{% extends "_layout.html" %}
{% block title %}Data types Specification{% endblock %}
{% block content %}
<h1>Data types Specification</h1>
<p>
  This document describes some data types common to all I2P-protocols, like I2NP, I2CP, NTCP, etc.
</p>

<h2 id="type_Integer">Integer</h2>
<h4>Description</h4>
<p>
  Represents a nonnegative integer.
</p>
<h4>Contents</h4>
<p>
  1 or more bytes in network byte order representing an unsigned integer
</p>

<h2 id="type_Date">Date</h2>
<h4>Description</h4>
<p>
  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.
</p>
<h4>Contents</h4>
<p>
  8 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_String">String</h2>
<h4>Description</h4>
<p>
  Represents a UTF-8 encoded string.
</p>
<h4>Contents</h4>
<p>
  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
</p>

<h2 id="type_Boolean"</h2>
<h4>Description</h4>
<p>
  A boolean value, supporting null/unknown representation
  0=false, 1=true, 2=unknown/null
</p>
<h4>Contents</h4>
<p>
  1 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_PublicKey">PublicKey</h2>
<h4>Description</h4>
<p>
  This structure is used in ElGamal encryption, representing only the exponent, not the primes, which are constant and defined in the appropiate spec.
</p>
<h4>Contents</h4>
<p>
  256 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_PrivateKey">PrivateKey</h2>
<h4>Description</h4>
<p>
  This structure is used in ElGama decryption, representing only the exponent, not the primes which are constant and defined in the appropiate spec.
</p>
<h4>Contents</h4>
<p>
  256 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_SessionKey">SessionKey</h2>
<h4>Description</h4>
<p>
  This structure is used for AES256 encryption and decryption.
</p>
<h4>Contents</h4>
<p>
  32 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_SigningPublicKey">SigningPublicKey</h2>
<h4>Description</h4>
<p>
  This structure is used for verifying DSA signatures.
</p>
<h4>Contents</h4>
<p>
  256 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_SigningPrivateKey">SigningPrivateKey</h2>
<h4>Description</h4>
<p>
  This structure is used for creating DSA signatures.
</p>
<h4>Contents</h4>
<p>
  20 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_Signature">Signature</h2>
<h4>Description</h4>
<p>
  This structure represents the DSA signature of some data.
</p>
<h4>Contents</h4>
<p>
  40 byte <a href="#type_Integer">Integer</a>
</p>

<h2 id="type_Hash">Hash</h2>
<h4>Description</h4>
<p>
  Represents the SHA256 of some data.
</p>
<h4>Contents</h4>
<p>
  32 bytes
</p>

<h2 id="type_Certificate">Certificate</h2>
<h4>Description</h4>
<p>
  A certificate is a container for various receipts or proof of works used throughout the I2P network.
</p>
<h4>Contents</h4>
<p>
  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.
</p>
<pre>
{% filter escape %}
+----+----+----+----+----+--//
|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
{% endfilter %}
</pre>


{% endblock %}