This question already has an answer here:
I have the php code for making HMAC md5 encryption
$input = 'foo';
$output = hash_hmac('md5', $input, $secretKey);
After making the hash,is there anyway I could get the $input back to text form.
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The difference between encryption (which MD5 is not) and hashing is that hashing is unidirectional. The answer is no.