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Agent skill
Implementing End To End Encryption For Messaging
Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary…
Install Implementing End To End Encryption For Messaging
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messaging --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .claude/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .claude/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messagingType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messaging --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .agents/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .agents/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messaging --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .cursor/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .cursor/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git --path skills/implementing-end-to-end-encryption-for-messaging--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messaging --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .gemini/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .gemini/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messagingInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .github/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .github/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install mukul975/Anthropic-Cybersecurity-Skills implementing-end-to-end-encryption-for-messaging --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/implementing-end-to-end-encryption-for-messaging .opencode/skills/implementing-end-to-end-encryption-for-messaging && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "implementing-end-to-end-encryption-for-messaging" agent skill from https://github.com/mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-end-to-end-encryption-for-messaging into .opencode/skills/implementing-end-to-end-encryption-for-messaging/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "implementing-end-to-end-encryption-for-messaging", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
implementing-end-to-end-encryption-for-messaging- GitHub stars
- 34k
- Token cost
- ~843 tokens
- SKILL.md length
- 327 words
- Files
- 8 (incl. scripts, references, assets)
- Skills in repo
- 644
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary…
- Building E2EE messaging
- SKILL.md covers Overview, When to Use, Prerequisites and Objectives, plus 3 more sections
- Runs Python scripts from its folder
- Evaluating forward-secrecy and key-management tradeoffs for a messaging system
What it does
Implementing End To End Encryption For Messaging is an agent skill from mukul975/Anthropic-Cybersecurity-Skills. Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary can decrypt messages. Use when designing or building E2EE messaging, or evaluating forward-secrecy and key-management tradeoffs for a messaging system.
Its SKILL.md is about 840 tokens, which your agent loads only when the skill is triggered. The skill folder holds 10 other files, including scripts, reference files and assets (for example `assets/template.md`, `references/api-reference.md` and `references/standards.md`).
It sits in Security, covering Cryptography and End-to-end testing. The repository describes itself as: 817 structured cybersecurity skills for AI agents · Mapped to 6 frameworks: MITRE ATT&CK, NIST CSF 2.0, MITRE ATLAS, D3FEND, NIST AI RMF & MITRE F3 (Fight Fraud) · agentskills.io…. The licence is Apache-2.0.
When your agent uses it
- Building E2EE messaging
- Evaluating forward-secrecy and key-management tradeoffs for a messaging system
Example prompts
- “Use the implementing-end-to-end-encryption-for-messaging skill to implement a simplified Signal Protocol-style end-to-end encryption scheme for…”
- “/implementing-end-to-end-encryption-for-messaging”
Requirements
- Python 3
What it can do on your machine
Read from SKILL.md and the folder at commit 54a7988. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Ships 2 files in scripts/ (Python), which the agent can run.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Implementing End To End Encryption For Messaging loads about 843 tokens when it runs, and up to ~2.4k if it reads all its reference files. Until then it costs about 99 tokens; SKILL.md has 327 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.
SKILL.md
The full file from mukul975/Anthropic-Cybersecurity-Skills at commit 54a7988, republished under its Apache-2.0 licence (© mukul975). 327 words, ~843 tokens.
Download SKILL.mdSave it as
.claude/skills/implementing-end-to-end-encryption-for-messaging/SKILL.md (or your agent's skills folder). This skill also uses 7 other files; get the full folder from GitHub.- name
- implementing-end-to-end-encryption-for-messaging
- description
- Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary can decrypt messages. Use when designing or building E2EE messaging, or evaluating forward-secrecy and key-management tradeoffs for a messaging system.
- domain
- cybersecurity
- subdomain
- cryptography
- tags
- cryptography, encryption, e2e, messaging, signal-protocol
- version
- 1.0
- author
- mahipal
- license
- Apache-2.0
- nist_csf
- PR.DS-01, PR.DS-02, PR.DS-10
- mitre_attack
- T1600, T1573, T1553, T1486
Implementing End-to-End Encryption for Messaging
Overview
End-to-end encryption (E2EE) ensures that only the communicating parties can read messages, with no intermediary (including the server) able to decrypt them. This skill implements a simplified version of the Signal Protocol's Double Ratchet algorithm, using X25519 for key exchange, HKDF for key derivation, and AES-256-GCM for message encryption.
When to Use
- When deploying or configuring implementing end to end encryption for messaging 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
- Implement X25519 Diffie-Hellman key exchange for session establishment
- Build the Double Ratchet key management algorithm
- Encrypt and decrypt messages with per-message keys
- Implement forward secrecy (compromise of current key does not reveal past messages)
- Handle out-of-order message delivery
- Implement key agreement using X3DH (Extended Triple Diffie-Hellman)
Key Concepts
Signal Protocol Components
| Component | Purpose | Algorithm |
|---|---|---|
| X3DH | Initial key agreement | X25519 |
| Double Ratchet | Ongoing key management | X25519 + HKDF + AES-GCM |
| Sending Chain | Per-message encryption keys | HMAC-SHA256 chain |
| Receiving Chain | Per-message decryption keys | HMAC-SHA256 chain |
| Root Chain | Derives new chain keys on DH ratchet | HKDF |
Forward Secrecy
Each message uses a unique encryption key derived from a ratcheting chain. After a key is used, it is deleted, ensuring that compromise of the current state does not reveal previously sent/received messages.
