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. Two sub-modes are exposed in the app: a telephony-grade Basic profile that even passes through a voice call, and an Ultrasonic profile above the limit of adult hearing.
Strong points
- Basic profile passes cleanly through any voice channel, including a Telegram or WhatsApp voice note, a regular phone call, and even a legacy landline. Every voice codec was designed to carry these tones.
- Ultrasonic profile is inaudible to the people in the room and rides at the upper edge of adult hearing.
- Same-room range of roughly a few metres for Basic and 30 cm to about 1 m for Ultrasonic.
Trade-offs
- Short-message oriented, not a file transport. Throughput is around 5 to 8 bytes per second on Basic and 10 to 15 bytes per second on Ultrasonic.
- Ultrasonic needs modern broadband speakers and microphones on both ends. Older budget phones whose audio response rolls off below 17 kilohertz cannot carry the signal.
When to useSame room, harsh acoustic environments, over a regular phone call when no other channel is available, or whenever the two people cannot see each other but can still hear or be heard.
Modes inside this channel
- BasicB
A telephony-grade profile carried on eight tones drawn from the classic DTMF row and column frequencies (697, 770, 852 and 941 hertz crossed with 1209, 1336, 1477 and 1633 hertz). Sixteen symbols per cycle, twenty-five symbols per second, heavy Reed-Solomon RS(15,9) parity. Effective throughput is about 5 to 8 bytes per second after error correction. A short plain-text message arrives in 10 to 15 seconds and survives a normal voice call.
+ Survives any voice codec, including phone calls- Audible: sounds like a brief telephony tone burst - UltrasonicU
A multi-tone carrier in the inaudible 17 to 19 kilohertz band, twenty symbols per second, around 10 to 15 bytes per second of throughput. A 5-character message arrives in about three seconds, a 50-character one in about six. Range sits between 30 cm and roughly 1 m and does not cross the room. Hearing-safe, comparable in level to ordinary music.
+ Inaudible to people in the room- Requires modern broadband audio hardware on both phones
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
Two user-visible sub-modes are exposed in the app: a telephony-grade Basic profile and an inaudible Ultrasonic profile.
| Sub-mode | Carrier | Throughput | Effective range | Audible? | Best for |
|---|---|---|---|---|---|
| Basic (DTMF-class) | Eight tones, 697 / 770 / 852 / 941 Hz rows crossed with 1209 / 1336 / 1477 / 1633 Hz columns. Sixteen symbols, twenty-five symbols per second, Reed-Solomon RS(15,9) parity. | ~5 to 8 bytes per second after error correction. 10 to 15 seconds for a 5 to 50 character message. | Up to a few metres in a quiet room. Also survives a normal phone call or a Telegram / WhatsApp / Bale / Soroush voice note. | Yes (telephony tone burst) | Same-room transfers, harsh acoustic environments, transmission over a voice call, situations where the parties cannot see each other. |
| Ultrasonic | Multi-tone carrier in the inaudible 17 to 19 kilohertz band. Twenty symbols per second. | ~10 to 15 bytes per second. About 3 seconds for a 5-character message, about 6 seconds for 50 characters. | 30 cm to roughly 1 m. Does not carry beyond the room. | No (above adult hearing range) | Same-room transfers where modern audio hardware is present on both phones and an inaudible transmission is preferred. |
Values measured with the standard speaker and microphone of a current-generation mobile device at one metre under indoor conditions. Real-world performance varies with room acoustics, speaker quality and microphone response.
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.