Authentication of a client device based on entropy from a server or other device

A method comprising:

• receiving, at a client device, a user credential;
• in response to receiving the user credential, sending, by the client device, a request for first entropy generated by a server, wherein the first entropy expires at a predefined time;
• receiving, by the client device, the first entropy generated by the server;
• determining, based on the first entropy, a key for a second entropy generated by the server;
• decrypting, by the client device and using the key for the second entropy, the second entropy generated by the server;
• accessing, by the client device, a stored user credential based on the first entropy generated by the server and the decrypted second entropy generated by the server, wherein accessing the stored user credential based on the first entropy and the second entropy comprises:
• determining a key for the stored user credential based on the decrypted second entropy;
• and
• decrypting the stored user credential using the key for the stored user credential;
• and
• authenticating a user of the client device by comparing the received user credential to the stored user credential.

An apparatus, comprising:

• a processor;
• and
• memory storing computer-executable instructions that, when executed by the processor, cause the apparatus to:
• determine first entropy for a client device, the first entropy having an expiration time;
• determine second entropy for the client device;
• generate a key for the second entropy using a passcode for a user of the client device and the first entropy, wherein the passcode is usable to authenticate the user;
• encrypt the second entropy using the key for the second entropy;
• generate a key for the passcode using the first entropy and the second entropy;
• encrypt the passcode using the generated key for the passcode;
• and
• send the encrypted second entropy and the encrypted passcode to the client device.