使用Java解密OpenSSL PEM编码的RSA私钥？

Question

我有一个加密的私钥，并且知道密码。

我需要使用Java库对其进行解密。

不过，我宁愿不要使用BouncyCastle，除非没有其他选择。根据以前的经验，有太多更改，没有足够的文档。

私钥的格式如下：

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,56F3A98D9CFFA77A

X5h7SUDStF1tL16lRM+AfZb1UBDQ0D1YbQ6vmIlXiK....
.....
/KK5CZmIGw==
-----END RSA PRIVATE KEY-----

我相信关键数据是Base64编码的，因为我看到的是\r\n64个字符。

我尝试了以下解密密钥：

import java.security.Key;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import javax.crypto.EncryptedPrivateKeyInfo;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;

public String decrypt(String keyDataStr, String passwordStr){
  // This key data start from "X5... to ==" 
  char [] password=passwordStr.toCharArray();
  byte [] keyDataBytes=com.sun.jersey.core.util.Base64.decode(keyDataStr);

  PBEKeySpec pbeSpec = new PBEKeySpec(password);
  EncryptedPrivateKeyInfo pkinfo = new EncryptedPrivateKeyInfo(keyDataBytes);
  SecretKeyFactory skf = SecretKeyFactory.getInstance(pkinfo.getAlgName());
  Key secret = skf.generateSecret(pbeSpec);
  PKCS8EncodedKeySpec keySpec = pkinfo.getKeySpec(secret);
  KeyFactory kf = KeyFactory.getInstance("RSA");
  PrivateKey pk=kf.generatePrivate(keySpec);
  return pk.toString();
}

我得到这个例外

java.io.IOException: DerInputStream.getLength(): lengthTag=50, too big.
    at sun.security.util.DerInputStream.getLength(DerInputStream.java:561)
    at sun.security.util.DerValue.init(DerValue.java:365)
    at sun.security.util.DerValue.<init>(DerValue.java:294)
    at javax.crypto.EncryptedPrivateKeyInfo.<init> (EncryptedPrivateKeyInfo.java:84)

我是否将正确的参数传递给EncryptedPrivateKeyInfo构造函数？

我该如何工作？

我尝试了Ericsonn的建议，但做了一点小改动，因为我正在使用Java
7，所以我无法使用Base64.getMimeCoder（），而是使用Base64.decode，但出现此错误，我得到这样的错误，输入长度必须是多个在com.sun.crypto.provider.CipherCore.doFinal（CipherCore.java:750）上使用填充密码解密时的8个

static RSAPrivateKey decrypt(String keyDataStr, String ivHex, String password)
            throws GeneralSecurityException, UnsupportedEncodingException
          {
            byte[] pw = password.getBytes(StandardCharsets.UTF_8);
            byte[] iv = h2b(ivHex);
            SecretKey secret = opensslKDF(pw, iv);
            Cipher cipher = Cipher.getInstance("DESede/CBC/NoPadding");
            cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
            byte [] keyBytes=Base64.decode(keyDataStr.getBytes("UTF-8"));
            byte[] pkcs1 = cipher.doFinal(keyBytes);
            /* See note for definition of "decodeRSAPrivatePKCS1" */
            RSAPrivateCrtKeySpec spec = decodeRSAPrivatePKCS1(pkcs1);
            KeyFactory rsa = KeyFactory.getInstance("RSA");
            return (RSAPrivateKey) rsa.generatePrivate(spec);
          }

          private static SecretKey opensslKDF(byte[] pw, byte[] iv)
            throws NoSuchAlgorithmException
          {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(pw);
            md5.update(iv);
            byte[] d0 = md5.digest();
            md5.update(d0);
            md5.update(pw);
            md5.update(iv);
            byte[] d1 = md5.digest();
            byte[] key = new byte[24];
            System.arraycopy(d0, 0, key, 0, 16);
            System.arraycopy(d1, 0, key, 16, 8);
            return new SecretKeySpec(key, "DESede");
          }

