1// Copyright 2022 Google LLC 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14// 15//////////////////////////////////////////////////////////////////////////////// 16 17package jwt 18 19import ( 20 "fmt" 21 22 "github.com/google/tink/go/core/primitiveset" 23 "github.com/google/tink/go/keyset" 24) 25 26// NewMAC generates a new instance of the JWT MAC primitive. 27func NewMAC(handle *keyset.Handle) (MAC, error) { 28 if handle == nil { 29 return nil, fmt.Errorf("keyset handle can't be nil") 30 } 31 ps, err := handle.PrimitivesWithKeyManager(nil) 32 if err != nil { 33 return nil, fmt.Errorf("jwt_mac_factory: cannot obtain primitive set: %v", err) 34 } 35 return newWrappedJWTMAC(ps) 36} 37 38// wrappedJWTMAC is a JWTMAC implementation that uses the underlying primitive set for JWT MAC. 39type wrappedJWTMAC struct { 40 ps *primitiveset.PrimitiveSet 41} 42 43var _ MAC = (*wrappedJWTMAC)(nil) 44 45func newWrappedJWTMAC(ps *primitiveset.PrimitiveSet) (*wrappedJWTMAC, error) { 46 if _, ok := (ps.Primary.Primitive).(*macWithKID); !ok { 47 return nil, fmt.Errorf("jwt_mac_factory: not a JWT MAC primitive") 48 } 49 for _, primitives := range ps.Entries { 50 for _, p := range primitives { 51 if _, ok := (p.Primitive).(*macWithKID); !ok { 52 return nil, fmt.Errorf("jwt_mac_factory: not a JWT MAC primitive") 53 } 54 } 55 } 56 return &wrappedJWTMAC{ps: ps}, nil 57} 58 59func (w *wrappedJWTMAC) ComputeMACAndEncode(token *RawJWT) (string, error) { 60 primary := w.ps.Primary 61 p, ok := (primary.Primitive).(*macWithKID) 62 if !ok { 63 return "", fmt.Errorf("jwt_mac_factory: not a JWT MAC primitive") 64 } 65 return p.ComputeMACAndEncodeWithKID(token, keyID(primary.KeyID, primary.PrefixType)) 66} 67 68func (w *wrappedJWTMAC) VerifyMACAndDecode(compact string, validator *Validator) (*VerifiedJWT, error) { 69 var interestingErr error 70 for _, s := range w.ps.Entries { 71 for _, e := range s { 72 p, ok := e.Primitive.(*macWithKID) 73 if !ok { 74 return nil, fmt.Errorf("jwt_mac_factory: not a JWT MAC primitive") 75 } 76 verifiedJWT, err := p.VerifyMACAndDecodeWithKID(compact, validator, keyID(e.KeyID, e.PrefixType)) 77 if err == nil { 78 return verifiedJWT, nil 79 } 80 if err != errJwtVerification { 81 // any error that is not the generic errJwtVerification is considered interesting 82 interestingErr = err 83 } 84 } 85 } 86 if interestingErr != nil { 87 return nil, interestingErr 88 } 89 return nil, errJwtVerification 90} 91