RC4 是一种简单的对称加密算法,在文本加密,通信加密等场景应用非常广泛。
在Web中可以用来对本地存储数据进行加密,比如存储cookie中的用户名和密码,敏感信息等。
以下是本人根据其思想基于JS实现的算法。
function rc4(data,key)
{
var pwd = key || 'COwC2GiRIaouOuiQSxamm8NO8U1s1jNNWuSwteOCnM3C6gHa';
var cipher = '';
var key = [];
var box = [];
var pwd_length = pwd.length;
var data_length = data.length;
for (i = 0; i < 256; i++) {
key[i] = pwd[i % pwd_length].charCodeAt();
box[i] = i;
}
for (j = i = 0; i < 256; i++) {
j = (j + box[i] + key[i]) % 256;
tmp = box[i];
box[i] = box[j];
box[j] = tmp;
}
for (a = j = i = 0; i < data_length; i++) {
a = (a + 1) % 256;
j = (j + box[a]) % 256;
tmp = box[a];
box[a] = box[j];
box[j] = tmp;
k = box[((box[a] + box[j]) % 256)];
cipher += String.fromCharCode(data[i].charCodeAt() ^ k);
}
return cipher;
}