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crypto: move certificate verification into x509.

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People have a need to verify certificates in situations other than TLS
client handshaking. Thus this CL moves certificate verification into
x509 and expands its abilities.

R=bradfitzgo
CC=golang-dev
https://golang.org/cl/4407046
This commit is contained in:
Adam Langley 2011-04-19 09:57:58 -04:00
parent 5500f027f7
commit c24c6d8340
9 changed files with 738 additions and 130 deletions
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49
src/pkg/crypto/tls/handshake_client.go
View file

@ -88,7 +88,6 @@ func (c *Conn) clientHandshake() os.Error {
finishedHash.Write(certMsg.marshal())
certs := make([]*x509.Certificate, len(certMsg.certificates))
chain := NewCASet()
for i, asn1Data := range certMsg.certificates {
cert, err := x509.ParseCertificate(asn1Data)
if err != nil {
@ -96,47 +95,29 @@ func (c *Conn) clientHandshake() os.Error {
return os.ErrorString("failed to parse certificate from server: " + err.String())
}
certs[i] = cert
chain.AddCert(cert)
}
// If we don't have a root CA set configured then anything is accepted.
// TODO(rsc): Find certificates for OS X 10.6.
for cur := certs[0]; c.config.RootCAs != nil; {
parent := c.config.RootCAs.FindVerifiedParent(cur)
if parent != nil {
break
if c.config.RootCAs != nil {
opts := x509.VerifyOptions{
Roots: c.config.RootCAs,
CurrentTime: c.config.Time(),
DNSName: c.config.ServerName,
Intermediates: x509.NewCertPool(),
}
parent = chain.FindVerifiedParent(cur)
if parent == nil {
for i, cert := range certs {
if i == 0 {
continue
}
opts.Intermediates.AddCert(cert)
}
c.verifiedChains, err = certs[0].Verify(opts)
if err != nil {
c.sendAlert(alertBadCertificate)
return os.ErrorString("could not find root certificate for chain")
return err
}
if !parent.BasicConstraintsValid || !parent.IsCA {
c.sendAlert(alertBadCertificate)
return os.ErrorString("intermediate certificate does not have CA bit set")
}
// KeyUsage status flags are ignored. From Engineering
// Security, Peter Gutmann: A European government CA marked its
// signing certificates as being valid for encryption only, but
// no-one noticed. Another European CA marked its signature
// keys as not being valid for signatures. A different CA
// marked its own trusted root certificate as being invalid for
// certificate signing. Another national CA distributed a
// certificate to be used to encrypt data for the country’s tax
// authority that was marked as only being usable for digital
// signatures but not for encryption. Yet another CA reversed
// the order of the bit flags in the keyUsage due to confusion
// over encoding endianness, essentially setting a random
// keyUsage in certificates that it issued. Another CA created
// a self-invalidating certificate by adding a certificate
// policy statement stipulating that the certificate had to be
// used strictly as specified in the keyUsage, and a keyUsage
// containing a flag indicating that the RSA encryption key
// could only be used for Diffie-Hellman key agreement.
cur = parent
}
if _, ok := certs[0].PublicKey.(*rsa.PublicKey); !ok {