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Implement MDC-using encryption #20

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Merged
merged 1 commit into from
Dec 12, 2015
Merged

Implement MDC-using encryption #20

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27 changes: 7 additions & 20 deletions libs/GPG.php
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Original file line number Diff line number Diff line change
Expand Up @@ -52,20 +52,6 @@ private function gpg_encrypt($key, $text) {
$rblock[$i] = GPG_Utility::c_random();
}


$iblock = GPG_AES::encrypt($iblock, $ekey);
for($i = 0; $i < $this->width; $i++) {
$ct[$i] = ($iblock[$i] ^= $rblock[$i]);
}

$iblock = GPG_AES::encrypt($iblock, $ekey);
$ct[$this->width] = ($iblock[0] ^ $rblock[$this->width - 2]);
$ct[$this->width + 1] = ($iblock[1] ^ $rblock[$this->width - 1]);

for($i = 0; $i < $this->width + 2; $i++) $cipher .= chr($ct[$i]);

$iblock = array_slice($ct, 2, $this->width + 2);

for($n = 0; $n < strlen($text); $n += $this->width) {
$iblock = GPG_AES::encrypt($iblock, $ekey);
for($i = 0; $i < $this->width; $i++) {
Expand All @@ -74,7 +60,7 @@ private function gpg_encrypt($key, $text) {
}
}

return substr($cipher, 0, $len + $this->width + 2);
return substr($cipher, 0, $len);
}

private function gpg_header($tag, $len)
Expand Down Expand Up @@ -158,15 +144,16 @@ private function gpg_literal($text)
if (strpos($text, "\r\n") === false)
$text = str_replace("\n", "\r\n", $text);

return
$this->gpg_header(0xac, strlen($text) + 10) . "t" .
chr(4) . "file\0\0\0\0" . $text;
return chr(11 | 0xC0) . chr(255) . $this->writeNumber(strlen($text) + 10, 4) . "t" . chr(4) . "file\0\0\0\0" . $text;
}

private function gpg_data($key, $text)
{
$enc = $this->gpg_encrypt($key, $this->gpg_literal($text));
return $this->gpg_header(0xa4, strlen($enc)) . $enc;
$prefix = GPG_Utility::s_random($this->width, 0);
$prefix .= substr($prefix, -2);
$mdc="\xD3\x14".hash('sha1', $prefix.$this->gpg_literal($text)."\xD3\x14", true);
$enc = $this->gpg_encrypt($key, $prefix.$this->gpg_literal($text).$mdc);
return chr(0x12 | 0xC0) . chr(255) . $this->writeNumber(1+strlen($enc), 4) . chr(1) . $enc;
}

/**
Expand Down