Bitcoin DNS Specs + Design

Operations

1. name preorder
2. name claim
3. name update
4. name transfer

Definitions

• hash160: a 20-byte ripemd160 hash
• salt: a random value appended to data in order to prevent reverse-lookups of the hashed data
• name hash: a hash160 of a given name and a random salt -name encoding: a given name converted from base 37 to base 256, then padded with zeros
• historical record hash: a hash of a data string generated from the combined list of the last block's valid names
• update hash: a hash of the data to be associated with a given name

Data Encoding

Constraints:

• 40 bytes available in OP_RETURN
• 1 byte = 256 values
• alphanumeric-dash-dot charspace = 38 values
• 1.5244 name characters can fit in each byte

Field lengths

• prefix = 1 byte
• name hash = 20 bytes
• previous block hash (truncated) = 19 bytes
• name = 19 bytes
• salt = 16 bytes
• update hash = 20 bytes

Name encoding lengths

• 18 bytes = 27.4 characters
• 19 bytes = 28.9 characters
• 20 bytes = 30.4 characters
• 24 bytes = 36.5 characters

Name Preorder (reserve)

• prefix (1 bytes)
• name hash (20 bytes)
• historical record hash (19 bytes)

Name Claim (reveal)

• prefix (1 bytes)
• name (19 bytes)
• salt (16 bytes)

Name Update

• prefix (1 bytes)
• name (19 bytes)
• update hash (20 bytes)

Name Transfer

• prefix (1 bytes)
• name (19 bytes)

Name ownership is transferred to the recipient of the first output. Name admin rights are given to the recipients of the second output.

Misc.

Example of a transaction with an OP_RETURN and multiple outputs: https://blockchain.info/tx/1ae39745fd3891c16806bba44e6540944d145452ff156cab03076d7c08462e38?show_adv=true