hpke: compress query string (#4147)

* hpke: compress query string

* only use v2 in authenticate if v2 was used for the initial request

* fix comment

authenticate/handlers.go

@@ -218,7 +218,12 @@ func (a *Authenticate) SignIn(w http.ResponseWriter, r *http.Request) error {
 
 	a.logAuthenticateEvent(r, profile)
 
-	redirectTo, err := urlutil.CallbackURL(state.hpkePrivateKey, proxyPublicKey, requestParams, profile)
+	encryptURLValues := hpke.EncryptURLValuesV1
+	if hpke.IsEncryptedURLV2(r.Form) {
+		encryptURLValues = hpke.EncryptURLValuesV2
+	}
+
+	redirectTo, err := urlutil.CallbackURL(state.hpkePrivateKey, proxyPublicKey, requestParams, profile, encryptURLValues)
 	if err != nil {
 		return httputil.NewError(http.StatusInternalServerError, err)
 	}

go.mod

@@ -156,7 +156,7 @@ require (
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
 	github.com/jackc/pgx/v5 v5.3.1
-	github.com/klauspost/compress v1.16.0 // indirect
+	github.com/klauspost/compress v1.16.0
 	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
 	github.com/libdns/libdns v0.2.1 // indirect
 	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect

internal/urlutil/known.go

@@ -40,6 +40,7 @@ func CallbackURL(
 	proxyPublicKey *hpke.PublicKey,
 	requestParams url.Values,
 	profile *identity.Profile,
+	encryptURLValues hpke.EncryptURLValuesFunc,
 ) (string, error) {
 	redirectURL, err := ParseAndValidateURL(requestParams.Get(QueryRedirectURI))
 	if err != nil {
@@ -76,7 +77,7 @@ func CallbackURL(
 
 	BuildTimeParameters(callbackParams, signInExpiry)
 
-	callbackParams, err = hpke.EncryptURLValues(authenticatePrivateKey, proxyPublicKey, callbackParams)
+	callbackParams, err = encryptURLValues(authenticatePrivateKey, proxyPublicKey, callbackParams)
 	if err != nil {
 		return "", fmt.Errorf("error encrypting callback params: %w", err)
 	}
@@ -115,7 +116,7 @@ func SignInURL(
 	q.Set(QueryVersion, versionStr())
 	q.Set(QueryRequestUUID, uuid.NewString())
 	BuildTimeParameters(q, signInExpiry)
-	q, err := hpke.EncryptURLValues(senderPrivateKey, authenticatePublicKey, q)
+	q, err := hpke.EncryptURLValuesV2(senderPrivateKey, authenticatePublicKey, q)
 	if err != nil {
 		return "", err
 	}

internal/urlutil/known_test.go

@@ -23,7 +23,7 @@ func TestCallbackURL(t *testing.T) {
 		QueryRedirectURI: {"https://redirect.example.com"},
 	}, &identity.Profile{
 		ProviderId: "IDP-1",
-	})
+	}, hpke.EncryptURLValuesV1)
 	require.NoError(t, err)
 
 	signInURL, err := ParseAndValidateURL(rawSignInURL)

pkg/hpke/url.go

@@ -3,35 +3,76 @@ package hpke
 import (
 	"fmt"
 	"net/url"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 // URL Parameters
 const (
-	ParamSenderPublicKey = "pomerium_hpke_sender_pub"
+	paramSenderPublicKey = "pomerium_hpke_sender_pub"
-	ParamQuery           = "pomerium_hpke_query"
+	paramQuery           = "pomerium_hpke_query"
+
+	paramSenderPublicKeyV2 = "k"
+	paramQueryV2           = "q"
 )
 
 // IsEncryptedURL returns true if the url.Values contain an HPKE encrypted query.
 func IsEncryptedURL(values url.Values) bool {
-	return values.Has(ParamSenderPublicKey) && values.Has(ParamQuery)
+	return IsEncryptedURLV1(values) || IsEncryptedURLV2(values)
 }
 
