Seems that we have one problem
The signature operation uses basically the same cryptographic algorithms from Nano, using Ed25519 and Blake2. If you don’t trust in theses algorithms you are intrinsically say that Nano isn’t secure. The explanation about Nanofy are detailed here. However, we can simply the explanation, the hash of the file, or any arbitrary data, is used as the destination of the block and the next following block have one specific address as destination. It makes possible to verify that the user already signs the content, also everyone can watch just one address.
We already have the OpenPGP that are capable to sign one arbitrary data. However, the key holder can change the data and create new valid signature of that, the verifier can't notice any problem, since the signature matches with the new file. The Nanofy fix this problem making possible to track all the signatures issued by the key holder. If you sign a new file the old one still alive. It’s very useful when we need to ensure that no previous data was changed.
It’s more about time than money, but time is money. The Nanofy itself is free, also the Nano can be considered free. If you have 0.000001 XRB, which is less than 0.001 USD, you are capable to make 500 quadrillions of signatures, this is more than enough for most use cases. The bottleneck is the proof of work needed for each block, that task usually takes one second per block and uses all the power of your device during the computation, consequently increasing the power consumption. In other side, the verification is also free and very fast, thanks to the Ed25519.
"Here we stand, healing what we thought would forever be broken."