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An ordinary application running on a regular computer can read files from a USB drive and transmit them over the Internet. Such an application need not look like a “virus”, and the computer need not be “infected” for that to happen. That’s why it is highly inadvisable to print Mycelium Entropy wallets intended for any serious amounts through a computer—​unless that computer will never be connected to the Internet, will always be physically secure, and you know what you are doing.

Please print your wallets directly on a printer from your Entropy.

It is, of course, perfectly safe to plug Mycelium Entropy into a computer. While the wallets generated this way should be considered compromised and should only be used for experiments, the device itself is not under any threat. Even a computer full of malware cannot compromise any previous or future wallets from this device. There are certain simple precautions that must be followed in the Configuration and Firmware Update mode; they are described in the corresponding section of this manual.

However, please keep in mind that some printers are more secure than others. The following advice is taken from a report by luckdragon69.

Printers without a hard drive:

Pretty much any home/personal printer will not have a hard drive, but most will have some kind of memory installed. The type of printer, as well as the model, will determine how much, if any, memory is installed.

Even old printers (laser, dot matrix, inkjet, etc.) had some kind of memory that they used for storing data while printing.

Most memory that is in home/personal printers only hold the data for the current print job from anywhere from a few lines to a few pages, as the job is being printed. Once the job is complete or the printer is turned off, any data that was in memory is erased and unrecoverable. Printers commonly use basic RAM memory, which is commonly referred to as volatile memory since it cannot store data once power is removed.

In some cases the printer may be using volatile memory with a battery backup. If it is, this should be mentioned in the user guide. In that case, leave it unplugged for however long the user guide says is too long.
Printers with a hard drive:

Large office printers usually have a hard disk that may keep either a full copy of everything they print, or metadata, containing the filename and the user who created the print job.

  • If the printer allows you to bypass its internal hard drive and print directly from RAM, select this setting for better security to ensure that print jobs are not stored on the printer hard drive.

  • If the printer allows you to overwrite the data immediately after printing (or scanning or faxing, if it’s an all-in-one device), select that option.

  • Almost all new models include a wipe disk function for decommissioning the printer, and most include disk encryption, so if one takes the disk out of the printer they won’t be able to read the information stored on it.

  • If you do choose to store print jobs on the drive, ensure that it is encrypted with a strong encryption method, such as AES.

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