1Shared Libraries
2================
3
4## bitcoinconsensus
5
6The purpose of this library is to make the verification functionality that is critical to Bitcoin's consensus available to other applications, e.g. to language bindings.
7
8### API
9
10The interface is defined in the C header `bitcoinconsensus.h` located in  `src/script/bitcoinconsensus.h`.
11
12#### Version
13
14`bitcoinconsensus_version` returns an `unsigned int` with the API version *(currently at an experimental `0`)*.
15
16#### Script Validation
17
18`bitcoinconsensus_verify_script` returns an `int` with the status of the verification. It will be `1` if the input script correctly spends the previous output `scriptPubKey`.
19
20##### Parameters
21- `const unsigned char *scriptPubKey` - The previous output script that encumbers spending.
22- `unsigned int scriptPubKeyLen` - The number of bytes for the `scriptPubKey`.
23- `const unsigned char *txTo` - The transaction with the input that is spending the previous output.
24- `unsigned int txToLen` - The number of bytes for the `txTo`.
25- `unsigned int nIn` - The index of the input in `txTo` that spends the `scriptPubKey`.
26- `unsigned int flags` - The script validation flags *(see below)*.
27- `bitcoinconsensus_error* err` - Will have the error/success code for the operation *(see below)*.
28
29##### Script Flags
30- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_NONE`
31- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_P2SH` - Evaluate P2SH ([BIP16](https://github.com/bitcoin/bips/blob/master/bip-0016.mediawiki)) subscripts
32- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_DERSIG` - Enforce strict DER ([BIP66](https://github.com/bitcoin/bips/blob/master/bip-0066.mediawiki)) compliance
33- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_NULLDUMMY` - Enforce NULLDUMMY ([BIP147](https://github.com/bitcoin/bips/blob/master/bip-0147.mediawiki))
34- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_CHECKLOCKTIMEVERIFY` - Enable CHECKLOCKTIMEVERIFY ([BIP65](https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki))
35- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_CHECKSEQUENCEVERIFY` - Enable CHECKSEQUENCEVERIFY ([BIP112](https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki))
36- `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_WITNESS` - Enable WITNESS ([BIP141](https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki))
37
38##### Errors
39- `bitcoinconsensus_ERR_OK` - No errors with input parameters *(see the return value of `bitcoinconsensus_verify_script` for the verification status)*
40- `bitcoinconsensus_ERR_TX_INDEX` - An invalid index for `txTo`
41- `bitcoinconsensus_ERR_TX_SIZE_MISMATCH` - `txToLen` did not match with the size of `txTo`
42- `bitcoinconsensus_ERR_DESERIALIZE` - An error deserializing `txTo`
43- `bitcoinconsensus_ERR_AMOUNT_REQUIRED` - Input amount is required if WITNESS is used
44
45### Example Implementations
46- [NBitcoin](https://github.com/NicolasDorier/NBitcoin/blob/master/NBitcoin/Script.cs#L814) (.NET Bindings)
47- [node-libbitcoinconsensus](https://github.com/bitpay/node-libbitcoinconsensus) (Node.js Bindings)
48- [java-libbitcoinconsensus](https://github.com/dexX7/java-libbitcoinconsensus) (Java Bindings)
49- [bitcoinconsensus-php](https://github.com/Bit-Wasp/bitcoinconsensus-php) (PHP Bindings)
50