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How to lock a coin with a custom puzzle

This tutorial teaches you how to lock a coin with a custom-made puzzle.

Create a puzzle#

Create whatever puzzle you want for your coin. We'll use a password-locked coin as an example for this tutorial.

(mod (password new_puzhash amount)    (defconstant CREATE_COIN 51)
    (if (= (sha256 password) (q . 0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824))        (list (list CREATE_COIN new_puzhash amount))        (x)    ))

0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 is the sha256 hash of the word hello.

Example valid solution: (hello 0x5f5767744f91c1c326d927a63d9b34fa7035c10e3eb838c44e3afe127c1b7675 2).

If password is correct, the puzzle will create a new coin with 2 mojos and lock it using a new puzzle hash 0x5f5767744f91c1c326d927a63d9b34fa7035c10e3eb838c44e3afe127c1b7675.

Any remaining change goes to a farmer as a fee.

Get compiled version of the custom puzzle#

There are multiple ways how you can get compiled version of your custom puzzle.

Using clvm_tools (official)#

You can compile your custom puzzle from the terminal using the clvm_tools repository (included in the official Chia repository). All you need to do is to use the run command with your puzzle provided as an argument.

run '(mod (password new_puzhash amount)    (defconstant CREATE_COIN 51)
    (if (= (sha256 password) (q . 0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824))        (list (list CREATE_COIN new_puzhash amount))        (x)    ))'

results in (a (q 2 (i (= (sha256 5) (q . 0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824)) (q 4 (c 2 (c 11 (c 23 ()))) ()) (q 8)) 1) (c (q . 51) 1)).

Using Chialisp web tool (unofficial)#

Paste your custom puzzle into the text area and hit Compile. The compiled version will appear in the Run Output section.

Get puzzle hash from a puzzle#

Using clvm_tools#

You can get the hash of your Chialisp puzzle with the opc -H <compiled_puzzle> command included in the official clvm_tools repository.

opc -H '(a (q 2 (i (= (sha256 5) (q . 0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824)) (q 4 (c 2 (c 11 (c 23 ()))) ()) (q 8)) 1) (c (q . 51) 1))'

The response of this command will be a puzzle hash on the first line and a serialized version of your puzzle on the second line.

Example response:

4843c869bba5f65aa1e806cd372dae5668ca3b69640d067e86837ca96b324e71ff02ffff01ff02ffff03ffff09ffff0bff0580ffff01a02cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b982480ffff01ff04ffff04ff02ffff04ff0bffff04ff17ff80808080ff8080ffff01ff088080ff0180ffff04ffff0133ff018080

As you can see from the first line of this response, puzzle hash for our custom puzzle is 0x4843c869bba5f65aa1e806cd372dae5668ca3b69640d067e86837ca96b324e71

Using Chialisp#

You can also use Chialisp itself to get the hash of the Chialisp puzzle. The puzzle to get a puzzle hash is following:

(mod (puzzle)    (defconstant TREE 1)
    (defun sha256tree1 (TREE)       (if (l TREE)           (sha256 2 (sha256tree1 (f TREE)) (sha256tree1 (r TREE)))           (sha256 1 TREE)       )    )
    (sha256tree1 puzzle))

A solution to this puzzle then needs to contain the compiled puzzle we want to hash in the first position (wrap the compiled puzzle with parentheses and provide it as a solution).

Example solution for the password-locked coin: ((a (q 2 (i (= (sha256 5) (q . 0x2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824)) (q 4 (c 2 (c 11 (c 23 ()))) ()) (q 8)) 1) (c (q . 51) 1)))

The resulting hash for this example puzzle is again 0x4843c869bba5f65aa1e806cd372dae5668ca3b69640d067e86837ca96b324e71.

Convert puzzle hash to a receive address#

You can convert a puzzle hash to a receive address and vice-versa. An address is just an encoded puzzle hash. And since a puzzle hash matches specific puzzle, it also means that a receive address matches a specific puzzle.

You can use Chia explorer's online tool for converting between puzzle hash to receive address. The puzzle hash is encoded to bech32m format with xch prefix to form a receive address. The receive address for the puzzle hash 0x4843c869bba5f65aa1e806cd372dae5668ca3b69640d067e86837ca96b324e71 is xch1fppus6dm5hm94g0gqmxnwtdw2e5v5wmfvsxsvl5xsd72j6ejfecsdnkf2e.

Send Chia to the receive address#

Use the Chia GUI or CLI to send a transaction as you would typically do with the amount you want. As a receive address, set the address from the previous step (password-locked coin example: xch1fppus6dm5hm94g0gqmxnwtdw2e5v5wmfvsxsvl5xsd72j6ejfecsdnkf2e). That will lock your coin with a new puzzle.