i2p.www/i2p2www/pages/site/docs/spec/common-structures.html

{% extends "global/layout.html" %}
{% block title %}{% trans %}Common structure Specification{% endtrans %}{% endblock %}
{% block lastupdated %}{% trans %}June 2013{% endtrans %}{% endblock %}
{% block accuratefor %}0.9.6{% endblock %}
{% block content %}
<h1>{% trans %}Data types Specification{% endtrans %}</h1>
<p>{% trans i2np=site_url('docs/protocol/i2np'),
i2cp=site_url('docs/protocol/i2cp'),
ssu=site_url('docs/transport/ssu') -%}
This document describes some data types common to all I2P protocols, like
<a href="{{ i2np }}">I2NP</a>, <a href="{{ i2cp }}">I2CP</a>,
<a href="{{ ssu }}">SSU</a>, etc.
{%- endtrans %}</p>

<h2 id="type_Integer">Integer</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Represents a non-negative integer.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
1 to 8 bytes in network byte order representing an unsigned integer
{% endtrans %}</p>

<h2 id="type_Date">Date</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
The number of milliseconds since midnight on January 1, 1970 in the GMT timezone.
If the number is 0, the date is undefined or null.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
8 byte <a href="#type_Integer">Integer</a>
{% endtrans %}</p>

<h2 id="type_String">String</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Represents a UTF-8 encoded string.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
1 or more bytes where the first byte is the number of bytes (not characters!)
in the string and the remaining 0-255 bytes are the non-null terminated UTF-8 encoded character array.
Length limit is 255 bytes (not characters). Length may be 0.
{% endtrans %}</p>

<h2 id="type_Boolean">Boolean</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
A boolean value, supporting null/unknown representation
0=false, 1=true, 2=unknown/null
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
1 byte <a href="#type_Integer">Integer</a>
{% endtrans %}</p>
<h4>{% trans %}Notes{% endtrans %}</h4>
<p>{% trans -%}
Deprecated - unused
{% endtrans %}</p>

<h2 id="type_PublicKey">PublicKey</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans cryptography=site_url('docs/how/cryptography') -%}
This structure is used in ElGamal encryption, representing only the exponent, not the primes, which are constant and defined in
<a href="{{ cryptography }}#elgamal">the cryptography specification</a>.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
256 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/PublicKey.html">Javadoc</a></h4>

<h2 id="type_PrivateKey">PrivateKey</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans cryptography=site_url('docs/how/cryptography') -%}
This structure is used in ElGamal decryption, representing only the exponent, not the primes which are constant and defined in
<a href="{{ cryptography }}#elgamal">the cryptography specification</a>.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
256 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/PrivateKey.html">Javadoc</a></h4>

<h2 id="type_SessionKey">SessionKey</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
This structure is used for AES256 encryption and decryption.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
32 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/SessionKey.html">Javadoc</a></h4>

<h2 id="type_SigningPublicKey">SigningPublicKey</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans cryptography=site_url('docs/how/cryptography') -%}
This structure is used for verifying <a href="{{ cryptography }}#DSA">DSA</a> signatures.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
128 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/SigningPublicKey.html">Javadoc</a></h4>

<h2 id="type_SigningPrivateKey">SigningPrivateKey</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans cryptography=site_url('docs/how/cryptography') -%}
This structure is used for creating <a href="{{ cryptography }}#DSA">DSA</a> signatures.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
20 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/SigningPrivateKey.html">Javadoc</a></h4>

<h2 id="type_Signature">Signature</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans cryptography=site_url('docs/how/cryptography') -%}
This structure represents the <a href="{{ cryptography }}#DSA">DSA</a> signature of some data.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
40 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/Signature.html">Javadoc</a></h4>

<h2 id="type_Hash">Hash</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Represents the SHA256 of some data.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
32 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/Hash.html">Javadoc</a></h4>

<h2 id="type_SessionTag">Session Tag</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
A random number
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
32 bytes
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/SessionTag.html">Javadoc</a></h4>

<h2 id="type_TunnelId">TunnelId</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Defines an identifier that is unique to each router in a tunnel.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
4 byte <a href="#type_Integer">Integer</a>
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/TunnelID.html">Javadoc</a></h4>

