Source: oauth2.go in package golang.org/x/oauth2/internal


package internal

import (
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"errors"
	"fmt"
)

ParseKey converts the binary contents of a private key file to an *rsa.PrivateKey. It detects whether the private key is in a PEM container or not. If so, it extracts the the private key from PEM container before conversion. It only supports PEM containers with no passphrase.

func ParseKey(key []byte) (*rsa.PrivateKey, error) {
	block, _ := pem.Decode(key)
	if block != nil {
		key = block.Bytes
	}
	parsedKey, err := x509.ParsePKCS8PrivateKey(key)
	if err != nil {
		parsedKey, err = x509.ParsePKCS1PrivateKey(key)
		if err != nil {
			return nil, fmt.Errorf("private key should be a PEM or plain PKCS1 or PKCS8; parse error: %v", err)
		}
	}
	parsed, ok := parsedKey.(*rsa.PrivateKey)
	if !ok {
		return nil, errors.New("private key is invalid")
	}
	return parsed, nil