Mivia Sign 1.0 · DCT spread-spectrum · 20-byte envelope
Mivia Sign writes a cryptographic watermark directly into the DCT coefficients of your audio. Inaudible. Robust to re-encoding, pitch-shift, tempo-change, and crop. Timestamp-anchored to Bitcoin.
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01 / 07
A typical 3-minute stereo track at 48 kHz is ~8.6 million samples per channel. Mivia Sign processes it at its native rate as a stream of independent frames — 4,096 samples each, about 85 ms of audio per frame.
02 / 07
Every frame carries the full 20-byte payload independently, soft-combined across frames by the LDPC decoder at verify time. That's why even aggressively cropped audio still verifies — any surviving slice of the file is a fresh chance to recover the signature.
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The frame goes through a discrete cosine transform, splitting it into 2,048 frequency coefficients. A psychoacoustic model computes a Schroeder+Terhardt masking threshold for the frame — the loudest noise the ear can't hear given what's already playing. The watermark hides below that curve.
04 / 07
A BLAKE3-derived master key generates a Walsh-Hadamard spread-spectrum carrier for every frame. Every bit of the 560-bit LDPC codeword projects onto hundreds of coefficients simultaneously, weighted by each bin's perceptual headroom. Without the key an attacker can't locate any single bit — it's smeared across the spectrum.
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Each coefficient is modulated with tiny additions to its log-magnitude, weighted by the masking threshold — tonal bins get a tighter safety margin than noise-like bins. Peak spectral distortion lands around −60 dBFS: confirmed inaudible on dense mixes in producer A/B listening.
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The 20 bytes in every frame: a magic byte, the algorithm version, a 4-byte issuer fingerprint, an 8-byte content hash pointing at the full manifest in the content-addressed store, a nonce, and a CRC. Expanded to 70 bytes with LDPC(560, 160); the soft-decision decoder pools carrier correlations across every surviving frame, recovering the envelope well past the per-frame error rate that would break a hard-decision BCH scheme.
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WAV / FLAC / AIFF round-trip at the same sample rate and bit depth with sample-level fidelity. MP3 round-trips at the source bitrate via a single quality-bounded re-encode — same container, same frame count, same listening experience. Nothing about the file's identity changes, except that it now carries your signature.
~−60 dBFS
Peak distortion
Inaudible on any consumer playback system. Held below the Schroeder+Terhardt masking threshold of the signal — tonal bins get a wider margin than noise bins.
20 bytes
Payload per frame
Magic, version, issuer, contract hash, nonce, CRC. Every frame carries the complete signature.
4 formats
Supported inputs
WAV · FLAC · AIFF · MP3. Lossless round-trips are sample-exact; MP3 signs via a single quality-bounded re-encode at the source bitrate.
LDPC
Error-correction headroom
Soft-decision LDPC(560, 160) recovers the signature under heavy re-encoding, noise, pitch-shift, tempo change, and crop — where BCH would have given up.
BTC
Timestamp anchoring
OpenTimestamps proof registered at sign time. Independently verifiable proof-of-existence backed by Bitcoin consensus.
1.0
Frozen forever
The Mivia Sign 1.0 algorithm bundle is locked via CI-gated constants. Every signed file works forever — future versions coexist, never supersede.
Create a free account and start signing. WAV, FLAC, AIFF, and MP3 supported out of the box.
Prefer to sign inside your DAW? AU / VST3, coming soon