func parseRsaPrivateKey()

in pkg/internal/token/clientcertcredential.go [114:135]

• 19 lines of code
• 5 McCabe index (conditional complexity)

func parseRsaPrivateKey(privateKeyPEM []byte) (*rsa.PrivateKey, error) {
	block, _ := pem.Decode(privateKeyPEM)
	if block == nil {
		return nil, fmt.Errorf("failed to decode a pem block from private key")
	}

	privatePkcs1Key, errPkcs1 := x509.ParsePKCS1PrivateKey(block.Bytes)
	if errPkcs1 == nil {
		return privatePkcs1Key, nil
	}

	privatePkcs8Key, errPkcs8 := x509.ParsePKCS8PrivateKey(block.Bytes)
	if errPkcs8 == nil {
		privatePkcs8RsaKey, ok := privatePkcs8Key.(*rsa.PrivateKey)
		if !ok {
			return nil, fmt.Errorf("pkcs8 contained non-RSA key. Expected RSA key")
		}
		return privatePkcs8RsaKey, nil
	}

	return nil, fmt.Errorf("failed to parse private key as Pkcs#1 or Pkcs#8. (%w), (%w)", errPkcs1, errPkcs8)
}