-// EncryptURLValues encrypts URL values using the Seal method.
+// IsEncryptedURLV1 returns true if the url.Values contain a V1 HPKE encrypted query.
-func EncryptURLValues(
+func IsEncryptedURLV1(values url.Values) bool {
+	return values.Has(paramSenderPublicKey) && values.Has(paramQuery)
+}
+
+// IsEncryptedURLV2 returns true if the url.Values contains a V2 HPKE encrypted query.
+func IsEncryptedURLV2(values url.Values) bool {
+	return values.Has(paramSenderPublicKeyV2) && values.Has(paramQueryV2)
+}
+
+// An EncryptURLValuesFunc is a function that encrypts url values.
+type EncryptURLValuesFunc func(senderPrivateKey *PrivateKey, receiverPublicKey *PublicKey, values url.Values) (encrypted url.Values, err error)
+
+// EncryptURLValuesV1 encrypts URL values using the Seal method.
+func EncryptURLValuesV1(
 	senderPrivateKey *PrivateKey,
 	receiverPublicKey *PublicKey,
 	values url.Values,
 ) (encrypted url.Values, err error) {
 	values = withoutHPKEParams(values)
 
-	sealed, err := Seal(senderPrivateKey, receiverPublicKey, []byte(values.Encode()))
+	encoded := encodeQueryStringV1(values)
+
+	sealed, err := Seal(senderPrivateKey, receiverPublicKey, encoded)
 	if err != nil {
 		return nil, fmt.Errorf("hpke: failed to seal URL values %w", err)
 	}
 
 	return url.Values{
-		ParamSenderPublicKey: {senderPrivateKey.PublicKey().String()},
+		paramSenderPublicKey: {senderPrivateKey.PublicKey().String()},
-		ParamQuery:           {encode(sealed)},
+		paramQuery:           {encode(sealed)},
+	}, nil
+}
+
+// EncryptURLValuesV2 encrypts URL values using the Seal method and compresses the query string.
+func EncryptURLValuesV2(
+	senderPrivateKey *PrivateKey,
+	receiverPublicKey *PublicKey,
+	values url.Values,
+) (encrypted url.Values, err error) {
+	values = withoutHPKEParams(values)
+
+	encoded := encodeQueryStringV2(values)
+
+	sealed, err := Seal(senderPrivateKey, receiverPublicKey, encoded)
+	if err != nil {
+		return nil, fmt.Errorf("hpke: failed to seal URL values %w", err)
+	}
+
+	return url.Values{
+		paramSenderPublicKeyV2: {senderPrivateKey.PublicKey().String()},
+		paramQueryV2:           {encode(sealed)},
 	}, nil
 }
 
@@ -40,19 +81,15 @@ func DecryptURLValues(
 	receiverPrivateKey *PrivateKey,
 	encrypted url.Values,
 ) (senderPublicKey *PublicKey, values url.Values, err error) {
-	if !encrypted.Has(ParamSenderPublicKey) {
+	var decrypted url.Values
-		return nil, nil, fmt.Errorf("hpke: missing sender public key in query parameters")
+	switch {
-	}
+	case IsEncryptedURLV1(encrypted):
-	if !encrypted.Has(ParamQuery) {
+		senderPublicKey, err = PublicKeyFromString(encrypted.Get(paramSenderPublicKey))
-		return nil, nil, fmt.Errorf("hpke: missing encrypted query in query parameters")
-	}
-
-	senderPublicKey, err = PublicKeyFromString(encrypted.Get(ParamSenderPublicKey))
 		if err != nil {
 			return nil, nil, fmt.Errorf("hpke: invalid sender public key parameter: %w", err)
 		}
 
-	sealed, err := decode(encrypted.Get(ParamQuery))
+		sealed, err := decode(encrypted.Get(paramQuery))
 		if err != nil {
 			return nil, nil, fmt.Errorf("hpke: failed decoding query parameter: %w", err)
 		}
@@ -62,10 +99,33 @@ func DecryptURLValues(
 			return nil, nil, fmt.Errorf("hpke: failed to open sealed message: %w", err)
 		}
 
-	decrypted, err := url.ParseQuery(string(message))
+		decrypted, err = decodeQueryStringV1(message)
 		if err != nil {
 			return nil, nil, fmt.Errorf("hpke: invalid query parameter: %w", err)
 		}
+	case IsEncryptedURLV2(encrypted):
+		senderPublicKey, err = PublicKeyFromString(encrypted.Get(paramSenderPublicKeyV2))
+		if err != nil {
+			return nil, nil, fmt.Errorf("hpke: invalid sender public key parameter: %w", err)
+		}
+
+		sealed, err := decode(encrypted.Get(paramQueryV2))
+		if err != nil {
+			return nil, nil, fmt.Errorf("hpke: failed decoding query parameter: %w", err)
+		}
+
+		message, err := Open(receiverPrivateKey, senderPublicKey, sealed)
+		if err != nil {
+			return nil, nil, fmt.Errorf("hpke: failed to open sealed message: %w", err)
+		}
+
+		decrypted, err = decodeQueryStringV2(message)
+		if err != nil {
+			return nil, nil, fmt.Errorf("hpke: invalid query parameter: %w", err)
+		}
+	default:
+		return nil, nil, fmt.Errorf("hpke: missing query parameters")
+	}
 
