350 lines
8.2 KiB
JavaScript
350 lines
8.2 KiB
JavaScript
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var crypto = require('crypto');
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var base32 = require('thirty-two');
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/*
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* Check a One Time Password based on a counter.
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*
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* First argument of callback is true if password check is successful,
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* or false if check fails.
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*
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* Second argument is the time step difference between the client and
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* the server. This argument is only passed if the password check is
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* successful.
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*
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* Arguments:
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*
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* args
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* K - Key for the one time password. This should be unique and secret for
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* every user as it is the seed used to calculate the HMAC
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*
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* P - Passcode to validate.
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*
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* W - The allowable margin for the counter. The function will check
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* W codes in the future against the provided passcode. Note,
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* it is the calling applications responsibility to keep track of
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* W and increment it for each password check, and also to adjust
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* it accordingly in the case where the client and server become
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* out of sync (second argument returns non zero).
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* E.g. if W = 100, and C = 5, this function will check the psscode
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* against all One Time Passcodes between 5 and 105.
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*
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* Default - 50
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*
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* C - Counter value. This should be stored by the application, must
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* be user specific, and be incremented for each request.
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*
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*/
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module.exports.checkHOTP = function(args, cb) {
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var hmac,
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digest,
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offset, h, v, p = 6, b,
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i,
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K = args.K || "",
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W = args.W || 50,
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C = args.C || 0,
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P = args.P || "";
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// Initiate the HMAC
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hmac = crypto.createHmac('SHA1', new Buffer(K))
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// Now loop through from C to C + W to determine if there is
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// a correct code
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for(i = C; i <= C+W; i++) {
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if(this._calcHMAC(K,i) === P) {
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// We have found a matching code, trigger callback
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// and pass offset
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cb(true, i - C);
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return;
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}
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}
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// If we get to here then no codes have matched, return false
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cb(false);
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return;
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};
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/*
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* Check a One Time Password based on a timer.
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*
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* First argument of callback is true if password check is successful,
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* or false if check fails.
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*
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* Second argument is the time step difference between the client and
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* the server. This argument is only passed if the password check is
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* successful.
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*
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* Arguments:
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*
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* args
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* K - Key for the one time password. This should be unique and secret for
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* every user as it is the seed used to calculate the HMAC
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*
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* P - Passcode to validate.
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*
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* W - The allowable margin for the counter. The function will check
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* W codes either side of the provided counter. Note,
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* it is the calling applications responsibility to keep track of
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* W and increment it for each password check, and also to adjust
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* it accordingly in the case where the client and server become
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* out of sync (second argument returns non zero).
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* E.g. if W = 5, and C = 1000, this function will check the psscode
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* against all One Time Passcodes between 995 and 1005.
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*
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* Default - 6
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*
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* T - The time step of the counter. This must be the same for
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* every request and is used to calculat C.
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*
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* Default - 30
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*
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*/
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module.exports.checkTOTP = function(args, cb) {
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var hmac,
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digest,
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offset, h, v, p = 6, b,
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C,i,
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K = args.K || "",
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W = args.W || 6,
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T = args.T || 30,
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P = args.P || "",
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_t;
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if(args._t) {
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// Time has been overwritten.
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console.log('#####################################');
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console.log('# NOTE: TOTP TIME VARIABLE HAS BEEN #');
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console.log('# OVERWRITTEN. THIS SHOULD ONLY BE #');
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console.log('# USED FOR TEST PURPOSES. #');
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console.log('#####################################');
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_t = args._t;
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} else {
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_t = new Date().getTime();
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}
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// Initiate the HMAC
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hmac = crypto.createHmac('SHA1', new Buffer(K))
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// Determine the value of the counter, C
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// This is the number of time steps in seconds since T0
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C = Math.floor((_t / 1000) / T);
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// Now loop through from C - W to C + W and check to see
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// if we have a valid code in that time line
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for(i = C-W; i <= C+W; i++) {
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if(this._calcHMAC(K,i) === P) {
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// We have found a matching code, trigger callback
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// and pass offset
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cb(true, i-C);
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return;
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}
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}
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// If we get to here then no codes have matched, return false
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cb(false);
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return;
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};
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/*
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* Gennerate a counter based One Time Password
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*
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* First argument of callback is the value of the One Time Password
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*
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* Arguments:
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*
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* args
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* K - Key for the one time password. This should be unique and secret for
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* every user as it is the seed used to calculate the HMAC
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*
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* C - Counter value. This should be stored by the application, must
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* be user specific, and be incremented for each request.
