Digital Signature generates a wrong value. (using PHP to generate the signature)

Question

I am trying to generate a digital signature from a string or text. I am using PHP to generate the digital signature.

This is the string that I am trying to generate the signature with from the ZHDASCRA53 up to ZTRENDRA53 22 including the line feed after it.

ZHDASCRA53  0800    20141014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ZDCSTANDING JOHN                20141014    Y   Y                           A96210
ZTRENDRA53  22

Below is the test certificate that I am using to generate the digital signature.

Below is the expected digital signature

RbcEYwvJgpONLxtaJxiL2XbFC/xJVwzamJN/2dkowulp7JYHAsNR/ktEcloDhM0G
5VIPQpCu2vqLf74i2VS5Whwz3nChauSGUC8Zl6qB4SqbYfV0bk/pT3mPMrdK/keu
g8U4nFa3ufW4pFslxW87IsglbZ0IlsnlPTJObg5Ku+M=

Below is the output of my digital signature:

OmpyizRj+4t27PoEMVlLxyYt6LGzyaKXsoXtZoTxd26PXfxYSeiflvAkhSIZNIn0 
zwNNnnC1t3BI25aOdItrKcSbNXKHtnnGpqpLWb6cFfLC3Q8DZpEAV/RrHPBCUNsK 
b8/u5CK7KRARyQWNDkWZLgnDg0G4hnlph7bwBTJW0Gs=

Below is the PHP code that I've been using to generate the digital signature:

$fp = fopen(getcwd() . "certificate.pem", "rb");
$priv_key = fread($fp, 30000);
fclose($fp);

$pkeyid = openssl_get_privatekey($priv_key);

openssl_sign($message, $signature, $pkeyid, OPENSSL_ALGO_MD5);

openssl_free_key($pkeyid);

$base64_signature = base64_encode($signature);

The variable $message contains the text / string that I have.

I have also tried

openssl dgst -md5 message.txt | openssl rsautl -sign -inkey certificate.pem | openssl enc -base64 -out base64_signature.txt

To generate a digital signature, but still it has a different output.

I have also read this post, I'm not sure if we are trying to do the same thing, it seems that the data we have are the same, though we use different names on our test data.

Digital Signature with wrong value

Really need help about this, I am still not sure what I am doing wrong.

Any help would be appreciated. Thanks a lot.

*Note: Edited the fopen to have "rb" instead of just "r".

what's the differences between r and rb in fopen

*Note: Edited also tried to do these:

shell_exec("openssl dgst -md5 message.txt | openssl rsautl -sign -inkey certificate.pem | openssl enc -base64 -out base64_signature.txt");

shell_exec("openssl dgst -md5 -sign certificate.pem message.txt | openssl enc -base64 -out base64_signature.txt");

then retrieved the output using fopen and fread didn't work as well.

More than likely it is due to the OPENSSL Algorithm being used. Try different values to see if one works for you: http://php.net/manual/en/openssl.signature-algos.php — MiltoxBeyond, Nov 08 '14 at 08:16
Thanks for the reply, I already tried OPENSSL_ALGO_SHA1 for php or -sha1 for openssl on cli, but the output is still different, currently the only allowed algorithm for what I am trying to achieve is MD5 or SHA1. — Benedict, Nov 08 '14 at 08:22
Did you try separating your certificate and key into independent files? Most examples I see use only the key as a .pem file. Not sure if it will help but worth a shot — MiltoxBeyond, Nov 08 '14 at 08:30
They have some examples in the docs on how to verify your signature here: http://php.net/manual/en/function.openssl-sign.php Just in case. — MiltoxBeyond, Nov 08 '14 at 08:41
$fp = fopen(getcwd() . "certificate.pem", "r"); $cert = fread($fp, 30000); fclose($fp); $pubkey = openssl_get_publickey($cert); $response = openssl_verify($message, $signature, $pubkey,"md5WithRSAEncryption"); I also have a function for verifying the signature that I am generating, this is what I am using, it passes the verification of the generated signature as well. but the problem is that it generates a different set of signature from the correct signature from my example. I also got that from php.net/manual/en/function.openssl-sign.php — Benedict, Nov 08 '14 at 08:51
@owlstead, It was given as like an example of what the actual message needed to be sent to the supplier / system would look like. Actually it would be a long process if I would state it here. — Benedict, Nov 12 '14 at 00:25
It could be the difference between PKCS#1 v1.5 padding mode and PSS. But I really would go back and ask for specifics, otherwise it may get into a wild goose hunt. Crypto doesn't usually give hints, just seemingly random numbers. — Maarten Bodewes, Nov 12 '14 at 00:27
Yeah, I've been trying to contact the supplier support about this but they wouldn't reply to me when it comes to like the coding part or how to do this, they dont have specifics in their documentation as well, its really weird that they don't give like a dev support or something, that's why I am trying my luck asking other devs and might find something useful. But yeah, I'll try again and ask about what you've mentioned. thanks — Benedict, Nov 12 '14 at 00:34

Digital Signature generates a wrong value. (using PHP to generate the signature)

0 Answers0