/
parser.go
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/
parser.go
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/**
* Copyright 2020 Comcast Cable Communications Management, LLC
*
* 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 key
import (
"context"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"errors"
)
var (
ErrorPEMRequired = errors.New("Keys must be PEM-encoded")
ErrorUnsupportedPrivateKeyFormat = errors.New("Private keys must be in PKCS1 or PKCS8 format")
ErrorNotRSAPrivateKey = errors.New("Only RSA private keys are supported")
ErrorNotRSAPublicKey = errors.New("Only RSA public keys or certificates are suppored")
)
// Parser parses a chunk of bytes into a Pair. Parser implementations must
// always be safe for concurrent access.
type Parser interface {
// Parse examines data to produce a Pair. If the returned error is not nil,
// the Pair will always be nil. This method is responsible for dealing with
// any required decoding, such as PEM or DER.
ParseKey(context.Context, Purpose, []byte) (Pair, error)
}
// defaultParser is the internal default Parser implementation
type defaultParser struct{}
func (p defaultParser) String() string {
return "defaultParser"
}
func (p defaultParser) parseRSAPrivateKey(ctx context.Context, purpose Purpose, decoded []byte) (Pair, error) {
var (
parsedKey interface{}
err error
)
if parsedKey, err = x509.ParsePKCS1PrivateKey(decoded); err != nil {
if parsedKey, err = x509.ParsePKCS8PrivateKey(decoded); err != nil {
return nil, ErrorUnsupportedPrivateKeyFormat
}
}
if ctx.Err() != nil {
return nil, ctx.Err()
}
privateKey, ok := parsedKey.(*rsa.PrivateKey)
if !ok {
return nil, ErrorNotRSAPrivateKey
}
return &rsaPair{
purpose: purpose,
public: privateKey.Public(),
private: privateKey,
}, nil
}
func (p defaultParser) parseRSAPublicKey(ctx context.Context, purpose Purpose, decoded []byte) (Pair, error) {
var (
parsedKey interface{}
err error
)
if parsedKey, err = x509.ParsePKIXPublicKey(decoded); err != nil {
return nil, err
}
if ctx.Err() != nil {
return nil, ctx.Err()
}
publicKey, ok := parsedKey.(*rsa.PublicKey)
if !ok {
return nil, ErrorNotRSAPublicKey
}
return &rsaPair{
purpose: purpose,
public: publicKey,
private: nil,
}, nil
}
func (p defaultParser) ParseKey(ctx context.Context, purpose Purpose, data []byte) (Pair, error) {
block, _ := pem.Decode(data)
if block == nil {
return nil, ErrorPEMRequired
}
if ctx.Err() != nil {
return nil, ctx.Err()
}
if purpose.RequiresPrivateKey() {
return p.parseRSAPrivateKey(ctx, purpose, block.Bytes)
} else {
return p.parseRSAPublicKey(ctx, purpose, block.Bytes)
}
}
// DefaultParser is the global, singleton default parser. All keys submitted to
// this parser must be PEM-encoded.
var DefaultParser Parser = defaultParser{}