 	values = withoutHPKEParams(encrypted)
 	for k, vs := range decrypted {
@@ -78,9 +138,33 @@ func DecryptURLValues(
 func withoutHPKEParams(values url.Values) url.Values {
 	filtered := make(url.Values)
 	for k, vs := range values {
-		if k != ParamSenderPublicKey && k != ParamQuery {
+		if k != paramSenderPublicKey && k != paramQuery && k != paramSenderPublicKeyV2 && k != paramQueryV2 {
 			filtered[k] = vs
 		}
 	}
 	return filtered
 }
+
+var zstdEncoder, _ = zstd.NewWriter(nil, zstd.WithEncoderLevel(zstd.SpeedBestCompression))
+
+func encodeQueryStringV1(values url.Values) []byte {
+	return []byte(values.Encode())
+}
+
+func encodeQueryStringV2(values url.Values) []byte {
+	return zstdEncoder.EncodeAll([]byte(values.Encode()), nil)
+}
+
+var zstdDecoder, _ = zstd.NewReader(nil)
+
+func decodeQueryStringV1(raw []byte) (url.Values, error) {
+	return url.ParseQuery(string(raw))
+}
+
+func decodeQueryStringV2(raw []byte) (url.Values, error) {
+	bs, err := zstdDecoder.DecodeAll(raw, nil)
+	if err != nil {
+		return nil, err
+	}
+	return url.ParseQuery(string(bs))
+}

pkg/hpke/url_test.go

@@ -2,6 +2,7 @@ package hpke
 
 import (
 	"net/url"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -9,18 +10,23 @@ import (
 )
 
 func TestEncryptURLValues(t *testing.T) {
+	t.Parallel()
+
 	k1, err := GeneratePrivateKey()
 	require.NoError(t, err)
 	k2, err := GeneratePrivateKey()
 	require.NoError(t, err)
 
-	encrypted, err := EncryptURLValues(k1, k2.PublicKey(), url.Values{
+	t.Run("v1", func(t *testing.T) {
+		t.Parallel()
+
+		encrypted, err := EncryptURLValuesV1(k1, k2.PublicKey(), url.Values{
 			"a": {"b", "c"},
 			"x": {"y", "z"},
 		})
 		assert.NoError(t, err)
-	assert.True(t, encrypted.Has(ParamSenderPublicKey))
+		assert.True(t, encrypted.Has(paramSenderPublicKey))
-	assert.True(t, encrypted.Has(ParamQuery))
+		assert.True(t, encrypted.Has(paramQuery))
 
 		assert.True(t, IsEncryptedURL(encrypted))
 
@@ -34,4 +40,40 @@ func TestEncryptURLValues(t *testing.T) {
 			"extra": {"value"},
 		}, decrypted)
 		assert.Equal(t, k1.PublicKey().String(), senderPublicKey.String())
+	})
+	t.Run("v2", func(t *testing.T) {
+		t.Parallel()
+
+		encrypted, err := EncryptURLValuesV2(k1, k2.PublicKey(), url.Values{
+			"a": {"b", "c"},
+			"x": {"y", "z"},
+		})
+		assert.NoError(t, err)
+		assert.True(t, encrypted.Has(paramSenderPublicKeyV2))
+		assert.True(t, encrypted.Has(paramQueryV2))
+
+		assert.True(t, IsEncryptedURL(encrypted))
+
+		encrypted.Set("extra", "value")
+		encrypted.Set("a", "notb")
+		senderPublicKey, decrypted, err := DecryptURLValues(k2, encrypted)
+		assert.NoError(t, err)
+		assert.Equal(t, url.Values{
+			"a":     {"b", "c"},
+			"x":     {"y", "z"},
+			"extra": {"value"},
+		}, decrypted)
+		assert.Equal(t, k1.PublicKey().String(), senderPublicKey.String())
+	})
+
+	t.Run("compresses", func(t *testing.T) {
+		t.Parallel()
+
+		encrypted, err := EncryptURLValuesV2(k1, k2.PublicKey(), url.Values{
+			"a": {strings.Repeat("b", 1024*128)},
+		})
+		assert.NoError(t, err)
+
+		assert.Less(t, len(encrypted.Encode()), 1024)
+	})
 }