public static int GetVerificationCode(int value, string secretStr)
{
byte[] val = new byte[8];
for (int i = 8; (i--) != 0; value >>= 8)
{
val[i] = (byte)(value & 0xFF);
}
byte[] secret = Base32Encoding.ToBytes(secretStr);
if (secret == null || secret.Length == 0)
{
return(-1);
}
System.Security.Cryptography.HMACSHA1 hmac = new System.Security.Cryptography.HMACSHA1(secret, true);
byte[] hash = hmac.ComputeHash(val);
int offset = hash[SHA1_DIGEST_LENGTH - 1] & 0xF;
uint truncatedHash = 0;
for (int i = 0; i < 4; ++i)
{
truncatedHash <<= 8;
truncatedHash |= hash[offset + i];
}
truncatedHash &= 0x7FFFFFFF;
truncatedHash %= 1000000;
return((int)truncatedHash);
}
public static string CreateNewSecret(int secretLengthInBits)
{
byte[] buf = new byte[secretLengthInBits / 8];
System.Security.Cryptography.RNGCryptoServiceProvider rnd = new System.Security.Cryptography.RNGCryptoServiceProvider();
rnd.GetBytes(buf);
return(Base32Encoding.ToString(buf));
}
