Fast base encoding / decoding of any given alphabet using bitcoin style leading zero compression.
WARNING: This module is NOT RFC3548 compliant, it cannot be used for base16 (hex), base32, or base64 encoding in a standards compliant manner.
Base58
var BASE58 = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
var bs58 = require('base-x')(BASE58)
var decoded = bs58.decode('5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr')
console.log(decoded)
// => Uint8Array(33) [
// 128, 237, 219, 220, 17, 104, 241, 218,
// 234, 219, 211, 228, 76, 30, 63, 143,
// 90, 40, 76, 32, 41, 247, 138, 210,
// 106, 249, 133, 131, 164, 153, 222, 91,
// 25
// ]
console.log(bs58.encode(decoded))
// => 5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLrSee below for a list of commonly recognized alphabets, and their respective base.
| Base | Alphabet |
|---|---|
| 2 | 01 |
| 8 | 01234567 |
| 11 | 0123456789a |
| 16 | 0123456789abcdef |
| 32 | 0123456789ABCDEFGHJKMNPQRSTVWXYZ |
| 32 | ybndrfg8ejkmcpqxot1uwisza345h769 (z-base-32) |
| 36 | 0123456789abcdefghijklmnopqrstuvwxyz |
| 58 | 123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz |
| 62 | 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ |
| 64 | ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/ |
| 67 | ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.!~ |
It encodes octet arrays by doing long divisions on all significant digits in the array, creating a representation of that number in the new base. Then for every leading zero in the input (not significant as a number) it will encode as a single leader character. This is the first in the alphabet and will decode as 8 bits. The other characters depend upon the base. For example, a base58 alphabet packs roughly 5.858 bits per character.
This means the encoded string 000f (using a base16, 0-f alphabet) will actually decode to 4 bytes unlike a canonical hex encoding which uniformly packs 4 bits into each character.
While unusual, this does mean that no padding is required and it works for bases like 43.
LICENSE MIT
A direct derivation of the base58 implementation from bitcoin/bitcoin, generalized for variable length alphabets.