https://www.semanticscholar.org/paper/Everything-you-Never-Wanted-to-Know-about-PKI-but-Gutmann-Garcia/ba8778b725273ed2475be18cd27a251575083a71 https://pdfs.semanticscholar.org/ba87/78b725273ed2475be18cd27a251575083a71.pdf Bonus — from line #700 on: https://github.com/golang/go/blob/master/src/crypto/x509/verify.go#L700 ±0¢