背景：

我创建了一个applet来提取从智能卡中提取的证书的公钥.
然后将该公钥存储在数据库中.
证书的私钥用于对数据进行签名,然后使用公钥来验证签名.
从证书中提取公钥的代码：

private byte[] getPublicKey(KeyStore paramKeyStore)
    throws GeneralSecurityException {
  Enumeration localEnumeration = paramKeyStore.aliases();

  if (localEnumeration.hasMoreElements()) {
    String element = (String) localEnumeration.nextElement();
    Certificate[] arrayOfCertificate =
        paramKeyStore.getCertificateChain(element);
    byte[] publicKeyByteArray =
        arrayOfCertificate[0].getPublicKey().getEncoded();

    return publicKeyByteArray;
  }
  throw new KeyStoreException("The keystore is empty!");
}

然后使用bytes2String方法将此publicKeyByteArray转换为字符串后,将其作为BLOB存储在数据库中：

private static String bytes2String(byte[] bytes) {
  StringBuilder string = new StringBuilder();
  for (byte b : bytes) {
    String hexString = Integer.toHexString(0x00FF & b);
    string.append(hexString.length() == 1 ? "0" + hexString : hexString);
  }
  return string.toString();
}

保存在数据库中的BLOB(密钥)的内容是：

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

从数据库中读取存储的公钥字节[]后,我尝试使用以下代码将其转换回公钥：

Cipher rsa;
rsa = Cipher.getInstance("RSA");
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(pkey.getBytes());
PublicKey pk = keyFactory.generatePublic(publicKeySpec);
rsa.init(Cipher.DECRYPT_MODE, pk);
byte[] cipherDecrypt = rsa.doFinal(encryptedText.getBytes());

但它给出了以下错误：

Caused by: java.security.InvalidKeyException: invalid key format
    at sun.security.x509.X509Key.decode(X509Key.java:387)
    at sun.security.x509.X509Key.decode(X509Key.java:403)
    at sun.security.rsa.RSAPublicKeyImpl.<init>(RSAPublicKeyImpl.java:83)
    at sun.security.rsa.RSAKeyFactory.generatePublic(RSAKeyFactory.java:298)
    at sun.security.rsa.RSAKeyFactory.engineGeneratePublic(RSAKeyFactory.java:201)

请提出此问题的原因和解决方法.

解决方法:

您从数据库中读取密钥的方式必定有错误.以下代码对我来说很好用：

String key = "3082012230..."; // full key omitted for brevity
byte[] derPublicKey = DatatypeConverter.parseHexBinary(key);

KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(derPublicKey);
keyFactory.generatePublic(publicKeySpec);

我猜,基于pkey.getBytes()的使用,你只是试图从字符串中获取字节而不是十六进制解码它.