          private static byte[] h2b(CharSequence s)
          {
            int len = s.length();
            byte[] b = new byte[len / 2];
            for (int src = 0, dst = 0; src < len; ++dst) {
              int hi = Character.digit(s.charAt(src++), 16);
              int lo = Character.digit(s.charAt(src++++), 16);
              b[dst] = (byte) (hi << 4 | lo);
            }
            return b;
          }
          static RSAPrivateCrtKeySpec decodeRSAPrivatePKCS1(byte[] encoded)
          {
            ByteBuffer input = ByteBuffer.wrap(encoded);
            if (der(input, 0x30) != input.remaining())
              throw new IllegalArgumentException("Excess data");
            if (!BigInteger.ZERO.equals(derint(input)))
              throw new IllegalArgumentException("Unsupported version");
            BigInteger n = derint(input);
            BigInteger e = derint(input);
            BigInteger d = derint(input);
            BigInteger p = derint(input);
            BigInteger q = derint(input);
            BigInteger ep = derint(input);
            BigInteger eq = derint(input);
            BigInteger c = derint(input);
            return new RSAPrivateCrtKeySpec(n, e, d, p, q, ep, eq, c);
          }

          private static BigInteger derint(ByteBuffer input)
          {
            byte[] value = new byte[der(input, 0x02)];
            input.get(value);
            return new BigInteger(+1, value);
          }


          private static int der(ByteBuffer input, int exp)
          {
            int tag = input.get() & 0xFF;
            if (tag != exp)
              throw new IllegalArgumentException("Unexpected tag");
            int n = input.get() & 0xFF;
            if (n < 128)
              return n;
            n &= 0x7F;
            if ((n < 1) || (n > 2))
              throw new IllegalArgumentException("Invalid length");
            int len = 0;
            while (n-- > 0) {
              len <<= 8;
              len |= input.get() & 0xFF;
            }
            return len;
          }

1640是keyDataStr.length（）和1228是keyBytes.length

Answer 1

您需要使用非标准的OpenSSL方法来获取解密密钥。然后使用它解密PKCS＃1编码的密钥-您使用的 不是
PKCS＃8信封。您还需要标题中的IV作为这些过程的输入。

看起来像这样：

  static RSAPrivateKey decrypt(String keyDataStr, String ivHex, String password)
    throws GeneralSecurityException
  {
    byte[] pw = password.getBytes(StandardCharsets.UTF_8);
    byte[] iv = h2b(ivHex);
    SecretKey secret = opensslKDF(pw, iv);
    Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
    byte[] pkcs1 = cipher.doFinal(Base64.getMimeDecoder().decode(keyDataStr));
    /* See note for definition of "decodeRSAPrivatePKCS1" */
    RSAPrivateCrtKeySpec spec = decodeRSAPrivatePKCS1(pkcs1);
    KeyFactory rsa = KeyFactory.getInstance("RSA");
    return (RSAPrivateKey) rsa.generatePrivate(spec);
  }

  private static SecretKey opensslKDF(byte[] pw, byte[] iv)
    throws NoSuchAlgorithmException
  {
    MessageDigest md5 = MessageDigest.getInstance("MD5");
    md5.update(pw);
    md5.update(iv);
    byte[] d0 = md5.digest();
    md5.update(d0);
    md5.update(pw);
    md5.update(iv);
    byte[] d1 = md5.digest();
    byte[] key = new byte[24];
    System.arraycopy(d0, 0, key, 0, 16);
    System.arraycopy(d1, 0, key, 16, 8);
    return new SecretKeySpec(key, "DESede");
  }

  private static byte[] h2b(CharSequence s)
  {
    int len = s.length();
    byte[] b = new byte[len / 2];
    for (int src = 0, dst = 0; src < len; ++dst) {
      int hi = Character.digit(s.charAt(src++), 16);
      int lo = Character.digit(s.charAt(src++), 16);
      b[dst] = (byte) (hi << 4 | lo);
    }
    return b;
  }

这已经是很多代码，因此我将链接到该方法定义的另一个答案。decodeRSAPrivatePKCS1()