X509 serial number using java

Question

I need to get some data from X509 certificate.

If I open a certificate file in windows, its showing its serial number in this format.

ex. 39 65 70 eb d8         


        

Answer 1

The first one is hexadecimal value of the certificate. The other one is decimal.

Now it depends on how you convert the initial certificate bytearray for printing it out.

Lets say this is your certificate:

byte[] cert = { (byte) 0xFD, (byte) 0xB1, (byte) 0xDD, ..., (byte) 0x00 };
BigInteger certVal = new BigInteger(cert);  
System.out.println("And result is  (hex): " + certVal.toString(16));