Tripcodes are a method of authentication that does not require registration. They are most often used in 2channel-style message boards or Futaba Channel-style imageboards. A tripcode is a hashed password by which a person can be identified by others. Authentication is the act of establishing or confirming something or someone as authentic. ... 2ch home page. ... An Internet forum, also known as a message board or discussion board, is a web application that provides for online discussions, and is the modern descendant of the bulletin board systems and existing Usenet news systems that were widespread in the 1980s and 1990s. ... Futaba Channel (ふたば(双葉)☆ちゃんねる), or Futaba for short, is one of Japans series of bulletin board systems. ... 3 major imageboards: Futaba Channel, 4chan, and iichan, along with the Overchan index. ...

A tripcode is the result of input to a cryptographic hash function on the message board server, usually entered in the same field as the name. Using the common 2channel format, name#tripcode when entered as a username becomes name!3GqYIJ3Obs when displayed in the post. The ! is the separator between name and tripcode; on some boards it is replaced with ◆. In cryptography, a cryptographic hash function is a hash function with certain additional security properties to make it suitable for use as a primitive in various information security applications, such as authentication and message integrity. ...

Readers of the board can identify postings made by the same user by comparing tripcodes. If two people use the same user name, they can be told apart because they, presumably, don't know each other's passwords that generate the different tripcodes. This way, the names and passwords don't have to be stored in a database. A database is an organized collection of data. ...

Tripcodes and their separators are usually not displayed in bold text, unlike the username, making it more difficult to fake them. As many boards use the same algorithm tripcodes are usually consistent.

Secure tripcodes

Tripcodes are not a very secure authentication method. Since the keyspace of 2channel-style tripcodes is not very large (2⁵⁴) some boards implement a secure tripcode along with normal tripcodes. In their case another hash is used that takes a second input (typically in the form of name#tripcode#securetripcode) and uses a secret salt stored on the server. As this salt is secret and site specific one cannot use a pre-computed preimage attack such as Rainbow tables. In cryptography, an algorithms key space refers to all possible keys that can be used to initialize it. ... In data encryption, salt is an initialization vector of a block cipher. ... In cryptography, a preimage attack on a cryptographic hash differs from a collision attack. ... A rainbow table is a special type of lookup table that is constructed by placing a plaintext password entry in a chain of keys and ciphertexts, generated by a one-way hash. ...

External links

• Discussion of tripcodes and English searchers
• A Japanese tripcode searcher