凯撒加密解密

凯撒加密解密

• 古罗马大帝凯撒发明:对字符串偏移

 

 

    public static String encrypt(String str, int key) {
        StringBuilder stringBuilder = new StringBuilder();
        char[] array = str.toCharArray();
        for (char c : array) {
            int value = c;
            value += key;
            char cs = (char) value;
            stringBuilder.append(cs);
        }
        return stringBuilder.toString();
    }

    public static String decryp(String str, int key) {
        StringBuilder stringBuilder = new StringBuilder();
        char[] array = str.toCharArray();
        for (char c : array) {
            int value = c;
            value -= key;
            char cs = (char) value;
            stringBuilder.append(cs);
        }
        return stringBuilder.toString();
    }

频度分析法破解凯撒加密算法

• 根据统计学破解凯撒算法：一篇英文文章字母e出现的概率很高