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feat: add helper to extract public key from script
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Signed-off-by: Anmol Sharma <anmolsharma0234@gmail.com>
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@theanmolsharma
theanmolsharma committed Apr 27, 2024
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185 changes: 185 additions & 0 deletions src/common/common.spec.ts
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import { extractPubKeyFromScript } from '@/common/common';

describe('Common', () => {
it.each([
{
description: 'P2PKH',
scriptPubKey: '76a91419c2f3ae0ca3b642bd3e49598b8da89f50c1416188ac',
scriptSig:
'483046022100ad79e6801dd9a8727f342f31c71c4912866f59dc6e7981878e92c5844a0ce929022100fb0d2393e813968648b9753b7e9871d90ab3d815ebf91820d704b19f4ed224d621025a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
witness: [],
expected:
'025a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
},
{
description: 'P2PKH',
scriptPubKey: '76a914d9317c66f54ff0a152ec50b1d19c25be50c8e15988ac',
scriptSig:
'48304602210086783ded73e961037e77d49d9deee4edc2b23136e9728d56e4491c80015c3a63022100fda4c0f21ea18de29edbce57f7134d613e044ee150a89e2e64700de2d4e83d4e2103bd85685d03d111699b15d046319febe77f8de5286e9e512703cdee1bf3be3792',
witness: [],
expected:
'03bd85685d03d111699b15d046319febe77f8de5286e9e512703cdee1bf3be3792',
},
{
description: 'P2TR',
scriptPubKey:
'51205a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
scriptSig: '',
witness: [
'c459b671370d12cfb5acee76da7e3ba7cc29b0b4653e3af8388591082660137d087fdc8e89a612cd5d15be0febe61fc7cdcf3161a26e599a4514aa5c3e86f47b',
],
expected:
'025a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
},
{
description: 'P2TR',
scriptPubKey:
'5120782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
scriptSig: '',
witness: [
'bd1e708f92dbeaf24a6b8dd22e59c6274355424d62baea976b449e220fd75b13578e262ab11b7aa58e037f0c6b0519b66803b7d9decaa1906dedebfb531c56c1',
],
expected:
'02782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
},
{
description: 'P2TR',
scriptPubKey:
'51208c8d23d4764feffcd5e72e380802540fa0f88e3d62ad5e0b47955f74d7b283c4',
scriptSig: '',
witness: [
'0a4d0dca6293f40499394d7eefe14a1de11e0e3454f51de2e802592abf5ee549042a1b1a8fb2e149ee9dd3f086c1b69b2f182565ab6ecf599b1ec9ebadfda6c5',
],
expected:
'028c8d23d4764feffcd5e72e380802540fa0f88e3d62ad5e0b47955f74d7b283c4',
},
{
description: 'P2PKH',
scriptPubKey: '76a9148cbc7dfe44f1579bff3340bbef1eddeaeb1fc97788ac',
scriptSig:
'463044021f24e010c6e475814740ba24c8cf9362c4db1276b7f46a7b1e63473159a80ec30221008198e8ece7b7f88e6c6cc6bb8c86f9f00b7458222a8c91addf6e1577bcf7697e2103e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85d',
witness: [],
expected:
'03e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85d',
},
{
description: 'P2PKH',
scriptPubKey: '76a9147cdd63cc408564188e8e472640e921c7c90e651d88ac',
scriptSig:
'473045022100a8c61b2d470e393279d1ba54f254b7c237de299580b7fa01ffcc940442ecec4502201afba952f4e4661c40acde7acc0341589031ba103a307b886eb867b23b850b972103782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
witness: [],
expected:
'03782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
},
{
description: 'P2TR - annex present, NUMS_H used as internal key',
scriptPubKey:
'5120da6f0595ecb302bbe73e2f221f05ab10f336b06817d36fd28fc6691725ddaa85',
scriptSig: '',
witness: [
'c459b671370d12cfb5acee76da7e3ba7cc29b0b4653e3af8388591082660137d087fdc8e89a612cd5d15be0febe61fc7cdcf3161a26e599a4514aa5c3e86f47b',
'205a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5ac',
'c150929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0',
'50',
],
expected: null,
},
{
description: 'P2TR - annex absent, NUMS_H used as internal key',
scriptPubKey:
'51200a3c9365ceb131f89b0a4feb6896ebd67bb15a98c31eaa3da143bb955a0f3fcb',
scriptSig: '',
witness: [
'268d31a9276f6380107d5321cafa6d9e8e5ea39204318fdc8206b31507c891c3bbcea3c99e2208d73bd127a8e8c5f1e45a54f1bd217205414ddb566ab7eda009',
