CreateChallenge Method

Creates the challenge.

Syntax

public void createChallenge();

Remarks

This method creates a Challenge. After calling this method the Challenge property will be populated with the created value.

When ChallengeType is set to ctRandom the following properties are applicable:

When ChallengeType is set to ctSignature the following properties are applicable:

In addition to creating the Challenge this method will also create the OCRASuite which defines parameters required by the other party to calculate a response. The following properties are applicable to OCRASuite creation:

Random Challenge Example

//First create the challenge on machine A
Ocra ocra = new Ocra();
ocra.ChallengeType = OcraChallengeTypes.ctRandom;
ocra.ChallengeLength = 10;
ocra.ChallengeFormat = OcraChallengeFormats.cfNumeric;
ocra.CreateChallenge();

string challenge = ocra.Challenge; //Value like "3891592139"
string ocraSuite = ocra.OCRASuite; //Value "OCRA-1:HOTP-SHA1-6:QN10"
//Send Challenge and OCRASuite to Machine B

//Upon receiving the challenge on Machine B, calculate a response
ocra = new Ocra();
ocra.OCRASuite = ocraSuite; //Received from other party
ocra.Challenge = challenge; //Received from other party
ocra.Key = "shared secret key";
ocra.CalculateResponse();

string response = ocra.Response; //Value like "574464"
//Send Response back to Machine A

//Upon receiving the response on Machine A, verify it
ocra = new Ocra();
ocra.OCRASuite = ocraSuite; //Original OCRASuite saved before sending the original challenge
ocra.Challenge = challenge; //Original challenge that was sent
ocra.Response = response;   //Received from other party
ocra.Key = "shared secret key";

bool isValid = ocra.VerifyResponse(); //Returns True if verified

Signature Challenge Example

//First create the challenge on machine A
Ocra ocra = new Ocra();
ocra.ChallengeType = OcraChallengeTypes.ctSignature;
ocra.ChallengeInput = "test input";
ocra.Key = "signature key";
ocra.ChallengeFormat = OcraChallengeFormats.cfHex;
ocra.CreateChallenge();

string challenge = ocra.Challenge; //Value like "973131F0"
string ocraSuite = ocra.OCRASuite; //Value "OCRA-1:HOTP-SHA1-6:QH08"
//Send Challenge and OCRASuite to Machine B

//Upon receiving the challenge on Machine B, calculate a response
ocra = new Ocra();
ocra.OCRASuite = ocraSuite; //Received from other party
ocra.Challenge = challenge; //Received from other party
ocra.Key = "shared secret key";
ocra.CalculateResponse();

string response = ocra.Response; //Value like "574464"
//Send Response back to Machine A

//Upon receiving the response on Machine A, verify it
ocra = new Ocra();
ocra.OCRASuite = ocraSuite; //Original OCRASuite saved before sending the original challenge
ocra.Challenge = challenge; //Original challenge that was sent
ocra.Response = response;   //Received from other party
ocra.Key = "shared secret key";

bool isValid = ocra.VerifyResponse(); //Returns True if verified