All our images are digitally signed and therefore it's possible to check their authenticity. You need to unzip the download package and issue those commands (Linux/macOS, you might need to install dependencies first, eg. `apt-get install gnupg p7zip` on Debian/Ubuntu or `brew install gnupg p7zip` on macOS):
Since it might happen that your download got somehow corrupted we integrate a checksum/hash for the image. After uncompressing the download you can compare the image's SHA-256 hash with the one contained in the `sha256sum.sha` file. On Windows you can use [7-Zip's built-in hash functionality](https://superuser.com/a/1024913) to display the SHA256 hash while on Linux/macOS you would do this
shasum -a 256 -c sha256sum.sha Armbian_*.img
Armbian_5.35_Clearfogpro_Debian_stretch_next_4.13.16.img: OK
**Important note:** Make sure you use a **good, reliable and fast** SD card. If you encounter boot or stability troubles in over 95 percent of the time it's either insufficient power supply or related to SD card (bad card, bad card reader, something went wrong when burning the image, card too slow to boot -- 'Class 10' highly recommended!). Armbian can simply not run on unreliable hardware so checking your SD card with either [F3](http://oss.digirati.com.br/f3/) or [H2testw](http://www.heise.de/download/h2testw.html) is mandatory if you run in problems. Since [counterfeit SD cards](http://www.happybison.com/reviews/how-to-check-and-spot-fake-micro-sd-card-8/) are still an issue checking with F3/H2testw directly after purchase is **highly recommended**.
7z and zip archives can be uncompressed with [7-Zip](http://www.7-zip.org/) on Windows, [Keka](http://www.kekaosx.com/en/) on OS X and 7z on Linux. Images shall only be written with [Etcher](https://www.etcher.io) on all platforms since unlike other tools Etcher validates burning results **saving you from corrupted SD card contents**.
Also important: Most SD cards are only optimised for sequential reads/writes as it's common with digital cameras. This is what the *speed class* is about. The SD Association defined [*Application Performance Class*](https://www.sdcard.org/developers/overview/application/index.html) as a standard for random IO performance.
At the time of this writing A1 and A2 cards are only widely available from SanDisk. Armbian **only** recommends A1 rated SD-Cards now ([A2 rated cards need yet lacking driver support and therefore show lower overall and especially random IO performance](https://github.com/ThomasKaiser/Knowledge/blob/master/articles/A1_and_A2_rated_SD_cards.md)). For example:
In case you chose an SD card that was already in use before please consider resetting it back to 'factory default' performance with [SD Formatter](https://www.sdcard.org/downloads/formatter_4/) before burning Armbian to it ([explanation in the forum](https://forum.armbian.com/index.php?/topic/3776-the-partition-is-not-resized-to-full-sd-card-size/&do=findComment&comment=27413)). Detailed information regarding ['factory default' SD card performance](https://forum.armbian.com/topic/954-sd-card-performance/?page=3&tab=comments#comment-49811).
Login as **root** on console (HDMI / serial) or via SSH and use password **1234**. You will be prompted to change this password at first login. You will then be asked to create a normal user account that is sudo enabled (beware of default QWERTY keyboard settings at this stage). Please use [this tool](http://angryip.org/), to find your board IP address.
On Allwinner devices after switching to boot from NAND or eMMC clearing the boot loader signature on the SD card is recommended: `dd if=/dev/zero of=/dev/mmcblkN bs=1024 seek=8 count=1` (replace `/dev/mmcblkN` with the correct device node -- in case you run this directly after `nand-sata-install` without a reboot in between then it's `/dev/mmcblk0`). When booting from eMMC to get SD cards auto-detected on Allwinner legacy images please consider changing `mmc0`'s `sdc_detmode` from 3 to 1 in the board's fex file (see [here](http://forum.armbian.com/index.php/topic/1702-orange-pi-plus-2e-where-is-16ghz-and-sd/?p=13163) for details).
