java - 尝试解密基于 AES 的加密文本时出现 BadPadding 异常

问题描述

问题场景： 我在 Ubuntu 中使用 OpenSSL AES-256-CBC 模式创建加密文件。

openssl aes-256-cbc -a -in avengers.txt -out avengers.enc 
test
test
File Content: avengersAssemble
avengers.enc file content: U2FsdGVkX194TyUFrb4gOn86XYaKjKP98YdOlQDJz+t/76mvVmNKl+NyKKUnYwYH

To Decrypt: openssl aes-256-cbc -a -d -in avengers.enc

现在我想avengers.enc使用java代码解密这个加密文件，即我只存储这个文件内容和密码（在这种情况下是测试）来解密它。

我的目标：我想使用从上述命令（128 或 192 或 256 cbc）加密的密码（对称加密）解密。

请帮忙。

我找到了这段代码，但它显示了 BadPadding 异常。请参考@Maarten Bodewes链接中的答案。

我从链接中找到的代码：

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.List;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.util.encoders.Base64;

public class OpenSSLDecryptor {
    private static final Charset ASCII = Charset.forName("ASCII");
    private static final int INDEX_KEY = 0;
    private static final int INDEX_IV = 1;
    private static final int ITERATIONS = 1;

    private static final int ARG_INDEX_FILENAME = 0;
    private static final int ARG_INDEX_PASSWORD = 1;

    private static final String file = 
    "D:\\Eclipse_Workspace\\Cryptography\\avengers.enc";
     private static final String password = "test";

    private static final int SALT_OFFSET = 8;
    private static final int SALT_SIZE = 8;
    private static final int CIPHERTEXT_OFFSET = SALT_OFFSET + SALT_SIZE;

    private static final int KEY_SIZE_BITS = 256;

    /**
     * Thanks go to Ola Bini for releasing this source on his blog.
     * The source was obtained from <a href="http://olabini.com/blog/tag/evp_bytestokey/">here</a> .
     */
    public static byte[][] EVP_BytesToKey(int key_len, int iv_len, MessageDigest md,
            byte[] salt, byte[] data, int count) {
        byte[][] both = new byte[2][];
        byte[] key = new byte[key_len];
        int key_ix = 0;
        byte[] iv = new byte[iv_len];
        int iv_ix = 0;
        both[0] = key;
        both[1] = iv;
        byte[] md_buf = null;
        int nkey = key_len;
        int niv = iv_len;
        int i = 0;
        if (data == null) {
            return both;
        }
        int addmd = 0;
        for (;;) {
            md.reset();
            if (addmd++ > 0) {
                md.update(md_buf);
            }
            md.update(data);
            if (null != salt) {
                md.update(salt, 0, 8);
            }
            md_buf = md.digest();
            for (i = 1; i < count; i++) {
                md.reset();
                md.update(md_buf);
                md_buf = md.digest();
            }
            i = 0;
            if (nkey > 0) {
                for (;;) {
                    if (nkey == 0)
                        break;
                    if (i == md_buf.length)
                        break;
                    key[key_ix++] = md_buf[i];
                    nkey--;
                    i++;
                }
            }
            if (niv > 0 && i != md_buf.length) {
                for (;;) {
                    if (niv == 0)
                        break;
                    if (i == md_buf.length)
                        break;
                    iv[iv_ix++] = md_buf[i];
                    niv--;
                    i++;
                }
            }
            if (nkey == 0 && niv == 0) {
                break;
            }
        }
        for (i = 0; i < md_buf.length; i++) {
            md_buf[i] = 0;
        }
        return both;
    }


    public static void main(String[] args) {
        try {
            // --- read base 64 encoded file ---

            //File f = new File(args[ARG_INDEX_FILENAME]);
            File f = new File(file);
            List<String> lines = Files.readAllLines(f.toPath(), ASCII);
            StringBuilder sb = new StringBuilder();
            for (String line : lines) {
                sb.append(line.trim());
            }
            String dataBase64 = sb.toString();
            byte[] headerSaltAndCipherText = Base64.decode(dataBase64);

            // --- extract salt & encrypted ---

            // header is "Salted__", ASCII encoded, if salt is being used (the default)
            byte[] salt = Arrays.copyOfRange(
                    headerSaltAndCipherText, SALT_OFFSET, SALT_OFFSET + SALT_SIZE);
            byte[] encrypted = Arrays.copyOfRange(
                    headerSaltAndCipherText, CIPHERTEXT_OFFSET, headerSaltAndCipherText.length);

            // --- specify cipher and digest for EVP_BytesToKey method ---

            Cipher aesCBC = Cipher.getInstance("AES/CBC/PKCS5Padding");
            MessageDigest md5 = MessageDigest.getInstance("MD5");

            // --- create key and IV  ---

            // the IV is useless, OpenSSL might as well have use zero's
            final byte[][] keyAndIV = EVP_BytesToKey(
                    KEY_SIZE_BITS / Byte.SIZE,
                    aesCBC.getBlockSize(),
                    md5,
                    salt,
                    password.getBytes(ASCII),
                    ITERATIONS); //args[ARG_INDEX_PASSWORD]
            SecretKeySpec key = new SecretKeySpec(keyAndIV[INDEX_KEY], "AES");
            IvParameterSpec iv = new IvParameterSpec(keyAndIV[INDEX_IV]);

            // --- initialize cipher instance and decrypt ---

            aesCBC.init(Cipher.DECRYPT_MODE, key, iv);
            byte[] decrypted = aesCBC.doFinal(encrypted);

            String answer = new String(decrypted, ASCII);
            System.out.println(answer);
        } catch (BadPaddingException e) {
            // AKA "something went wrong"
            throw new IllegalStateException(
                    "Bad password, algorithm, mode or padding;" +
                    " no salt, wrong number of iterations or corrupted ciphertext.");
        } catch (IllegalBlockSizeException e) {
            throw new IllegalStateException(
                    "Bad algorithm, mode or corrupted (resized) ciphertext.");
        } catch (GeneralSecurityException e) {
            throw new IllegalStateException(e);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }        
}

例外：

javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:991)
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:847)
    at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
    at javax.crypto.Cipher.doFinal(Cipher.java:2164)
    at symmetric.main(symmetric.java:146)

标签： javaencryptionopensslaesencryption-symmetric

OpenSSL使用EVP_BytesToKeywith 使用 Message Digest 算法，如md5,sha256等。在上面的代码中，函数EVP_ByteToKey有一个 MessageDigest 参数，MD5但在加密时未在 OpenSSL 命令中添加 MD5。下面是与消息摘要算法（即 MD5）一起使用的实际命令。

openssl aes-256-cbc -a -in avengers.txt -out avengers.enc -md md5
 openssl aes-256-cbc -a -d -in avengers.enc -md md5

MessageDigest md5 = MessageDigest.getInstance("SHA-256"); 要使用任何其他消息摘要算法，只需在消息摘要算法下的引用链接中传递该算法。此外，必须传递-md sha256命令。请参阅 openSSL 的手册页

java - 尝试解密基于 AES 的加密文本时出现 BadPadding 异常

问题描述

解决方案

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