[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"skill:01M6AF45ZQHGFHFR8ZX96WS4TY":3,"skill-same:01M6AF45ZQHGFHFR8ZX96WS4TY":117},{"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":33,"linkOnly":34,"markdownContent":35,"markdownBody":36,"frontMatter":37,"refName":50,"commitSha":51,"skillDirectory":52,"forksCount":53,"repositoryHtmlUrl":54,"repositoryHomepageUrl":55,"ownerHtmlUrl":56,"ownerBlogUrl":57,"ownerDescription":58,"updatedAt":59,"install":60,"resources":73},"01M6AF45ZQHGFHFR8ZX96WS4TY","implementing-end-to-end-encryption-for-messaging",null,"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.","mukul975\u002FAnthropic-Cybersecurity-Skills","mukul975","https:\u002F\u002Favatars.githubusercontent.com\u002Fu\u002F42860185?v=4","01M6ADEQR8T5M4EEG6C67BQCWF","Mahipal","01M6ADJPMYWG1E5GM1FWBE3128",35990,"Apache-2.0","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002FSKILL.md",[],[19,20,21,22,23,24,25,26,27,28,29,30,31,32],"messaging","encryption","implementing end to end encryption for messaging","cybersecurity","components","pr","core","protocol","server","messages","cryptography","key-management","e2e","signal-protocol","2026-11-10 10:12:30",false,"---\nname: implementing-end-to-end-encryption-for-messaging\ndescription: 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.\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\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 authentication\n",{"name":5,"tags":38,"author":39,"domain":22,"license":15,"version":40,"nist_csf":41,"subdomain":29,"description":7,"mitre_attack":45},[29,20,31,19,32],"mahipal","1.0",[42,43,44],"PR.DS-01","PR.DS-02","PR.DS-10",[46,47,48,49],"T1600","T1573","T1553","T1486","main","54a798831d2266a3ca61ce68a7acb80b81160d57","skills\u002Fimplementing-end-to-end-encryption-for-messaging",4395,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills","https:\u002F\u002Fmahipal.engineer\u002FAnthropic-Cybersecurity-Skills\u002F","https:\u002F\u002Fgithub.com\u002Fmukul975","Mahipal.engineer","🔐 Cybersecurity | 💻 Dev | 📷 Street Photographer\r\n🎓 MSc | 📚 Research & AI Security","2026-08-31 12:32:44",{"source":8,"skillName":5,"commands":61,"prompt":71,"zipAvailable":72},[62,65,68],{"tool":63,"command":64},"npx","npx skills add mukul975\u002FAnthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging",{"tool":66,"command":67},"bunx","bunx skills add mukul975\u002FAnthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging",{"tool":69,"command":70},"pnpm","pnpm dlx skills add mukul975\u002FAnthropic-Cybersecurity-Skills --skill implementing-end-to-end-encryption-for-messaging","安装技能，技能地址：https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002FSKILL.md",true,[74,80,86,91,95,99,103,107,113],{"path":75,"resourceType":76,"resourceTypeDesc":77,"sizeBytes":78,"sourceHtmlUrl":79},"agents\u002Fopenai.yaml","REFERENCE","参考文档",137,"https:\u002F\u002Fgithub.com\u002Ffderuiter\u002FQRCraftly-web\u002Fblob\u002Fmain\u002F.agents\u002Fskills\u002Fask-matt\u002Fagents\u002Fopenai.yaml",{"path":81,"resourceType":82,"resourceTypeDesc":83,"sizeBytes":84,"sourceHtmlUrl":85},"assets\u002Ftemplate.md","ASSET","资产文件",1468,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Fassets\u002Ftemplate.md",{"path":87,"resourceType":87,"resourceTypeDesc":88,"sizeBytes":89,"sourceHtmlUrl":90},"LICENSE","许可证",11255,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002FLICENSE",{"path":92,"resourceType":76,"resourceTypeDesc":77,"sizeBytes":93,"sourceHtmlUrl":94},"references\u002Fapi-reference.md",1890,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Freferences\u002Fapi-reference.md",{"path":96,"resourceType":76,"resourceTypeDesc":77,"sizeBytes":97,"sourceHtmlUrl":98},"references\u002FPHASE-BOUNDARIES.md",4249,"https:\u002F\u002Fgithub.com\u002Ffderuiter\u002FQRCraftly-web\u002Fblob\u002Fmain\u002F.agents\u002Fskills\u002Fask-matt\u002Freferences\u002FPHASE-BOUNDARIES.md",{"path":100,"resourceType":76,"resourceTypeDesc":77,"sizeBytes":101,"sourceHtmlUrl":102},"references\u002Fstandards.md",1467,