Choose the channel that fits the situation.
Taftan covers same-room transfer, screen-to-camera transfer and concealment inside a messaging platform. Every channel applies encryption before sending.
Acoustic
Data over sound
The sending device plays a modulated audio signal through its speaker. The receiving device captures it through its microphone and reconstructs the message. Both devices use the standard speaker and microphone that come built into every phone. No Bluetooth pairing, Wi-Fi or SIM card involved. It works in basements, on planes and anywhere with no network signal, as long as both devices can hear each other.
Strong points
- Effective from close range up to about eight metres under normal indoor conditions.
- Eight selectable tiers across three mode families: audible, resilient and ultrasonic. Each tier balances throughput, noise tolerance and audibility for a specific environment.
- Automatically falls back to a more resilient tier when ambient noise is high.
Trade-offs
- Both devices need to be within hearing range of each other.
- Throughput is approximately 20 to 100 bytes per second depending on the mode. Not suitable for video or large files.
When to useTwo people in the same location. In-person meetings. Moving data between two devices. Any situation where nothing should travel over a wired or wireless network.
Modes inside this channel
- AudibleA
A modulated signal in the human-audible range (roughly 1.5 to 2.5 kHz). The highest throughput of the three modes. Best for quiet environments.
+ Highest throughput- Audible to anyone nearby - ResilientB
A lower-frequency signal with enhanced forward error correction. Designed for noisy places including traffic, background conversation and general ambient noise.
+ Noise-tolerant- Reduced throughput - UltrasonicC
A signal above the human hearing range (roughly 18 to 20 kHz). Nobody in the room can hear it. Throughput is equivalent to the audible mode.
+ Inaudible to humans- Speaker variation may reduce effective range
Four steps to move a message from one device to the other.
The process is the same for every transfer. Switching channels is a single tap.
Compose the message.
Plain text, a password, a recovery code or a file from device storage. The acoustic channel handles a few kilobytes; the optical channel handles larger files.
Choose a channel.
Acoustic, Optical or Steganographic. Taftan suggests the most appropriate option for the current context, but the choice is always yours.
Agree on a shared key.
Choose a typed passphrase, or use any file already on your device as the key. Share the passphrase in person, on paper, or by voice beforehand. If using a key file, both devices must have an identical copy. The key is the one element an observer cannot intercept.
Send. The other device decrypts.
Play the audio signal, show the screen or send the photograph. The receiving party points their device at the source or opens the photo in Taftan. The message comes through.
- 01
Compose the message.
Plain text, a password, a recovery code or a file from device storage. The acoustic channel handles a few kilobytes; the optical channel handles larger files.
- 02
Choose a channel.
Acoustic, Optical or Steganographic. Taftan suggests the most appropriate option for the current context, but the choice is always yours.
- 03
Agree on a shared key.
Choose a typed passphrase, or use any file already on your device as the key. Share the passphrase in person, on paper, or by voice beforehand. If using a key file, both devices must have an identical copy. The key is the one element an observer cannot intercept.
- 04
Send. The other device decrypts.
Play the audio signal, show the screen or send the photograph. The receiving party points their device at the source or opens the photo in Taftan. The message comes through.
Taftan runs without an account, without registration and without a server. Nothing in the app records who sent what to whom or when it was used.
Acoustic channel modes
Measured performance parameters for each acoustic channel mode.
| Tier | Type | Throughput | Effective range | Audible? | Recommended for |
|---|---|---|---|---|---|
| Voice-call resilient | Audible | Under 1 byte per second | Up to 8 m | Yes | Transmission through an active phone call or extreme acoustic interference |
| Voice-call standard | Audible | Approximately 2 bytes per second | Up to 8 m | Yes | Transmission through a phone call with moderate quality |
| Audible rugged | Audible | Under 1 byte per second | Up to 8 m | Yes | Extremely difficult acoustic environments where reliability matters more than speed |
| Audible long-range | Audible | Approximately 1 byte per second | Up to 8 m | Yes | Larger rooms where maximum range is needed |
| Audible balanced | Audible | Approximately 5 bytes per second | Up to 6 m | Yes | Standard indoor transfers |
| Audible quick | Audible | Approximately 15 bytes per second | Up to 4 m | Yes | Quiet environments where higher throughput is needed |
| Ultrasonic long-range | Ultrasonic | Approximately 1 byte per second | Up to 4 m | No | Silent environments requiring maximum range |
| Ultrasonic balanced | Ultrasonic | Approximately 5 bytes per second | Up to 3 m | No | Standard silent transfers: offices, libraries, secure meetings |
Values measured using standard mobile device speakers and microphones at one metre under indoor conditions. Real-world performance ranges from 50 to 100 per cent of these values depending on the acoustic environment.
Choose a channel that works with your messaging platform.
If you need to send through a messaging app, this table shows what each platform does to the attached file. Pick the row, column and mode accordingly.
OKTransmitted without modification. Use Silent mode.
LossyUse Robust mode. Capacity will be reduced.
NoSelect a different channel for this platform.
| Platform | Photo (default) | File / document | Voice note |
|---|---|---|---|
| Signal | OK | OK | Lossy |
| Telegram | Lossy | OK | Lossy |
| Lossy | OK | No | |
| Instagram DM | Lossy | n/a | No |
| iMessage | OK | OK | Lossy |
| OK | OK | OK |
Most messaging platforms re-encode voice notes, so the acoustic channel rarely survives transmission in voice note form. For those scenarios, send the audio as a file attachment or use the steganographic channel instead.
Two devices. One shared password. No intermediary.
Install Taftan on both devices, agree on the password through a separate channel beforehand, and run a quick test transfer using whichever channel fits your situation.