J4L PDF digital signature - Version 1.0 Java component that creates/adds a digital signature to a PDF file. It is very easy to use, just 2 lines of Java code are required. This signature ensures the integrity of your document and its authentication. In other words, the receiver of the document knows you have created that document (authentication) and noone has modified it (integrity). The signature created will use the algorithms RSA signature, SHA1 hash and PKCS7 encoding.