ThinkForU PDF Encryption Checker
Upload PDF to Check Encryption
Drop your PDF here
or click to select from your device
PDF never leaves your device · 100% private · No signup
—
Encrypted
—
Algorithm
—
Key Length
—
Open Password
—
Owner Password
—
PDF Version
Encryption Details
Encryption status
—
Algorithm
—
Key length
—
Security handler
—
Handler revision
—
Open (user) password
—
Owner password
—
Metadata encrypted
—
PDF version
—
File size
—
Page count
—
Security & Compliance Assessment
—
—
PDF Encryption Methods
Strong
AES-256 (PDF 1.7 / 2.0)
NSA-approved, used by governments & banks. Recommended for all sensitive documents. No known practical attacks.
Moderate
AES-128 (PDF 1.6)
Adequate for most uses. No known practical breaks, but 256-bit is preferred for long-term security.
Weak
RC4-128 (PDF 1.4–1.5)
Known cryptographic weaknesses. Deprecated in modern security standards. Upgrade if possible.
Broken
RC4-40 (PDF 1.1–1.3)
Considered broken. A 40-bit key can be brute-forced in seconds with modern hardware. Do not use for sensitive content.
None
No Encryption
No encryption applied. Content is fully accessible to anyone with the file. Add AES-256 for sensitive documents.
100% Private
- PDF never uploaded to any server
- Powered by pdf-lib — runs in your browser
- Read-only — does not modify your PDF
- No signup · No limits · 100% free
Free PDF Utilities Suite
Free & No Login Required | Zero Data Storage
📁
PDF Merger
Combine multiple PDF documents into a single file easily.
🖼️
Image to PDF Converter
Convert your photos and pictures into high-quality PDF files.
📸
PDF to Image Converter
Extract pictures and convert PDF pages into image formats.
💎
PNG to PDF Converter
Convert transparent PNG graphics into clean PDF layouts.
📝
PDF to Text Extractor
Extract text scripts directly from your PDF files online.
🖼️
JPG to PDF Converter
Batch convert JPG photographs into single PDF packages.
✂️
Split PDF Online
Separate and extract individual page sets from a large PDF.
🔢
Add PDF Page Numbers
Insert custom dynamic pagination numbers to your PDF pages.
🛡️
Add PDF Watermark
Protect documents by stamping secure watermarks onto your PDF.
🌐
HTML to PDF Converter
Render complete web pages or raw HTML files straight to PDF.
🕵️
PDF Metadata Remover
Wipe hidden author records, titles, and tags from any PDF.
🔤
Text to PDF Converter
Convert raw notepad text scripts or strings into clean PDF layout.
📉
PDF Compressor
Reduce overall file sizes while keeping clean layout PDF views.
🖼️
PDF to JPG Converter
Transform individual file layouts into high-res JPG PDF frames.
🔄
Rotate PDF Online
Flip upside-down pages or sideways views within your PDF.
👁️
PDF Viewer Online
Read and inspect structured pages inside a 100% private PDF viewer.
🍏
HEIC to PDF Converter
Convert Apple HEIC photos directly into standard ready-to-print PDF.
🔚
PDF Font Finder
Identify and inspect precise typography types used inside any PDF.
📊
PDF Sentence Counter
Analyze metric counts and fetch true sentence counts in a PDF file.
📊
PDF Table Extractor
Pull structured table information or datasheet grids from your PDF.
ℹ️
PDF Version Checker
Determine version parameters and format standards of any PDF asset.
📐
PDF to SVG Converter
Convert layouts into scalable vector graphics from high-res PDF.
🔍
PDF Image DPI Checker
Check resolution densities and pixel metrics inside embedded PDF elements.
⏱️
PDF Reading Time Estimator
Estimate total read length requirements across document text inside PDF.
🔤
PDF Character Counter
Run precise metrics tracking space allocations and letters in a PDF.
🔓
PDF Permission Checker
Verify printing, content modification, and copying access within a PDF.
Free PDF Encryption Checker — Check PDF Security Strength & Algorithm Online
Not all PDF encryption is equal. A PDF encrypted with RC4-40 from 2001 can be cracked in seconds. A PDF with AES-256 meets government-grade security standards. Before sharing sensitive documents — contracts, financial records, medical files, legal briefs — you should know exactly what encryption is protecting them. This tool reads the raw encryption metadata from your PDF using pdf-lib in your browser and gives you an instant security strength rating with actionable compliance guidance. Your file never leaves your device.
