However, I work for a French company and I cannot prohibit user from using special key in their password. Could you Help me? Thank You. Join our community to see this answer! Unlock 1 Answer and 7 Comments. Andrew Hancock - VMware vExpert. See if this solution works for you by signing up for a 7 day free trial.
What do I get with a subscription? With your subscription - you'll gain access to our exclusive IT community of thousands of IT pros. We can't always guarantee that the perfect solution to your specific problem will be waiting for you. This isn't necessarily a problem for a dictionary that can be optimized for the specific language, but if you want to get the same performance out of a regular expression, you would have to have a single branched expression with a size proportional to the entire dictionary.
I should probably add that the task is to determine, in O n time, that. Dennis Jones. No, but such code would often run the first time the user uses the software, and first impressions are important. But that is not what the OP asked for. He didn't ask for a dictionary. There are two overloaded public GeneratePassword method calls taking the Secret Key and Counter Value as required inputs. There are a few private variables for use later in the code ModTable allows for trimming of the Hash result based on output length desired, FormatTable is used for padding the string result based on desired length and a RFCMinimumKeyLengthBytes to specify the minimum length of the secret key.
If you follow the industry standard convention of storing your Secret Keys as base32 encoded UTF-8 strings, use the first overloaded method and pass in the encoded password. Otherwise, pass the plain text Secret Key as an array of bytes using the second overloaded GeneratePassword method keep in mind the rule that the prover and verifier must always match input values so be careful that client and server use the same string encoding.
As you can see, the first overloaded method simply converts the base32 encoded Secret Key string into an array of bytes and calls the main GeneratePassword method. We define an offset based on the last byte of the hash digest and then extract 4-bytes from the hash starting at that offset value. We then truncate value to the length requested via a mod operation and left-pad the integer result with zeros.
The RFCs provides test vectors to validate our custom implementation which can easily be implemented in two DUnit tests as shown below:. Combined with the base32 encoding from the first article in the series , we now have everything needed to implement one-time passwords in Delphi! This code will continue to be used in this blog series dedicated to building a custom RADAuthenticator app intended to replace the Google Authenticator app.
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