Signing methods

ATick for Java signs with a credential file or with an external key holder (USB token, smart-card, HSM, Windows certificate store). Every signing call takes its configuration as a single JSON options string, and every failure throws Atick.AtickException (a RuntimeException).

import io.github.aniketc068.atick.Atick;
import java.nio.file.*;

1. PFX / P12 / PEM file

Atick.signPfx is the primary method. It accepts both PKCS#12(.pfx / .p12) and PEM — the format is auto-detected.

byte[] pdf = Files.readAllBytes(Path.of("in.pdf"));
byte[] pfx = Files.readAllBytes(Path.of("signer.pfx"));

byte[] signed = Atick.signPfx(pdf, pfx,
    "{\"password\":\"••••\",\"cn\":\"Aniket\",\"reason\":\"Approved\",\"pades\":true}");

Files.write(Path.of("out.pdf"), signed);

PEM credentials

A PEM credential is an unencrypted PKCS#8 / PKCS#1 private key plus one or more CERTIFICATE blocks. Pass its bytes as the pfx argument and use an empty password (""):

byte[] pem = Files.readAllBytes(Path.of("signer.pem"));

byte[] signed = Atick.signPfx(pdf, pem,
    "{\"password\":\"\",\"cn\":\"Aniket\",\"pades\":true}");

Because the format is auto-detected, the same signPfx call works for .pfx, .p12, and .pem. Only the passworddiffers: the PKCS#12 passphrase for .pfx/.p12, and "" for PEM.

2. USB token / smart-card / HSM / Windows store (deferred flow)

ATick for Java does not load PKCS#11 libraries or the Windows store itself. To sign with a key that never leaves a token, card, HSM, or the OS store, use the deferred flow: ATick prepares the document and hands you the exact bytes to sign, you produce the CMS signature with your own JCA provider (for example SunPKCS11, SunMSCAPI, or a vendor provider), and ATick embeds it.

// Step 1 — prepare. Returns { prepared, bytesToSign }.
byte[][] out = Atick.prepare(pdf,
    "{\"cn\":\"Aniket\",\"reason\":\"Approved\",\"pades\":true,\"hash_algo\":\"sha256\"}");
byte[] prepared    = out[0];
byte[] bytesToSign = out[1];

// Step 2 — produce a CMS signature with your own provider.
//   Sign `bytesToSign` using the token / smart-card / HSM / Windows-store key.
//   This is your JCA code (SunPKCS11, SunMSCAPI, or a vendor provider).
byte[] cms = signWithMyProvider(bytesToSign);   // returns a CMS/PKCS#7 SignedData

// Step 3 — embed the CMS into the prepared document.
byte[] signed = Atick.embed(prepared, cms);
Files.write(Path.of("out.pdf"), signed);

The CMS you build in step 2 must cover bytesToSignexactly and use the same hash_algo you passed to Atick.prepare. This is the standard eSign / detached-signature pattern: ATick owns the PDF structure, your provider owns the private key.

If you have the key material in software (a .pfx/.p12/.pem), ATick can also build the CMS for you with Atick.cmsPfx, then Atick.embed:

byte[][] out = Atick.prepare(pdf, "{\"cn\":\"Aniket\",\"pades\":true}");
byte[] cms    = Atick.cmsPfx(out[1], pfx, "{\"password\":\"••••\",\"pades\":true}");
byte[] signed = Atick.embed(out[0], cms);

Common options

All signing calls (signPfx, prepare / cmsPfx, signField) accept the same JSON keys.

signPfx additionally accepts "open_password" (decrypt an encrypted input), and "encrypt_password" / "owner_password" (password-protect the output).

Appearance options

The visible signature block is also configured through the same JSON: cn, org, ou, location, reason, text, date, dn, body, heading, show_mark, green_tick, always_check, mark_color (hex "#E53935", name "blue", or [r,g,b]), mark_gradient, mark_scale, text_color, bg_color, border, font_size, width, height, page, rect ([x1,y1,x2,y2]), and placements([[page,[x1,y1,x2,y2]], …]).

byte[] signed = Atick.signPfx(pdf, pfx,
    "{\"password\":\"••••\",\"cn\":\"Aniket\",\"reason\":\"Approved\","
  + "\"show_mark\":true,\"green_tick\":true,\"mark_color\":\"#E53935\","
  + "\"page\":1,\"rect\":[36,36,236,96],\"pades\":true}");

Multi-signatory (sign an already-signed PDF)

ATick signs as an incremental update: existing signatures keep their byte ranges and stay valid. Just sign the already-signed PDF again — the field name is auto-uniquified so it never collides.

byte[] v1 = Atick.signPfx(pdf, pfx, "{\"password\":\"••••\",\"cn\":\"Aniket\",\"pades\":true}"); // Atick_1
byte[] v2 = Atick.signPfx(v1,  pfx, "{\"password\":\"••••\",\"cn\":\"Reviewer\",\"pades\":true}"); // Atick_2

The same holds for the deferred flow: run Atick.prepare → external CMS → Atick.embed on the already-signed bytes to add another signature.

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