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Imported from mukul975/anthropic-cybersecurity-skills (skills/implementing-digital-signatures-with-ed25519/SKILL.md). Install upstream with npx skills add mukul975/anthropic-cybersecurity-skills --skill implementing-digital-signatures-with-ed25519. Copyright stays with the author (Apache-2.0).

Implementing Digital Signatures with Ed25519

Name: implementing-digital-signatures-with-ed25519
Author: mukul975

Overview

Ed25519 is a high-performance digital signature algorithm using the Edwards curve Curve25519. It provides 128-bit security with 64-byte signatures and 32-byte keys, offering significant advantages over RSA and ECDSA including deterministic signatures (no random nonce needed), resistance to side-channel attacks, and fast verification. This skill covers implementing Ed25519 for document signing, code signing, and API authentication.

When to Use

When deploying or configuring implementing digital signatures with ed25519 capabilities in your environment
When establishing security controls aligned to compliance requirements
When building or improving security architecture for this domain
When conducting security assessments that require this implementation

Prerequisites

Familiarity with cryptography concepts and tools
Access to a test or lab environment for safe execution
Python 3.8+ with required dependencies installed
Appropriate authorization for any testing activities

Objectives

Generate Ed25519 key pairs for signing
Sign messages and files with Ed25519
Verify signatures against public keys
Implement multi-signature verification
Build a simple code signing system
Compare Ed25519 performance with RSA and ECDSA

Key Concepts

Ed25519 vs RSA vs ECDSA

Property	Ed25519	RSA-3072	ECDSA P-256
Security	128-bit	128-bit	128-bit
Public key size	32 bytes	384 bytes	64 bytes
Signature size	64 bytes	384 bytes	64 bytes
Key generation	~50 us	~100 ms	~1 ms
Sign	~70 us	~5 ms	~200 us
Verify	~200 us	~200 us	~500 us
Deterministic	Yes	No (PSS)	No (unless RFC 6979)

Key Properties

Deterministic: Same message + key always produces same signature
Collision-resistant: No separate hash function needed
Side-channel resistant: Constant-time implementation
Small keys: 32 bytes each (public and private)

Security Considerations

Ed25519 does not support key recovery from signatures
Verify the full message, not a hash (Ed25519 hashes internally)
Public keys must be validated before use (check for low-order points)
Private keys should be stored encrypted at rest
Ed25519 is not yet approved for all NIST use cases (Ed448 is preferred for federal)

Validation Criteria

Key pair generation produces valid Ed25519 keys
Signature verification succeeds for valid message
Signature verification fails for tampered message
Signature verification fails for wrong public key
Deterministic: same input produces same signature
File signing and verification works correctly
Performance meets or exceeds RSA-3072

Use it

Copy one of these into your project. Installing also returns the manifest and these snippets.

yaml

targets:
  - https://api.opensmartroute.ai/api/v1/registry/mukul975-anthropic-cybersecurity-skills-implementing-dig-b4b8ba/manifest   # or paste the manifest below

Manifest

An Open Capability Manifest: the router reads it to know what this does, what it costs and when to pick it.

mukul975-anthropic-cybersecurity-skills-implementing-dig-b4b8ba.ocm.jsonjson

{
  "ocm": "1",
  "id": "mukul975-anthropic-cybersecurity-skills-implementing-dig-b4b8ba",
  "kind": "skill",
  "name": "implementing-digital-signatures-with-ed25519",
  "description": "Implements digital signatures using the Ed25519 algorithm (Curve25519), covering key-pair generation, signing, signature verification, and security tradeoffs versus RSA and ECDSA. Use when adding message or artifact signing and authentication-integrity checks to a system, or when advising on Ed25519 key properties and validation criteria.",
  "publisher": "mukul975",
  "version": "1.0.0",
  "capabilities": {
    "domains": [
      "general"
    ],
    "tags": [
      "skill-md",
      "cryptography",
      "digital-signatures",
      "ed25519",
      "authentication",
      "integrity",
      "skills-sh"
    ],
    "languages": [
      "en"
    ]
  },
  "quality_prior": 0.6,
  "examples": [
    "Implements digital signatures using the Ed25519 algorithm (Curve25519), covering key-pair generation, signing, signature verification, and security tradeoffs versus RSA and ECDSA. Use when adding message or artifact signing and authentication-integrity checks to a system, or when advising on Ed25519 key properties and validation criteria."
  ],
  "primary": false,
  "metadata": {
    "source": {
      "provider": "skills.sh",
      "repository": "https://github.com/mukul975/anthropic-cybersecurity-skills",
      "path": "skills/implementing-digital-signatures-with-ed25519/SKILL.md",
      "ref": "HEAD",
      "url": "https://github.com/mukul975/anthropic-cybersecurity-skills/blob/HEAD/skills/implementing-digital-signatures-with-ed25519/SKILL.md",
      "key": "mukul975/anthropic-cybersecurity-skills/skills/implementing-digital-signatures-with-ed25519/SKILL.md"
    },
    "license": "Apache-2.0"
  },
  "instructions": "# Implementing Digital Signatures with Ed25519\n\n## Overview\n\nEd25519 is a high-performance digital signature algorithm using the Edwards curve Curve25519. It provides 128-bit security with 64-byte signatures and 32-byte keys, offering significant advantages over RSA and ECDSA including deterministic signatures (no random nonce needed), resistance to side-channel attacks, and fast verification. This skill covers implementing Ed25519 for document signing, code signing, and API authentication.\n\n\n## When to Use\n\n- When deploying or configuring implementing digital signatures with ed25519 capabilit",
  "cost": {
    "context_tokens": 706
  }
}

Fetch it by URL: GET /api/v1/registry/mukul975-anthropic-cybersecurity-skills-implementing-dig-b4b8ba/manifest?version=1.0.0

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