fossd

A simple readable Fallout Shelter Save Decryptor

Features:

• Simple: all default values defined, ~12 lines of crypto variable definitions, ~5 lines of operating code
• Multiple Interfaces: can be used either as a module in another program, or as a CLI tool
• Compositable: designed for simple shell scripting flows

Usage

foss-decrypt < Vault111.sav | jq '.vault.storage.Lunchbox += 100' | foss-encrypt > Vault222.sav

Implementation details (for other implementations)

The data is padded to the cipher's blocksize (32?) using PKCS7

the key derivitation function is PBKDF2HMAC, using SHA1, with 1000 iterations, and an output length of 32 bytes. The salt is the bytes tu89geji340t89u2 (ascii format)

we then derive a key using the bytes UGxheWVy (ascii format)

The cipher is AES (using the key prior) in CBC mode (using the bytes tu89geji340t89u2 (ascii format) as the initial vector)