dart_base_x

Description:

dart base x

dart-base-x #
Inspired by base-x.
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.
Install #
dart pub add dart_base_x
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Example #
Base58
import 'dart:typed_data';

import 'package:dart_base_x/dart_base_x.dart';

void main() {
String base58 = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

BaseXCodec bs58 = BaseXCodec(base58);

Uint8List decoded =
bs58.decode('5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr');

print(decoded);
// => [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, 19, 164, 248, 99]

print(bs58.encode(decoded));
// => 5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr
}

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Alphabets #
See 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-_.!~



How it works #
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.