AGOtp Class Reference
| Inherits from | NSObject |
| Declared in | AGOtp.h AGOtp.m |
Overview
The Otp class generates a one-time password (OTP) using the HMAC-Based One-Time Password Algorithm described in RFC6238: http://tools.ietf.org/html/rfc6238
The HOTP algorithm is based on an increasing counter value and a static symmetric key known only to the token and the validation service. In order to create the HOTP value, we will use the HMAC- SHA-1 algorithm, as defined in RFC 2104.
As the output of the HMAC-SHA-1 calculation is 160 bits, we must truncate this value to something that can be easily entered by a user.
HOTP(K,C) = Truncate(HMAC-SHA-1(K,C))
Where:
- Truncate represents the function that converts an HMAC-SHA-1 value into an HOTP value as defined in Section 5.3 of RFC4226.
The Key (K), the Counter ©, and Data values are hashed high-order byte first.
The HOTP values generated by the HOTP generator are treated as big endian.
Tasks
-
– initWithSecret:Returns an AGOtp object initialized with a secret specified by the given string.
-
– generateOTPForCounter:Generate an OTP token using the specified counter.
-
– generateOTPEntry point to generate an OTP token.
Instance Methods
generateOTP
Entry point to generate an OTP token.
- (NSString *)generateOTPReturn Value
An NSString that contains the token with leading zero-padding as required.
Discussion
Entry point to generate an OTP token.
NOTE: Subclasses should override this method.
Declared In
AGOtp.hgenerateOTPForCounter:
Generate an OTP token using the specified counter.
- (NSString *)generateOTPForCounter:(uint64_t)counterParameters
- counter
The counter to use.
Return Value
An NSString that contains the token with leading zero-padding as required.
Discussion
Generate an OTP token using the specified counter.
Declared In
AGOtp.hinitWithSecret:
Returns an AGOtp object initialized with a secret specified by the given string.
- (id)initWithSecret:(NSData *)secretParameters
- secret
The secret to use.
Return Value
An AGTotp object initialized by the specified secret.
Discussion
Returns an AGOtp object initialized with a secret specified by the given string.
Declared In
AGOtp.h