Security Considerations
- Delete message keys immediately after decryption
- Implement message ordering and replay protection
- Use authenticated encryption (AES-GCM) for all messages
- Protect identity keys with device-level security
- Verify identity keys out-of-band (safety numbers)
Validation Criteria
- X25519 key exchange produces shared secret
- Messages encrypt and decrypt correctly between two parties
- Different messages produce different ciphertexts
- Forward secrecy: old keys cannot decrypt new messages
- Out-of-order messages can be decrypted
- Tampered messages are rejected by authentication
© mukul975, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 7 other files (scripts, references, assets) in skills/implementing-end-to-end-encryption-for-messaging of mukul975/Anthropic-Cybersecurity-Skills.
- SKILL.md
- LICENSE
- assets/template.md
- references/api-reference.md
- references/standards.md
- references/workflows.md
- scripts/agent.py
- scripts/process.py
Open the folder on GitHubat commit 54a7988
Compare with similar skills
Implementing End To End Encryption For Messaging next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Implementing End To End Encryption For Messaging this skillmukul975/Anthropic-Cybersecurity-Skills | 34k | — | ~843 | Automated safety check: Pass | Apache-2.0 | |
| Bom Explorecdxgen/cdxgen | 1.1k | — | ~1.2k | Automated safety check: Pass | Apache-2.0 | |
| Webcrypt MCPputervision/state-memory-mcp | 114 | — | ~847 | Automated safety check: Pass | MIT | |
| Crypto Analysishypnguyen1209/offensive-claude | 388 | — | ~2.2k | Automated safety check: Pass | MIT | |
| Security Reviewvalory-xyz/open-autonomy | 129 | — | ~11k | Automated safety check: Notes | Apache-2.0 | |
| Hashcat Password Recovery WorkflowAgentSecOps/SecOpsAgentKit | 220 | 1 repos | ~3.3k | Automated safety check: Notes | Custom licence |
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Related
Categories
Questions about Implementing End To End Encryption For Messaging
What does Implementing End To End Encryption For Messaging do?
Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary…. Implementing End To End Encryption For Messaging is an agent skill from mukul975/Anthropic-Cybersecurity-Skills. Implements a simplified Signal Protocol-style end-to-end encryption scheme for messaging, covering key exchange, forward secrecy, and the core cryptographic components so no server or intermediary can decrypt messages.
When should I use Implementing End To End Encryption For Messaging?
Implementing End To End Encryption For Messaging fits situations like: building E2EE messaging; evaluating forward-secrecy and key-management tradeoffs for a messaging system.
How do I install Implementing End To End Encryption For Messaging in Claude Code?
Run `npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a claude-code`. Or copy the skill folder (skills/implementing-end-to-end-encryption-for-messaging in mukul975/Anthropic-Cybersecurity-Skills) into .claude/skills/implementing-end-to-end-encryption-for-messaging in your project. Claude Code loads it when a task matches its description.
How do I install Implementing End To End Encryption For Messaging in Codex?
Run `npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a codex`. Or copy the skill folder (skills/implementing-end-to-end-encryption-for-messaging in mukul975/Anthropic-Cybersecurity-Skills) into .agents/skills/implementing-end-to-end-encryption-for-messaging in your project. Codex loads it when a task matches its description.
Can I use Implementing End To End Encryption For Messaging in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/implementing-end-to-end-encryption-for-messaging, .gemini/skills/implementing-end-to-end-encryption-for-messaging, .github/skills/implementing-end-to-end-encryption-for-messaging and .opencode/skills/implementing-end-to-end-encryption-for-messaging in your project.
What does Implementing End To End Encryption For Messaging need to run?
Going by SKILL.md and its folder, Implementing End To End Encryption For Messaging needs Python for the scripts in its folder. Our summary lists: Python 3.
Does Implementing End To End Encryption For Messaging access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Implementing End To End Encryption For Messaging safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.
What licence does Implementing End To End Encryption For Messaging use?
Implementing End To End Encryption For Messaging is published under the Apache-2.0 licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Implementing End To End Encryption For Messaging use?
About 843 tokens (SKILL.md is roughly 3.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.6k tokens, read only when the agent opens those files.
What are the alternatives to Implementing End To End Encryption For Messaging?
Skills that share tags, products or a category with Implementing End To End Encryption For Messaging: Bom Explore (cdxgen/cdxgen, 1.1k stars), Webcrypt MCP (putervision/state-memory-mcp, 114 stars), Crypto Analysis (hypnguyen1209/offensive-claude, 388 stars) and Security Review (valory-xyz/open-autonomy, 129 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Implementing End To End Encryption For Messaging?
mukul975 (a GitHub user) maintains it in mukul975/Anthropic-Cybersecurity-Skills, which has 33,993 GitHub stars. The repository holds 644 skills in this directory. The repository was last updated on August 31, 2026.
Source: mukul975/Anthropic-Cybersecurity-Skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.