2cp Main Documentation