CC-796: Remove dependency on unsupported version of go-oidc

vendor/gopkg.in/square/go-jose.v2/jwk.go

@@ -17,15 +17,20 @@
 package jose
 
 import (
+	"bytes"
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/rsa"
+	"crypto/sha1"
+	"crypto/sha256"
 	"crypto/x509"
 	"encoding/base64"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"math/big"
+	"net/url"
 	"reflect"
 	"strings"
 
@@ -57,16 +62,31 @@ type rawJSONWebKey struct {
 	Dq *byteBuffer `json:"dq,omitempty"`
 	Qi *byteBuffer `json:"qi,omitempty"`
 	// Certificates
-	X5c []string `json:"x5c,omitempty"`
+	X5c       []string `json:"x5c,omitempty"`
+	X5u       *url.URL `json:"x5u,omitempty"`
+	X5tSHA1   string   `json:"x5t,omitempty"`
+	X5tSHA256 string   `json:"x5t#S256,omitempty"`
 }
 
 // JSONWebKey represents a public or private key in JWK format.
 type JSONWebKey struct {
-	Key          interface{}
+	// Cryptographic key, can be a symmetric or asymmetric key.
+	Key interface{}
+	// Key identifier, parsed from `kid` header.
+	KeyID string
+	// Key algorithm, parsed from `alg` header.
+	Algorithm string
+	// Key use, parsed from `use` header.
+	Use string
+
+	// X.509 certificate chain, parsed from `x5c` header.
 	Certificates []*x509.Certificate
-	KeyID        string
-	Algorithm    string
-	Use          string
+	// X.509 certificate URL, parsed from `x5u` header.
+	CertificatesURL *url.URL
+	// X.509 certificate thumbprint (SHA-1), parsed from `x5t` header.
+	CertificateThumbprintSHA1 []byte
+	// X.509 certificate thumbprint (SHA-256), parsed from `x5t#S256` header.
+	CertificateThumbprintSHA256 []byte
 }
 
 // MarshalJSON serializes the given key to its JSON representation.
@@ -105,6 +125,39 @@ func (k JSONWebKey) MarshalJSON() ([]byte, error) {
 		raw.X5c = append(raw.X5c, base64.StdEncoding.EncodeToString(cert.Raw))
 	}
 
+	x5tSHA1Len := len(k.CertificateThumbprintSHA1)
+	x5tSHA256Len := len(k.CertificateThumbprintSHA256)
+	if x5tSHA1Len > 0 {
+		if x5tSHA1Len != sha1.Size {
+			return nil, fmt.Errorf("square/go-jose: invalid SHA-1 thumbprint (must be %d bytes, not %d)", sha1.Size, x5tSHA1Len)
+		}
+		raw.X5tSHA1 = base64.RawURLEncoding.EncodeToString(k.CertificateThumbprintSHA1)
+	}
+	if x5tSHA256Len > 0 {
+		if x5tSHA256Len != sha256.Size {
+			return nil, fmt.Errorf("square/go-jose: invalid SHA-256 thumbprint (must be %d bytes, not %d)", sha256.Size, x5tSHA256Len)
+		}
+		raw.X5tSHA256 = base64.RawURLEncoding.EncodeToString(k.CertificateThumbprintSHA256)
+	}
+
+	// If cert chain is attached (as opposed to being behind a URL), check the
+	// keys thumbprints to make sure they match what is expected. This is to
+	// ensure we don't accidentally produce a JWK with semantically inconsistent
+	// data in the headers.
+	if len(k.Certificates) > 0 {
+		expectedSHA1 := sha1.Sum(k.Certificates[0].Raw)
+		expectedSHA256 := sha256.Sum256(k.Certificates[0].Raw)
+
+		if len(k.CertificateThumbprintSHA1) > 0 && !bytes.Equal(k.CertificateThumbprintSHA1, expectedSHA1[:]) {
+			return nil, errors.New("square/go-jose: invalid SHA-1 thumbprint, does not match cert chain")
+		}
+		if len(k.CertificateThumbprintSHA256) > 0 && !bytes.Equal(k.CertificateThumbprintSHA256, expectedSHA256[:]) {
+			return nil, errors.New("square/go-jose: invalid or SHA-256 thumbprint, does not match cert chain")
+		}
+	}
+
+	raw.X5u = k.CertificatesURL
+
 	return json.Marshal(raw)
 }
 