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*
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*/
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module.exports.getHOTP = function(args, cb) {
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var hmac,
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digest,
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offset, h, v, p = 6, b,
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i,
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K = args.K || "",
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C = args.C || 0,
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// Initiate the HMAC
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hmac = crypto.createHmac('SHA1', new Buffer(K))
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cb(this._calcHMAC(K,C));
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};
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/*
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* Gennerate a time based One Time Password
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*
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* First argument of callback is the value of the One Time Password
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*
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* Arguments:
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*
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* args
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* K - Key for the one time password. This should be unique and secret for
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* every user as it is the seed used to calculate the HMAC
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*
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* T - The time step of the counter. This must be the same for
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* every request and is used to calculat C.
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*
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* Default - 30
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*
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*/
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module.exports.getTOTP = function(args, cb) {
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var hmac,
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digest,
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offset, h, v, p = 6, b,
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C,i,
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K = args.K || "",
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T = args.T || 30,
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_t;
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if(args._t) {
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// Time has been overwritten.
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console.log('#####################################');
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console.log('# NOTE: TOTP TIME VARIABLE HAS BEEN #');
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console.log('# OVERWRITTEN. THIS SHOULD ONLY BE #');
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console.log('# USED FOR TEST PURPOSES. #');
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console.log('#####################################');
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_t = args._t;
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} else {
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_t = new Date().getTime();
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}
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// Initiate the HMAC
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hmac = crypto.createHmac('SHA1', new Buffer(K))
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// Determine the value of the counter, C
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// This is the number of time steps in seconds since T0
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C = Math.floor((_t / 1000) / T);
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cb(this._calcHMAC(K,C));
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};
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/*
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* Helper function to convert a string to a base32 encoded string
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*
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* Arguments:
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*
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* str - String to encode
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*
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* Returns: Base 32 encoded string
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*/
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module.exports.encBase32 = function(str) {
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return base32.encode(str);
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};
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/*
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* Helper function to convert a base32 encoded string to an ascii string
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*
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* Arguments:
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*
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* b32 - String to decode
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*
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* Returns: ASCII string
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*/
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module.exports.decBase32 = function(b32) {
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return base32.decode(b32);
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};
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/******************************************************************
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* NOTE: Any functions below this line are private and therefore *
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* may change without providing backwards compatibility with *
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* previous versions. You should not call the functions below *
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* directly. *
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*******************************************************************/
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/*
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* Private functon to calculate an HMAC.
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*
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* Arguments
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*
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* K - Key value
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* C - Counter value
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*
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* Returns - truncated HMAC
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*/
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module.exports._calcHMAC = function(K, C) {
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var hmac = crypto.createHmac('SHA1', new Buffer(K)),
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digest,
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offset, h, v, p = 6, b;
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// Create the byte array
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b = new Buffer(this._intToBytes(C)),
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// Update the HMAC witht he byte array
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hmac.update(b);
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// Diget the HMAC
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digest = hmac.digest('hex');
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// Get byte array
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h = this._hexToBytes(digest);
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// Truncate
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offset = h[19] & 0xf;
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v = (h[offset] & 0x7f) << 24 | (h[offset + 1] & 0xff) << 16 | (h[offset + 2] & 0xff) << 8 | (h[offset + 3] & 0xff);
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v = "" + v;
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v = v.substr(v.length - p, p);
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return v;
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};
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/*
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* Private function to convert an integer to a byte array
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*
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* Arguments
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*
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* num - Integer
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*
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* Returns - byte array
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*/
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module.exports._intToBytes = function(num) {
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var bytes = [],
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i;
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for(i=7;i>=0;i--) {
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bytes[i] = num & (255);
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num = num >> 8;
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}
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return bytes;
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};
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/*
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* Private function to convert a hex value to a byte array
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*
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* Arguments
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*
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* hex - Hex value
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*
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* Returns - byte array
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*/
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module.exports._hexToBytes = function(hex) {
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for(var bytes = [], c = 0; c < hex.length; c += 2)
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bytes.push(parseInt(hex.substr(c, 2), 16));
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return bytes;
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};
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