<h2 id="type_Certificate">Certificate</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
A certificate is a container for various receipts or proof of works used throughout the I2P network.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
1 byte <a href="#type_Integer">Integer</a> specifying certificate type, followed by a 2 <a href="#type_Integer">Integer</a> specifying the size of the certificate payload, then that many bytes.
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+-//
|type| length  | payload
+----+----+----+----+----+-//

type :: Integer
        length -> 1 byte

        case 0 -> NULL
        case 1 -> HASHCASH
        case 2 -> HIDDEN
        case 3 -> SIGNED
        case 4 -> MULTIPLE

length :: Integer
          length -> 2 bytes

payload :: data
           length -> $length bytes
{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<ul>
<li>{% trans -%}
For <a href="#struct_RouterIdentity">Router Identities</a>, the Certificate is always NULL, no others are currently implemented.
{%- endtrans %}</li>

<li>{% trans i2np=site_url('docs/spec/i2np') -%}
For <a href="{{ i2np }}#struct_GarlicClove">Garlic Cloves</a>, the Certificate is always NULL, no others are currently implemented.
{%- endtrans %}</li>

<li>{% trans i2np=site_url('docs/spec/i2np') -%}
For <a href="{{ i2np }}#msg_Garlic">Garlic Messages</a>, the Certificate is always NULL, no others are currently implemented.
{%- endtrans %}</li>

<li>{% trans -%}
For <a href="#struct_Destination">Destinations</a>, the Certificate may be non-NULL,
however non-NULL certs are not widely used, and any checking is left to the application-level.
{%- endtrans %}</li>
</ul>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/Certificate.html">Javadoc</a></h4>


<h2 id="type_Mapping">Mapping</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
A set of key/value mappings or properties
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
A 2-byte size Integer followed by a series of String=String; pairs
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
|  size   |key_string (len + data) | =  |
+----+----+----+----+----+----+----+----+
| val_string (len + data)     | ;  | ...
+----+----+----+----+----+----+----+
size :: Integer
        length -> 2 bytes
        Total number of bytes that follow

key_string :: String
              A string (one byte length followed by UTF-8 encoded characters)

= :: A single byte containing '='

val_string :: String
              A string (one byte length followed by UTF-8 encoded characters)

; :: A single byte containing ';'

{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<ul>
<li>{% trans -%}
The encoding isn't optimal - we either need the '=' and ';' characters, or the string lengths, but not both
{%- endtrans %}</li>

<li>{% trans -%}
Some documentation says that the strings may not include '=' or ';' but this encoding supports them
{%- endtrans %}</li>

<li>{% trans -%}
Strings are defined to be UTF-8 but in the current implementation, I2CP uses UTF-8 but I2NP does not.
For example,
UTF-8 strings in a RouterInfo options mapping in a I2NP Database Store Message will be corrupted.
{%- endtrans %}</li>

<li>{% trans -%}
Mappings contained in I2NP messages (i.e. in a RouterAddress or RouterInfo)
must be sorted by key so that the signature will be invariant.
{%- endtrans %}</li>

<li>{% trans -%}
Key and value string length limits are 255 bytes (not characters) each, plus the length byte. Length byte may be 0.
{%- endtrans %}</li>

<li>{% trans -%}
Total length limit is 65535 bytes, plus the 2 byte size field, or 65537 total.
{%- endtrans %}</li>
</ul>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/DataHelper.html">Javadoc</a></h4>



<h1>{% trans %}Common structure specification{% endtrans %}</h1>

<h2 id="struct_RouterIdentity">RouterIdentity</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Defines the way to uniquely identify a particular router
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
<a href="#type_PublicKey">PublicKey</a> followed by <a href="#type_SigningPublicKey">SigningPublicKey</a> and then a <a href="#type_Certificate">Certificate</a>
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
| public_key                            |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| signing_key                           |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| certificate                           |
+----+----+----+-//

public_key :: PublicKey
              length -> 256 bytes

signing_key :: SigningPublicKey
               length -> 128 bytes

certificate :: Certificate
               length -> >= 3 bytes

total length: 387+ bytes
{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<p>{% trans -%}
The certificate for a RouterIdentity is currently unused and is always NULL.
{%- endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/RouterIdentity.html">Javadoc</a></h4>

<h2 id="struct_Destination">Destination</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
A Destination defines a particular endpoint to which messages can be directed for secure delivery.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
<a href="#type_PublicKey">PublicKey</a> followed by a <a href="#type_SigningPublicKey">SigningPublicKey</a> and then a <a href="#type_Certificate">Certificate</a>
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
| public_key                            |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| signing_public_key                    |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| certificate
+-//

public_key :: PublicKey
              length -> 256 bytes

signing_public_key :: SigningPublicKey
                      length -> 128 bytes

certificate :: Certificate
               length -> >= 3 bytes

total length: 387+ bytes
{% endhighlight %}

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/Destination.html">Javadoc</a></h4>

