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How to Share Large Files Securely Over the Internet

· 3 min read file-sharingsecuritycloud-storageencryption

Email attachment limits cap out around 25 MB, and consumer file-transfer sites often leave links open to anyone who stumbles across them. Sharing large files securely comes down to three controls: encrypt the transfer, restrict who can open the link, and make access expire. Whether you are sending a client a 4 GB video or handing tax documents to an accountant, this guide gives you options at different trust levels.

What you need

  • The file(s) to send and their total size
  • A cloud storage account with link sharing (Google Drive, Dropbox, OneDrive) or a dedicated service (Signal, Tresorit, wormhole/cp, Firefox Send successors like SendGB or Filemail)
  • For high-sensitivity files: 7-Zip, Cryptomator, or age for pre-upload encryption
  • The recipient's email address or Signal number

Step by step

  1. Classify the content. Public marketing video? Convenience matters most. Contracts, medical records, financials? Encryption and access control matter most. This decides which tier below you use.
  2. For everyday large files, upload to your cloud drive, right-click, choose Share, and set the link to restricted access — specific people must sign in to view. Never use "anyone with the link" for anything private.
  3. Set an expiration date on the share (Dropbox and OneDrive support this natively; on Google Drive use the Apps Script or third-party expiry tools). Thirty days suits most business needs.
  4. Disable download permission only when the recipient merely needs to view; accept that determined users can always re-record or screenshot, so treat "view only" as friction, not security.
  5. For maximum sensitivity, encrypt before sending: create an encrypted 7z archive with AES-256 in 7-Zip, or run age -o file.age -r <recipient-key> file for key-based encryption. Send the passphrase through a different channel than the file — text them the code while emailing the archive.
  6. Alternatively use Signal or WhatsApp direct send for files up to their size caps (100 MB / 2 GB): messages are end-to-end encrypted automatically with zero setup.
  7. Verify receipt, then revoke the link. Deleting the share after confirmation closes the exposure window entirely.
  8. Log what you sent, to whom, and when the link dies — future audits and incident responses depend on this record.

Common mistakes

  • Emailing the passphrase with the encrypted archive. Split channels or the encryption is theater.
  • Leaving "anyone with the link" enabled indefinitely on old shares. Audit your shared-with-anyone lists quarterly in Drive and Dropbox settings.
  • Using public Wi-Fi without HTTPS links — always confirm the URL starts with https before uploading.

Related guides

Pre-upload encryption deserves its own walkthrough: [[encrypt-files-before-upload]] compares Cryptomator, 7-Zip, and age in detail. Expiring shares pair well with retention habits from [[setup-3-2-1-backup-rule]], and if the recipient reports a corrupted or conflicted file, [[prevent-cloud-sync-conflicts]] and [[recover-file-version-history]] cover the likely causes and fixes.

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