VoiceSign

The first open-source voice signature tool for individuals.

VoiceSign lets you embed an inaudible cryptographic watermark into any voice recording, binding it to your identity. Later, anyone can verify that a recording was signed by you. The watermark survives common audio transformations and is imperceptible to the human ear (target SNR: 42-46 dB).

Created by Eliot Cohen Bacrie, Founder and CEO of Oravys Inc.

Web version available at voicesign.eu

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Why VoiceSign?

In a world of voice cloning and audio deepfakes, proving that a voice recording is genuinely yours matters. VoiceSign gives individuals a simple, free tool to:

• Sign your voice memos, podcasts, or recordings with your identity
• Verify that a recording was signed by a specific person
• Prove provenance of your original audio content
• Protect yourself against voice impersonation and unauthorized use

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Install

pip install voicesign

Dependencies: numpy. For non-WAV audio formats (MP3, FLAC, M4A), you also need ffmpeg installed on your system.

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Quick Start

Python API

import voicesign

# Read your audio file
with open("my_recording.wav", "rb") as f:
    audio = f.read()

# Sign it with your identity
signed = voicesign.sign(audio, identity="Alice Johnson", salt="my-secret-salt")

# Save the signed version
with open("signed_recording.wav", "wb") as f:
    f.write(signed)

# Later, verify it
with open("signed_recording.wav", "rb") as f:
    audio = f.read()

result = voicesign.verify(audio, identity="Alice Johnson", salt="my-secret-salt")

print(result["detected"])     # True
print(result["confidence"])   # 0.95 (95% confidence)
print(result["correlation"])  # 0.87

Command Line

# Sign a recording
voicesign sign -i "Alice Johnson" -s "my-secret" recording.wav

# Output: recording_signed.wav

# Verify a recording
voicesign verify -i "Alice Johnson" -s "my-secret" recording_signed.wav

# Output: MATCH - Voice signature detected for: Alice Johnson
#         Confidence: 95.23%

Custom output path

voicesign sign -i "Alice Johnson" -s "my-secret" -o output.wav input.wav

Non-WAV formats (requires ffmpeg)

voicesign sign -i "Alice Johnson" podcast.mp3
voicesign verify -i "Alice Johnson" podcast_signed.wav

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How It Works

VoiceSign uses spread-spectrum audio watermarking in the frequency domain:

1. Seed derivation - A SHA-256 hash of your salt + identity produces a deterministic seed.
2. PN sequence generation - A pseudo-random noise (PN) sequence of +1/-1 values is generated from the seed.
3. Frequency-domain embedding - The audio is split into 100ms segments. For each segment, the PN sequence is added to the real part of the FFT coefficients in the 2-6 kHz band at low amplitude.
4. Detection - Pearson correlation between the expected PN sequence and the actual frequency coefficients. High correlation = signature present.

The watermark is:

• Inaudible - Embedded at ~42-46 dB SNR, below human perception
• Robust - Survives format conversion, mild compression, and noise
• Deterministic - Same identity + salt always produces the same watermark
• Lightweight - Pure numpy, no ML models, runs instantly on any machine

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API Reference

voicesign.sign(audio_bytes, identity, salt=None, file_format="wav")

Embed an identity watermark into audio.

Parameter	Type	Description
audio_bytes	bytes	Raw audio file content
identity	str	Identity string to bind (name, email, etc.)
salt	str or None	Secret salt for watermark generation
file_format	str	Input format: wav, mp3, flac, m4a

Returns: bytes - Watermarked audio as 16-bit mono WAV.

voicesign.verify(audio_bytes, identity, salt=None, file_format="wav")

Check whether audio contains a watermark for a given identity.

Parameter	Type	Description
audio_bytes	bytes	Raw audio file content
identity	str	Identity string to check against
salt	str or None	Must match the salt used during signing
file_format	str	Input format: wav, mp3, flac, m4a

Returns: dict with keys:

• detected (bool) - Whether a matching watermark was found
• confidence (float) - Confidence score between 0 and 1
• correlation (float) - Raw Pearson correlation value
• identity_match (str) - The identity string tested

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Security Notes

• Salt matters. Anyone who knows your salt and identity can forge your watermark. Keep your salt private.
• Not tamper-proof. A determined adversary who knows the algorithm and your salt can remove or overwrite the watermark. VoiceSign provides provenance, not DRM.
• Use unique salts. Different salts for different contexts (personal, professional, etc.) prevent cross-context tracking.

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Attribution

VoiceSign is created by Eliot Cohen Bacrie and powered by Oravys Inc.

If you use VoiceSign in your project, please include attribution:

Powered by Oravys Inc., created by Eliot Cohen Bacrie

See the NOTICE file for full attribution requirements.

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Web Version

For a no-install experience, use the web version at:

voicesign.eu

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License

Apache 2.0 with attribution requirements. See LICENSE and NOTICE.

Copyright 2024-2026 Oravys Inc.

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Powered by Oravys Inc. - Voice Intelligence