// CompareExpiryUbiquity ranks two certificate chains based on the exiry dates of intermediates and roots.
// Certs expire later are ranked higher than ones expire earlier. The ranking between chains are determined by
// the first pair of intermediates, scanned from the root level, that ar ranked differently.
func CompareExpiryUbiquity(chain1, chain2 []*x509.Certificate) int {
for i := 0; ; i++ {
if i >= len(chain1) || i >= len(chain2) {
break
}
c1 := chain1[len(chain1)-1-i]
c2 := chain2[len(chain2)-1-i]
t1 := &c1.NotAfter
t2 := &c2.NotAfter
// Check if expiry dates valid. Return if one or other is invalid.
// Otherwise rank by expiry date. Later is ranked higher.
c1Valid := helpers.ValidExpiry(c1)
c2Valid := helpers.ValidExpiry(c2)
if c1Valid && !c2Valid {
return 1
}
if !c1Valid && c2Valid {
return -1
}
r := compareTime(t1, t2)
// Return when we find rank difference.
if r != 0 {
return r
}
}
return 0
}
func chainValidation(addr, hostname string) (grade Grade, output Output, err error) {
chain, err := getChain(addr, defaultTLSConfig(hostname))
if err != nil {
return
}
var warnings []string
for i := 0; i < len(chain)-1; i++ {
cert, parent := chain[i], chain[i+1]
valid := helpers.ValidExpiry(cert)
if !valid {
warnings = append(warnings, fmt.Sprintf("Certificate for %s is valid for too long", cert.Subject.CommonName))
}
revoked, ok := revoke.VerifyCertificate(cert)
if !ok {
warnings = append(warnings, fmt.Sprintf("couldn't check if %s is revoked", cert.Subject.CommonName))
}
if revoked {
err = fmt.Errorf("%s is revoked", cert.Subject.CommonName)
return
}
if !parent.IsCA {
err = fmt.Errorf("%s is not a CA", parent.Subject.CommonName)
return
}
if !bytes.Equal(cert.AuthorityKeyId, parent.SubjectKeyId) {
err = fmt.Errorf("%s AuthorityKeyId differs from %s SubjectKeyId", cert.Subject.CommonName, parent.Subject.CommonName)
return
}
if err = cert.CheckSignatureFrom(parent); err != nil {
return
}
switch cert.SignatureAlgorithm {
case x509.ECDSAWithSHA1:
warnings = append(warnings, fmt.Sprintf("%s is signed by ECDSAWithSHA1", cert.Subject.CommonName))
case x509.SHA1WithRSA:
warnings = append(warnings, fmt.Sprintf("%s is signed by RSAWithSHA1", cert.Subject.CommonName))
}
}
if len(warnings) == 0 {
grade = Good
} else {
grade = Warning
output = warnings
}
return
}
