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 API 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
B32 for Encrypted Leasesets Design 0.9.47 HTML | TXT
Common structures Specification Design 0.9.61 HTML | TXT
Low-level Cryptography Specification Design 0.9.47 HTML | TXT
Plugin Specification Design 0.9.53 HTML | TXT
Red25519 Signature Scheme Design 0.9.47 HTML | TXT
Software Update Specification Design 0.9.55 HTML | TXT
Tunnel Creation Specification Design 0.9.41 HTML | TXT
Tunnel Message Specification Design 0.9.49 HTML | TXT
NTCP 2 Transports 0.9.61 HTML | TXT
SSU Protocol Specification Transports 0.9.61 HTML | TXT
SSU2 Transports 0.9.61 HTML | TXT
Datagram Specification Protocols 0.9.39 HTML | TXT
ECIES-X25519 Router Messages Protocols 0.9.49 HTML | TXT
ECIES-X25519 Tunnel Creation Protocols 0.9.51 HTML | TXT
ECIES-X25519-AEAD-Ratchet Protocols 0.9.47 HTML | TXT
Encrypted LeaseSet Specification Protocols 0.9.41 HTML | TXT
I2CP Specification Protocols 0.9.62 HTML | TXT
I2NP Specification Protocols 0.9.62 HTML | TXT
Streaming Protocol Specification Protocols 0.9.59 HTML | TXT
Access Filter Format Specification Formats 0.9.40 HTML | TXT
Addressbook Subscription Feed Commands Formats 0.9.49 HTML | TXT
Blockfile and Hosts Database Specification Formats 0.9.59 HTML | TXT
Configuration File Specification Formats 0.9.57 HTML | TXT
GeoIP File Specification Formats 0.9.9 HTML | TXT

Other specification documents

Current specifications: These may eventually be migrated to the new format. Obsolete specifications: