...

If you are looking for information on how to set up encryption key and configure other download settings in mi2b2, please refer to this page instead.

In this document, when we say "random" or "randomly", we mean "pseudo-random" and "pseudo-randomly", that is, the randomness is produced by a deterministic algorithm to simulate true randomness, which can only be reliably obtained via observing natural phenomena.

...

A key (randomly generated via the key-generation mechanism or user-provided) and the initialization vector are then used in the encryption process.

...

Users have two ways of obtaining a key for encryption (see Key Dialog). The first is to generate a random key automatically. mi2b2 will use the build-in Java cryptographic methods to generate a key and write that key to a file. The file then can be shared among different users to open all images encrypted with that key.

...

The zipped study file is organized hierarchically by Study UID (top level), Series ID (mid level), and Image Instance ID. The first two levels are directories, named by their IDs. These IDs are produced using DICOM standards, and those who know how to read the IDs can identify what institution, department, machine, and date/time the particular study started, and use the assembled information to narrow down or identify the patient. To prevent this kind of attack, when encryption is chosen, mi2b2 will rename these studies, series, and images. Studie UIDs and Series IDs will be hashed (using the MD5 cryptographic hash function). The hashed value (16-bytes long) is then written out to be a string of 16 hexadecimal numbers (32 characters, 2 characters per 1 hexadecimal number) and pre-pended with "Study-" or "Series-" appropriately and appended with ".encrypted" (1, 2). The image files, on the other hand, are named "Study-num", where num stands for the instance number of that image in its series. The image files are also appended with ".encrypted" (3). This helps the users identify which files appear before which.

...