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Freferences\u002Fstandards.md",{"path":104,"resourceType":76,"resourceTypeDesc":77,"sizeBytes":105,"sourceHtmlUrl":106},"references\u002Fworkflows.md",3034,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Freferences\u002Fworkflows.md",{"path":108,"resourceType":109,"resourceTypeDesc":110,"sizeBytes":111,"sourceHtmlUrl":112},"scripts\u002Fagent.py","SCRIPT","脚本",5321,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Fscripts\u002Fagent.py",{"path":114,"resourceType":109,"resourceTypeDesc":110,"sizeBytes":115,"sourceHtmlUrl":116},"scripts\u002Fprocess.py",12729,"https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fimplementing-end-to-end-encryption-for-messaging\u002Fscripts\u002Fprocess.py",[118,148,172,200,226,253],{"skillNo":119,"name":120,"nameZh":6,"description":121,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":122,"categories":123,"keywords":129,"publishedAt":33},"01M6AGDM3HJXTKXX15ZZ0ZVCJ3","verifying-build-provenance-with-slsa-sigstore","Verifies artifact signatures and SLSA provenance using Sigstore's cosign (verify, verify-attestation, verify-blob-attestation) and slsa-verifier (verify-artifact), enforcing keyless OIDC builder identity and source repo against SLSA Build levels. Use in CI\u002FCD before deploying artifacts, when consuming third-party attestations, establishing a SLSA Build L3 pipeline, or confirming provenance during incident response or admission control.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fverifying-build-provenance-with-slsa-sigstore\u002FSKILL.md",[124],{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},"01JBSEEDCAT000000000000023","Skill与智能体开发","SCENARIO","使用场景",[130,131,132,133,134,22,135,136,24,137,138,139,140,141,142,143,144,145,146,147],"sigstore","provenance","slsa","verifying build provenance with slsa sigstore","security","incident response","identity","code","artifacts","ci","supply-chain","pipeline","supply-chain-security","t1195","attestation","code-signing","cosign","keyless",{"skillNo":149,"name":150,"nameZh":6,"description":151,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":152,"categories":153,"keywords":155,"publishedAt":33},"01M6AGDGBPWYVZ2F11GFKJ4HZ9","validating-tpm-measured-boot-attestation","Verifies TPM 2.0 measured-boot integrity and remote attestation with tpm2-tools -- reading PCRs (tpm2_pcrread), replaying the boot event log, generating and checking signed quotes (tpm2_quote\u002Ftpm2_checkquote), and sealing secrets to a PCR policy. Use to confirm a system booted trusted firmware\u002Fkernel for Zero Trust device posture, detect boot-chain tampering via PCR drift, or build a golden-value baseline for fleet attestation.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fvalidating-tpm-measured-boot-attestation\u002FSKILL.md",[154],{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},[156,144,157,158,134,159,22,24,160,161,162,163,164,165,166,167,168,169,170,171],"boot","TPM","validating tpm measured boot attestation","policy","verification","ZeRO","firmware","Tools","measured-boot","PCR","integrity","secrets","remote-attestation","tpm2-tools","integrity-verification","trusted-computing",{"skillNo":173,"name":174,"nameZh":6,"description":175,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":176,"categories":177,"keywords":182,"publishedAt":33},"01M6AGDCW0Y4FXZ3362GT1941M","validating-backup-integrity-for-recovery","Validates backup integrity through cryptographic hash verification, automated restore testing, corruption detection, and recoverability checks to confirm backups are reliable for disaster recovery and ransomware response. Use before relying on backups for recovery, when building post-backup validation pipelines, auditing backup infrastructure for compliance, or checking immutable\u002Fair-gapped backups for silent corruption or tampering.