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[stable30] fix(migration): Decrypt ownCloud secrets v2 #49537

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Nov 28, 2024
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[stable30] fix(migration): Decrypt ownCloud secrets v2 #49537

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32 changes: 29 additions & 3 deletions lib/private/Security/Crypto.php
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,25 @@ private function decryptWithoutSecret(string $authenticatedCiphertext, string $p
throw new Exception('Authenticated ciphertext could not be decoded.');
}

/*
* Rearrange arguments for legacy ownCloud migrations
*
* The original scheme consistent of three parts. Nextcloud added a
* fourth at the end as "2" or later "3", ownCloud added "v2" at the
* beginning.
*/
$originalParts = $parts;
$isOwnCloudV2Migration = $partCount === 4 && $originalParts[0] === 'v2';
if ($isOwnCloudV2Migration) {
$parts = [
$parts[1],
$parts[2],
$parts[3],
'2'
];
}

// Convert hex-encoded values to binary
$ciphertext = $this->hex2bin($parts[0]);
$iv = $parts[1];
$hmac = $this->hex2bin($parts[2]);
Expand All @@ -124,7 +143,7 @@ private function decryptWithoutSecret(string $authenticatedCiphertext, string $p
$iv = $this->hex2bin($iv);
}

if ($version === '3') {
if ($version === '3' || $isOwnCloudV2Migration) {
$keyMaterial = hash_hkdf('sha512', $password);
$encryptionKey = substr($keyMaterial, 0, 32);
$hmacKey = substr($keyMaterial, 32);
Expand All @@ -133,8 +152,15 @@ private function decryptWithoutSecret(string $authenticatedCiphertext, string $p
$this->cipher->setPassword($encryptionKey);
$this->cipher->setIV($iv);

if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $hmacKey), $hmac)) {
throw new Exception('HMAC does not match.');
if ($isOwnCloudV2Migration) {
// ownCloud uses the binary IV for HMAC calculation
if (!hash_equals($this->calculateHMAC($parts[0] . $iv, $hmacKey), $hmac)) {
throw new Exception('HMAC does not match.');
}
} else {
if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $hmacKey), $hmac)) {
throw new Exception('HMAC does not match.');
}
}

$result = $this->cipher->decrypt($ciphertext);
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13 changes: 13 additions & 0 deletions tests/lib/Security/CryptoTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,19 @@ public function testVersion2CiphertextDecryptsToCorrectPlaintext() {
);
}

/**
* Test data taken from https://github.com/owncloud/core/blob/9deb8196b20354c8de0cd720ad4d18d52ccc96d8/tests/lib/Security/CryptoTest.php#L56-L60
*/
public function testOcVersion2CiphertextDecryptsToCorrectPlaintext() {
$this->assertSame(
'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt.',
$this->crypto->decrypt(
'v2|d57dbe4d1317cdf19d4ddc2df807f6b5d63ab1e119c46590ce54bae56a9cd3969168c4ec1600ac9758dd7e7afb9c4c962dd23072c1463add1d9c77c467723b37bb768ef00e3c50898e59247cbb59ce56b74ce5990648ffe9e40d0e95076c27a785bdcf32c219ea4ad5c316b1f12f48c1|6bd21db258a5e406a2c288a444de195f|a19111a4cf1a11ee95fc1734699c20964eaa05bb007e1cecc4cc6872f827a4b7deedc977c13b138d728d68116aa3d82f9673e20c7e447a9788aa3be994b67cd6',
'ThisIsAVeryS3cur3P4ssw0rd'
)
);
}

public function testVersion3CiphertextDecryptsToCorrectPlaintext() {
$this->assertSame(
'Another plaintext value that will be encrypted with version 3. It addresses the related key issue. Old ciphertexts should be decrypted properly, but only use the better version for encryption.',
Expand Down
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