Abstract: During a software activation process, a processing device may provide a software license key to be communicated to an activation authority. The software license key may be provided to the activation authority via one of a number of communication methods, such as, for example, via a telephone, via a facsimile, via e-mail, via a text message, or via other communication methods. A length of the software license key may be based on an expected amount of time to provide the software license key to the activation authority. When the expected amount of time is relatively long, the software license key may be relatively short. When the expected amount of time is relatively short, the software license key may be relatively long. In some embodiments, a relatively short software license key may be a unique subset of a relatively long software license key.

Abstract: In various embodiments, a server may be provided. The server may respond to a request for a service, from a processing device, with a challenge. The challenge may include a partial key for a memory-intensive operation, a number of iterations of the memory-intensive operation to perform, and a result of performing the number of iterations of the memory-intensive operation. Upon receiving the challenge, the processing device may choose a complete key consistent with the partial key and may produce a proposed result by performing the memory-intensive operation for the number of iterations. When the proposed result matches the result included in the challenge, the processing device may send a challenge answer, including the chosen complete key, to the server. Upon receiving a correct challenge answer from the processing device, the server may access the requested service and may return a result of the access to the processing device.

Abstract: During a software activation process, a processing device may provide a software license key to be communicated to an activation authority. The software license key may be provided to the activation authority via one of a number of communication methods, such as, for example, via a telephone, via a facsimile, via e-mail, via a text message, or via other communication methods. A length of the software license key may be based on an expected amount of time to provide the software license key to the activation authority. When the expected amount of time is relatively long, the software license key may be relatively short. When the expected amount of time is relatively short, the software license key may be relatively long. In some embodiments, a relatively short software license key may be a unique subset of a relatively long software license key.

Abstract: In various embodiments, a server may be provided. The server may respond to a request for a service, from a processing device, with a challenge. The challenge may include a partial key for a memory-intensive operation, a number of iterations of the memory-intensive operation to perform, and a result of performing the number of iterations of the memory-intensive operation. Upon receiving the challenge, the processing device may choose a complete key consistent with the partial key and may produce a proposed result by performing the memory-intensive operation for the number of iterations. When the proposed result matches the result included in the challenge, the processing device may send a challenge answer, including the chosen complete key, to the server. Upon receiving a correct challenge answer from the processing device, the server may access the requested service and may return a result of the access to the processing device.