65 lines
1.8 KiB
TypeScript
65 lines
1.8 KiB
TypeScript
/**
|
|
* The [Base58 Encoding](link-base58) scheme allows a **numeric** value
|
|
* to be encoded as a compact string using a radix of 58 using only
|
|
* alpha-numeric characters. Confusingly similar characters are omitted
|
|
* (i.e. ``"l0O"``).
|
|
*
|
|
* Note that Base58 encodes a **numeric** value, not arbitrary bytes,
|
|
* since any zero-bytes on the left would get removed. To mitigate this
|
|
* issue most schemes that use Base58 choose specific high-order values
|
|
* to ensure non-zero prefixes.
|
|
*
|
|
* @_subsection: api/utils:Base58 Encoding [base58]
|
|
*/
|
|
|
|
import { getBytes } from "./data.js";
|
|
import { assertArgument } from "./errors.js";
|
|
import { toBigInt } from "./maths.js";
|
|
|
|
import type { BytesLike } from "./index.js";
|
|
|
|
|
|
const Alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
|
|
let Lookup: null | Record<string, bigint> = null;
|
|
|
|
function getAlpha(letter: string): bigint {
|
|
if (Lookup == null) {
|
|
Lookup = { };
|
|
for (let i = 0; i < Alphabet.length; i++) {
|
|
Lookup[Alphabet[i]] = BigInt(i);
|
|
}
|
|
}
|
|
const result = Lookup[letter];
|
|
assertArgument(result != null, `invalid base58 value`, "letter", letter);
|
|
return result;
|
|
}
|
|
|
|
|
|
const BN_0 = BigInt(0);
|
|
const BN_58 = BigInt(58);
|
|
|
|
/**
|
|
* Encode %%value%% as a Base58-encoded string.
|
|
*/
|
|
export function encodeBase58(_value: BytesLike): string {
|
|
let value = toBigInt(getBytes(_value));
|
|
let result = "";
|
|
while (value) {
|
|
result = Alphabet[Number(value % BN_58)] + result;
|
|
value /= BN_58;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Decode the Base58-encoded %%value%%.
|
|
*/
|
|
export function decodeBase58(value: string): bigint {
|
|
let result = BN_0;
|
|
for (let i = 0; i < value.length; i++) {
|
|
result *= BN_58;
|
|
result += getAlpha(value[i]);
|
|
}
|
|
return result;
|
|
}
|