Tripcodes are a unique and simple way to verify your identity while still maintaining anonymity. They are most often used in 2channel-style message boards or Futaba Channel-style Imageboards.

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 public. The ! here serves as a separator between name and tripcode. It sometimes changes between boards and is configurable by the respective admin. On 2channel the separator is . Tripcodes and their separators are usually not displayed in bold text, unlike the username, making it more difficult to fake them.

= Secure tripcodes =

The 2channel tripcode algorithm has the flaw that, because it has no secret key, tripcodes can be reversed with a brute-force search. Some boards (such as Kareha and Shiichan) implement a secure tripcode. Secure tripcodes change on every board, but are much more resistant to preimage attacks.

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