github.com/zntrio/harp/v2@v2.0.9/pkg/sdk/value/signature/paseto/builders.go (about)

     1  // Licensed to Elasticsearch B.V. under one or more contributor
     2  // license agreements. See the NOTICE file distributed with
     3  // this work for additional information regarding copyright
     4  // ownership. Elasticsearch B.V. licenses this file to you under
     5  // the Apache License, Version 2.0 (the "License"); you may
     6  // not use this file except in compliance with the License.
     7  // You may obtain a copy of the License at
     8  //
     9  //     http://www.apache.org/licenses/LICENSE-2.0
    10  //
    11  // Unless required by applicable law or agreed to in writing,
    12  // software distributed under the License is distributed on an
    13  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    14  // KIND, either express or implied.  See the License for the
    15  // specific language governing permissions and limitations
    16  // under the License.
    17  
    18  package paseto
    19  
    20  import (
    21  	"encoding/base64"
    22  	"encoding/json"
    23  	"fmt"
    24  	"strings"
    25  
    26  	"gopkg.in/square/go-jose.v2"
    27  
    28  	"github.com/zntrio/harp/v2/pkg/sdk/value"
    29  	"github.com/zntrio/harp/v2/pkg/sdk/value/signature"
    30  )
    31  
    32  func init() {
    33  	signature.Register("paseto", Transformer)
    34  }
    35  
    36  // Transformer returns a PASETO signature value transformer instance.
    37  func Transformer(key string) (value.Transformer, error) {
    38  	// Remove the prefix
    39  	key = strings.TrimPrefix(key, "paseto:")
    40  
    41  	// Decode key
    42  	keyRaw, err := base64.RawURLEncoding.DecodeString(key)
    43  	if err != nil {
    44  		return nil, fmt.Errorf("unable to decode transformer key: %w", err)
    45  	}
    46  
    47  	// Check JWK encoding
    48  	var jwk jose.JSONWebKey
    49  	if errJSON := json.Unmarshal(keyRaw, &jwk); errJSON != nil {
    50  		return nil, fmt.Errorf("unable to decode the transformer key: %w", errJSON)
    51  	}
    52  
    53  	// Delegate to instance
    54  	return &pasetoTransformer{
    55  		key: jwk.Key,
    56  	}, err
    57  }