C#

HOTP Algorithm: HMAC-Based One-Time Password Algorithm

See more Encryption Examples

Demonstrates how to generate an HMAC one-time password (HOTP) as specified in RFC 4226.

Note: This example requires Chilkat v9.5.0.77 or greater.

C#

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

//  Duplicate the following results from RFC 4226

//  Appendix D - HOTP Algorithm: Test Values
//  
//    The following test data uses the ASCII string
//    "12345678901234567890" for the secret:
//  
//    Secret = 0x3132333435363738393031323334353637383930
//  
//                      Truncated
//    Count    Hexadecimal    Decimal        HOTP
//    0        4c93cf18       1284755224     755224
//    1        41397eea       1094287082     287082
//    2         82fef30        137359152     359152
//    3        66ef7655       1726969429     969429
//    4        61c5938a       1640338314     338314
//    5        33c083d4        868254676     254676
//    6        7256c032       1918287922     287922
//    7         4e5b397         82162583     162583
//    8        2823443f        673399871     399871
//    9        2679dc69        645520489     520489

string secret = "12345678901234567890";
int count;
for (count = 0; count <= 9; count++) {
    string counterHex = crypt.EncodeInt(count,8,false,"hex");
    string hotp = crypt.Hotp(secret,"ascii",counterHex,6,-1,"sha1");
    Debug.WriteLine(Convert.ToString(count) + "  HOTP = " + hotp);
}

//  Output is:
//  0  HOTP = 755224
//  1  HOTP = 287082
//  2  HOTP = 359152
//  3  HOTP = 969429
//  4  HOTP = 338314
//  5  HOTP = 254676
//  6  HOTP = 287922
//  7  HOTP = 162583
//  8  HOTP = 399871
//  9  HOTP = 520489