Quick start guide

Create a Rust project

To create the project named java_rust_ffi, run:

cargo new java_rust_ffi 

Place the certificate

Copy Certificate_pkcs12.p12 in the new folder.

Move lib.rs

Move lib.rs file to the src directory.

Create Java project structure

Inside java_rust_ffi, create:

java/org/example 

Then, place C2paTest.java inside example.

Edit lib.rs

a. Open src/lib.rs and update host and certificate details with your own credentials.

const SAD_API_URL: &str = "https://clientauth.demo.one.digicert.com/documentmanager/csc/v1/credentials/authorize"; 
const SIGNING_API_URL: &str = "https://clientauth.demo.one.digicert.com/documentmanager/csc/v1/signatures/signHash"; 
const CLIENT_CERT_PATH: &str = "Certificate_pkcs12.p12"; 
const CLIENT_CERT_PASS: &str = "_IRX_7WZgHMG "; 

b. Make the edits below to update the file with your Credential ID and PIN.

let request_body = SADRequest {      
        credentialID: "basic_np-14-08-2025-11-01-44-165".to_string(),
        numSignatures: 1,
        hash: vec![hash.to_string()],
        PIN: "sha123".to_string(), 
    }; 
    let request_body = SignRequest {
        credentialID: "basic_np-14-08-2025-11-01-44-165".to_string(),
        SAD: sad.to_string(), 
        hash: vec![hash.to_string()],
            signAlgo: "Your signAlgo".to_string(),
            signAlgoParams: 
"MDSgDzANBglghkgBZQMEAgEFAKEcMBoGCSqGSIb3DQEBCDANBglghkgBZQMEAgEFAKIDAgEg" 
            .to_string(), 
         }; 

Update certificate content

Update lib.rs file with your user certificate content.

Replace Cargo.toml

Replace Cargo.toml in java_rust_ffi with the one provided in references.

Replace main.rs

Replace src/main.rs with the provided main.rs in references.

Build Rust library

Change directory to the one you created by using cargo new <directory_name> before running the commands below. In the sample code, this is java_rust_ffi. 

Run cd <directory_name>. In the sample code, this is cd java_rust_ffi.

To build Rust library, run commands:

cargo clean 
cargo generate-lockfile 
cargo update 
cargo build --release 

Copy compiled library

This build places the compiled library in target/release/. Create a folder lib inside your project directory java_rust_ffi. Then copy the compiled library libc2pa_rs.dylib to the lib folder. 

The compiled library looks different in different operating systems. For example:

Download JNA

Copy lib folder

Copy lib now populated with the files jna-5.14.0.jar and libc2pa_rs.dylib into java/.

Create C2paLibrary.java

In java/org/example, place the file C2paLibrary.java from reference files.

Add images you want to sign

Create a folder called Images in the Java folder. Place all images to be signed in the Images folder.  

This code sample considers that an image A.jpg is placed inside the folder ...java/Images. The image path that needs to be signed is provided in C2paTest.java. You are able to change the input file name/ path in C2paTest.java.

Compile and run Java

Verify project setup

Verify your project setup with the below screenshot:

Signed image

Output signed image with_claim.jpg is generated in the folder java/. The path/ filename of the signed image is provided in C2paTest.java. You may change the output file name/ path in C2paTest.java.