@@ -116,28 +169,61 @@ func (k *JSONWebKey) UnmarshalJSON(data []byte) (err error) {
 		return err
 	}
 
+	certs, err := parseCertificateChain(raw.X5c)
+	if err != nil {
+		return fmt.Errorf("square/go-jose: failed to unmarshal x5c field: %s", err)
+	}
+
 	var key interface{}
+	var certPub interface{}
+	var keyPub interface{}
+
+	if len(certs) > 0 {
+		// We need to check that leaf public key matches the key embedded in this
+		// JWK, as required by the standard (see RFC 7517, Section 4.7). Otherwise
+		// the JWK parsed could be semantically invalid. Technically, should also
+		// check key usage fields and other extensions on the cert here, but the
+		// standard doesn't exactly explain how they're supposed to map from the
+		// JWK representation to the X.509 extensions.
+		certPub = certs[0].PublicKey
+	}
+
 	switch raw.Kty {
 	case "EC":
 		if raw.D != nil {
 			key, err = raw.ecPrivateKey()
+			if err == nil {
+				keyPub = key.(*ecdsa.PrivateKey).Public()
+			}
 		} else {
 			key, err = raw.ecPublicKey()
+			keyPub = key
 		}
 	case "RSA":
 		if raw.D != nil {
 			key, err = raw.rsaPrivateKey()
+			if err == nil {
+				keyPub = key.(*rsa.PrivateKey).Public()
+			}
 		} else {
 			key, err = raw.rsaPublicKey()
+			keyPub = key
 		}
 	case "oct":
+		if certPub != nil {
+			return errors.New("square/go-jose: invalid JWK, found 'oct' (symmetric) key with cert chain")
+		}
 		key, err = raw.symmetricKey()
 	case "OKP":
 		if raw.Crv == "Ed25519" && raw.X != nil {
 			if raw.D != nil {
 				key, err = raw.edPrivateKey()
+				if err == nil {
+					keyPub = key.(ed25519.PrivateKey).Public()
+				}
 			} else {
 				key, err = raw.edPublicKey()
+				keyPub = key
 			}
 		} else {
 			err = fmt.Errorf("square/go-jose: unknown curve %s'", raw.Crv)
@@ -146,12 +232,78 @@ func (k *JSONWebKey) UnmarshalJSON(data []byte) (err error) {
 		err = fmt.Errorf("square/go-jose: unknown json web key type '%s'", raw.Kty)
 	}
 
-	if err == nil {
-		*k = JSONWebKey{Key: key, KeyID: raw.Kid, Algorithm: raw.Alg, Use: raw.Use}
+	if err != nil {
+		return
+	}
 
