Not able to unzip .b64 extension

[Aggarwal Amit]

Hello, 
 
I am trying to unzip a file with .b64 extension. Using unzip or gunzip,
I am not able to unzip it and it throws an error saying it is not a
valid zip file.
The file is created by openssl while signing a jar file. Can anyone tell
me how I can unzip this file with .b64 extension using ANT ?
 
Best Regards
Amit Aggarwal