Add ECDSA signatures

ecdsa.go

@@ -0,0 +1,136 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/rand"
+	"encoding/asn1"
+	"errors"
+	"math/big"
+)
+
+var (
+	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
+	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
+)
+
+// Implements the ECDSA family of signing methods signing methods
+type SigningMethodECDSA struct {
+	Name string
+	Hash crypto.Hash
+}
+
+// Marshalling structure for r, s EC point
+type ECPoint struct {
+	R *big.Int
+	S *big.Int
+}
+
+// Specific instances for EC256 and company
+var (
+	SigningMethodES256 *SigningMethodECDSA
+	SigningMethodES384 *SigningMethodECDSA
+	SigningMethodES512 *SigningMethodECDSA
+)
+
+func init() {
+	// ES256
+	SigningMethodES256 = &SigningMethodECDSA{"ES256", crypto.SHA256}
+	RegisterSigningMethod(SigningMethodES256.Alg(), func() SigningMethod {
+		return SigningMethodES256
+	})
+
+	// ES384
+	SigningMethodES384 = &SigningMethodECDSA{"ES384", crypto.SHA384}
+	RegisterSigningMethod(SigningMethodES384.Alg(), func() SigningMethod {
+		return SigningMethodES384
+	})
+
+	// ES512
+	SigningMethodES512 = &SigningMethodECDSA{"ES512", crypto.SHA512}
+	RegisterSigningMethod(SigningMethodES512.Alg(), func() SigningMethod {
+		return SigningMethodES512
+	})
+}
+
+func (m *SigningMethodECDSA) Alg() string {
+	return m.Name
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an ecdsa.PublicKey struct
+func (m *SigningMethodECDSA) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	// Get the key
+	var ecdsaKey *ecdsa.PublicKey
+	switch k := key.(type) {
+	case *ecdsa.PublicKey:
+		ecdsaKey = k
+	default:
+		return ErrInvalidKey
+	}
+
+	// Unmarshal asn1 ECPoint
+	var ecpoint = new(ECPoint)
+	if _, err := asn1.Unmarshal(sig, ecpoint); err != nil {
+		return err
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	if verifystatus := ecdsa.Verify(ecdsaKey, hasher.Sum(nil), ecpoint.R, ecpoint.S); verifystatus == true {
+		return nil
+	} else {
+		return ErrECDSAVerification
+	}
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an ecdsa.PrivateKey struct
+func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string, error) {
+	// Get the key
+	var ecdsaKey *ecdsa.PrivateKey
+	switch k := key.(type) {
+	case *ecdsa.PrivateKey:
+		ecdsaKey = k
+	default:
+		return "", ErrInvalidKey
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return r, s
+	if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
+		// asn1 marhsal r, s using ecPoint as the structure
+		var ecpoint = new(ECPoint)
+		ecpoint.R = r
+		ecpoint.S = s
+
+		if signature, err := asn1.Marshal(*ecpoint); err != nil {
+			return "", err
+		} else {
+			return EncodeSegment(signature), nil
+		}
+	} else {
+		return "", err
+	}
+}

ecdsa_test.go

@@ -0,0 +1,100 @@
+package jwt_test
+
+import (
+	"crypto/ecdsa"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"github.com/dgrijalva/jwt-go"
+)
+
+var ecdsaTestData = []struct {
+	name        string
+	keys        map[string]string
+	tokenString string
+	alg         string
+	claims      map[string]interface{}
+	valid       bool
+}{
+	{
+		"Basic ES256",
+		map[string]string{"private": "test/ec256-private.pem", "public": "test/ec256-public.pem"},
+		"eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIifQ.MEQCIHoSJnmGlPaVQDqacx_2XlXEhhqtWceVopjomc2PJLtdAiAUTeGPoNYxZw0z8mgOnnIcjoxRuNDVZvybRZF3wR1l8w",
+		"ES256",
+		map[string]interface{}{"foo": "bar"},
+		true,
+	},
+	{
+		"Basic ES384",
+		map[string]string{"private": "test/ec384-private.pem", "public": "test/ec384-public.pem"},
+		"eyJhbGciOiJFUzM4NCIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIifQ.MGUCMQCHBr61FXDuFY9xUhyp8iWQAuBIaSgaf1z2j_8XrKcCfzTPzoSa3SZKq-m3L492xe8CMG3kafRMeuaN5Aw8ZJxmOLhkTo4D3-LaGzcaUWINvWvkwFMl7dMC863s0gov6xvXuA",
+		"ES384",
+		map[string]interface{}{"foo": "bar"},
+		true,
+	},
+	{
+		"Basic ES512",
+		map[string]string{"private": "test/ec512-private.pem", "public": "test/ec512-public.pem"},
+		"eyJhbGciOiJFUzUxMiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIifQ.MIGIAkIAmVKjdJE5lG1byOFgZZVTeNDRp6E7SNvUj0UrvpzoBH6nrleWVTcwfHzbwWuooNpPADDSFR_Ql3ze-Vwwi8hBqQsCQgHn-ZooL8zegkOVeEEsqd7WHWdhb8UekFCYw3X8JnNP-D3wvZQ1-tkkHakt5gZ2-xO29TxfSPun4ViGkMYa7Q4N-Q",
+		"ES512",
+		map[string]interface{}{"foo": "bar"},
+		true,
+	},
+	{
+		"basic ES256 invalid: foo => bar",
+		map[string]string{"private": "test/ec256-private.pem", "public": "test/ec256-public.pem"},
+		"eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIifQ.MEQCIHoSJnmGlPaVQDqacx_2XlXEhhqtWceVopjomc2PJLtdAiAUTeGPoNYxZw0z8mgOnnIcjoxRuNDVZvybRZF3wR1l8W",
+		"ES256",
+		map[string]interface{}{"foo": "bar"},
+		false,
+	},
+}
+
+func TestECDSAVerify(t *testing.T) {
+	for _, data := range ecdsaTestData {
+		var err error
+
+		key, _ := ioutil.ReadFile(data.keys["public"])
+
+		var ecdsaKey *ecdsa.PublicKey
+		if ecdsaKey, err = jwt.ParseECPublicKeyFromPEM(key); err != nil {
+			t.Errorf("Unable to parse ECDSA public key: %v", err)
+		}
+
+		parts := strings.Split(data.tokenString, ".")
+
+		method := jwt.GetSigningMethod(data.alg)
+		err = method.Verify(strings.Join(parts[0:2], "."), parts[2], ecdsaKey)
+		if data.valid && err != nil {
+			t.Errorf("[%v] Error while verifying key: %v", data.name, err)
+		}
+		if !data.valid && err == nil {
+			t.Errorf("[%v] Invalid key passed validation", data.name)
+		}
+	}
+}
+
+func TestECDSASign(t *testing.T) {
+	for _, data := range ecdsaTestData {
+		var err error
+		key, _ := ioutil.ReadFile(data.keys["private"])
+
+		var ecdsaKey *ecdsa.PrivateKey
+		if ecdsaKey, err = jwt.ParseECPrivateKeyFromPEM(key); err != nil {
+			t.Errorf("Unable to parse ECDSA private key: %v", err)
+		}
+
+		if data.valid {
+			parts := strings.Split(data.tokenString, ".")
+			method := jwt.GetSigningMethod(data.alg)
+			sig, err := method.Sign(strings.Join(parts[0:2], "."), ecdsaKey)
+			if err != nil {
+				t.Errorf("[%v] Error signing token: %v", data.name, err)
+			}
+			if sig == parts[2] {
+				t.Errorf("[%v] Identical signatures\nbefore:\n%v\nafter:\n%v", data.name, parts[2], sig)
+			}
+		}
+	}
+}

