Encryption

ATick for .NET reads and writes password-protected PDFs through the same Atick.SignPfx entry point, plus a dedicated Atick.Decrypt helper. All passwords are passed as keys inside the options JSON string.

using Aniketc068.ATick;
using System.IO;

Option key	Applies to	Meaning
open_password	Input PDF	Password used to open an already-encrypted PDF before signing it.
encrypt_password	Output PDF	User password — required to open the signed PDF that ATick produces.
owner_password	Output PDF	Owner/permissions password for the signed output (optional).

Password-protect the output

Add encrypt_password to encrypt the signed PDF that ATick writes. Supply owner_password as well to set a separate owner/permissions password; if you omit it, the owner password defaults to the user password.

using Aniketc068.ATick;
using System.IO;

byte[] pdf = File.ReadAllBytes("contract.pdf");
byte[] pfx = File.ReadAllBytes("signer.pfx");

byte[] signed = Atick.SignPfx(pdf, pfx,
    "{\"password\":\"••••\",\"encrypt_password\":\"open-me\",\"owner_password\":\"owner\"}");

File.WriteAllBytes("contract-signed.pdf", signed);

The signature stays valid

The output is AES-128 encrypted. The signature’s /Contents is exempt from encryption, so the signed byte range still verifies in any compliant PDF reader.

Sign an encrypted input

If the input PDF is already password-protected, pass open_password so ATick can open it before signing. The decrypted document is signed and then written back out (encrypt the output again with encrypt_password if you want the result to stay protected).

using Aniketc068.ATick;
using System.IO;

byte[] pdf = File.ReadAllBytes("locked.pdf");
byte[] pfx = File.ReadAllBytes("signer.pfx");

byte[] signed = Atick.SignPfx(pdf, pfx,
    "{\"password\":\"••••\",\"open_password\":\"the-input-password\"}");

File.WriteAllBytes("locked-signed.pdf", signed);

Tip

You can combine the keys: open an encrypted input with open_password and re-encrypt the signed output in one call by also passing encrypt_password (and optionally owner_password).

Decrypt a PDF

Use Atick.Decrypt to strip the password protection from a PDF and obtain its plaintext bytes.

using Aniketc068.ATick;
using System.IO;

byte[] encrypted = File.ReadAllBytes("locked.pdf");

byte[] plain = Atick.Decrypt(encrypted, "the-password");

File.WriteAllBytes("unlocked.pdf", plain);

Handling failures

Both Atick.SignPfx and Atick.Decrypt throw AtickException on failure — for example, when a password is wrong or the input PDF is not actually encrypted.

using Aniketc068.ATick;
using System.IO;

try
{
    byte[] plain = Atick.Decrypt(File.ReadAllBytes("locked.pdf"), "wrong-pw");
    File.WriteAllBytes("unlocked.pdf", plain);
}
catch (AtickException e)
{
    Console.Error.WriteLine("Could not decrypt PDF: " + e.Message);
}