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Fixes related key issue. #23496

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merged 2 commits into from
Oct 27, 2020
Merged

Fixes related key issue. #23496

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648b60f
Derive encryption key & MAC key from a single key.
lynn-stephenson Oct 16, 2020
a3bdb0c
Implement unit tests for versions 1 and 2.
lynn-stephenson Oct 16, 2020
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22 changes: 15 additions & 7 deletions lib/private/Security/Crypto.php
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
* @author Lukas Reschke <[email protected]>
* @author Morris Jobke <[email protected]>
* @author Roeland Jago Douma <[email protected]>
* @author Lynn Stephenson <[email protected]>
*
* @license AGPL-3.0
*
Expand Down Expand Up @@ -90,16 +91,17 @@ public function encrypt(string $plaintext, string $password = ''): string {
if ($password === '') {
$password = $this->config->getSystemValue('secret');
}
$this->cipher->setPassword($password);
$keyMaterial = hash_hkdf('sha512', $password);
$this->cipher->setPassword(substr($keyMaterial, 0, 32));

$iv = \random_bytes($this->ivLength);
$this->cipher->setIV($iv);

$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
$iv = bin2hex($iv);
$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, $password));
$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, substr($keyMaterial, 32)));

return $ciphertext.'|'.$iv.'|'.$hmac.'|2';
return $ciphertext.'|'.$iv.'|'.$hmac.'|3';
}

/**
Expand All @@ -114,7 +116,7 @@ public function decrypt(string $authenticatedCiphertext, string $password = ''):
if ($password === '') {
$password = $this->config->getSystemValue('secret');
}
$this->cipher->setPassword($password);
$hmacKey = $encryptionKey = $password;

$parts = explode('|', $authenticatedCiphertext);
$partCount = \count($parts);
Expand All @@ -128,14 +130,20 @@ public function decrypt(string $authenticatedCiphertext, string $password = ''):

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

if ($version === '3') {
$keyMaterial = hash_hkdf('sha512', $password);
$encryptionKey = substr($keyMaterial, 0, 32);
$hmacKey = substr($keyMaterial, 32);
}
}
$this->cipher->setPassword($encryptionKey);
$this->cipher->setIV($iv);

if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $password), $hmac)) {
if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $hmacKey), $hmac)) {
throw new \Exception('HMAC does not match.');
}

Expand Down
20 changes: 20 additions & 0 deletions tests/lib/Security/CryptoTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -75,4 +75,24 @@ public function testLegacy() {

$this->assertSame('legacy test', $this->crypto->decrypt($cipherText, $password));
}

public function testVersion2CiphertextDecryptsToCorrectPlaintext() {
$this->assertSame(
'This is a plaintext value that will be encrypted with version 2. Which addresses the reduced permutations on the IV.',
$this->crypto->decrypt(
'be006387f753e8728717e43cfc5526c37adf7b2c9b4a113ceec03b7b0bccfebee74e0acfa0015c5712b4376dacbd7bce26a8fbca916fdccee46203d8289f6b2e4c19318044d375edfc67c72e6c3ae329d4c276b8d866ac1b281844e81f7681fe83d90bc4b6fffa4f3cbc157d64257a493b67fd2af3c8976cb76df520f5739305|02e78ea7c73a32f3b407c54227a9d2ce|3e7a09628f818b7b1cd7724467f5b1b33135de6d2ec62d8c0361be4f2c5203385f10babdcae017d7b30abe5be2117803e3195fb6d9ef20949fe35dad5e9241ea|2',
'insecure-static-password'
)
);
}

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.',
$this->crypto->decrypt(
'c99823461db746aa74f819c8640e9e3c367fa3bb9c21dff905b5dd14072c1d1b0da8b7e6b7307bf1561b6ba7aaa932a16c23b1fd5217dc019d55233ef0813c65fccaeabd6ea3a971ce1bbbdfda790ae00fb4442693cbb50072e02875b9f50591df74d00e96fd5b9bd13cb02a5f57b062ec98a4c64fc518ed325d097454883adbfc1687c2af995a392407c5e040a54afee4b2997ab158fe48ef67ccf721a6a7031fcb44d51170892ce7971021a7f3a00d19002eb9b007efe7aecf397ec0dc22064fb5d4a15ad83949f0804feca3c69cdd|8476f53c8d49a7e119798a70086d8911|ae3f7e23d469fbc791714ceb07d854624b1bbd39ac6a4edc05d552e10659adfdcada3a059fae737ffd7d842dd3fcc84bcc364cd298e814dd4967de4ad4a658eb|3',
'insecure-static-password'
)
);
}
}