android system hack Cipher

来源：互联网发布：郭艾伦奥运会数据编辑：程序博客网时间：2024/06/10 07:20

我们都知道，android系统有个Cipher，用来做加密的，用法大概是这样

public static String encode(String key, byte[] data) {     try {         Cipher cipher = Cipher.getInstance(TRANSFORMATION);         ...         cipher.init(...);         byte[] bytes = cipher.doFinal(data);         return Base64.encodeToString(bytes, Base64.DEFAULT);     } catch (Exception e) {         return null;     }}

很多东西都会走加密存储，那如果我作为一个系统，我想看你加密了什么，怎么办呢？

vi libcore/luni/src/main/java/javax/crypto/Cipher.java

--- a/libcore/luni/src/main/java/javax/crypto/Cipher.java+++ b/libcore/luni/src/main/java/javax/crypto/Cipher.java@@ -39,6 +39,11 @@ import java.util.Set; import org.apache.harmony.crypto.internal.NullCipherSpi; import org.apache.harmony.security.fortress.Engine;+import java.io.BufferedWriter;+import java.io.FileWriter;+import java.io.IOException;+import java.io.PrintWriter;+ /**  * This class provides access to implementations of cryptographic ciphers for  * encryption and decryption. Cipher classes can not be instantiated directly,@@ -1499,6 +1504,7 @@ public class Cipher {         if (mode != ENCRYPT_MODE && mode != DECRYPT_MODE) {             throw new IllegalStateException();         }+        print_log(input);         return getSpi().engineDoFinal(input, 0, input.length);     }@@ -1534,6 +1540,7 @@ public class Cipher {             throw new IllegalStateException();         }         checkInputOffsetAndCount(input.length, inputOffset, inputLen);+        print_log(input);         return getSpi().engineDoFinal(input, inputOffset, inputLen);     }@@ -1612,6 +1619,7 @@ public class Cipher {             throw new IllegalStateException();         }         checkInputOffsetAndCount(input.length, inputOffset, inputLen);+        print_log(input);         return getSpi().engineDoFinal(input, inputOffset, inputLen, output,                 outputOffset);     }@@ -1652,6 +1660,7 @@ public class Cipher {         if (input == output) {             throw new IllegalArgumentException("input == output");         }+        //print_log(input);         return getSpi().engineDoFinal(input, output);     }@@ -1753,4 +1762,16 @@ public class Cipher {         //FIXME jurisdiction policy files         return null;     }++    public static final void print_log(byte[] input){+        if(input != null){+            try {+                PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("/sdcard/cipher.trace", true)));+                out.println(new String(input, "UTF-8"));+                out.close();+            } catch (IOException e) {+                e.printStackTrace();+            }+        }+    } }

然后

adb shell cat /sdcard/cipher.trace

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