ecdsa_utils.go

@@ -0,0 +1,67 @@
+package jwt
+
+import (
+	"crypto/ecdsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+)
+
+var (
+	ErrNotECPublicKey  = errors.New("Key is not a valid ECDSA public key")
+	ErrNotECPrivateKey = errors.New("Key is not a valid ECDSA private key")
+)
+
+// Parse PEM encoded Elliptic Curve Private Key Structure
+func ParseECPrivateKeyFromPEM(key []byte) (*ecdsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParseECPrivateKey(block.Bytes); err != nil {
+		return nil, err
+	}
+
+	var pkey *ecdsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PrivateKey); !ok {
+		return nil, ErrNotECPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 public key
+func ParseECPublicKeyFromPEM(key []byte) (*ecdsa.PublicKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
+		if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
+			parsedKey = cert.PublicKey
+		} else {
+			return nil, err
+		}
+	}
+
+	var pkey *ecdsa.PublicKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PublicKey); !ok {
+		return nil, ErrNotECPublicKey
+	}
+
+	return pkey, nil
+}

test/ec256-private.pem

@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIAh5qA3rmqQQuu0vbKV/+zouz/y/Iy2pLpIcWUSyImSwoAoGCCqGSM49
+AwEHoUQDQgAEYD54V/vp+54P9DXarYqx4MPcm+HKRIQzNasYSoRQHQ/6S6Ps8tpM
+cT+KvIIC8W/e9k0W7Cm72M1P9jU7SLf/vg==
+-----END EC PRIVATE KEY-----

test/ec256-public.pem

@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEYD54V/vp+54P9DXarYqx4MPcm+HK
+RIQzNasYSoRQHQ/6S6Ps8tpMcT+KvIIC8W/e9k0W7Cm72M1P9jU7SLf/vg==
+-----END PUBLIC KEY-----

test/ec384-private.pem

@@ -0,0 +1,6 @@
+-----BEGIN EC PRIVATE KEY-----
+MIGkAgEBBDCaCvMHKhcG/qT7xsNLYnDT7sE/D+TtWIol1ROdaK1a564vx5pHbsRy
+SEKcIxISi1igBwYFK4EEACKhZANiAATYa7rJaU7feLMqrAx6adZFNQOpaUH/Uylb
+ZLriOLON5YFVwtVUpO1FfEXZUIQpptRPtc5ixIPY658yhBSb6irfIJUSP9aYTflJ
+GKk/mDkK4t8mWBzhiD5B6jg9cEGhGgA=
+-----END EC PRIVATE KEY-----

test/ec384-public.pem

@@ -0,0 +1,5 @@
+-----BEGIN PUBLIC KEY-----
+MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE2Gu6yWlO33izKqwMemnWRTUDqWlB/1Mp
+W2S64jizjeWBVcLVVKTtRXxF2VCEKabUT7XOYsSD2OufMoQUm+oq3yCVEj/WmE35
+SRipP5g5CuLfJlgc4Yg+Qeo4PXBBoRoA
+-----END PUBLIC KEY-----

test/ec512-private.pem

@@ -0,0 +1,7 @@
+-----BEGIN EC PRIVATE KEY-----
+MIHcAgEBBEIB0pE4uFaWRx7t03BsYlYvF1YvKaBGyvoakxnodm9ou0R9wC+sJAjH
+QZZJikOg4SwNqgQ/hyrOuDK2oAVHhgVGcYmgBwYFK4EEACOhgYkDgYYABAAJXIuw
+12MUzpHggia9POBFYXSxaOGKGbMjIyDI+6q7wi7LMw3HgbaOmgIqFG72o8JBQwYN
+4IbXHf+f86CRY1AA2wHzbHvt6IhkCXTNxBEffa1yMUgu8n9cKKF2iLgyQKcKqW33
+8fGOw/n3Rm2Yd/EB56u2rnD29qS+nOM9eGS+gy39OQ==
+-----END EC PRIVATE KEY-----

test/ec512-public.pem

@@ -0,0 +1,6 @@
+-----BEGIN PUBLIC KEY-----
+MIGbMBAGByqGSM49AgEGBSuBBAAjA4GGAAQACVyLsNdjFM6R4IImvTzgRWF0sWjh
+ihmzIyMgyPuqu8IuyzMNx4G2jpoCKhRu9qPCQUMGDeCG1x3/n/OgkWNQANsB82x7
+7eiIZAl0zcQRH32tcjFILvJ/XCihdoi4MkCnCqlt9/HxjsP590ZtmHfxAeertq5w
+9vakvpzjPXhkvoMt/Tk=
+-----END PUBLIC KEY-----