Security Strength Rating
Four-level rating: Strong (AES-256), Moderate (AES-128), Weak (RC4-128), Broken (RC4-40 / No encryption). Visual strength meter.
Algorithm & Key Length
Detects RC4 40/128-bit and AES 128/256-bit encryption. Shows exact key length and security handler revision.
Password Status
Detects whether a user (open) password and/or owner (permissions) password is set — critical for compliance audits.
Compliance Assessment
Checks against HIPAA, GDPR, NIST, and ISO 27001 guidance — flags whether your encryption meets standard requirements.
Actionable Next Steps
Clear guidance on what to do — whether to upgrade encryption, add a password, or confirm your document is properly secured.
100% Private
pdf-lib reads the encryption metadata locally in your browser. The file never touches any server — safe for confidential documents.
Who Needs a PDF Encryption Checker?
- Compliance officers: Audit PDF documents to verify they meet HIPAA, GDPR, or internal security policies before distribution. Confirm that patient records, financial statements, and legal contracts use approved encryption standards.
- Legal professionals: Verify that confidential case files, contracts, and court submissions received from other parties have appropriate encryption before storing or forwarding them.
- IT security teams: Audit PDF documents across an organisation to identify files using deprecated RC4 encryption that need to be re-secured with modern AES-256.
- Healthcare providers: Check that medical records, test results, and patient reports exported as PDFs are encrypted to AES-128 or AES-256 as required by HIPAA technical safeguards.
- Financial institutions: Verify that statements, reports, and client documents use encryption standards that meet PCI-DSS and SOC 2 requirements.
- Document creators: Test that a PDF exported from Word, Adobe Acrobat, InDesign, or any other tool actually has the encryption settings you intended before sending it to a client.
Frequently Asked Questions
What is the strongest PDF encryption available?
AES-256 (Advanced Encryption Standard with a 256-bit key) is the strongest PDF encryption available. It is used in PDF 1.7 (with the Extensions dictionary) and PDF 2.0, approved by NIST, and is the same encryption used by governments and financial institutions for classified data. The NSA has approved AES-192 and AES-256 for top-secret information. No practical attack on AES-256 is currently known. For sensitive documents, always use AES-256 when possible.
Can a PDF be encrypted without requiring a password to open?
Yes — this is a widely misunderstood feature of PDF security. A PDF creator can set an empty string as the user (open) password, so the file opens without prompting for a password. At the same time, a secret owner password enforces restrictions (no printing, no copying, etc.). The file is genuinely encrypted — the content is scrambled — but the user password is empty so PDF viewers open it automatically. This tool detects this scenario and reports it clearly.
Why is RC4 considered weak or broken?
RC4 is a stream cipher from 1987 with multiple known cryptographic weaknesses discovered since the 1990s. RC4-40 (used in early PDFs) uses only a 40-bit key, which can be brute-forced in seconds on modern hardware. RC4-128 is stronger but still has statistical biases that can be exploited. RC4 was officially deprecated in PDF 2.0 (ISO 32000-2) and should not be used for any document requiring real security. AES replaced it as the PDF encryption standard from PDF 1.6 (2004) onwards.
Is my PDF uploaded to a server?
Never. This tool uses pdf-lib — an open-source JavaScript library — to parse the PDF's raw bytes and read the encryption dictionary entirely within your browser. Nothing is transmitted to any server. This makes it safe to use on highly confidential documents: classified reports, medical records, legal contracts, and financial statements. See our Zero Data Storage Policy.
What does "metadata encrypted" mean?
PDF metadata includes document title, author, subject, creator application, and creation date stored in the XMP metadata stream. When "metadata encrypted" is Yes, this information is also scrambled along with the document content — a third party cannot read the author or title without the password. When No, the metadata remains readable even if the document content is encrypted. For maximum privacy on sensitive documents, metadata encryption should be enabled. This is controlled by the /EncryptMetadata flag in the PDF encryption dictionary.
How do I add AES-256 encryption to a PDF?
AES-256 encryption can be added using Adobe Acrobat (File → Properties → Security → Password Security, select Compatibility: Acrobat X or later for AES-256), Foxit PDF Editor, PDF-XChange Editor, or online tools like Smallpdf and iLovePDF. In LibreOffice, export as PDF and enable the "Encrypt the PDF document" option. Note: this tool only checks existing encryption — it does not add encryption. Use a PDF editor to apply protection.