Decode base64 string - php - php

Question

Is there any way to decode this string??
Actual string : 其他語言測試 - testing
base64 encode while sending on mail as subject as
"=?iso-2022-jp?B?GyRCQjZCPjhsOEBCLDtuGyhCIC0gdGVzdGluZw==?="
<?php
echo base64_decode('GyRCQjZCPjhsOEBCLDtuGyhCIC0gdGVzdGluZw==');
?>
This is base 64 encode, I couldn't decode it to actual Chinese string.Since it has been encoded using "iso-2022-jp", I have also tried online base64decode.org site to decode this string, but I couldn't find the original string, how can I do that?

Answer 1

Use iconv():
<?php
$input = base64_decode('GyRCQjZCPjhsOEBCLDtuGyhCIC0gdGVzdGluZw==');//$BB6B>8l8#B,;n(B - testing
$input_encoding = 'iso-2022-jp';
echo iconv($input_encoding, 'UTF-8', $input); //其他語言測試 - testing
?>

Answer 2

What you are looking at is MIME header encoding. It can be decoded by mb_decode_mimeheader(), and generated by mb_encode_mimeheader(). For example:
<?php
mb_internal_encoding("utf-8");
$subj = "=?iso-2022-jp?B?GyRCQjZCPjhsOEBCLDtuGyhCIC0gdGVzdGluZw==?=";
print mb_decode_mimeheader($subj);
?>
其他語言測試 - testing
(The call to mb_internal_encoding() is necessary here because the contents of the subject line can't be represented in the default internal encoding of ISO8859-1.)

Answer 3

Try encoding the string to UTF-8 first and then encode it to base 64.
Same when decoding, decode the string from base64 and then from UTF-8.
This is working for me:
php > $base = "其他語言測試 - testing";
php > $encoded = base64_encode(utf8_encode($base));
php > $decoded = utf8_decode(base64_decode($encoded));
php > echo ($decoded === $base) . "\n";
1