Hello, I'm implementing a security daemon on the vehicular communication scope. I could receive a message with a signature and the compressed X coordinate of a point to verify that signature. The elliptic curve can be either the secp256 or the brainpoolp256r1 and the algorithm is ECDSA.
My question is: how can I recover the ECC Point (and so the public key) given only the compressed X coordinate? I followed some links which explain it (and many others) https://www.cryptopp.com/wiki/Point_Compression https://stackoverflow.com/questions/16576434/crypto-and-compressed-ec-keys but they don't fit my problem. I tried to produce code to resolve the problem (https://pastebin.com/JFLxuW1X) but it doesn't work. Can you help me please? -- You received this message because you are subscribed to "Crypto++ Users". More information about Crypto++ and this group is available at http://www.cryptopp.com and http://groups.google.com/forum/#!forum/cryptopp-users. --- You received this message because you are subscribed to the Google Groups "Crypto++ Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
