Algid 解析错误，不是序列

尝试使用该方法从文件中读取 RSA 私钥时

public PrivateKey getPrivateKey()
        throws NoSuchAlgorithmException,
        InvalidKeySpecException, IOException {

    final InputStream inputStream = getClass().getClassLoader()
                    .getResourceAsStream("privatekey");
    byte[] privKeyBytes = null;
    try {
        privKeyBytes = IOUtils.toByteArray(inputStream);
    } catch (final IOException exception) {
        LOGGER.error("", exception);
        IOUtils.closeQuietly(inputStream);
    }

    LOGGER.debug("privKeyBytes: {}", privKeyBytes);

    String BEGIN = "-----BEGIN RSA PRIVATE KEY-----";
    String END = "-----END RSA PRIVATE KEY-----";
    String str = new String(privKeyBytes);
    if (str.contains(BEGIN) && str.contains(END)) {
        str = str.substring(BEGIN.length(), str.lastIndexOf(END));
    }

    KeyFactory fac = KeyFactory.getInstance("RSA");
    EncodedKeySpec privKeySpec =
            new PKCS8EncodedKeySpec(Base64.decode(str.getBytes()));
    return fac.generatePrivate(privKeySpec);
}

我遇到异常

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : algid parse error, not a sequence
    at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:200) ~[na:1.6.0_23]
    at java.security.KeyFactory.generatePrivate(KeyFactory.java:342) ~[na:1.6.0_23]

在 fac.generatePrivate（privKeySpec） 调用。

此错误是什么意思？

谢谢

德米特里