各位帮忙看下这段加密，感谢感谢。AES/CBC/PKCS5Padding

梦迪丶

首先，我的目的是解密他的post，在APK中找到了这段代码，麻烦大神们给看看他这个key，还有偏移值是怎么计算出来的。
代码如下：

[Java] 纯文本查看 复制代码

package com.cmic.sso.sdk.d;

import com.google.devtools.build.android.desugar.runtime.ThrowableExtension;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class a {
    public static String a(byte[] arg5, String arg6) {
        String v0_2;
        try {
            SecretKeySpec v0_1 = new SecretKeySpec(arg5, "AES");
            Cipher v1 = Cipher.getInstance("AES/CBC/PKCS5Padding");
            v1.init(1, ((Key)v0_1), new IvParameterSpec(new byte[v1.getBlockSize()]));
            v0_2 = b.a(v1.doFinal(arg6.getBytes("UTF-8")));
        }
        catch(Exception v0) {
            ThrowableExtension.printStackTrace(((Throwable)v0));
            v0_2 = null;
        }

        return v0_2;
    }

    public static byte[] a() {
        byte[] v0 = new byte[16];
        new SecureRandom().nextBytes(v0);
        return v0;
    }

    public static String b(byte[] arg6, String arg7) {
        String v0_2;
        try {
            byte[] v0_1 = b.a(arg7);
            SecretKeySpec v1 = new SecretKeySpec(arg6, "AES");
            Cipher v2 = Cipher.getInstance("AES/CBC/PKCS5Padding");
            v2.init(2, ((Key)v1), new IvParameterSpec(new byte[v2.getBlockSize()]));
            v0_2 = new String(v2.doFinal(v0_1), "UTF-8");
        }
        catch(Exception v0) {
            ThrowableExtension.printStackTrace(((Throwable)v0));
            v0_2 = null;
        }

        return v0_2;
    }
}

下面是他调用的b.a的代码：

[Java] 纯文本查看 复制代码

package com.cmic.sso.sdk.d;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class b {
    private static final char[] a;

    static {
        b.a = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
    }

    public static String a(byte[] arg9) {
        int v4 = arg9.length;
        StringBuffer v5 = new StringBuffer(arg9.length * 3 / 2);
        int v6 = v4 - 3;
        int v2 = 0;
        int v0;
        for(v0 = 0; v0 <= v6; v0 = v3) {
            int v3 = (arg9[v0] & 255) << 16 | (arg9[v0 + 1] & 255) << 8 | arg9[v0 + 2] & 255;
            v5.append(b.a[v3 >> 18 & 63]);
            v5.append(b.a[v3 >> 12 & 63]);
            v5.append(b.a[v3 >> 6 & 63]);
            v5.append(b.a[v3 & 63]);
            v3 = v0 + 3;
            v0 = v2 + 1;
            if(v2 >= 14) {
                v5.append(" ");
                v0 = 0;
            }

            v2 = v0;
        }

        if(v0 == -2 + v4) {
            v0 = (arg9[v0 + 1] & 255) << 8 | (arg9[v0] & 255) << 16;
            v5.append(b.a[v0 >> 18 & 63]);
            v5.append(b.a[v0 >> 12 & 63]);
            v5.append(b.a[v0 >> 6 & 63]);
            v5.append("=");
        }
        else if(v0 == -1 + v4) {
            v0 = (arg9[v0] & 255) << 16;
            v5.append(b.a[v0 >> 18 & 63]);
            v5.append(b.a[v0 >> 12 & 63]);
            v5.append("==");
        }

        return v5.toString();
    }

    public static byte[] a(String arg5) {
        ByteArrayOutputStream v0 = new ByteArrayOutputStream();
        try {
            b.a(arg5, ((OutputStream)v0));
        }
        catch(IOException v0_1) {
            throw new RuntimeException();
        }

        byte[] v1 = v0.toByteArray();
        try {
            v0.close();
        }
        catch(IOException v0_1) {
            System.err.println("Error while decoding BASE64: " + v0_1.toString());
        }

        return v1;
    }

    private static int a(char arg3) {
        int v0;
        if(arg3 < 65 || arg3 > 90) {
            if(arg3 >= 97 && arg3 <= 122) {
                return arg3 - 71;
            }

            if(arg3 >= 48 && arg3 <= 57) {
                return arg3 + 4;
            }

            switch(arg3) {
                case 43: {
                    goto label_31;
                }
                case 47: {
                    return 63;
                }
                case 61: {
                    return 0;
                }
            }

            throw new RuntimeException("unexpected code: " + arg3);
            return 63;
        label_31:
            v0 = 62;
        }
        else {
            v0 = arg3 - 65;
        }

        return v0;
    }

    private static void a(String arg5, OutputStream arg6) throws IOException {
        int v4 = 61;
        int v0 = 0;
        int v1 = arg5.length();
        while(true) {
            if(v0 < v1 && arg5.charAt(v0) <= 32) {
                ++v0;
                continue;
            }

            if(v0 != v1) {
                int v2 = (b.a(arg5.charAt(v0)) << 18) + (b.a(arg5.charAt(v0 + 1)) << 12) + (b.a(arg5.charAt(v0 + 2)) << 6) + b.a(arg5.charAt(v0 + 3));
                arg6.write(v2 >> 16 & 255);
                if(arg5.charAt(v0 + 2) != v4) {
                    arg6.write(v2 >> 8 & 255);
                    if(arg5.charAt(v0 + 3) != v4) {
                        arg6.write(v2 & 255);
                        v0 += 4;
                        continue;
                    }
                }
            }

            return;
        }
    }
}

xixicoco

直接给app，你这样没法调试的

梦迪丶

xixicoco 发表于 2019-12-14 17:11
直接给app，你这样没法调试的

好的，感谢大神帮忙。链接：https://pan.baidu.com/s/17NKBmiCZ_2euB9T7A8HPpQ
提取码：q6vm