[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"skill:01M6HM1ZDXAHFY4485TKAFXCT4":3,"skill-same:01M6HM1ZDXAHFY4485TKAFXCT4":114},{"skillNo":4,"name":5,"nameZh":6,"description":7,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":16,"categories":17,"keywords":18,"publishedAt":39,"linkOnly":40,"markdownContent":41,"markdownBody":42,"frontMatter":43,"refName":57,"commitSha":58,"skillDirectory":59,"forksCount":60,"repositoryHtmlUrl":61,"repositoryHomepageUrl":6,"ownerHtmlUrl":62,"ownerBlogUrl":6,"ownerDescription":63,"updatedAt":64,"install":65,"resources":78},"01M6HM1ZDXAHFY4485TKAFXCT4","implementing-end-to-end-encryption-for-messaging",null,"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","HenriqueMC17\u002Fagente-core","HenriqueMC17","https:\u002F\u002Favatars.githubusercontent.com\u002Fu\u002F206460478?v=4","01M6HB63HBBF18AC4H09XTB549","Henrique Monteiro Cardoso","01M6HB63NGSQXWKWCFWW2B20W0",1,"Apache-2.0","https:\u002F\u002Fgithub.com\u002FHenriqueMC17\u002Fagente-core\u002Fblob\u002Fmain\u002Fmodules\u002Fimplementing-end-to-end-encryption-for-messaging\u002FSKILL.md",[],[19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38],"for","implementing","messaging","encryption","end","implementing end to end encryption for messaging","read","can","with","communicating","e2ee","only","version","cybersecurity","signal-protocol","e2e","messages","server","protocol","pr","2026-11-10 10:12:30",false,"---\nname: implementing-end-to-end-encryption-for-messaging\ndescription: 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\ndomain: cybersecurity\nsubdomain: cryptography\ntags:\n- cryptography\n- encryption\n- e2e\n- messaging\n- signal-protocol\nversion: '1.0'\nauthor: mahipal\nlicense: Apache-2.0\nnist_csf:\n- PR.DS-01\n- PR.DS-02\n- PR.DS-10\nmitre_attack:\n- T1600\n- T1573\n- T1553\n- T1486\ncategory: implementing-end-to-end-encryption-for-messaging\n---\n# Implementing End-to-End Encryption for Messaging\n\n## Overview\n\nEnd-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.\n\n\n## When to Use\n\n- When deploying or configuring implementing end to end encryption for messaging capabilities in your environment\n- When establishing security controls aligned to compliance requirements\n- When building or improving security architecture for this domain\n- When conducting security assessments that require this implementation\n\n## Prerequisites\n\n- Familiarity with cryptography concepts and tools\n- Access to a test or lab environment for safe execution\n- Python 3.8+ with required dependencies installed\n- Appropriate authorization for any testing activities\n\n## Objectives\n\n- Implement X25519 Diffie-Hellman key exchange for session establishment\n- Build the Double Ratchet key management algorithm\n- Encrypt and decrypt messages with per-message keys\n- Implement forward secrecy (compromise of current key does not reveal past messages)\n- Handle out-of-order message delivery\n- Implement key agreement using X3DH (Extended Triple Diffie-Hellman)\n\n## Key Concepts\n\n### Signal Protocol Components\n\n| Component | Purpose | Algorithm |\n|-----------|---------|-----------|\n| X3DH | Initial key agreement | X25519 |\n| Double Ratchet | Ongoing key management | X25519 + HKDF + AES-GCM |\n| Sending Chain | Per-message encryption keys | HMAC-SHA256 chain |\n| Receiving Chain | Per-message decryption keys | HMAC-SHA256 chain |\n| Root Chain | Derives new chain keys on DH ratchet | HKDF |\n\n### Forward Secrecy\n\nEach 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\u002Freceived messages.\n\n## Security Considerations\n\n- Delete message keys immediately after decryption\n- Implement message ordering and replay protection\n- Use authenticated encryption (AES-GCM) for all messages\n- Protect identity keys with device-level security\n- Verify identity keys out-of-band (safety numbers)\n\n## Validation Criteria\n\n- [ ] X25519 key exchange produces shared secret\n- [ ] Messages encrypt and decrypt correctly between two parties\n- [ ] Different messages produce different ciphertexts\n- [ ] Forward secrecy: old keys cannot decrypt new messages\n- [ ] Out-of-order messages can be decrypted\n- [ ] Tampered messages are rejected by authentication\n","# Implementing End-to-End Encryption for Messaging\n\n## Overview\n\nEnd-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.\n\n\n## When to Use\n\n- When deploying or configuring implementing end to end encryption for messaging capabilities in your environment\n- When establishing security controls aligned to compliance requirements\n- When building or improving security architecture for this domain\n- When conducting security assessments that require this implementation\n\n## Prerequisites\n\n- Familiarity with cryptography concepts and tools\n- Access to a test or lab environment for safe execution\n- Python 3.8+ with required dependencies installed\n- Appropriate authorization for any testing activities\n\n## Objectives\n\n- Implement X25519 Diffie-Hellman key exchange for session establishment\n- Build the Double Ratchet key management algorithm\n- Encrypt and decrypt messages with per-message keys\n- Implement forward secrecy (compromise of current key does not reveal past messages)\n- Handle out-of-order message delivery\n- Implement key agreement using X3DH (Extended Triple Diffie-Hellman)\n\n## Key Concepts\n\n### Signal Protocol Components\n\n| Component | Purpose | Algorithm |\n|-----------|---------|-----------|\n| X3DH | Initial key agreement | X25519 |\n| Double Ratchet | Ongoing key management | X25519 + HKDF + AES-GCM |\n| Sending Chain | Per-message encryption keys | HMAC-SHA256 chain |\n| Receiving Chain | Per-message decryption keys | HMAC-SHA256 chain |\n| Root Chain | Derives new chain keys on DH ratchet | HKDF |\n\n### Forward Secrecy\n\nEach 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\u002Freceived messages.\n\n## Security Considerations\n\n- Delete message keys immediately after decryption\n- Implement message ordering and replay protection\n- Use authenticated encryption (AES-GCM) for all messages\n- Protect identity keys with device-level security\n- Verify identity keys out-of-band (safety numbers)\n\n## Validation Criteria\n\n- [ ] X25519 key exchange produces shared secret\n- [ ] Messages encrypt and decrypt correctly between two parties\n- [ ] Different messages produce different ciphertexts\n- [ ] Forward secrecy: old keys cannot decrypt new messages\n- [ ] Out-of-order messages can be decrypted\n- [ ] Tampered messages are rejected by 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