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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| import nacl from "tweetnacl"; | ||
| import { hmac, sha512 } from "hash.js"; | ||
| import { bytesToHex } from "../bytes_to_hex"; | ||
|
|
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| type Hex = string; | ||
| type Path = string; | ||
|
|
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| type Keys = { | ||
| key: Hex; | ||
| chainCode: Hex; | ||
| }; | ||
|
|
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| const pathRegex = /^m(\/[0-9]+')+$/; | ||
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| const replaceDerive = (val: string): string => val.replace("'", ""); | ||
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| const HMAC_KEY = "656432353531392073656564"; // ed25519 seed | ||
| const HARDENED_OFFSET = 0x80000000; | ||
|
|
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| export const getMasterKeyFromSeed = (seed: Hex): Keys => { | ||
| // @ts-ignore | ||
| const h = hmac(sha512, HMAC_KEY, "hex"); | ||
| const I = h.update(seed, "hex").digest("hex"); | ||
| const IL = I.slice(0, 64); | ||
| const IR = I.slice(64); | ||
| return { | ||
| key: IL, | ||
| chainCode: IR, | ||
| }; | ||
| }; | ||
|
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| export const CKDPriv = ({ key, chainCode }: Keys, index: number): Keys => { | ||
| const indexBuffer = Buffer.allocUnsafe(4); | ||
| indexBuffer.writeUInt32BE(index, 0); | ||
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| const buffer = new ArrayBuffer(4); | ||
| new DataView(buffer).setUint32(0, index); | ||
| const indexBytes = new Uint8Array(buffer); | ||
| const zero = new Uint8Array([0]); | ||
| const data = bytesToHex(zero) + key + bytesToHex(indexBytes); | ||
|
|
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| // @ts-ignore | ||
| const I = hmac(sha512, chainCode, "hex").update(data, "hex").digest("hex"); | ||
| const IL = I.slice(0, 64); | ||
| const IR = I.slice(64); | ||
| return { | ||
| key: IL, | ||
| chainCode: IR, | ||
| }; | ||
| }; | ||
|
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| export const getPublicKey = (privateKey: Uint8Array, withZeroByte = true): Uint8Array => { | ||
| const keyPair = nacl.sign.keyPair.fromSeed(privateKey); | ||
| const signPk = keyPair.secretKey.subarray(32); | ||
| const zero = new Uint8Array([0]); | ||
| return withZeroByte ? new Uint8Array([...zero, ...signPk]) : signPk; | ||
| }; | ||
|
|
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| export const isValidPath = (path: string): boolean => { | ||
| if (!pathRegex.test(path)) { | ||
| return false; | ||
| } | ||
| return !path | ||
| .split("/") | ||
| .slice(1) | ||
| .map(replaceDerive) | ||
| .some(Number.isNaN as any); | ||
| }; | ||
|
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| export const derivePath = (path: Path, seed: Hex, offset = HARDENED_OFFSET): Keys => { | ||
| if (!isValidPath(path)) { | ||
| throw new Error("Invalid derivation path"); | ||
| } | ||
|
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| const { key, chainCode } = getMasterKeyFromSeed(seed); | ||
| const segments = path | ||
| .split("/") | ||
| .slice(1) | ||
| .map(replaceDerive) | ||
| .map((el) => parseInt(el, 10)); | ||
|
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| return segments.reduce((parentKeys, segment) => CKDPriv(parentKeys, segment + offset), { key, chainCode }); | ||
| }; |
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