'20e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85dac',
'c150929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0',
],
expected: null,
},
{
description: 'P2PKH',
scriptPubKey: '76a9147cdd63cc408564188e8e472640e921c7c90e651d88ac',
scriptSig:
'0075473045022100a8c61b2d470e393279d1ba54f254b7c237de299580b7fa01ffcc940442ecec4502201afba952f4e4661c40acde7acc0341589031ba103a307b886eb867b23b850b972103782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
witness: [],
expected:
'03782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c379937323338',
},
{
description: 'P2PKH',
scriptPubKey: '76a914c82c5ec473cbc6c86e5ef410e36f9495adcf979988ac',
scriptSig:
'5163473045022100e7d26e77290b37128f5215ade25b9b908ce87cc9a4d498908b5bb8fd6daa1b8d022002568c3a8226f4f0436510283052bfb780b76f3fe4aa60c4c5eb118e43b187372102e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85d67483046022100c0d3c851d3bd562ae93d56bcefd735ea57c027af46145a4d5e9cac113bfeb0c2022100ee5b2239af199fa9b7aa1d98da83a29d0a2cf1e4f29e2f37134ce386d51c544c2102ad0f26ddc7b3fcc340155963b3051b85289c1869612ecb290184ac952e2864ec68',
witness: [],
expected:
'02e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85d',
},
{
description: 'P2PKH - uncompressed key used',
scriptPubKey: '76a9144b92ac4ac6fe6212393894addda332f2e47a315688ac',
scriptSig:
'473045022100a8c61b2d470e393279d1ba54f254b7c237de299580b7fa01ffcc940442ecec4502201afba952f4e4661c40acde7acc0341589031ba103a307b886eb867b23b850b974104782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c3799373233387c5343bf58e23269e903335b958a12182f9849297321e8d710e49a8727129cab',
witness: [],
expected: null,
},
{
description: 'P2WPKH - uncompressed key used',
scriptPubKey: '00140423f731a07491364e8dce98b7c00bda63336950',
scriptSig: '',
witness: [
'3045022100e7d26e77290b37128f5215ade25b9b908ce87cc9a4d498908b5bb8fd6daa1b8d022002568c3a8226f4f0436510283052bfb780b76f3fe4aa60c4c5eb118e43b18737',
'04e0ec4f64b3fa2e463ccfcf4e856e37d5e1e20275bc89ec1def9eb098eff1f85d6fe8190e189be57d0d5bcd17dbcbcd04c9b4a1c5f605b10d5c90abfcc0d12884',
],
expected: null,
},
{
description: 'P2SH-P2WPKH',
scriptPubKey: 'a9148629db5007d5fcfbdbb466637af09daf9125969387',
scriptSig: '16001419c2f3ae0ca3b642bd3e49598b8da89f50c14161',
witness: [
'3046022100ad79e6801dd9a8727f342f31c71c4912866f59dc6e7981878e92c5844a0ce929022100fb0d2393e813968648b9753b7e9871d90ab3d815ebf91820d704b19f4ed224d6',
'025a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
],
expected:
'025a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5',
},
{
description: 'P2SH-P2WPKH - uncompressed key used',
scriptPubKey: 'a9146c9bf136fbb7305fd99d771a95127fcf87dedd0d87',
scriptSig: '1600144b92ac4ac6fe6212393894addda332f2e47a3156',
witness: [
'3045022100a8c61b2d470e393279d1ba54f254b7c237de299580b7fa01ffcc940442ecec4502201afba952f4e4661c40acde7acc0341589031ba103a307b886eb867b23b850b97',
'04782eeb913431ca6e9b8c2fd80a5f72ed2024ef72a3c6fb10263c3799373233387c5343bf58e23269e903335b958a12182f9849297321e8d710e49a8727129cab',
],
expected: null,
},
{
description: 'P2SH - 2 of 3 multisig',
scriptPubKey: 'a9141044ddc6cea09e4ac40fbec2ba34ad62de6db25b87',
scriptSig:
'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',
witness: [],
expected: null,
},
{
description: 'P2PKH - uncompressed key used',
scriptPubKey: '76a914460e8b41545d2dbe7e0671f0f573e2232814260a88ac',
scriptSig:
'483046022100ad79e6801dd9a8727f342f31c71c4912866f59dc6e7981878e92c5844a0ce929022100fb0d2393e813968648b9753b7e9871d90ab3d815ebf91820d704b19f4ed224d641045a1e61f898173040e20616d43e9f496fba90338a39faa1ed98fcbaeee4dd9be5c61836c9b1688ba431f7ea3039742251f62f0dca3da1bee58a47fa9b456c2d52',
witness: [],
expected: null,
},
])(
'should extract public key from script: $description',
({ scriptPubKey, scriptSig, witness, expected }) => {
const pubKey = extractPubKeyFromScript(
Buffer.from(scriptPubKey, 'hex'),
Buffer.from(scriptSig, 'hex'),
witness.map((w) => Buffer.from(w, 'hex')),
);

