Chữ ký số PDF

Thêm chữ ký số mật mã vào PDF của bạn bằng chứng chỉ X.509. Hỗ trợ định dạng PKCS#12 (.pfx, .p12) và PEM. Khóa riêng của bạn không bao giờ rời khỏi trình duyệt.

Internet connection required

Signing may need to fetch certificate chain information from your certificate issuer's server to validate the signature.

Nhấp để chọn tệp hoặc kéo và thả

PDF Documents

Tệp của bạn không bao giờ rời khỏi thiết bị.

How It Works

1

Upload PDF

Select the PDF document you want to sign

2

Upload Certificate

Provide your .pfx or .p12 certificate file and password

3

Sign & Download

Digital signature is applied to PDF and signed document is ready for download

Related PDF Tools

Encrypt PDF

Password protect your PDF

Decrypt PDF

Remove PDF password

Flatten PDF

Make annotations permanent

Sanitize PDF

Remove hidden data

Change Permissions

Set PDF permissions

Commonly Asked Questions

What is a digital signature?

A digital signature is a cryptographic mechanism that verifies the authenticity and integrity of a document. Unlike a drawn signature, it uses public key cryptography (X.509 certificates) to prove the signer's identity.

What certificate formats are supported?

We support PKCS#12 format certificates (.pfx, .p12) which contain both your certificate and private key in a single encrypted file. These are commonly issued by certificate authorities.

Is my private key safe?

Yes! All processing happens entirely in your browser. Your certificate, private key, and PDF files never leave your device or get uploaded to any server.

Will the signature be valid in PDF readers?

Yes, the tool creates standard PKCS#7 detached signatures that are recognized by all major PDF viewers. For full validation, use a certificate from a trusted Certificate Authority.