The Tools package comes with a basic DigitalSignature tool that allows signing with a specific keystore and password. The DigitalSignature tool can be used with the UI components such as DocumentActivity and PdfViewCtrlTabHostFragment2 . You can also use the tool with PDFViewCtrl through ToolManager .

By default, the signature tool does not sign with a certificate. Certificate-based signatures can be enabled using ToolManagerBuilder which will add a certificate picker and password input field to the signature UI flow.

Alternatively you can define a certificate file and password in ToolManagerBuilder. This will disable the additional signing flow for digital signatures and use the specified certificate instead.

ToolManagerBuilder tmBuilder = ToolManagerBuilder.from()
    .setUseDigitalSignature(true)
    // Optionally specify a default certificate file and password
    .setDigitalSignatureKeystorePath("my_keystore_path")
    .setDigitalSignatureKeystorePassword("my_keystore_password");
ViewerConfig.Builder builder = new ViewerConfig.Builder();
ViewerConfig config = builder
    //...
    .toolManagerBuilder(tmBuilder)
    .build();

The signed document is then saved to a separate file.