Sharing files securely requires protecting both content and metadata. Standard file sharing services log who uploads, who downloads, and what files contain. Secure file sharing uses encryption, anonymity tools, and careful practices to protect your privacy and recipient privacy.

File Sharing Threats

Content Exposure

Unencrypted files can be read by file hosting services, internet providers, and anyone intercepting traffic. Even "secure" commercial services often have access to stored files.

File content might reveal sensitive information, personal data, or confidential communications. Protecting this content is the primary security concern.

Metadata Leaks

File sharing creates metadata: who uploaded, when, who downloaded, IP addresses, file sizes, and names. This metadata reveals patterns even if content stays encrypted.

Services tracking metadata can link uploaders to downloaders, exposing relationships you might want private.

Identity Links

Most file sharing requires accounts linked to email, phone numbers, or payment information. This connects your real identity to file transfers.

OnionShare - Anonymous Sharing

How OnionShare Works

OnionShare creates temporary Tor hidden services from your computer. Recipients connect to your .onion address through Tor Browser and download files directly from you.

No third-party servers store files. No accounts required. No metadata logs. Files transfer directly between sender and receiver through Tor.

Installing OnionShare

Download from onionshare.org. Available for Windows, Mac, and Linux. Installation is straightforward - standard installer process.

Tails OS includes OnionShare by default. If using Tails, no installation needed.

Sharing Files

Open OnionShare, click "Share Files" tab, add files or folders you want to share. Click "Start Sharing" and OnionShare generates a .onion address.

Send this address to recipients through secure channel (Signal, encrypted email, etc.). They open it in Tor Browser and download your files.

OnionShare must stay running while recipients download. Once downloads complete, stop sharing to close the hidden service.

Receiving Files

OnionShare's "Receive Files" mode creates upload portals. Recipients can anonymously upload files to you through generated .onion address.

This enables anonymous file drops. Share the address, recipients upload files, you receive them with no identity linkage.

Advanced Features

OnionShare offers password protection for shared links. This prevents unauthorized access even if .onion address leaks.

Auto-stop timer closes sharing after specified time. This ensures you don't accidentally leave file shares running.

Persistent addresses let you use same .onion URL across sessions rather than generating new one each time.

Best Practice: Use OnionShare for sensitive file transfers requiring anonymity. Its temporary nature and direct transfer model provides excellent security for one-time shares.

Encrypted File Hosting

End-to-End Encrypted Services

Some cloud storage encrypts files client-side before upload. Services like Tresorit, Sync.com, or MEGA claim zero-knowledge encryption where providers can't access file content.

Files encrypt on your device. Only you have decryption keys. Services store encrypted blobs they can't read.

Limitations

End-to-end encryption protects content but not metadata. Services still know who uploads, file sizes, access times, and sharing patterns.

Most require accounts with email or payment. This links identity to file activity even if content stays private.

You're trusting service claims about encryption. Closed-source services might have backdoors. Open-source alternatives provide more confidence.

Cryptomator

Cryptomator is open-source tool creating encrypted vaults in cloud storage. Works with Dropbox, Google Drive, or any cloud provider.

You encrypt files locally before they upload to cloud. Cloud service sees only encrypted data. You control encryption keys completely.

This provides end-to-end encryption with cloud services that don't natively support it.

Manual Encryption

GPG File Encryption

Encrypt files with GPG before uploading anywhere. Recipients decrypt with corresponding keys. This works with any file sharing service since files remain encrypted throughout.

Command line: gpg --encrypt --recipient [email protected] filename

Or use GUI tools like Kleopatra or GPG Suite providing point-and-click encryption.

Symmetric Encryption

For sharing with people without GPG setup, use symmetric encryption. You set password, recipients need that password to decrypt.

Share password through separate channel from encrypted file. Send file via email, share password via Signal or phone.

7-Zip with Passwords

7-Zip creates password-protected archives with AES-256 encryption. Simple alternative to GPG for basic encryption needs.

