Simple tool to produce digital signatures using the secp256k1 library.
To produce a keypair, start with a 32-byte hex-encoded private key. To get the corresponding public key run
sighacker publickey <hex-encoded secret key>
To sign a message using a hex-encoded private key, simply run the tool as
sighacker sign <secret key> 'This is my message'
which will output a hex-encoded signature. To verify the signature, given a hex-encoded public key, type
sighacker verify <public key> <signature> 'This is my message'
However, SigHacker is capable of more interesting things. In particular it can produce sign-to-contract signatures, which commit to some extra data. To do this run
sighacker signtocontract <secret key> <hex-encoded commitment> <message>
The output will be two lines. The first is the hex-encoded signature, and the
second is the hex-encoded original nonce. You can verify a commitment with
nonce N by computing N' = sha256(N || commitment) and checking that the
result is used in the signature.