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

Windows shows the hexadecimal representation of the serial number, whereas Java returns a BigInteger result from X509Certificate.getSerialNumber().

To display the BigInteger as a hexadecimal value, just call toString(16).

BigInteger bi = new BigInteger("76292708057987193002565060032465481997");
System.out.println(bi.toString(16));

Will output:

396570ebd89f28204ec2a06b9848310d