前言：

對於異或加密，在博文 異或加密 已經有了詳細說明，這邊博文將其用Android 實現。

例項：

Activity 中新增兩個呼叫的程式碼：

    private void testEncryptionXOR() {
        Button exor = (Button) findViewById(R.id.encrypt_xor);
        exor.setOnClickListener(this);

        Button dxor = (Button) findViewById(R.id.decrypt_xor);
        dxor.setOnClickListener(this);

        mXOREncryption = new XOREncryption(KEY_XOR);
    }

    private void xorEncryption() {
//        String strSource = "hliuhiufhliuhsd;jfijso;goshgosjogijsgo;j";
        String strSource = "呵呵哈哈";
        if (mXOREncryption != null) {
            Log.d(TAG, "==== strSource = " + strSource);
            mStrEncrypted = mXOREncryption.strEncrypt(strSource);
            Log.d(TAG, "==== strEncrypted = " + mStrEncrypted);
        }
    }

    private void xorDecrypted() {
        if (mXOREncryption != null) {
            String ret = mXOREncryption.strDecrypt(mStrEncrypted);
            Log.d(TAG, "==== strDecrypted = " + ret);
        }
    }
 

XOREncryption 程式碼（後期會進一步補充對於檔案的XOR 加密）：

public class XOREncryption {
    private final String mKey;

    public XOREncryption(String key) {
        mKey = key;

        if (TextUtils.isEmpty(mKey)) {
            throw new IllegalArgumentException("key is empty...");
        }
    }

    public String strEncrypt(final String strSource) {
        int i, j;
        StringBuilder sb = new StringBuilder();
        for (i = 0, j = 0; i < strSource.length(); i++) {
            j = i % mKey.length();
            sb.append((char) (strSource.charAt(i) ^ mKey.charAt(j)));
        }
        return sb.toString();
    }

    // 再次進行異或運算就可以解密
    public String strDecrypt(final String strSource) {
        return strEncrypt(strSource);
    }
}
 

執行的結果：

--------- beginning of main
--------- beginning of system
11-29 06:28:53.221  3633  3633 D TestEncryptionActivity: ==== strSource = 呵呵哈哈
11-29 06:28:53.221  3633  3633 D TestEncryptionActivity: ==== strEncrypted = 吔向咭咢
11-29 06:28:55.027  3633  3633 D TestEncryptionActivity: ==== strDecrypted = 呵呵哈哈