Missing leading zeroes while retrieving serial number of a x509 cert

Question

I\'m trying to get serial number from a X.509 Cert.. When i compare the Serial number generated by my code with the actual serial number(on windows), leading zeroes of the

Answer 1

BigInteger has a toByteArray() method that re-adds the leading 00s:

byte[] serialNumBA = certificate.getSerialNumber().toByteArray()

Now you have several ways to convert the byte array to a hex string:

How to convert a byte array to a hex string in Java?

For example with Apache commons codec:

String serialNum = Hex.encodeHexString(serialNumBA);