Please run:
helm repo add ygdrassil https://sergiofernandezcordero.github.io/ygdrassil/
To verify packages signature just download and install my GPG key:
gpg --keyserver keyserver.ubuntu.com --recv-keys e3e2ffdb10aa04f4f5bfc3ddba423683c442d8f6
Then you can both verify the package signature and integrity bith fetching it or installing it:
helm fetch --verify ygdrassil/_package_
helm install --verify myservice ygdrassil/_package_