<h2 id="struct_Lease">Lease</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Defines the authorization for a particular tunnel to receive messages targeting a <a href="#struct_Destination">Destination</a>.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
SHA256 <a href="#type_Hash">Hash</a> of the
<a href="#struct_RouterIdentity">RouterIdentity</a> of the gateway router, then the <a href="#type_TunnelId">TunnelId</a>, and finally an end <a href="#type_Date">Date</a>
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
| tunnel_gw                             |
+                                       +
|                                       |
+                                       +
|                                       |
+                                       +
|                                       |
+----+----+----+----+----+----+----+----+
|     tunnel_id     |      end_date
+----+----+----+----+----+----+----+----+
                    |
+----+----+----+----+

tunnel_gw :: Hash of the RouterIdentity of the tunnel gateway
             length -> >= 32 bytes

tunnel_id :: TunnelId
             length -> 4 bytes

end_date :: Date
            length -> 8 bytes
{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<ul>
<li>{% trans -%}
Total size: 44 bytes
{%- endtrans %}</li>
</ul>


<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/Lease.html">Javadoc</a></h4>

<h2 id="struct_LeaseSet">LeaseSet</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Contains all of the currently authorized <a href="#struct_Lease">Lease</a>s for a particular <a href="#struct_Destination">Destination</a>, the <a href="#type_PublicKey">PublicKey</a> to which garlic messages can be encrypted,
and then the <a href="#type_SigningPublicKey">public key</a> that can be used to revoke this particular version of the structure. The <a href="#struct_LeaseSet">LeaseSet</a> is one of the two structures stored in the network database(
the other being <a href="#struct_RouterInfo">RouterInfo</a>), and is keyed under the SHA256 of the contained <a href="#struct_Destination">Destination</a>.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
<a href="#struct_Destination">Destination</a>, followed by a <a href="#type_PublicKey">PublicKey</a> for encryption, then a <a href="#type_SigningPublicKey">SigningPublicKey</a> which can be used to revoke this version of the <a href="#struct_LeaseSet">LeaseSet</a>,
then a 1 byte <a href="#type_Integer">Integer</a> specifying how many <a href="#struct_Lease">Lease</a> structures are in the set, followed by the actual <a href="#struct_Lease">Lease</a> structures and finally a <a href="#type_Signature">Signature</a>  of the previous
bytes signed by the <a href="#struct_Destination">Destination's</a> <a href="#type_SigningPrivateKey">SigningPrivateKey</a>
{%- endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
| destination                           |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| encryption_key                        |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| signing_key                           |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
|num | Lease 0                          |
+----+                                  +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| Lease 1                               |
+                                       +
|                                       |
~                                       ~

~                                       ~
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| Lease ($num-1)                        |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| signature                             |
+                                       +
|                                       |
+                                       +
|                                       |
+                                       +
|                                       |
+                                       +
|                                       |
+----+----+----+----+----+----+----+----+

destination :: Destination
               length -> >= 387 bytes

encryption_key :: PublicKey
                  length -> 256 bytes

signing_key :: SigningPublicKey
               length -> 128 bytes

num :: Integer
       length -> 1 byte
       value: 0 <= num <= 16

leases :: [Lease]
          length -> >= $num*44 bytes

signature :: Signature
             length -> 40 bytes

{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<ul>
<li>{% trans -%}
The public key of the destination was used for the old i2cp-to-i2cp encryption
which was disabled in version 0.6, it is currently unused?
{%- endtrans %}</li>

<li>{% trans elgamalaes=site_url('docs/how/elgamal-aes') -%}
The encryption key is used for end-to-end <a href="{{ elgamalaes }}">ElGamal/AES+SessionTag</a> encryption.
It is currently generated anew at every router startup, it is not persistent.
{%- endtrans %}</li>

<li>{% trans -%}
The signature may be verified using the signing public key of the destination.
{%- endtrans %}</li>

<li>{% trans -%}
The signing_key is currently unused. It was intended for LeaseSet revocation, which is unimplemented.
It is currently generated anew at every router startup, it is not persistent.
{%- endtrans %}</li>
<li>{% trans -%}
The earliest expiration of all the Leases is treated as the timestamp or version of the LeaseSet.
Routers will generally not accept a store of a LeaseSet unless it is "newer" than the current one.
Take care when publishing a new LeaseSet where the oldest Lease is the same as the oldest Lease
in the previous LeaseSet. The publishing router should generally increment the expiration
of the oldest Lease by at least 1 ms in that case.
{%- endtrans %}</li>
<li>{% trans -%}
Prior to release 0.9.7, when included in a DatabaseStore Message sent by the originating router,
the router set all the published leases' expirations to the same value, that of the
earliest lease. As of release 0.9.7, the router publishes the actual lease expiration for each lease.
This is an implementation detail and not part of the structures specification.
{%- endtrans %}</li>
</ul>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/LeaseSet.html">Javadoc</a></h4>



