Anthropic-Cybersecurity-Skills/skills/implementing-digital-signatures-with-ed25519/assets/template.md

Ed25519 Digital Signatures Template

Quick Reference

from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey

# Generate
private_key = Ed25519PrivateKey.generate()
public_key = private_key.public_key()

# Sign
signature = private_key.sign(b"message data")

# Verify
public_key.verify(signature, b"message data")  # raises InvalidSignature on failure

Key Formats

Format	Private Key Size	Public Key Size	Signature Size
Raw	32 bytes	32 bytes	64 bytes
PEM (PKCS#8)	~119 bytes	~90 bytes	N/A
SSH	~83 bytes	~51 bytes	~83 bytes

Use Cases

• API request authentication (sign request body)
• Software/code signing
• Document signing
• Git commit signing (ssh-ed25519)
• JWT signing (EdDSA algorithm)
• Certificate signing (X.509 with Ed25519)