3/19/2024 0 Comments Google authenticator hotp vs totpThe challenge response mechanism also prevents replay attacks and the signature from the key is also single use. The private key is still stored in the security key. The key also requires a human to physically press the button ( HID protocol), so it cannot be activated remotely.Įven if an attacker manages to infect the server and steal the public key from the server, they would still not be able to sign the challenge and login. It is a hardware security token, so even if the computer is infected with malware, attackers wont be able to steal the secret key in it. So the attacker cannot gain access to the real signature. Since the domain of the website is used to generate the key, during a phishing attack it will generate a different key and the checksum will fail. The server verifies the signature using the public key. The device then signs the challenge with the private key using ECDSA ( Elliptic Curve Digital Signature Algorithm) and sends this to the server. The security key applies the same process to generate the same private key and uses the checksum to confirm that the nonce did come from the device. The server generates a challenge - a random number and passes this along with the nonce and checksum generated on registration. The secret key never leaves the device.įor logging in after registration, the user needs to plug in the key and press the button. From this private key, a public key is generated with a checksum, also secured by secure hash and sends this to the server along with the nonce. FIDO U2F uses HMAC-SHA-256 which is more secure than TOTP hash function ( SHA-1). When the user first wants to register a key with an account, the security key generates a private key with a random number ( nonce) and uses a secure hashing function to hash the nonce, domain of the website that the user is in in and a secret key. The user also does not have to type in the key unlike OTPs. It works out of the box without any device drivers or software installations. If a victim enters the username/password and the OTP into a malicious page, the attacker can quickly use them on the target site, thus gaining control of the user's account.įIDO U2F is an open authentication standard, which allows users to access online services with a physical security key. OTP, HOTP and TOTP are still susceptible to phishing attacks. It is impossible for the attacker to guess the secret keys based on any OTP. The server should additionally account for time drifts.Īuthenticator apps such as Google Authenticator, Authy, 1Password can be used to generate TOTP. If the code is not used in this window, it will become invalid and a new code has to be generated. Each code is generally valid for 30 seconds. It is similar to HOTP, but the counter is replaced with timestamp values. TOTP is used to generate a regularly changing code based on a shared secret and current time. Yubico's Yubikey is an example of OTP generator that uses HOTP. The HOTP code is valid until a new code is generated, which is now seen as a vulnerability. To calculate an OTP, the shared secret and the counter are fed into the HMAC algorithm, which uses SHA-1 as a hash function. The HOTP generator and the server are synced each time the code is validated. Each time HOTP is requested and validated, the counter is incremented. Similar to OTP, HOTP is generated with a shared secret and the moving factor is based on a counter. Sim porting attacks allows an attacker to take over the victim's number to their own device and receive SMS destined to the victim. It might be more convenient, but is less secure. Many services use SMS OTP as a second form of authentication. Industry standard algorithms such as SHA-1 generate OTPs with a shared secret and a moving factor. It is therefore also resistant to replay attacks since one OTP is only tied to one session. OTPs are generated with algorithms generating random numbers. The user receives an SMS or a voice call with their One Time Password. Generally a combination of username/password and a second authentication factor is used to authenticate the user to the service.Ĭommon 2FA authentication methods include:īiometric (Fingerprint, Retina pattern, facial recognition)įIDO U2F - Fast Identity Online Universal Second Factor So, even if your password is stolen or your phone is lost, it is highly unlikely for the attacker to gain access to your account. With 2FA, a compromise of one of these factors will not provide access to the account.
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