Signal

Signal Protocol Specifications

The Signal Protocol Specifications define the core cryptographic protocols that underpin Signal's end-to-end encrypted messaging. These include the X3DH (Extended Triple Diffie-Hellman) key agreement protocol for establishing shared secrets between parties, the Double Ratchet Algorithm for deriving new encryption keys per message, the PQXDH (Post-Quantum Extended Diffie-Hellman) protocol for quantum-resistant key agreement, and XEdDSA for EdDSA-compatible signature schemes. These specifications are published independently so they can be adopted by other projects beyond Signal itself.

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Documentation

📖
Documentation
https://signal.org/docs/

Other Resources

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APIsJSON
https://raw.githubusercontent.com/api-evangelist/signal/refs/heads/main/apis.yml

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API entry from apis.yml

apis.yml Raw ↑ 
aid: signal:signal-protocol-specifications
name: Signal Protocol Specifications
tags:
- Encryption
- Messaging
- Cryptography
- Security
- Protocols
humanURL: https://signal.org/docs/
properties:
- url: https://signal.org/docs/
  type: Documentation
description: The Signal Protocol Specifications define the core cryptographic protocols that underpin
  Signal's end-to-end encrypted messaging. These include the X3DH (Extended Triple Diffie-Hellman) key
  agreement protocol for establishing shared secrets between parties, the Double Ratchet Algorithm for
  deriving new encryption keys per message, the PQXDH (Post-Quantum Extended Diffie-Hellman) protocol
  for quantum-resistant key agreement, and XEdDSA for EdDSA-compatible signature schemes. These specifications
  are published independently so they can be adopted by other projects beyond Signal itself.