all: support route scoped sessions

Signed-off-by: Bobby DeSimone <bobbydesimone@gmail.com>

internal/cryptutil/certificates.go

@@ -1,9 +1,12 @@
 package cryptutil // import "github.com/pomerium/pomerium/internal/cryptutil"
 
 import (
+	"crypto/ecdsa"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/base64"
+	"encoding/pem"
+	"errors"
 	"fmt"
 	"io/ioutil"
 )
@@ -49,3 +52,80 @@ func bytesToCertPool(b []byte) (*x509.CertPool, error) {
 	}
 	return certPool, nil
 }
+
+// DecodePublicKey decodes a PEM-encoded ECDSA public key.
+func DecodePublicKey(encodedKey []byte) (*ecdsa.PublicKey, error) {
+	block, _ := pem.Decode(encodedKey)
+	if block == nil {
+		return nil, fmt.Errorf("cryptutil: decoded nil PEM block")
+	}
+	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
+	if err != nil {
+		return nil, err
+	}
+
+	ecdsaPub, ok := pub.(*ecdsa.PublicKey)
+	if !ok {
+		return nil, errors.New("cryptutil: data was not an ECDSA public key")
+	}
+
+	return ecdsaPub, nil
+}
+
+// EncodePublicKey encodes an ECDSA public key to PEM format.
+func EncodePublicKey(key *ecdsa.PublicKey) ([]byte, error) {
+	derBytes, err := x509.MarshalPKIXPublicKey(key)
+	if err != nil {
+		return nil, err
+	}
+
+	block := &pem.Block{
+		Type:  "PUBLIC KEY",
+		Bytes: derBytes,
+	}
+
+	return pem.EncodeToMemory(block), nil
+}
+
+// DecodePrivateKey decodes a PEM-encoded ECDSA private key.
+func DecodePrivateKey(encodedKey []byte) (*ecdsa.PrivateKey, error) {
+	var skippedTypes []string
+	var block *pem.Block
+
+	for {
+		block, encodedKey = pem.Decode(encodedKey)
+
+		if block == nil {
+			return nil, fmt.Errorf("cryptutil: failed to find EC PRIVATE KEY in PEM data after skipping types %v", skippedTypes)
+		}
+
+		if block.Type == "EC PRIVATE KEY" {
+			break
+		} else {
+			skippedTypes = append(skippedTypes, block.Type)
+			continue
+		}
+	}
+
+	privKey, err := x509.ParseECPrivateKey(block.Bytes)
+	if err != nil {
+		return nil, err
+	}
+
+	return privKey, nil
+}
+
+// EncodePrivateKey encodes an ECDSA private key to PEM format.
+func EncodePrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
+	derKey, err := x509.MarshalECPrivateKey(key)
+	if err != nil {
+		return nil, err
+	}
+
+	keyBlock := &pem.Block{
+		Type:  "EC PRIVATE KEY",
+		Bytes: derKey,
+	}
+
+	return pem.EncodeToMemory(keyBlock), nil
+}