In both work and personal life, we constantly share important files through messaging apps — contracts, financial statements, medical records, identity documents, and more. Yet most messaging platforms don't provide genuine end-to-end encryption for file transfers. This means your sensitive files could be read by servers, intercepted by hackers, or accessed by insiders. SafeW's encrypted file transfer ensures that every file is end-to-end encrypted from the moment it leaves your device until it arrives on the recipient's — no one else can open these files. Haven't installed SafeW yet? Start with the Installation Guide.
How to Send Encrypted Files
SafeW's file transfer feature is designed for simplicity. The entire encryption process happens automatically in the background — you interact with it just like sending any regular attachment.
Sending Files in One-on-One Chats
Step-by-Step Instructions
- Open the chat conversation with your recipient
- Tap the attachment button (📎 icon) to the left of the message input field
- Choose the file source: Gallery, Camera, Documents, or File Manager
- Select the file(s) you want to send (multi-select is supported)
- Optionally add a text caption or description
- Tap the send button — the file is automatically encrypted and sent
During the upload, you'll see a progress bar. The file is first encrypted on your device, then uploaded to the server as ciphertext, and finally downloaded and decrypted by the recipient's device. The entire process is transparent to you — just operate normally and SafeW handles all the cryptographic work behind the scenes.
Sending Files in Group Chats
Group file transfers are equally protected with end-to-end encryption. The process is identical to one-on-one chats — tap the attachment button in the group chat, select your files, and send. Each file is individually encrypted for every group member, ensuring only group participants can download and view the contents.
Supported File Types and Sizes
| File Type | Supported Formats | Max Size |
|---|---|---|
| Documents | PDF, DOC, DOCX, XLS, XLSX, PPT, TXT | 500MB |
| Images | JPG, PNG, GIF, WEBP, HEIC, BMP | 500MB |
| Videos | MP4, MOV, AVI, MKV, WEBM | 500MB |
| Audio | MP3, WAV, AAC, OGG, FLAC | 500MB |
| Archives | ZIP, RAR, 7Z, TAR.GZ | 500MB |
| Other | Any file format | 500MB |
How File Encryption Works Under the Hood
Understanding how SafeW encrypts your files helps you appreciate why this approach is fundamentally more secure than traditional file sharing methods.
The Encryption Process Explained
- Local Encryption: The file is encrypted on your device using the AES-256 symmetric encryption algorithm. AES-256 is the strongest symmetric encryption standard available, certified by the U.S. National Security Agency (NSA) for protecting top-secret classified information
- Key Generation: Each file uses a unique, randomly generated encryption key derived through the Signal Protocol's Double Ratchet algorithm. Even when the same person sends multiple files, every file has a completely different key
- Key Exchange: The file's encryption key is securely transmitted to the recipient through the already-established end-to-end encrypted channel
- Encrypted Upload: The encrypted file (ciphertext) is uploaded to SafeW's server. The server only sees an unreadable blob of encrypted data
- Encrypted Download: The recipient downloads the ciphertext from the server
- Local Decryption: The recipient's device uses the corresponding key to decrypt the file locally, restoring the original content
Comparison with Traditional File Transfer Methods
| Transfer Method | Encryption Type | Server Readable? | Interception Risk |
|---|---|---|---|
| Email Attachments | ⚠️ TLS | Yes | Medium-High |
| Cloud Storage Links | ⚠️ TLS | Yes | Medium-High |
| Standard Messengers | ⚠️ TLS | Yes | Medium |
| SafeW File Transfer | ✅ E2EE | No | Extremely Low |
Advanced File Transfer Features
Disappearing Files
For particularly sensitive files, you can send them in a conversation with disappearing messages enabled. After the recipient views the file, it automatically deletes from both devices within the configured timeframe:
- Send files normally in a conversation where disappearing messages are already enabled
- Files auto-delete according to the conversation's disappearing message timer
- Once deleted, files cannot be recovered
- Ideal for sending temporary passwords, verification code screenshots, or sensitive contracts
File Forwarding Protection
SafeW lets you restrict the recipient's ability to forward files:
- Enable "Prevent Forwarding" to block recipients from sharing files with others
- Combined with screenshot protection, this creates a robust defense against file content leaks
- Particularly useful for highly confidential business documents
Batch File Transfer
Need to send multiple files at once? SafeW supports batch selection and sending:
How to Send Multiple Files
- Tap the attachment button
- Long-press the first file in the file picker to enter multi-select mode
- Check all the files you want to send
- Tap send — all files are encrypted and uploaded sequentially
File Transfer Security Best Practices
Verify Identity Before Sending: Before sharing sensitive files, verify the recipient's identity using safety number verification to guard against man-in-the-middle attacks.
Use Disappearing Messages for Temporary Files: For passwords, verification codes, and other temporary information, use short-duration disappearing messages.
Compress Large Files First: Compressing large files before sending saves transfer time and reduces storage usage on both ends.
Regularly Clean Up Received Files: Periodically delete sensitive files from your device to minimize data exposure risk.
Prefer Trusted Networks: While SafeW's file transfer is end-to-end encrypted, using trusted networks (rather than public WiFi) adds an additional layer of metadata protection.
Important Notes
Storage Space: Received files occupy local device storage. Ensure your device has sufficient space before receiving large files.
Network Conditions: Large file transfers require a stable network connection. If a transfer is interrupted, SafeW supports resumable uploads and downloads.
File Retention Period: Files not downloaded by the recipient are retained on the server for approximately 30 days (in encrypted form). After expiration, files must be resent.
Want to learn more about SafeW's encryption technology? Read What Is End-to-End Encryption? Need to transfer files securely in groups? Check out the Group Encrypted Chat Guide. Also see our Privacy Tips and Online Privacy Protection Checklist.