A simple tool for simple people.

This is a code port of 3 different programs:

• 3ds_encrypt.py
• 3ds_decrypt.py
• woodsec (part of wooddumper)

This tool allows you to encrypt and decrypt your personally dumped NDS and N3DS roms with minimal hassle. The only caveat right now is that you need a keys.bin file for your personally obtained encryption keys.

NDecrypt.exe <operation> [flags] <path> ...

Possible values for <operation>:
e, encrypt - Encrypt the input files
d, decrypt - Decrypt the input files

Possible values for [flags] (one or more can be used):
-c, --citra           - Enable using aes_keys.txt instead of keys.bin
-dev, --development   - Enable using development keys, if available
-f, --force           - Force operation by avoiding sanity checks
-h, --hash            - Output size and hashes to a companion file
-k, --keyfile <path>  - Path to keys.bin or aes_keys.txt

<path> can be any file or folder that contains uncompressed items.
More than one path can be specified at a time.

Note: This overwrites the input files, so make backups if you're working on your original, personal dumps.

Note: Mixed folders or inputs are also accepted, you can decrypt or encrypt multiple files, regardless of their type. This being said, you can only do encrypt OR decrypt at one time.

You (possibly*) are! In fact, you may be asking, "Hey, what was that keys.bin you mentioned??". I'm glad you asked. It's used only for Nintendo 3DS and New 3DS files. Since some people don't like reading code, you need the 9 16-bit keys in little endian format (most common extraction methods produce big endian, so keep that in mind). It's recommended that you fill with 0x00 if you don't have access to a particular value so it doesn't mess up the read. They need to be in the following order:

• Hardware constant
• KeyX0x18 / slot0x18KeyX
• KeyX0x1B / slot0x1BKeyX
• KeyX0x25 / slot0x25KeyX
• KeyX0x2C / slot0x2CKeyX
• DevKeyX0x18
• DevKeyX0x1B
• DevKeyX0x25
• DevKeyX0x2C

The last 4 are only required if you use the -dev flag. Once again, don't ask for these, please. If you're missing a required key, then things won't work. Don't blame me, blame society. Or something. And yes, I'll fix this being required across the board at some point.

*If you choose to use the -c option, you can instead provide your personally filled out aes_keys.txt file in the same folder as NDecrypt and that can be used instead. Please note that if you choose to use this file, you will not be able to use the -dev flag. If you forget and happen to use them together, NDecrypt will disable that flag for you. You're welcome.

As much as I'd like to think that this program is entirely without flaws, numbers need to speak for themselves sometimes. Here's a list of the supported sets and their current compatibility percentages with woodsec and the Python scripts (as of 2020-12-19):

• Nintendo DS - >99% compatible (Both encryption and decryption)
• Nintendo DSi - 100% compatible (Both encryption and decryption)
• Nintendo 3DS - 100% compatible (Both encryption and decryption)
• Nintendo New 3DS - 100% compatible (Both encryption and decryption)

Please note the above numbers are based on the current, documented values. The notable exceptions to this tend to be unlicensed carts which may be dumped incorrectly or have odd information stored in their secure area.

I'd like to thank the developers of the original programs for doing the actual hard work to figure things out. I'd also like to thank everyone who helped to test this against the original programs and made code suggestions.

This program is ONLY for use with personally dumped files and keys and is not meant for enabling illegal activity. I do not condone using this program for anything other than personal use and research. If this program is used for anything other than that, I cannot be held liable for anything that happens.