PEM to DER decoding using JCE API

Question

Hi,
I need to convert PEM files to DER format within my
Java code (each PEM file is coming in as a String object).
Does anyone know of a way to do this using the Sun JCE
(or IBM provider)?
Thanks much

Answer 1

I figured out how to do this. In case someone else runs into
this problem in the future, here's one solution.
1. Strip the delimiters , i.e "-----BEGIN PRIVATE KEY-----"
and "-----END PRIVATE KEY-----" from the PEM file. You
will be left with the Base64 encode text.
2. Use a Base64 decoder class (e.g com.ibm.misc.BASE64Decoder)
to decode the Base64 back to the original DER bytes.
For example:
//privateKeyStr String contains the PEM data
int pemStartIndex = privateKeyStr.indexOf("\n") + 1;
int pemEndIndex = privateKeyStr.indexOf("-----END");
String pemStr = privateKeyStr.substring(pemStartIndex, pemEndIndex);
byte[] keyData = null;
com.ibm.misc.BASE64Decoder base64 = new com.ibm.misc.BASE64Decoder();
keyData = base64.decodeBuffer(pemStr); //keyData now contains DER data
That's it.