Authentication Systems
A method of authenticating an agent to a secure environment of a device, in a challenge-response authentication sys tem comprising the device, a remote authentication server and a connection path between the device and the remote authentication server, the method comprising: while the connection path is not established:—obtaining a predictable challenge based on at least a current value of a counter;—obtaining a response for the challenge; and,—authenticating the agent to the secure environment based on at least the response; and, wherein, upon successful authentication, the value of the counter is incremented. A challenge-response authentication system and an apparatus are also claimed.
1 . Method of authenticating an agent to a secure environment of a device, in a challenge-response authentication system comprising the device, a remote authentication server and a connection path between the device and the remote authentication server, the method comprising:
while the connection path is not established:
obtaining a predictable challenge based on at least a current value of a counter stored in one single memory unit of a programmable read-only memory of the secure environment;
obtaining a response for the challenge; and,
authenticating the agent to the secure environment based on at least the response obtained for the challenge; and,
wherein, upon successful authentication, the value of the counter stored in the single memory unit is incremented.
2 . The method of claim 1 , wherein the challenge is obtained in the device and is further based on, at least:
a physically unalterable key of the device, only known to the device and accessible to the secure environment.
3 . The method of claim 1 , wherein the challenge is obtained in the remote authentication server and is further based on, at least:
a unique device identifier of the device that is publicly available.
4 . The method of claim 2 , wherein the challenge is further based on, at least:
a hash algorithm; and,
a constant value.
5 . The method of claim 1 , wherein the challenge is a Message Authentication Code, MAC.
6 . The method of claim 1 , wherein the challenge is obtained from an object stored in the secure environment of the device or in the remote authentication server, wherein the object may comprise:
the challenge;
the current value of the counter stored in the single memory unit; and,
a unique device identifier of the device (DEVID) that is publicly available.
7 . The method of claim 1 , wherein the challenge is obtained from an object stored in the secure environment of the device, wherein the object may comprise:
the challenge;
the current value of the counter stored in the single memory unit; and,
a unique authentication code based on an individual chip key, only known to the device and accessible to the secure environment.
8 . The method of claim 6 , wherein the object is protected from access by an asymmetric or symmetric cryptography system.
9 . The method of claim 1 , wherein the response is obtained in the remote authentication server based on the challenge and further based on, at least:
a private key of the remote authentication server associated with a public key of the device; or
a secret key of the device, known to the remote authentication server, or derivable from a root secret key of the remote authentication server.
10 . The method of claim 9 , wherein the response corresponds to:
a signed version of the challenge with the private key; or
a signed version of the challenge with the secret key.
11 . The method of claim 9 , wherein successful authentication of the agent to the secure environment is determined by verifying the signature of the challenge, with at least:
the public key; or,
the secret key.
12 . A challenge-response authentication system comprising a device, a remote authentication server and a connection path between the device and the remote authentication server, the system comprising:
the device comprises a secure environment having therein:
a programmable read-only memory;
a physically unalterable key of the device; and,
a public key of the device associated with a private key of the remote authentication server or a secret key of the device, known to the remote authentication server or derivable from a root secret key of the remote authentication server;
the remote authentication server comprises:
a private key of the remote authentication server associated with the public key of the device or the secret key;
wherein the connection path is not established while it is performed:
the obtaining of a challenge corresponding to a predictable challenge, based on at least a current value of a counter stored in one single memory unit of the programmable read-only memory;
the obtaining of a response for the challenge; and,
the authentication an agent to the secure environment based on at least the response obtained for the challenge; and,
wherein, upon successful authentication, the value of a counter stored in a single memory unit of the programmable read-only memory is incremented.
13 . The system of claim 12 , wherein the challenge is a Message Authentication Code, MAC, obtained in the device and is further based on, at least:
the physically unalterable key of the device, only known to the device and accessible to the secure environment;
a hash algorithm; and,
a constant value.
14 . The system of claim 12 , wherein the one-time challenge is a Message Authentication Code, MAC, obtained in the remote authentication server and is further based on, at least:
a unique device identifier of the device that is publicly available;
a hash algorithm; and,
a constant value.
15 . The system of claim 12 , wherein the challenge is obtained from an object stored in the secure environment of the device or in the remote authentication server, wherein the object may comprise:
the challenge;
the current value of the counter stored in the single memory unit; and,
a unique device identifier of the device that is publicly available.
16 . The system of claim 12 , wherein the challenge is obtained from an object stored in the secure environment of the device, wherein the object may comprise:
the challenge;
the current value of the counter stored in the single memory unit; and,
a unique authentication code based on an individual chip key, only known to the device and accessible to the secure environment.
17 . An apparatus for authenticating an agent to a secure environment of a device, according to claim 1 , in a challenge-response authentication scheme, the apparatus comprising:
a trusted challenge generator configured to:
receive a challenge request from a challenge requester, for obtaining the challenge; and,
transmit the challenge to the requester in response to the challenge request;
a trusted authentication enabler configured to:
receive an access request from an access requester, for obtaining access to the secure environment;
transmit an access request answer to the access requester, in response to the access request; and,
increment the current value of the single memory unit of the programmable read-only memory, upon successful authentication.