func (t *AssetManagementChaincode) isCaller(stub *shim.ChaincodeStub, certificate []byte) (bool, error) {
// In order to enforce access control, we require that the
// metadata contains the signature under the signing key corresponding
// to the verification key inside certificate of
// the payload of the transaction (namely, function name and args) and
// the transaction binding (to avoid copying attacks)
// Verify \sigma=Sign(certificate.sk, tx.Payload||tx.Binding) against certificate.vk
// \sigma is in the metadata
sigma, err := stub.GetCallerMetadata()
if err != nil {
return false, errors.New("Failed getting metadata")
}
payload, err := stub.GetPayload()
if err != nil {
return false, errors.New("Failed getting payload")
}
binding, err := stub.GetBinding()
if err != nil {
return false, errors.New("Failed getting binding")
}
myLogger.Debug("passed certificate [% x]", certificate)
myLogger.Debug("passed sigma [% x]", sigma)
myLogger.Debug("passed payload [% x]", payload)
myLogger.Debug("passed binding [% x]", binding)
return stub.VerifySignature(
certificate,
sigma,
append(payload, binding...),
)
}