64 lines
1.7 KiB
TypeScript
64 lines
1.7 KiB
TypeScript
import * as bip66 from './bip66';
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import * as types from './types';
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const { typeforce } = types;
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const ZERO = Buffer.alloc(1, 0);
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function toDER(x: Buffer): Buffer {
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let i = 0;
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while (x[i] === 0) ++i;
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if (i === x.length) return ZERO;
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x = x.slice(i);
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if (x[0] & 0x80) return Buffer.concat([ZERO, x], 1 + x.length);
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return x;
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}
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function fromDER(x: Buffer): Buffer {
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if (x[0] === 0x00) x = x.slice(1);
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const buffer = Buffer.alloc(32, 0);
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const bstart = Math.max(0, 32 - x.length);
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x.copy(buffer, bstart);
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return buffer;
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}
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interface ScriptSignature {
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signature: Buffer;
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hashType: number;
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}
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// BIP62: 1 byte hashType flag (only 0x01, 0x02, 0x03, 0x81, 0x82 and 0x83 are allowed)
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export function decode(buffer: Buffer): ScriptSignature {
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const hashType = buffer.readUInt8(buffer.length - 1);
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const hashTypeMod = hashType & ~0x80;
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if (hashTypeMod <= 0 || hashTypeMod >= 4)
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throw new Error('Invalid hashType ' + hashType);
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const decoded = bip66.decode(buffer.slice(0, -1));
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const r = fromDER(decoded.r);
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const s = fromDER(decoded.s);
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const signature = Buffer.concat([r, s], 64);
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return { signature, hashType };
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}
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export function encode(signature: Buffer, hashType: number): Buffer {
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typeforce(
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{
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signature: types.BufferN(64),
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hashType: types.UInt8,
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},
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{ signature, hashType },
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);
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const hashTypeMod = hashType & ~0x80;
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if (hashTypeMod <= 0 || hashTypeMod >= 4)
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throw new Error('Invalid hashType ' + hashType);
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const hashTypeBuffer = Buffer.allocUnsafe(1);
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hashTypeBuffer.writeUInt8(hashType, 0);
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const r = toDER(signature.slice(0, 32));
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const s = toDER(signature.slice(32, 64));
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return Buffer.concat([bip66.encode(r, s), hashTypeBuffer]);
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}
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