64 lines
1.6 KiB
JavaScript
64 lines
1.6 KiB
JavaScript
let bip66 = require('bip66')
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let Buffer = require('safe-buffer').Buffer
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let typeforce = require('typeforce')
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let types = require('./types')
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let ZERO = Buffer.alloc(1, 0)
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function toDER (x) {
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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) {
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if (x[0] === 0x00) x = x.slice(1)
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let buffer = Buffer.alloc(32, 0)
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let 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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// BIP62: 1 byte hashType flag (only 0x01, 0x02, 0x03, 0x81, 0x82 and 0x83 are allowed)
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function decode (buffer) {
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let hashType = buffer.readUInt8(buffer.length - 1)
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let hashTypeMod = hashType & ~0x80
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if (hashTypeMod <= 0 || hashTypeMod >= 4) throw new Error('Invalid hashType ' + hashType)
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let decode = bip66.decode(buffer.slice(0, -1))
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let r = fromDER(decode.r)
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let s = fromDER(decode.s)
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return {
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signature: Buffer.concat([r, s], 64),
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hashType: hashType
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}
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}
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function encode (signature, hashType) {
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typeforce({
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signature: types.BufferN(64),
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hashType: types.UInt8
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}, { signature, hashType })
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let hashTypeMod = hashType & ~0x80
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if (hashTypeMod <= 0 || hashTypeMod >= 4) throw new Error('Invalid hashType ' + hashType)
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let hashTypeBuffer = Buffer.allocUnsafe(1)
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hashTypeBuffer.writeUInt8(hashType, 0)
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let r = toDER(signature.slice(0, 32))
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let s = toDER(signature.slice(32, 64))
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return Buffer.concat([
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bip66.encode(r, s),
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hashTypeBuffer
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])
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}
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module.exports = {
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decode: decode,
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encode: encode
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}
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