关于加密还原问题，急待！！！

[opet_zhu]

public static String encrypt(String password)
{
char c1[] = password.toCharArray();

for (int i = 0; i < password.length(); i++)
{
c1[i] = (char) (i + c1[i]);
}

return new String(c1);
}

public static void main(String[] args) {
System.out.println(encrypt("opet123456"));
// 输出为：oqgw579;=?

}

现在我想写个函数，传入"oqgw579;=?" 输出为：opet123456
请大侠们帮我看看。写个函数。谢谢

[mickey_uuu]

public static String decrypt(String encryptPassword)
{
char c1[] = encryptPassword.toCharArray();

for (int i = 0; i < encryptPassword.length(); i++)
{
c1[i] = (char) (c1[i]-i);
}

return new String(c1);
}