LedgerAssets, the developer of an app called Uproov that timestamps photos on bitcoin's blockchain, has announced it is to launch an application for phone calls.

Called Call Recorder Blockchain, the app can be set to record users' phone calls in the background, automatically saving proof that that call was made at a certain point in time.

John Bulich, co-founder of Uproov and its Australia-based parent firm LedgerAssets, said:

Bulich framed the service as a way to provide evidence following misunderstandings in phone conversations with companies or individuals.

He further suggested that current standard call recording apps have had millions of downloads, but, as their recordings are vulnerable to editing, their utility may be in doubt.

"Uproov takes it to a whole new level. It's impossible to change any part of the recording as its 'key' is written into the blockchain, which is of course immutable," he said.

To use the app to log a call, the recording mode must be switched to 'on' and every call will be saved, either locally on the device or, if desired, by uploading it to the firm's servers.

Once created, the audio file is hashed and a unique key created from it which is written into the blockchain. No information about the call or the user can be determined from the data stored on the blockchain, the firm says.

In future, if the user needs to verify the call recording is still in its original state, the recording can be hashed again using the same standard algorithms, which will produce the identical key for that audio file – providing no changes have been made.

Bulich said:

The app could be invaluable if a user ever needed to rely on the audio files in a legal dispute, he suggested. Although he did concede that the legal status of evidence recorded on the blockchain does not yet have precedent since the technology is so new.

The new app will be launched "in the next few days" for Android devices, said Bulich. Meanwhile, the call logging feature is already functional in the Android version of the Uproov app.

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