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When users download a study from the mi2b2 server's cache, the study is copied from the cache, and written to the user's download location. The study resides on the cache as a zip file. As the zip file is being streamed to user's mi2b2 client, the client performs unzipping and encryption as the stream goes onimage data streams in. That is, the client does not wait for the entire zip file to complete downloading before unzipping and encrypting. As long as there is enough data soon a sufficient data is available to unzip, the client will unzip, encrypt that chunk of data, and write to disk when appropriate.

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This ensures that there is not a unencrypted zip file sitting at the download location at any time. This measure prevents attackers, for example, interrupting the power supply after downloading completes but before encryption process takes place to obtain unencrypted images.

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