gotosocial/vendor/gopkg.in/square/go-jose.v2/jwk.go
Tobi Smethurst 98263a7de6
Grand test fixup (#138)
* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig
2021-08-12 21:03:24 +02:00

760 lines
21 KiB
Go

/*-
* Copyright 2014 Square Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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"
"golang.org/x/crypto/ed25519"
"gopkg.in/square/go-jose.v2/json"
)
// rawJSONWebKey represents a public or private key in JWK format, used for parsing/serializing.
type rawJSONWebKey struct {
Use string `json:"use,omitempty"`
Kty string `json:"kty,omitempty"`
Kid string `json:"kid,omitempty"`
Crv string `json:"crv,omitempty"`
Alg string `json:"alg,omitempty"`
K *byteBuffer `json:"k,omitempty"`
X *byteBuffer `json:"x,omitempty"`
Y *byteBuffer `json:"y,omitempty"`
N *byteBuffer `json:"n,omitempty"`
E *byteBuffer `json:"e,omitempty"`
// -- Following fields are only used for private keys --
// RSA uses D, P and Q, while ECDSA uses only D. Fields Dp, Dq, and Qi are
// completely optional. Therefore for RSA/ECDSA, D != nil is a contract that
// we have a private key whereas D == nil means we have only a public key.
D *byteBuffer `json:"d,omitempty"`
P *byteBuffer `json:"p,omitempty"`
Q *byteBuffer `json:"q,omitempty"`
Dp *byteBuffer `json:"dp,omitempty"`
Dq *byteBuffer `json:"dq,omitempty"`
Qi *byteBuffer `json:"qi,omitempty"`
// Certificates
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 {
// 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
// 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.
func (k JSONWebKey) MarshalJSON() ([]byte, error) {
var raw *rawJSONWebKey
var err error
switch key := k.Key.(type) {
case ed25519.PublicKey:
raw = fromEdPublicKey(key)
case *ecdsa.PublicKey:
raw, err = fromEcPublicKey(key)
case *rsa.PublicKey:
raw = fromRsaPublicKey(key)
case ed25519.PrivateKey:
raw, err = fromEdPrivateKey(key)
case *ecdsa.PrivateKey:
raw, err = fromEcPrivateKey(key)
case *rsa.PrivateKey:
raw, err = fromRsaPrivateKey(key)
case []byte:
raw, err = fromSymmetricKey(key)
default:
return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key))
}
if err != nil {
return nil, err
}
raw.Kid = k.KeyID
raw.Alg = k.Algorithm
raw.Use = k.Use
for _, cert := range k.Certificates {
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)
}
// UnmarshalJSON reads a key from its JSON representation.
func (k *JSONWebKey) UnmarshalJSON(data []byte) (err error) {
var raw rawJSONWebKey
err = json.Unmarshal(data, &raw)
if err != nil {
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)
}
default:
err = fmt.Errorf("square/go-jose: unknown json web key type '%s'", raw.Kty)
}
if err != nil {
return
}
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 to 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("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")
}
}
return
}
// JSONWebKeySet represents a JWK Set object.
type JSONWebKeySet struct {
Keys []JSONWebKey `json:"keys"`
}
// Key convenience method returns keys by key ID. Specification states
// that a JWK Set "SHOULD" use distinct key IDs, but allows for some
// cases where they are not distinct. Hence method returns a slice
// of JSONWebKeys.
func (s *JSONWebKeySet) Key(kid string) []JSONWebKey {
var keys []JSONWebKey
for _, key := range s.Keys {
if key.KeyID == kid {
keys = append(keys, key)
}
}
return keys
}
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"}`
func ecThumbprintInput(curve elliptic.Curve, x, y *big.Int) (string, error) {
coordLength := curveSize(curve)
crv, err := curveName(curve)
if err != nil {
return "", err
}
if len(x.Bytes()) > coordLength || len(y.Bytes()) > coordLength {
return "", errors.New("square/go-jose: invalid elliptic key (too large)")
}
return fmt.Sprintf(ecThumbprintTemplate, crv,
newFixedSizeBuffer(x.Bytes(), coordLength).base64(),
newFixedSizeBuffer(y.Bytes(), coordLength).base64()), nil
}
func rsaThumbprintInput(n *big.Int, e int) (string, error) {
return fmt.Sprintf(rsaThumbprintTemplate,
newBufferFromInt(uint64(e)).base64(),
newBuffer(n.Bytes()).base64()), nil
}
func edThumbprintInput(ed ed25519.PublicKey) (string, error) {
crv := "Ed25519"
if len(ed) > 32 {
return "", errors.New("square/go-jose: invalid elliptic key (too large)")
}
return fmt.Sprintf(edThumbprintTemplate, crv,
newFixedSizeBuffer(ed, 32).base64()), nil
}
// Thumbprint computes the JWK Thumbprint of a key using the
// indicated hash algorithm.
func (k *JSONWebKey) Thumbprint(hash crypto.Hash) ([]byte, error) {
var input string
var err error
switch key := k.Key.(type) {
case ed25519.PublicKey:
input, err = edThumbprintInput(key)
case *ecdsa.PublicKey:
input, err = ecThumbprintInput(key.Curve, key.X, key.Y)
case *ecdsa.PrivateKey:
input, err = ecThumbprintInput(key.Curve, key.X, key.Y)
case *rsa.PublicKey:
input, err = rsaThumbprintInput(key.N, key.E)
case *rsa.PrivateKey:
input, err = rsaThumbprintInput(key.N, key.E)
case ed25519.PrivateKey:
input, err = edThumbprintInput(ed25519.PublicKey(key[32:]))
default:
return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key))
}
if err != nil {
return nil, err
}
h := hash.New()
h.Write([]byte(input))
return h.Sum(nil), nil
}
// IsPublic returns true if the JWK represents a public key (not symmetric, not private).
func (k *JSONWebKey) IsPublic() bool {
switch k.Key.(type) {
case *ecdsa.PublicKey, *rsa.PublicKey, ed25519.PublicKey:
return true
default:
return false
}
}
// Public creates JSONWebKey with corresponding publik key if JWK represents asymmetric private key.
func (k *JSONWebKey) Public() JSONWebKey {
if k.IsPublic() {
return *k
}
ret := *k
switch key := k.Key.(type) {
case *ecdsa.PrivateKey:
ret.Key = key.Public()
case *rsa.PrivateKey:
ret.Key = key.Public()
case ed25519.PrivateKey:
ret.Key = key.Public()
default:
return JSONWebKey{} // returning invalid key
}
return ret
}
// Valid checks that the key contains the expected parameters.
func (k *JSONWebKey) Valid() bool {
if k.Key == nil {
return false
}
switch key := k.Key.(type) {
case *ecdsa.PublicKey:
if key.Curve == nil || key.X == nil || key.Y == nil {
return false
}
case *ecdsa.PrivateKey:
if key.Curve == nil || key.X == nil || key.Y == nil || key.D == nil {
return false
}
case *rsa.PublicKey:
if key.N == nil || key.E == 0 {
return false
}
case *rsa.PrivateKey:
if key.N == nil || key.E == 0 || key.D == nil || len(key.Primes) < 2 {
return false
}
case ed25519.PublicKey:
if len(key) != 32 {
return false
}
case ed25519.PrivateKey:
if len(key) != 64 {
return false
}
default:
return false
}
return true
}
func (key rawJSONWebKey) rsaPublicKey() (*rsa.PublicKey, error) {
if key.N == nil || key.E == nil {
return nil, fmt.Errorf("square/go-jose: invalid RSA key, missing n/e values")
}
return &rsa.PublicKey{
N: key.N.bigInt(),
E: key.E.toInt(),
}, nil
}
func fromEdPublicKey(pub ed25519.PublicKey) *rawJSONWebKey {
return &rawJSONWebKey{
Kty: "OKP",
Crv: "Ed25519",
X: newBuffer(pub),
}
}
func fromRsaPublicKey(pub *rsa.PublicKey) *rawJSONWebKey {
return &rawJSONWebKey{
Kty: "RSA",
N: newBuffer(pub.N.Bytes()),
E: newBufferFromInt(uint64(pub.E)),
}
}
func (key rawJSONWebKey) ecPublicKey() (*ecdsa.PublicKey, error) {
var curve elliptic.Curve
switch key.Crv {
case "P-256":
curve = elliptic.P256()
case "P-384":
curve = elliptic.P384()
case "P-521":
curve = elliptic.P521()
default:
return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv)
}
if key.X == nil || key.Y == nil {
return nil, errors.New("square/go-jose: invalid EC key, missing x/y values")
}
// The length of this octet string MUST be the full size of a coordinate for
// the curve specified in the "crv" parameter.
// https://tools.ietf.org/html/rfc7518#section-6.2.1.2
if curveSize(curve) != len(key.X.data) {
return nil, fmt.Errorf("square/go-jose: invalid EC public key, wrong length for x")
}
if curveSize(curve) != len(key.Y.data) {
return nil, fmt.Errorf("square/go-jose: invalid EC public key, wrong length for y")
}
x := key.X.bigInt()
y := key.Y.bigInt()
if !curve.IsOnCurve(x, y) {
return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve")
}
return &ecdsa.PublicKey{
Curve: curve,
X: x,
Y: y,
}, nil
}
func fromEcPublicKey(pub *ecdsa.PublicKey) (*rawJSONWebKey, error) {
if pub == nil || pub.X == nil || pub.Y == nil {
return nil, fmt.Errorf("square/go-jose: invalid EC key (nil, or X/Y missing)")
}
name, err := curveName(pub.Curve)
if err != nil {
return nil, err
}
size := curveSize(pub.Curve)
xBytes := pub.X.Bytes()
yBytes := pub.Y.Bytes()
if len(xBytes) > size || len(yBytes) > size {
return nil, fmt.Errorf("square/go-jose: invalid EC key (X/Y too large)")
}
key := &rawJSONWebKey{
Kty: "EC",
Crv: name,
X: newFixedSizeBuffer(xBytes, size),
Y: newFixedSizeBuffer(yBytes, size),
}
return key, nil
}
func (key rawJSONWebKey) edPrivateKey() (ed25519.PrivateKey, error) {
var missing []string
switch {
case key.D == nil:
missing = append(missing, "D")
case key.X == nil:
missing = append(missing, "X")
}
if len(missing) > 0 {
return nil, fmt.Errorf("square/go-jose: invalid Ed25519 private key, missing %s value(s)", strings.Join(missing, ", "))
}
privateKey := make([]byte, ed25519.PrivateKeySize)
copy(privateKey[0:32], key.D.bytes())
copy(privateKey[32:], key.X.bytes())
rv := ed25519.PrivateKey(privateKey)
return rv, nil
}
func (key rawJSONWebKey) edPublicKey() (ed25519.PublicKey, error) {
if key.X == nil {
return nil, fmt.Errorf("square/go-jose: invalid Ed key, missing x value")
}
publicKey := make([]byte, ed25519.PublicKeySize)
copy(publicKey[0:32], key.X.bytes())
rv := ed25519.PublicKey(publicKey)
return rv, nil
}
func (key rawJSONWebKey) rsaPrivateKey() (*rsa.PrivateKey, error) {
var missing []string
switch {
case key.N == nil:
missing = append(missing, "N")
case key.E == nil:
missing = append(missing, "E")
case key.D == nil:
missing = append(missing, "D")
case key.P == nil:
missing = append(missing, "P")
case key.Q == nil:
missing = append(missing, "Q")
}
if len(missing) > 0 {
return nil, fmt.Errorf("square/go-jose: invalid RSA private key, missing %s value(s)", strings.Join(missing, ", "))
}
rv := &rsa.PrivateKey{
PublicKey: rsa.PublicKey{
N: key.N.bigInt(),
E: key.E.toInt(),
},
D: key.D.bigInt(),
Primes: []*big.Int{
key.P.bigInt(),
key.Q.bigInt(),
},
}
if key.Dp != nil {
rv.Precomputed.Dp = key.Dp.bigInt()
}
if key.Dq != nil {
rv.Precomputed.Dq = key.Dq.bigInt()
}
if key.Qi != nil {
rv.Precomputed.Qinv = key.Qi.bigInt()
}
err := rv.Validate()
return rv, err
}
func fromEdPrivateKey(ed ed25519.PrivateKey) (*rawJSONWebKey, error) {
raw := fromEdPublicKey(ed25519.PublicKey(ed[32:]))
raw.D = newBuffer(ed[0:32])
return raw, nil
}
func fromRsaPrivateKey(rsa *rsa.PrivateKey) (*rawJSONWebKey, error) {
if len(rsa.Primes) != 2 {
return nil, ErrUnsupportedKeyType
}
raw := fromRsaPublicKey(&rsa.PublicKey)
raw.D = newBuffer(rsa.D.Bytes())
raw.P = newBuffer(rsa.Primes[0].Bytes())
raw.Q = newBuffer(rsa.Primes[1].Bytes())
if rsa.Precomputed.Dp != nil {
raw.Dp = newBuffer(rsa.Precomputed.Dp.Bytes())
}
if rsa.Precomputed.Dq != nil {
raw.Dq = newBuffer(rsa.Precomputed.Dq.Bytes())
}
if rsa.Precomputed.Qinv != nil {
raw.Qi = newBuffer(rsa.Precomputed.Qinv.Bytes())
}
return raw, nil
}
func (key rawJSONWebKey) ecPrivateKey() (*ecdsa.PrivateKey, error) {
var curve elliptic.Curve
switch key.Crv {
case "P-256":
curve = elliptic.P256()
case "P-384":
curve = elliptic.P384()
case "P-521":
curve = elliptic.P521()
default:
return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv)
}
if key.X == nil || key.Y == nil || key.D == nil {
return nil, fmt.Errorf("square/go-jose: invalid EC private key, missing x/y/d values")
}
// The length of this octet string MUST be the full size of a coordinate for
// the curve specified in the "crv" parameter.
// https://tools.ietf.org/html/rfc7518#section-6.2.1.2
if curveSize(curve) != len(key.X.data) {
return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for x")
}
if curveSize(curve) != len(key.Y.data) {
return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for y")
}
// https://tools.ietf.org/html/rfc7518#section-6.2.2.1
if dSize(curve) != len(key.D.data) {
return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for d")
}
x := key.X.bigInt()
y := key.Y.bigInt()
if !curve.IsOnCurve(x, y) {
return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve")
}
return &ecdsa.PrivateKey{
PublicKey: ecdsa.PublicKey{
Curve: curve,
X: x,
Y: y,
},
D: key.D.bigInt(),
}, nil
}
func fromEcPrivateKey(ec *ecdsa.PrivateKey) (*rawJSONWebKey, error) {
raw, err := fromEcPublicKey(&ec.PublicKey)
if err != nil {
return nil, err
}
if ec.D == nil {
return nil, fmt.Errorf("square/go-jose: invalid EC private key")
}
raw.D = newFixedSizeBuffer(ec.D.Bytes(), dSize(ec.PublicKey.Curve))
return raw, nil
}
// dSize returns the size in octets for the "d" member of an elliptic curve
// private key.
// The length of this octet string MUST be ceiling(log-base-2(n)/8)
// octets (where n is the order of the curve).
// https://tools.ietf.org/html/rfc7518#section-6.2.2.1
func dSize(curve elliptic.Curve) int {
order := curve.Params().P
bitLen := order.BitLen()
size := bitLen / 8
if bitLen%8 != 0 {
size = size + 1
}
return size
}
func fromSymmetricKey(key []byte) (*rawJSONWebKey, error) {
return &rawJSONWebKey{
Kty: "oct",
K: newBuffer(key),
}, nil
}
func (key rawJSONWebKey) symmetricKey() ([]byte, error) {
if key.K == nil {
return nil, fmt.Errorf("square/go-jose: invalid OCT (symmetric) key, missing k value")
}
return key.K.bytes(), nil
}