Math/BinaryField: fix for excessively large degrees

This commit is contained in:
terrafrost 2023-11-21 19:10:46 -06:00
parent 9bfd136259
commit 964d78101a
2 changed files with 25 additions and 0 deletions

View File

@ -48,6 +48,15 @@ class BinaryField extends FiniteField
public function __construct(...$indices) public function __construct(...$indices)
{ {
$m = array_shift($indices); $m = array_shift($indices);
if ($m > 571) {
/* sect571r1 and sect571k1 are the largest binary curves that https://www.secg.org/sec2-v2.pdf defines
altho theoretically there may be legit reasons to use binary finite fields with larger degrees
imposing a limit on the maximum size is both reasonable and precedented. in particular,
http://tools.ietf.org/html/rfc4253#section-6.1 (The Secure Shell (SSH) Transport Layer Protocol) says
"implementations SHOULD check that the packet length is reasonable in order for the implementation to
avoid denial of service and/or buffer overflow attacks" */
throw new \OutOfBoundsException('Degrees larger than 571 are not supported');
}
$val = str_repeat('0', $m) . '1'; $val = str_repeat('0', $m) . '1';
foreach ($indices as $index) { foreach ($indices as $index) {
$val[$index] = '1'; $val[$index] = '1';

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@ -704,4 +704,20 @@ cN6W+k8UvGf+Y/lDWNbFitQocabsDUvSN0edHH3UKP5QPTz4cOlyIPMrXQ==
$this->assertTrue($key->verify('hello world!', $signature)); $this->assertTrue($key->verify('hello world!', $signature));
} }
public function testExcessivelyLargeBinaryField()
{
$this->expectException('\OutOfBoundsException');
$key = '-----BEGIN PUBLIC KEY-----
MIIBDDCB0wYHKoZIzj0CATCBxwIBATAgBgcqhkjOPQECMBUCBH////8GCSqGSM49
AQIDAgICAMEwTQQZABeFj+t6mJdRaeFx93tAh94JisipEd97AQQZAP37Sb/mw6if
rK2qeh5bvHzBwuXYMUeIFAMVABA/rsdNaW5naHVhUXV3f8Wxke8wBDMEAfSBvF8P
+Ep0rWzfb970v2F5YlNy2MDF4QAl45nykDcSzPPqnjoa0X+wsyAbavfOGwUCGQEA
AAAAAAAAAAAAAADH80p3j0Q6zJIOukkCAQIDNAAEAE2mUTAwdPK952h3G8ZinK8B
z9DYTLdGkQDqox3AtEs9nn6kE1O/vHE4bqMegjj4gbA=
-----END PUBLIC KEY-----';
$key = EC::loadFormat('PKCS8', $key);
$this->assertInstanceOf(PublicKey::class, $key);
}
} }