(Concurrently Secure) Blind Schnorr from Schnorr

ePrint Report: (Concurrently Secure) Blind Schnorr from Schnorr

Georg Fuchsbauer, Mathias Wolf

Many applications of blind signatures, such as those for blockchains, require the resulting signatures to be compatible with the existing system. This makes schemes that produce Schnorr signatures, which are now supported by major cryptocurrencies, including Bitcoin, desirable. Unfortunately, the existing blind-signing protocol has been shown insecure when users can open signing sessions concurrently (Eurocrypt'21). On the other hand, only allowing sequential sessions opens the door to denial-of-service …

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