add support for ECDSA private keys

fixes #158

crypto/proof_source.go

@@ -0,0 +1,97 @@
+package crypto
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/tls"
+	"errors"
+	"strings"
+)
+
+// proofSource stores a key and a certificate for the server proof
+type proofSource struct {
+	config *tls.Config
+}
+
+// NewProofSource loads the key and cert from files
+func NewProofSource(tlsConfig *tls.Config) (Signer, error) {
+	return &proofSource{config: tlsConfig}, nil
+}
+
+// SignServerProof signs CHLO and server config for use in the server proof
+func (ps *proofSource) SignServerProof(sni string, chlo []byte, serverConfigData []byte) ([]byte, error) {
+	cert, err := ps.getCertForSNI(sni)
+	if err != nil {
+		return nil, err
+	}
+
+	hash := sha256.New()
+	if len(chlo) > 0 {
+		hash.Write([]byte("QUIC CHLO and server config signature\x00"))
+		chloHash := sha256.Sum256(chlo)
+		hash.Write([]byte{32, 0, 0, 0})
+		hash.Write(chloHash[:])
+	} else {
+		// TODO: Remove when we drop support for version 30
+		hash.Write([]byte("QUIC server config signature\x00"))
+	}
+	hash.Write(serverConfigData)
+
+	key, ok := cert.PrivateKey.(crypto.Signer)
+	if !ok {
+		return nil, errors.New("expected PrivateKey to implement crypto.Signer")
+	}
+
+	opts := crypto.SignerOpts(crypto.SHA256)
+
+	if _, ok = key.(*rsa.PrivateKey); ok {
+		opts = &rsa.PSSOptions{SaltLength: 32, Hash: crypto.SHA256}
+	}
+
+	return key.Sign(rand.Reader, hash.Sum(nil), opts)
+}
+
+// GetCertsCompressed gets the certificate in the format described by the QUIC crypto doc
+func (ps *proofSource) GetCertsCompressed(sni string, pCommonSetHashes, pCachedHashes []byte) ([]byte, error) {
+	cert, err := ps.getCertForSNI(sni)
+	if err != nil {
+		return nil, err
+	}
+	return compressChain(cert.Certificate, pCommonSetHashes, pCachedHashes)
+}
+
+// GetLeafCert gets the leaf certificate
+func (ps *proofSource) GetLeafCert(sni string) ([]byte, error) {
+	cert, err := ps.getCertForSNI(sni)
+	if err != nil {
+		return nil, err
+	}
+	return cert.Certificate[0], nil
+}
+
+func (ps *proofSource) getCertForSNI(sni string) (*tls.Certificate, error) {
+	if ps.config.GetCertificate != nil {
+		cert, err := ps.config.GetCertificate(&tls.ClientHelloInfo{ServerName: sni})
+		if err != nil {
+			return nil, err
+		}
+		if cert != nil {
+			return cert, nil
+		}
+	}
+	if len(ps.config.NameToCertificate) != 0 {
+		if cert, ok := ps.config.NameToCertificate[sni]; ok {
+			return cert, nil
+		}
+		wildcardSNI := "*" + strings.TrimLeftFunc(sni, func(r rune) bool { return r != '.' })
+		if cert, ok := ps.config.NameToCertificate[wildcardSNI]; ok {
+			return cert, nil
+		}
+	}
+	if len(ps.config.Certificates) != 0 {
+		return &ps.config.Certificates[0], nil
+	}
+	return nil, errors.New("no matching certificate found")
+}