openssl enc -aes-128-ctr -d -in another_code.nsp -out decrypted.nsp -K 4E5350304E5350300000000000000000 -iv 00000000000000000000000000000000 -nosalt Mount or extract the decrypted NSP. Inside exefs/main we find a simple homebrew that XORs an array with 0x42 and prints the result.

dd if=another_code.nsp of=hint.bin bs=1 skip=1720000 count=256 Running strings hint.bin reveals:

encryption: AES-128-CTR key hint: first 8 bytes of NSP0 magic repeated twice iv = 0x0000000000000000 The NSP0 magic is 4E 53 50 30 → ASCII NSP0 . Repeated twice → 4E 53 50 30 4E 53 50 30 .

Simulate the XOR routine (Python snippet):

The file is encrypted, but the developer left a clue: “Sometimes the key is right in front of you — just another code.”

Here’s a write-up for a fictional cybersecurity challenge called — suitable for a CTF or reverse engineering lab. Challenge Title: Another Code NSP Category: Reverse Engineering / Cryptography Difficulty: Medium Points: 350 Description We found another suspicious Nintendo Switch package (NSP) file. It claims to be a simple homebrew game, but our analysts think there’s something hidden beneath the surface.

4E5350304E5350300000000000000000 The encrypted section starts after the first 0x800 bytes. Use OpenSSL: