137 lines
3 KiB
Go
137 lines
3 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2018 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package openid
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import (
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"crypto"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rsa"
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"encoding/base64"
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"encoding/binary"
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"errors"
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"fmt"
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"math/big"
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"strings"
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)
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// JWKS - https://tools.ietf.org/html/rfc7517
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type JWKS struct {
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Keys []*JWKS `json:"keys,omitempty"`
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Kty string `json:"kty"`
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Use string `json:"use,omitempty"`
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Kid string `json:"kid,omitempty"`
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Alg string `json:"alg,omitempty"`
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Crv string `json:"crv,omitempty"`
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X string `json:"x,omitempty"`
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Y string `json:"y,omitempty"`
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D string `json:"d,omitempty"`
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N string `json:"n,omitempty"`
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E string `json:"e,omitempty"`
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K string `json:"k,omitempty"`
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}
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func safeDecode(str string) ([]byte, error) {
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lenMod4 := len(str) % 4
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if lenMod4 > 0 {
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str = str + strings.Repeat("=", 4-lenMod4)
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}
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return base64.URLEncoding.DecodeString(str)
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}
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var (
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errMalformedJWKRSAKey = errors.New("malformed JWK RSA key")
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errMalformedJWKECKey = errors.New("malformed JWK EC key")
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)
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// DecodePublicKey - decodes JSON Web Key (JWK) as public key
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func (key *JWKS) DecodePublicKey() (crypto.PublicKey, error) {
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switch key.Kty {
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case "RSA":
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if key.N == "" || key.E == "" {
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return nil, errMalformedJWKRSAKey
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}
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// decode exponent
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data, err := safeDecode(key.E)
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if err != nil {
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return nil, errMalformedJWKRSAKey
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}
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if len(data) < 4 {
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ndata := make([]byte, 4)
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copy(ndata[4-len(data):], data)
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data = ndata
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}
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pubKey := &rsa.PublicKey{
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N: &big.Int{},
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E: int(binary.BigEndian.Uint32(data[:])),
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}
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data, err = safeDecode(key.N)
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if err != nil {
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return nil, errMalformedJWKRSAKey
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}
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pubKey.N.SetBytes(data)
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return pubKey, nil
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case "EC":
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if key.Crv == "" || key.X == "" || key.Y == "" {
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return nil, errMalformedJWKECKey
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}
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var curve elliptic.Curve
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switch key.Crv {
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case "P-224":
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curve = elliptic.P224()
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case "P-256":
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curve = elliptic.P256()
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case "P-384":
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curve = elliptic.P384()
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case "P-521":
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curve = elliptic.P521()
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default:
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return nil, fmt.Errorf("Unknown curve type: %s", key.Crv)
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}
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pubKey := &ecdsa.PublicKey{
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Curve: curve,
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X: &big.Int{},
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Y: &big.Int{},
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}
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data, err := safeDecode(key.X)
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if err != nil {
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return nil, errMalformedJWKECKey
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}
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pubKey.X.SetBytes(data)
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data, err = safeDecode(key.Y)
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if err != nil {
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return nil, errMalformedJWKECKey
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}
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pubKey.Y.SetBytes(data)
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return pubKey, nil
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default:
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return nil, fmt.Errorf("Unknown JWK key type %s", key.Kty)
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}
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}
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