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[stable21] Explicitly check hex2bin input #26694

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Merged
rullzer merged 1 commit into from
Apr 22, 2021
Merged

[stable21] Explicitly check hex2bin input #26694

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22 changes: 19 additions & 3 deletions lib/private/Security/Crypto.php
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Original file line number Diff line number Diff line change
Expand Up @@ -124,14 +124,14 @@ public function decrypt(string $authenticatedCiphertext, string $password = ''):
throw new \Exception('Authenticated ciphertext could not be decoded.');
}

$ciphertext = hex2bin($parts[0]);
$ciphertext = $this->hex2bin($parts[0]);
$iv = $parts[1];
$hmac = hex2bin($parts[2]);
$hmac = $this->hex2bin($parts[2]);

if ($partCount === 4) {
$version = $parts[3];
if ($version >= '2') {
$iv = hex2bin($iv);
$iv = $this->hex2bin($iv);
}

if ($version === '3') {
Expand All @@ -154,4 +154,20 @@ public function decrypt(string $authenticatedCiphertext, string $password = ''):

return $result;
}

private function hex2bin(string $hex): string {
if (!ctype_xdigit($hex)) {
throw new \RuntimeException('String contains non hex chars: ' . $hex);
}
if (strlen($hex) % 2 !== 0) {
throw new \RuntimeException('Hex string is not of even length: ' . $hex);
}
$result = hex2bin($hex);

if ($result === false) {
throw new \RuntimeException('Hex to bin conversion failed: ' . $hex);
}

return $result;
}
}