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Base62 encoder and decoder for arbitrary data

License: MIT License

PHP 97.20% Makefile 2.80%

encoder decoder php base62

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base62's Issues

Can't successfully convert low-value UUIDs without blowing up.

The Problem

When I tried to use this with my phpexpertsinc/ConciseUUID project, the tests all failed on low value UUIDs.

InvalidArgumentException: $bytes string should contain 16 characters.

Here is a test case:

use Ramsey\Uuid\Uuid;
use Tuupola\Base62Proxy as Base62;

$uuid = Uuid::fromBytes(Base62::decode($conciseUuid));

Here's the test data:

    $badUuids = [
            '0023a441-a3a3-4d9e-bd65-de3381c3a226' => '00GHs6XflJ51yCvZ4TwH4g',
            '1ee9a026-48ef-4592-9d87-88ceea7bc35e' => '0wKXIE87UgfjIvSPLkAHao',
            '0e0aa2a8-1a10-45e4-a67a-c97b9c5a7d19' => '0QUkgNC86JAY1A8JhVZ7iT',
            '1ad0d525-97c9-4c08-ad56-59acd47e3f7c' => '0obEi3noEliUnbTQbhMrLo',
   ];

The Solution

I solved this using ext-gmp via:

    // 3. We pad zeros to the beginning, as the result returned by gmp_strval after base conversion
    // is not always 22 characters long.
    $uuid = str_pad($uuid, 22, '0', STR_PAD_LEFT);

[Suggestion] Add support to encode hex directly

$hex = '123456abcdef';
Base62::encode($hex);  // "JngPBzse6O99qumM"
Base62::encode(hex2bin($hex)); // "5gOMRIbf"

I think it is better to add encodeHex and decodeHex methods, then we can encode hex directly like Base62::encodeHex($hex). And for internal, we may call encodeHex for string encoding like:

public function encodeHex($data)
{
    return ctype_xdigit($data) ? gmp_strval(gmp_init($data, 16), 62) : '';
}

public function encode($data, $integer = false)
{
    if (is_integer($data) || true === $integer) {
        return gmp_strval(gmp_init($data, 10), 62);
    }

    return $this->encodeHex(bin2hex($data));
}

Intolerant of truncated data, inelegant failure mode

This is something of an edge case, but it's reasonably important if encoded strings are embedded in URLs - incomplete data is better than trashed data. If I encode a string using base62, then remove 1 or more chars from the end of the string, then decode it again, it results in complete garbage output.

This is in contrast to similar encoders that degrade more gracefully, such as PHP's built-in base64 functions. In this example I've chosen an input length that does not result in padding in the base64 encoder, as deleting padding is always harmless:

$str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567';

$base62 = new Tuupola\Base62;
$e = $base62->encode($str);
$d = $base62->decode(substr($e, 0, -1));
var_dump($str, $e, $d);

$e = base64_encode($str);
$d = base64_decode(substr($e, 0, -1));
var_dump($str, $e, $d);

Output:

string(60) "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567"
string(81) "4p1Nflx8o0gcd8e3xWM0Idxg3Fuxk4R0eRc9fYLj2B83X5FRXw82YB3KaoyYLuNBn1LJW2KwVqMIAhO5P"
string(60) "���`�G�`�܎���"�d�3i��3y�`��S�d6ϙ�}��6��\&}7	�l�}O�\000�!ۮG�"
string(60) "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567"
string(80) "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWjAxMjM0NTY3"
string(59) "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456"

Note that while the base62 output is unusable, the base64 output just loses a single character at the end.

I suspect this may be because the entire input string is treated as a single GMP number, rather than treating it as a byte stream, or encoding in chunks of a few chars at a time. It's noticeable when you encode nearly identical strings - in base62 they result in completely different output after the difference, rather than only differing in the areas where the input strings are different (as seen in base64). For example:

$str1 = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567';
$str2 = 'abcdefghijklmnopqrstuvwxyz_BCDEFGHIJKLMNOPQRSTUVWXYZ01234567';
var_dump($base62->encode($str1), $base62->encode($str2), base64_encode($str1), base64_encode($str2));

Output (^ indicates difference in output):

string(81) "4p1Nflx8o0gcd8e3xWM0Idxg3Fuxk4R0eRc9fYLj2B83X5FRXw82YB3KaoyYLuNBn1LJW2KwVqMIAhO5P"
string(81) "4p1Nflx8o0gcd8e3xWM0Idxg3Fuxk4R0eRcBcpzqd0KogZYJMSqRuFsDRn11xfrgKLFGaYUmPtLLlF5V9"
                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
string(80) "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWjAxMjM0NTY3"
string(80) "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpfQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWjAxMjM0NTY3"
                                               ^

Big integer output wrong with pure PHP encoder

The characters option can be others like 1234567890?

Leading 0x00 stripped from binary data

I met a leading \0 string when running tests, is this normal?

There was 1 failure:

1) Tuupola\Base62\Base62Test::testShouldEncodeAndDecodeRandomBytes
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-Binary String: 0x00486eea2de87439fc081b892616a3b0f1f098df86e2cdd23e7d21f5f046a30a1a6662fff6c3c017b1d4853a1fdd7dc00975016d9c2801b9df659fadc6abe1109b1e1f3960367603e75bb9ddf9d8097af5948f74df585d05bbee61aff992f3d35577e31aafce7d4342d3a68da0d5ca8d46bde2f7e7f555cf6a1938c4f52bdd43
+Binary String: 0x486eea2de87439fc081b892616a3b0f1f098df86e2cdd23e7d21f5f046a30a1a6662fff6c3c017b1d4853a1fdd7dc00975016d9c2801b9df659fadc6abe1109b1e1f3960367603e75bb9ddf9d8097af5948f74df585d05bbee61aff992f3d35577e31aafce7d4342d3a68da0d5ca8d46bde2f7e7f555cf6a1938c4f52bdd43

/private/tmp/base62/tests/Base62Test.php:41

FAILURES!

tuupola / base62 Goto Github PK

base62's People

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base62's Issues

Can't successfully convert low-value UUIDs without blowing up.

The Problem

The Solution

[Suggestion] Add support to encode hex directly

Intolerant of truncated data, inelegant failure mode

Big integer output wrong with pure PHP encoder

Leading 0x00 stripped from binary data

Which base62 algorithm does this implement?

Site certificate is expired base62.io

FYI JavaScript port

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