115 lines
2.7 KiB
Markdown
115 lines
2.7 KiB
Markdown
---
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id: tezos-specific
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title: Tezos Domain-Specific Operations
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---
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LIGO is a language for writing Tezos smart contracts. It would be a little odd if
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it didn't have any Tezos specific functions. This page will tell you about them.
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## Pack and Unpack
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Michelson provides the `PACK` and `UNPACK` instructions for data serialization.
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`PACK` converts Michelson data structures to a binary format, and `UNPACK`
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reverses it. This functionality can be accessed from within LIGO.
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> ⚠️ There should be a message here about the dangers of using `UNPACK` on untrusted
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data, perhaps about executable code?
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function id_string (const p : string) : option(string) is block {
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const packed : bytes = bytes_pack(p) ;
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} with (bytes_unpack(packed): option(string))
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```
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<!--CameLIGO-->
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```cameligo
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let id_string (p: string) : string option =
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let packed: bytes = Bytes.pack p in
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((Bytes.unpack packed): string option)
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```
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<!--ReasonLIGO-->
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```reasonligo
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let id_string = (p: string) : option(string) => {
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let packed : bytes = Bytes.pack(p);
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((Bytes.unpack(packed)): option(string));
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Hashing Keys
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function check_hash_key (const kh1 : key_hash; const k2 : key) : bool * key_hash is block {
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var ret : bool := False ;
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var kh2 : key_hash := crypto_hash_key(k2) ;
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if kh1 = kh2 then ret := True else skip;
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} with (ret, kh2)
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```
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<!--CameLIGO-->
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```cameligo
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let check_hash_key (kh1, k2: key_hash * key) : bool * key_hash =
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let kh2 : key_hash = Crypto.hash_key k2 in
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if kh1 = kh2
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then (true, kh2)
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else (false, kh2)
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```
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<!--ReasonLIGO-->
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```reasonligo
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let check_hash_key = (kh1_k2: (key_hash, key)) : (bool, key_hash) => {
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let kh1, k2 = kh1_k2;
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let kh2 : key_hash = Crypto.hash_key(k2);
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if (kh1 == kh2) {
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(true, kh2);
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}
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else {
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(false, kh2);
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}
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Checking Signatures
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> ⚠️ There is no way to *generate* a signed message in LIGO. This is because that
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would require storing a private key on chain, at which point it isn't very private
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anymore.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function check_signature
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(const pk: key;
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const signed: signature;
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const msg: bytes) : bool
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is crypto_check(pk, signed, msg)
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```
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<!--CameLIGO-->
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```cameligo
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let check_signature (pk, signed, msg: key * signature * bytes) : bool =
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Crypto.check pk signed msg
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```
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<!--ReasonLIGO-->
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```reasonligo
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let check_signature = (param: (key, signature, bytes)) : bool => {
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let pk, signed, msg = param;
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Crypto.check(pk, signed, msg);
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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