if (expected === null) expect(pubKey).toBeNull();
else expect(pubKey.toString('hex')).toEqual(expected);
},
);
});
103 changes: 99 additions & 4 deletions src/common/common.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
import { createHash } from 'crypto';
import { publicKeyVerify } from 'secp256k1';
import { NUMS_H } from '@/common/constants';

export const camelToSnakeCase = (inputString: string) => {
return inputString
.split('.')
Expand All @@ -8,8 +12,99 @@ export const camelToSnakeCase = (inputString: string) => {
.toUpperCase();
};

export const extractPubKeyFromScript = (script: string): string | null => {
throw new Error(
`Not implemented! Cannot extract public key from script: ${script}`,
);
const verifyPubKey = (pubKey: Buffer): boolean => {
return pubKey.length === 33 && publicKeyVerify(pubKey);
};

const hash160 = (buffer: Buffer): Buffer => {
const sha256 = createHash('sha256').update(buffer).digest();
return createHash('ripemd160').update(sha256).digest();
};

export const extractPubKeyFromScript = (
scriptPubKey: Buffer,
scriptSig: Buffer,
witness: Buffer[] = [],
): Buffer | null => {
// P2PKH
// scriptPubKey: OP_DUP OP_HASH160 OP_PUSHBYTES_20 <20 bytes> OP_EQUALVERIFY OP_CHECKSIG
if (
scriptPubKey.length === 25 &&
scriptPubKey[0] === 0x76 &&
scriptPubKey[1] === 0xa9 &&
scriptPubKey[2] === 0x14 &&
scriptPubKey[23] === 0x88 &&
scriptPubKey[24] === 0xac
) {
const pubKeyHash = scriptPubKey.subarray(3, 23);
// we have to do this because P2PKH scriptSig are malleable
// segwit fixes this
// a better way to do this would be to parse the scriptSig
for (let i = scriptSig.length; i >= 33; i--) {
const pubKey = scriptSig.subarray(i - 33, i);
if (hash160(pubKey).equals(pubKeyHash) && publicKeyVerify(pubKey))
return pubKey;
}
}

// P2WPKH
// scriptPubKey: OP_0 OP_PUSHBYTES_20 <20 bytes>
if (
scriptPubKey.length === 22 &&
scriptPubKey[0] === 0x00 &&
scriptPubKey[1] === 0x14
) {
const pubKey = witness[1];
if (verifyPubKey(pubKey)) return pubKey;
}

// P2SH
// scriptPubKey: OP_HASH160 OP_PUSHBYTES_20 <20 bytes> OP_EQUAL
if (
scriptPubKey.length === 23 &&
scriptPubKey[0] === 0xa9 &&
scriptPubKey[1] === 0x14 &&
scriptPubKey[22] === 0x87
) {
const redeemScript = scriptSig.subarray(1);
// check if redeemScript is P2WPKH
if (
redeemScript.length === 22 &&
redeemScript[0] === 0x00 &&
redeemScript[1] === 0x14
) {
const pubKey = witness[1];
if (verifyPubKey(pubKey)) {
return pubKey;
}
}
}

// P2TR
// scriptPubKey: OP_1 OP_PUSHBYTES_32 <32 bytes>
if (
scriptPubKey.length === 34 &&
scriptPubKey[0] === 0x51 &&
scriptPubKey[1] === 0x20
) {
if (witness.length >= 1) {
// remove annex
if (witness.length > 1 && witness[witness.length - 1][0] === 0x50)
witness.pop();

if (witness.length > 1) {
const controlBlock = witness[witness.length - 1];
const internalKey = controlBlock.subarray(1, 33);
if (internalKey.equals(NUMS_H)) return null;
}

const pubKey = Buffer.concat([
Buffer.from([0x02]),
scriptPubKey.subarray(2),
]);
if (verifyPubKey(pubKey)) return pubKey;
}
}

return null;
};
4 changes: 4 additions & 0 deletions src/common/constants.ts
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export const NUMS_H = Buffer.from(
'50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0',
'hex',
);

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