Question

I’m not php expert and I don’t know what’s the difference(1) between a and b.

a.)eval('return "'.base64_decode("encoded_text").'";')

b.)base64_decode("encoded_text")

-I THINK, a is php code and b is just string. And my other question is:

What is the difference(2) between c and d?

c.)eval('return "'.base64_decode("encoded_text").'";')

d.)eval(base64_decode("encoded_text"))

So I have 2 questions. Who can answer/help ?

Thanks.

Answer 1

Let’s label your 2 cases as Case X (part a and b) and Y (part c and d).

Case X

For this, both of the parts have no difference from each other. In fact, part a has some redundancy.

If you evaluate them slowly, you will notice how redundant it is:

Part a
In this part, the difference is that you add the eval statement with return in the string for evaluation.

1. echo eval('return "'.base64_decode("encoded_text").'";');
2. echo eval('return "decoded_text";')'
3. echo "decoded_text";

Part b

1. echo base64_decode("encoded_text");
2. echo "decoded_text";

Case Y

For this, there’s grave difference.

Part c

1. echo eval('return "'.base64_decode("encoded_text").'";');
2. echo eval('return "decoded_text";')'
3. echo "decoded_text";

Part d

1. echo eval(base64_decode("encoded_text"));
2. echo eval("decoded_text"); – there may be a syntax error here, because decoded_text may or may not be proper PHP code.