Right-click files, choose 7-Zip > Add to archive, set strong password. Share archive normally, share password securely.

Anonymous File Hosting

Temporary Upload Services

Services like Send (send.vis.ee) or PrivateBin provide temporary encrypted file hosting. Files auto-delete after download or time period.

Upload files, receive link, share link with recipient. File disappears after accessed or time expires. No accounts needed for basic use.

Dark Web File Hosting

Some dark web services offer anonymous file hosting through .onion addresses. These often require payment in cryptocurrency and provide various retention periods.

Research reputation carefully. Many dark web file hosts are scams or honeypots. Stick to established services with community verification.

IPFS

InterPlanetary File System provides decentralized file storage. Files upload to distributed network rather than single server.

IPFS offers content addressing - files identified by cryptographic hash of content rather than location. This enables permanent addressing and verification.

However, IPFS doesn't provide privacy by default. Encrypt files before IPFS upload for private sharing.

Secure Communication Channels

Signal for File Sharing

Signal supports end-to-end encrypted file sharing up to 100MB. Files transfer encrypted through Signal infrastructure.

This suits moderate-size files shared with existing Signal contacts. Easier than setting up OnionShare for small transfers.

Session Messenger

Session provides anonymous encrypted messaging with file sharing. No phone numbers required unlike Signal.

Better for anonymous file sharing with unknown parties. Based on Lokinet providing onion routing similar to Tor.

Best Practices

Encrypt Before Upload

Always encrypt sensitive files before uploading to any service. Don't trust service encryption alone - add your own layer.

Separate Channels

Share encrypted files through one channel, share decryption passwords through different channel. If one channel compromises, files remain protected.

Verify Recipients

Confirm recipient identity before sharing sensitive files. Attackers might impersonate contacts to receive confidential information.

Delete After Sharing

Remove files from hosting services after successful transfer. Don't leave files online permanently unless necessary.

Use Tor for Anonymity

Access file sharing services through Tor when anonymity matters. This hides your IP from services and any surveillance.

Critical Security: Filename metadata leaks information. Rename files to generic names before sharing if filenames contain sensitive information. "project_proposal_2026.docx" reveals more than "document.docx".

Large File Challenges

Size Limitations

OnionShare handles large files but requires keeping computer on during transfers. Tor connections are slower making very large transfers time-consuming.

Split large files into chunks. Share chunks separately or use tools like 7-Zip creating multi-volume archives.

Torrenting Anonymously

BitTorrent provides efficient large file distribution. For anonymous torrenting, use Tribler which integrates Tor-like anonymity.

Never torrent through regular Tor. This overloads network and leaks IP. Purpose-built tools like Tribler required.

Receiving Files Safely

Scan for Malware

Downloaded files might contain malware. Scan with antivirus before opening. Better yet, open in isolated environment like virtual machine.

Verify File Integrity

If sender provides file hash, verify received file matches. This confirms file wasn't corrupted or tampered during transfer.

Metadata Removal

Documents contain metadata revealing author, creation date, editing history. Use metadata removal tools before sharing documents to strip this information.

ExifTool removes metadata from most file types. MAT2 (Metadata Anonymisation Toolkit) provides GUI for metadata removal.

Legal Considerations

Secure file sharing itself is legal. Privacy is legitimate right. However, sharing copyrighted material, illegal content, or stolen data remains illegal regardless of encryption or anonymity.

Encrypted file sharing doesn't grant immunity from laws. It provides privacy, not legal protection for illegal acts.

Final Thoughts

Secure file sharing requires combining multiple techniques: encryption for content protection, anonymity tools for metadata protection, and good operational security throughout.

OnionShare excels for one-time anonymous transfers. Encrypted cloud storage works for ongoing file access. Manual encryption with GPG provides maximum control.

Choose methods matching your threat model and technical skill. Perfect security isn't necessary for every file transfer - match security level to sensitivity level.