<h2 id="struct_RouterAddress">RouterAddress</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
This structure defines the means to contact a router through a transport protocol.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
1 byte <a href="#type_Integer">Integer</a> defining the relative cost of using the address, where 0 is free and 255 is expensive, followed by the expiration <a href="#type_Date">Date</a> after which the address should not be used, or if null, the address never expires.
After that comes a <a href="#type_String">String</a> defining the transport protocol this router address uses. Finally there is a <a href="#type_Mapping">Mapping</a> containing all of the transport specific options necessary to establish the connection, such as
IP address, port number, email address, URL, etc.
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+
|cost|
+----+----+----+----+----+----+----+----+
| expiration                            |
+----+----+----+----+-//-+----+----+----+
| transport_style                       |
+----+----+----+----+-//-+----+----+----+
| options                               |
+----+----+----+----+-//-+----+----+----+

cost :: Integer
        length -> 1 byte

        case 0 -> free
        case 255 -> expensive

expiration :: Date
              length -> 8 bytes

              case null -> never expires

transport_style :: String
                   length -> 1-256 bytes

options :: Mapping
{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<ul>
<li>{% trans -%}
Cost is typically 5 or 6 for SSU, and 10 or 11 for NTCP.
{%- endtrans %}</li>

<li>{% trans -%}
Expiration is currently unused, always null (all zeroes)).
As of release 0.9.3, the expiration is assumed zero and not stored, so any non-zero expiration
will fail in the RouterInfo signature verification.
Implementing expiration (or another use for these bytes) will be a backwards-incompatible change.
{%- endtrans %}</li>
</ul>


<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/RouterAddress.html">Javadoc</a></h4>

<h2 id="struct_RouterInfo">RouterInfo</h2>
<h4>{% trans %}Description{% endtrans %}</h4>
<p>{% trans -%}
Defines all of the data that a router wants to publish for the network to see. The <a href="#struct_RouterInfo">RouterInfo</a> is one of two structures stored in the network database(the other being <a href="#struct_LeaseSet">LeaseSet</a>, and is keyed under the SHA256 of
the contained <a href="#struct_RouterIdentity">RouterIdentity</a>.
{% endtrans %}</p>
<h4>{% trans %}Contents{% endtrans %}</h4>
<p>{% trans -%}
<a href="#struct_RouterIdentity">RouterIdentity</a> followed by the <a href="#type_Date">Date</a>, when the entry was published
{% endtrans %}</p>
{% highlight lang='dataspec' %}
+----+----+----+----+----+----+----+----+
| router_ident                          |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| published                             |
+----+----+----+----+----+----+----+----+
|size| RouterAddress 0                  |
+----+                                  +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| RouterAddress 1                       |
+                                       +
|                                       |
~                                       ~
~                                       ~

~                                       ~
~                                       ~
|                                       |
+----+----+----+----+----+----+----+----+
| RouterAddress ($size-1)               |
+                                       +
|                                       |
~                                       ~

~                                       ~
|                                       |
+----+----+----+----+-//-+----+----+----+
|psiz| options                          |
+----+----+----+----+-//-+----+----+----+
| signature                             |
+                                       +
|                                       |
+                                       +
|                                       |
+                                       +
|                                       |
+                                       +
|                                       |
+----+----+----+----+----+----+----+----+

router_ident :: RouterIdentity
                length -> >= 387 bytes

published :: Date
             length -> 8 bytes

size :: Integer
        length -> 1 byte

addresses :: [RouterAddress]
             length -> >= $size*267 bytes

peer_size :: Integer
             length -> 1 byte

             value -> 0

options :: Mapping

signature :: Signature
             length -> 40 bytes

{% endhighlight %}

<h4>{% trans %}Notes{% endtrans %}</h4>
<p>{% trans -%}
The peer_size Integer may be followed by a list of that many router hashes.
This is currently unused. It was intended for a form of restricted routes, which is unimplemented.
{% endtrans %}</p>

<p>{% trans -%}
The signature may be verified using the signing public key of the router_ident.
{% endtrans %}</p>

<h4><a href="http://docs.i2p-projekt.de/javadoc/net/i2p/data/RouterInfo.html">Javadoc</a></h4>


<h2 id="struct_DeliveryInstructions">Delivery Instructions</h2>
<p>{% trans tunnelmessage=site_url('docs/spec/tunnel-message') -%}
Defined in the <a href="{{ tunnelmessage }}#delivery">Tunnel Message Specification</a>.
{% endtrans %}</p>
{% endblock %}