Load ASN.1 private key to generate an RSA signature

[PlanetIrata]

Hi,

I'm using phpseclib 1.0.23 because I can't achieve to make version 3 work without using composer to install it, I want a zip file

I'd like to load a private key saved in a ASN.1 binary file but it doesn't work. Here is my code so far...

$priv_key = file_get_contents('./my.rsa.private.key.txt');
$asn1 = new File_ASN1();
$decoded = $asn1->decodeBER(base64_encode($priv_key));
print_r($decoded);   // <-- THIS OUTPUT SEEMS OK : Array ( [0] => Array ( [type] => 1 [constant] => 13 [content] => EGA.....Om9jx [length] => 75 ) )
$rsa->loadKey($decoded[0]);  // <-- DON'T WORK RETURN FALSE

Any help ?

[terrafrost]

You can make phpseclib 3.0 work "without" Composer using the instructions at https://phpseclib.com/docs/install#without-composer .

That said, for 1.0... why can't you just do this?:

$rsa = new Crypt_RSA();
$rsa->loadKey($priv_key);

If you're gonna go the $asn1->decodeBER(base64_encode($priv_key)); route then you'd also need to call asn1map as well and doing so is a fair amount more complicated in the 1.0 branch.;

[PlanetIrata]

Hi @terrafrost

I tried this at first attempt:

$rsa = new Crypt_RSA();
$priv_key = file_get_contents('./my.rsa.private.key.txt');
$rsa->loadKey($priv_key);  // <-- return false

But loadKey returns false and RSA sign doesn't do anything after that...

Will try with phpseclib 3.0 ...

[PlanetIrata]

Do not work better with phpseclib 3...

Tried to load my key as exponent and modulus, but I have a 30 seconds timeout while trying to sign anything:

$rsa = PublicKeyLoader::load([
        // Modulus
        'n' => new BigInteger('5BDD6AFB1E1AFB50D1B2989F70B549B8D44AE3712B444F2C5D862C46C99526E998B79BF0B4F1461524E39D263F3130B9E08F3B17C2070785EFB0EDEC1E75C6C2B8185FA9596886D5DAF8B68E92FCF5F1B33E7CD772845555B086D2A2466B6398A04DFE1C727BB020ED2BF3F03D2826F89616D0846C18B1D87064616FAD394462', 16),

        // Exponent
        'e' => new BigInteger('6FE4F5D0AFCC16E8A5CC68955D4EF28255A546D06F34DD103540B9A7D202AEC96353072DB65D9C360E9030F413971142EE6A28974767CCF3ABFA4E7ADDAEAD81D3F8AE5FF1B8241CA9EF51C10941FFFA74482A636CBD909D29CF7A0346653D3C286EA1F392F4968AEF1489EC4B4BCEA4F248F3931B1C9BE2808DBD33B049731A', 16)
    ]
)
->withPadding(RSA::SIGNATURE_PKCS1)
->withHash('md5')
->withMGFHash('md5')
->asPrivateKey()
;

echo $rsa->sign("toto");   // <-- Fatal error: Maximum execution time of 30 seconds exceeded

Note that my private key was generated with an external app with these parameters:

• Prime test iterations = 100
• key size = 1024

Do I need to pass these parameters to the PublicKeyLoader::load array ?

[terrafrost]

$rsa = new Crypt_RSA();
$priv_key = file_get_contents('./my.rsa.private.key.txt');
$rsa->loadKey($priv_key);  // <-- return false

Would be helpful to see the key - or at least a key that reproduces the problem. As is I can only speculate as to why that doesn't work.

$rsa = $key->asPrivateKey();
echo $key->sign("toto");   // <-- Fatal error: Maximum execution time of 30 seconds exceeded

You'd need to do $rsa->sign("toto") vs $key->sign("toto"), as public key objects don't implement the sign() method.

That said, when I did it with $rsa->sign("toto") took me 0.164s to run it and that was with the PHP64 engine. Like the GMP engine is waaaaaay faster but 0.164s is still plenty fast. This was on PHP 8.3

So if echo $key->sign("toto"); wasn't a typo then it's not clear why you're not getting this error:

Fatal error: Uncaught Error: Call to undefined method phpseclib3\Crypt\RSA\PublicKey::sign() in \path\to\whatever.php

If echo $key->sign("toto"); was a typo then I'd need to see your php.ini to have at least recommendations as to how to speed it up. But even with that, tbh, even PHP 5.6 / 32-bit mode should still be plenty fast. xdebug could slow thing down but idk how by much off hand.

[PlanetIrata]

@terrafrost I fixed the code from my previous comment and changes Modulus and Exponent to a key that timout on my computer. The previous one was working for unknown reason...

[terrafrost]

Apologies for the delay - I've been traveling / vacationing.

Anyway, I was able to reproduce the issue and 2689c72 fixed it for me. Does it fix it for you?

[PlanetIrata]

Apologies for the delay - I've been traveling / vacationing.

Anyway, I was able to reproduce the issue and 2689c72 fixed it for me. Does it fix it for you?

@terrafrost Yes it fixes the timeout, thanks !