-		k.Certificates, err = parseCertificateChain(raw.X5c)
+	if certPub != nil && keyPub != nil {
+		if !reflect.DeepEqual(certPub, keyPub) {
+			return errors.New("square/go-jose: invalid JWK, public keys in key and x5c fields do not match")
+		}
+	}
+
+	*k = JSONWebKey{Key: key, KeyID: raw.Kid, Algorithm: raw.Alg, Use: raw.Use, Certificates: certs}
+
+	k.CertificatesURL = raw.X5u
+
+	// x5t parameters are base64url-encoded SHA thumbprints
+	// See RFC 7517, Section 4.8, https://tools.ietf.org/html/rfc7517#section-4.8
+	x5tSHA1bytes, err := base64.RawURLEncoding.DecodeString(raw.X5tSHA1)
+	if err != nil {
+		return errors.New("square/go-jose: invalid JWK, x5t header has invalid encoding")
+	}
+
+	// RFC 7517, Section 4.8 is ambiguous as to whether the digest output should be byte or hex,
+	// for this reason, after base64 decoding, if the size is sha1.Size it's likely that the value is a byte encoded
+	// checksum so we skip this. Otherwise if the checksum was hex encoded we expect a 40 byte sized array so we'll
+	// try to hex decode it. When Marshalling this value we'll always use a base64 encoded version of byte format checksum.
+	if len(x5tSHA1bytes) == 2*sha1.Size {
+		hx, err := hex.DecodeString(string(x5tSHA1bytes))
 		if err != nil {
-			return fmt.Errorf("failed to unmarshal x5c field: %s", err)
+			return fmt.Errorf("square/go-jose: invalid JWK, unable to hex decode x5t: %v", err)
+
+		}
+		x5tSHA1bytes = hx
+	}
+
+	k.CertificateThumbprintSHA1 = x5tSHA1bytes
+
+	x5tSHA256bytes, err := base64.RawURLEncoding.DecodeString(raw.X5tSHA256)
+	if err != nil {
+		return errors.New("square/go-jose: invalid JWK, x5t#S256 header has invalid encoding")
+	}
+
+	if len(x5tSHA256bytes) == 2*sha256.Size {
+		hx256, err := hex.DecodeString(string(x5tSHA256bytes))
+		if err != nil {
+			return fmt.Errorf("square/go-jose: invalid JWK, unable to hex decode x5t#S256: %v", err)
+		}
+		x5tSHA256bytes = hx256
+	}
+
+	k.CertificateThumbprintSHA256 = x5tSHA256bytes
+
+	x5tSHA1Len := len(k.CertificateThumbprintSHA1)
+	x5tSHA256Len := len(k.CertificateThumbprintSHA256)
+	if x5tSHA1Len > 0 && x5tSHA1Len != sha1.Size {
+		return errors.New("square/go-jose: invalid JWK, x5t header is of incorrect size")
+	}
+	if x5tSHA256Len > 0 && x5tSHA256Len != sha256.Size {
+		return errors.New("square/go-jose: invalid JWK, x5t#S256 header is of incorrect size")
+	}
+
+	// If certificate chain *and* thumbprints are set, verify correctness.
+	if len(k.Certificates) > 0 {
+		leaf := k.Certificates[0]
+		sha1sum := sha1.Sum(leaf.Raw)
+		sha256sum := sha256.Sum256(leaf.Raw)
+
+		if len(k.CertificateThumbprintSHA1) > 0 && !bytes.Equal(sha1sum[:], k.CertificateThumbprintSHA1) {
+			return errors.New("square/go-jose: invalid JWK, x5c thumbprint does not match x5t value")
+		}
+
+		if len(k.CertificateThumbprintSHA256) > 0 && !bytes.Equal(sha256sum[:], k.CertificateThumbprintSHA256) {
+			return errors.New("square/go-jose: invalid JWK, x5c thumbprint does not match x5t#S256 value")
 		}
 	}
 
@@ -180,7 +332,7 @@ func (s *JSONWebKeySet) Key(kid string) []JSONWebKey {
 
 const rsaThumbprintTemplate = `{"e":"%s","kty":"RSA","n":"%s"}`
 const ecThumbprintTemplate = `{"crv":"%s","kty":"EC","x":"%s","y":"%s"}`
-const edThumbprintTemplate = `{"crv":"%s","kty":"OKP",x":"%s"}`
+const edThumbprintTemplate = `{"crv":"%s","kty":"OKP","x":"%s"}`
 
 func ecThumbprintInput(curve elliptic.Curve, x, y *big.Int) (string, error) {
 	coordLength := curveSize(curve)
@@ -254,7 +406,7 @@ func (k *JSONWebKey) IsPublic() bool {
 	}
 }
 
-// Public creates JSONWebKey with corresponding publik key if JWK represents asymmetric private key.
+// Public creates JSONWebKey with corresponding public key if JWK represents asymmetric private key.
 func (k *JSONWebKey) Public() JSONWebKey {
 	if k.IsPublic() {
 		return *k