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Fvalidating-backup-integrity-for-recovery\u002FSKILL.md",[178,181],{"categoryNo":179,"categoryName":180,"taxonomyType":127,"taxonomyTypeDesc":128},"01JBSEEDCAT000000000000008","测试与质量",{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},[166,183,184,185,186,22,187,188,160,189,190,191,192,193,194,195,196,197,198,199],"backup","recovery","validating backup integrity for recovery","testing","infrastructure","validation","compliance","hash-verification","incident-response","ransomware","cryptocurrency","detection","t1078","t1490","immutable","disaster-recovery","restore-testing",{"skillNo":201,"name":202,"nameZh":6,"description":203,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":204,"categories":205,"keywords":207,"publishedAt":33},"01M6AGD9GBG2KZ336AE763J3WH","triaging-windows-with-kape","Runs KAPE (Kroll Artifact Parser and Extractor) to collect targeted forensic artifacts (registry hives, $MFT, event logs, prefetch, browser data) via Targets and parse them with Modules wrapping Eric Zimmerman's EZ Tools (PECmd, MFTECmd, RECmd). Use during early incident containment\u002Ftriage when full disk imaging is impractical but a defensible, parseable Windows artifact set is needed quickly, including at-scale remote collection.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Ftriaging-windows-with-kape\u002FSKILL.md",[206],{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},[208,209,210,22,211,212,213,214,215,216,217,218,219,220,221,222,163,223,224,225],"windows","kape","triaging windows with kape","registry","browser","logs","windows-forensics","dfir","mft","mftecmd","data","prefetch","eric-zimmerman","digital-forensics","SET","collection","pecmd","artifact-collection",{"skillNo":227,"name":228,"nameZh":6,"description":229,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":230,"categories":231,"keywords":233,"publishedAt":33},"01M6AGD5PW5J4EVZM958WD74ZQ","triaging-vulnerabilities-with-ssvc-framework","Triages and prioritizes vulnerabilities with CISA's Stakeholder-Specific Vulnerability Categorization (SSVC) decision tree, weighing exploitation status (via the CISA KEV catalog and FIRST EPSS API), technical impact, automatability, and mission prevalence to output Track\u002FTrack*\u002FAttend\u002FAct decisions. Use when prioritizing vulnerability scan results (OpenVAS, Nessus, Qualys) for remediation planning beyond raw CVSS scores.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Ftriaging-vulnerabilities-with-ssvc-framework\u002FSKILL.md",[232],{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},[234,235,236,22,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252],"vulnerabilities","framework","triaging vulnerabilities with ssvc framework","status","planning","CISA","vulnerability-management","risk-management","nessus","qualys","openvas","cvss","remediation","risk","vulnerability","api","prioritization","ssvc","decision-tree",{"skillNo":254,"name":255,"nameZh":6,"description":256,"descriptionZh":6,"repositoryFullName":8,"ownerLogin":9,"ownerAvatarUrl":10,"ownerAccountNo":11,"ownerDisplayName":12,"repositoryNo":13,"starsCount":14,"licenseSpdxId":15,"licenseFileUrl":6,"sourceHtmlUrl":257,"categories":258,"keywords":260,"publishedAt":33},"01M6AGD24TTQQM4CXG69E3B9TJ","triaging-security-incident","Performs initial triage of security incidents using the NIST SP 800-61r3 and SANS PICERL frameworks, classifying incident type, assigning priority by business impact, and routing to the appropriate response team. Use when a SIEM\u002FEDR alert needs human classification, concurrent alerts must be prioritized, or a user report or threat-intel IOC match requires initial incident categorization.","https:\u002F\u002Fgithub.com\u002Fmukul975\u002FAnthropic-Cybersecurity-Skills\u002Fblob\u002Fmain\u002Fskills\u002Ftriaging-security-incident\u002FSKILL.md",[259],{"categoryNo":125,"categoryName":126,"taxonomyType":127,"taxonomyTypeDesc":128},[134,261,22,262,263,264,265,266,267,268,269,195,270,196,271,272,273,274,275,276],"triaging security incident","siem","file","ioc","soc","NIST-800-61","NIST","severity","edr","execution","analysis","classification","severity-classification","incident-triage","SANS-PICERL","SOC-operations"]