以太坊椭圆曲线Specp256k1通过消息的hash和签名（对消息的hash的签名）来恢复出公钥和计算r值

源代码 https://github.com/ethereum/go-ethereum/blob/master/crypto/secp256k1/secp256.go 

// RecoverPubkey returns the the public key of the signer.

// msg must be the 32-byte hash of the message to be signed.

// sig must be a 65-byte compact ECDSA signature containing the

// recovery id as the last element.

RecoverPubkey(msg []byte, sig []byte)

其中”sig must be a 65-byte compact ECDSA signature containing the recovery id as the last element.“，说明了最后一个recovery id指的是 rG的x坐标。

 

 

。。。细节之后解释。