使用 Java 解密 OpenSSL PEM 编码的 RSA 私钥？

Question

我有一个加密的私钥，我知道密码。

我需要使用 Java 库对其进行解密。

不过我不想使用 BouncyCastle，除非别无选择。根据以往的经验，变化太大，文档不够。

私钥是这样的形式：

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

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

我认为关键数据是 Base64 编码的，因为我在 64 个字符后看到 \r\n。

我尝试了以下方法来解密密钥：

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();
}

我得到这个异常

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？

我怎样才能使这个工作？

我尝试了 Ericsonn 的建议，因为我在工作 Java 7，我做了一个小改动，我无法使用 Base64.getMimeCoder() 而是使用 Base64.decode，我得到了这个错误当在 com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:750)

处使用填充密码解密时，我收到这样的错误 Input length must be multiple of 8

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() 而 1228 是 keyBytes.length

Answer 1

您需要使用 non-standard、OpenSSL 方法来导出解密密钥。然后使用它来解密 PKCS-#1 编码的密钥——您正在使用的是 而不是 PKCS #8 信封。您还需要 header 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;
  }

这已经是很多代码了，所以我将 link 到另一个答案来定义 the decodeRSAPrivatePKCS1() method.

Answer 2

Java 下面的代码示例显示了如何构造解密密钥以从使用 openssl 1.0.x genrsa 命令创建的加密私钥中获取基础 RSA 密钥；具体来自以下可能已被利用的 genrsa 选项：

-des encrypt the generated key with DES in cbc mode

-des3 encrypt the generated key with DES in ede cbc mode (168 bit key)

-aes128, -aes192, -aes256 encrypt PEM output with cbc aes

以上选项会生成格式为 ...

的加密 RSA 私钥

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AAA,BBB
...

其中 AAA 是以下之一：

DES-CBC, DES-EDE3-CBC, AES-128-CBC, AES-192-CBC, AES-256-CBC

AND BBB 是十六进制编码的 IV 值

KeyFactory factory = KeyFactory.getInstance("RSA");
KeySpec keySpec = null;
RSAPrivateKey privateKey = null;

Matcher matcher = OPENSSL_ENCRYPTED_RSA_PRIVATEKEY_PATTERN.matcher(pemContents);
if (matcher.matches())
{
    String encryptionDetails = matcher.group(1).trim(); // e.g. AES-256-CBC,XXXXXXX
    String encryptedKey = matcher.group(2).replaceAll("\s", ""); // remove tabs / spaces / newlines / carriage return etc

    System.out.println("PEM appears to be OpenSSL Encrypted RSA Private Key; Encryption details : "
        + encryptionDetails + "; Key : " + encryptedKey);

    byte[] encryptedBinaryKey = java.util.Base64.getDecoder().decode(encryptedKey);

    String[] encryptionDetailsParts = encryptionDetails.split(",");
    if (encryptionDetailsParts.length == 2)
    {
        String encryptionAlgorithm = encryptionDetailsParts[0];
        String encryptedAlgorithmParams = encryptionDetailsParts[1]; // i.e. the initialization vector in hex

        byte[] pw = new String(password).getBytes(StandardCharsets.UTF_8);
        byte[] iv = fromHex(encryptedAlgorithmParams);

        MessageDigest digest = MessageDigest.getInstance("MD5");

        // we need to come up with the encryption key
        
        // first round digest based on password and first 8-bytes of IV ..
        digest.update(pw);
        digest.update(iv, 0, 8);

        byte[] round1Digest = digest.digest(); // The digest is reset after this call is made.
        
        // second round digest based on first round digest, password, and first 8-bytes of IV ...
        digest.update(round1Digest);
        digest.update(pw);
        digest.update(iv, 0, 8);

        byte[] round2Digest = digest.digest();

        Cipher cipher = null;
        SecretKey secretKey = null;
        byte[] key = null;
        byte[] pkcs1 = null;

        if ("AES-256-CBC".equals(encryptionAlgorithm))
        {
            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

            key = new byte[32]; // 256 bit key  (block size still 128-bit)
            System.arraycopy(round1Digest, 0, key, 0, 16);
            System.arraycopy(round2Digest, 0, key, 16, 16);

            secretKey = new SecretKeySpec(key, "AES");
        }
        else if ("AES-192-CBC".equals(encryptionAlgorithm))
        {
            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

            key = new byte[24]; // key size of 24 bytes
            System.arraycopy(round1Digest, 0, key, 0, 16);
            System.arraycopy(round2Digest, 0, key, 16, 8);

            secretKey = new SecretKeySpec(key, "AES");
        }
        else if ("AES-128-CBC".equals(encryptionAlgorithm))
        {
            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

            key = new byte[16]; // 128 bit key
            System.arraycopy(round1Digest, 0, key, 0, 16);

            secretKey = new SecretKeySpec(key, "AES");
        }
        else if ("DES-EDE3-CBC".equals(encryptionAlgorithm))
        {
            cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
            
            key = new byte[24]; // key size of 24 bytes
            System.arraycopy(round1Digest, 0, key, 0, 16);
            System.arraycopy(round2Digest, 0, key, 16, 8);

            secretKey = new SecretKeySpec(key, "DESede");
        }
        else if ("DES-CBC".equals(encryptionAlgorithm))
        {
            cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
            
            key = new byte[8]; // key size of 8 bytes
            System.arraycopy(round1Digest, 0, key, 0, 8);

            secretKey = new SecretKeySpec(key, "DES");
        }

        cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));

        pkcs1 = cipher.doFinal(encryptedBinaryKey);

        keySpec = pkcs1ParsePrivateKey(pkcs1);

        privateKey = (RSAPrivateKey) factory.generatePrivate(keySpec);
    }
}

正则表达式 ...

static final String OPENSSL_ENCRYPTED_RSA_PRIVATEKEY_REGEX = "\s*" 
+ "-----BEGIN RSA PUBLIC KEY-----" + "\s*"
+ "Proc-Type: 4,ENCRYPTED" + "\s*"
+ "DEK-Info:" + "\s*([^\s]+)" + "\s+"
+ "([\s\S]*)"
+ "-----END RSA PUBLIC KEY-----" + "\s*";

static final Pattern OPENSSL_ENCRYPTED_RSA_PRIVATEKEY_PATTERN = Pattern.compile(OPENSSL_ENCRYPTED_RSA_PRIVATEKEY_REGEX);

fromHex(...) 方法 ...

public static byte[] fromHex(String hexString)
{
    byte[] bytes = new byte[hexString.length() / 2];
    for (int i = 0; i < hexString.length(); i += 2)
    {
        bytes[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)
            + Character.digit(hexString.charAt(i + 1), 16));
    }
    return bytes;
}

使用 Java 解密 OpenSSL PEM 编码的 RSA 私钥？

Decrypting an OpenSSL PEM Encoded RSA private key with Java?

java

encryption

openssl

pkcs#8

pkcs#1