This page provides the specifications for various components of the I2P network and router software. These are living documents, and the specifications are updated as modifications are made to the network and software. The proposal documents that track changes to these specifications can be viewed here.

  • "Last updated" is the last date when the specification given within a document was altered in any way, except for changes to the "accurate for" information.
  • The "accurate for" column gives the version of the I2P network and reference Java implementation that the document is verified to be valid for. Because the documents are usually only updated when changes are made, the listed versions can sometimes be several releases behind. This does not mean that documents with old listed versions are necessarily inaccurate, but small differences may creep in during the course of development. Periodic reviews are conducted to update the "accurate for" information.

The I2P Project is committed to maintaining accurate, current documentation. If you find any inaccuracies in the documents linked below, please enter a ticket identifying the problem.

Title Category Last updated Accurate for Link
Common structures Specification Design 0.9.49 HTML | TXT
Low-level Cryptography Specification Design 0.9.47 HTML | TXT
Tunnel Creation Specification Design 0.9.41 HTML | TXT
Tunnel Message Specification Design 0.9.49 HTML | TXT
NTCP 2 Transports 0.9.50 HTML | TXT
SSU Protocol Specification Transports 0.9.52 HTML | TXT
Datagram Specification Protocols 0.9.39 HTML | TXT
ECIES-X25519-AEAD-Ratchet Protocols 0.9.47 HTML | TXT
Encrypted LeaseSet Specification Protocols 0.9.41 HTML | TXT
I2CP Specification Protocols 0.9.48 HTML | TXT
I2NP Specification Protocols 0.9.51 HTML | TXT
Streaming Library Specification Protocols 0.9.46 HTML | TXT
Access Filter Format Specification 0.9.40 HTML | TXT
Addressbook Subscription Feed Commands 0.9.49 HTML | TXT
B32 for Encrypted Leasesets 0.9.47 HTML | TXT
Blockfile and Hosts Database Specification 0.9.47 HTML | TXT
Configuration File Specification 0.9.45 HTML | TXT
ECIES-X25519 Router Messages None HTML | TXT
ECIES-X25519 Tunnel Creation None HTML | TXT
GeoIP File Specification 0.9.9 HTML | TXT
Plugin Specification 0.9.43 HTML | TXT
Red25519 Signature Scheme 0.9.47 HTML | TXT
Software Update Specification 0.9.51 HTML | TXT

Other specification documents

These will eventually be migrated to the new specifications system.