The R5N Distributed Hash Table

Introduction Distributed Hash Tables (DHTs) are a key data structure for the construction of completely decentralized applications. DHTs are important because they generally provide a robust and efficient means to distribute the storage and retrieval of key-value pairs. This document contains the technical specification of the R5N DHT , a secure DHT routing algorithm and data structure for decentralized applications. This document defines the normative wire format of peer-to-peer messages, routing algorithms, cryptographic routines and security considerations for use by implementors. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .

Peer-to-peer wire formats

Bloomfilter

Processing options

Extended query

PUT message

where:

MSIZE: denotes the size of this message in network byte order.
MTYPE: is the 16-bit message type. This type can be one of the DHT message types but for put messages it must be set to the value 146 in network byte order.
OPTIONS: is a 32-bit options field (see below).
BTYPE: is a 32-bit block type field. The block type indicates the content type of the payload. In network byte order.
HOPCOUNT: is a 32-bit number indicating how many hops this message has traversed to far. In network byte order.
REPLICATIONLVL: is a 32-bit number indicating the desired replication level of the data. In network byte order.
PATH_LEN: is a 32-bit number indicating the length of the PUT path recorded in PUTPATH. As PUTPATH is optiona, this value may be zero. In network byte order.
EXPIRATION: denotes the absolute 64-bit expiration date of the content. In microseconds since midnight (0 hour), January 1, 1970 in network byte order.
BLOOMFILTER: A bloomfilter (for peer identities) to stop circular routes.
KEY: The key under which the PUT request wants to store content under.
PUTPATH: the variable-length PUT path. The path consists of a list of PATH_LEN peer IDs.
PAYLOAD: the variable-length resource record data payload. The contents are defined by the respective type of the resource record.

GET message

where:

MSIZE: denotes the size of this message in network byte order.
MTYPE: is the 16-bit message type. This type can be one of the DHT message types but for put messages it must be set to the value 146 in network byte order.
OPTIONS: is a 32-bit options field (see below).
BTYPE: is a 32-bit block type field. The block type indicates the content type of the payload. In network byte order.
HOPCOUNT: is a 32-bit number indicating how many hops this message has traversed to far. In network byte order.
REPLICATIONLVL: is a 32-bit number indicating the desired replication level of the data. In network byte order.
XQUERY_SIZE: is a 32-bit number indicating the length of the optional extended query XQUERY. In network byte order.
BF_MUTATOR: The bloomfilter mutator.
BLOOMFILTER: A bloomfilter (for peer identities) to stop circular routes.
KEY: The key under which the PUT request wants to store content under.
XQUERY: the variable-length extended query. Optional.
BF_RESULT: the variable-length result bloomfilter.

RESULT message

where:

MSIZE: denotes the size of this message in network byte order.
MTYPE: is the 16-bit message type. This type can be one of the DHT message types but for put messages it must be set to the value 146 in network byte order.
OPTIONS: is a 32-bit options field (see below).
BTYPE: is a 32-bit block type field. The block type indicates the content type of the payload. In network byte order.
PUT_PATH_LEN: is a 32-bit number indicating the length of the PUT path recorded in PUTPATH. As PUTPATH is optiona, this value may be zero. In network byte order.
GET_PATH_LEN: is a 32-bit number indicating the length of the GET path recorded in GETPATH. As PUTPATH is optiona, this value may be zero. In network byte order.
EXPIRATION: denotes the absolute 64-bit expiration date of the content. In microseconds since midnight (0 hour), January 1, 1970 in network byte order.
KEY: The key under which the PUT request wants to store content under.
PUTPATH: the variable-length PUT path. The path consists of a list of PATH_LEN peer IDs.
GETPATH: the variable-length PUT path. The path consists of a list of PATH_LEN peer IDs.
PAYLOAD: the variable-length resource record data payload. The contents are defined by the respective type of the resource record.

GANA Considerations GANA is requested to create a "DHT Block Types" registry. The registry shall record for each entry:

Name: The name of the record type (case-insensitive ASCII string, restricted to alphanumeric characters
Number: 32-bit, above 65535
Comment: Optionally, a brief English text describing the purpose of the record type (in UTF-8)
Contact: Optionally, the contact information of a person to contact for further information
References: Optionally, references describing the record type (such as an RFC)

The registration policy for this sub-registry is "First Come First Served", as described in . GANA is requested to populate this registry as follows:

GANA is requested to amend the "GNUnet Signature Purpose" registry as follows: