save-tools

Vanilla JS Save tools for the Yo-kai Watch Franchise. For documentation on the save system (including inner workings and data point locations), please look at save-docs - and finally if you have any questions, requests or bug reports feel free to open an issue, pull request or DM me on discord (@n123original). These are entirely script-based so they can be used in Node.js projects if needed. [note: include minimum ES version for use]. Usage Examples can also be found in comments at the top of the scripts.

Tool 1: Encryption Manager

• Used for Yo-kai Watch 1, Yo-kai Watch 2 and Yo-kai Watch Blasters.
• Functionality:
  • Checks version encryption (needed for Yo-kai Watch 2 as encryption varies for v1 vs v2 saves); includes an W.I.P alternative - an experimental header metadata parsing method promising higher efficiency (although it cannot guarantee complete accuracy without further research).
    • Also has a header mode to tell if something is a valid decrypted head.yw for Yo-kai Watch 2 and Yo-kai Watch Blasters.
  • Base Encryption
    • Used for Yo-kai Watch 1 saves, and Yo-kai Watch 2 + Yo-kai Watch Blasters header files (head.yw).
  • Advanced Encryption
    • Used for Yo-kai Watch 2 saves (and Blasters saves?).
    • Requires a header file for Blasters saves and V2 Yo-kai Watch 2 saves.
• Examples:
  • extractAESKey(headerData) - An async function that accepts an encrypted head.yw (for YW2) and extracts the AES Key.
  • DEFAULT_V1_AES_KEY - the AES key (in a string representation of the hex) for V1 save files in Yo-kai Watch 2
  • decryptV1Save(fileData, keyHex, dontTouchThisParam) - An async function that accepts fileData and a key obtained from extractAESKey. Despite it saying v1save - this works for all YW2 Save Files.
  • encryptV1Save(fileData) - despite the name this encrypts any YW2 Save File using advanced encryption where fileData is a Uint8Array containing the game.ywd (ywd = decrypted .yw)
  • fullBaseEncrypt(fileBuffer) - An async function which uses base encryption on the file buffer (A Uint8Array) - this is used for head.yw's (header files) and YW1 Saves.
  • fullBaseDecrypt(fileBuffer) - An async function which uses base decryption on the file buffer (A Uint8Array) - this is used for head.yw's (header files) and YW1 Saves.

Dependencies:

• SJCL, also known as Stanford Javascript Crypto Library.
  • The Lib is included with the appropriate license - props to them (I originally handled AES-CCM myself but I couldn't guarantee there would be no implementation bugs).
  • The Lib MUST be loaded before the encryption manager - otherwise things will break (I have added a failsafe where it'll just throw and refuse to do anything).

Tool 2: SectionParser

• Used for Yo-kai Watch 2, and Yo-kai Watch Blasters.
• Functionality:
  • Parses and validates section trees by exporting them as JSON.

Tool 3: Data Manager

• Contains (YW2) data for Section Tags (Meanings of each ID), ID Data for everything from ParamIDs to locationIDs to equipped wallpapers and contact menu data.

Supported Games

Tool / Game	Yo-kai Watch 1	Yo-kai Watch 2	Yo-kai Watch Blasters
Encryption Manager	✅ (Base Encryption)	✅ (Base + Advanced Encryption, version check)	⚠️ (Base + Advanced Encryption, header always required)
SectionParser	❌ (Isn't needed as the game uses direct offsets)	✅ (Uses section parsing for header and save files).	✅ (Uses section parsing for header and save files).
Data Manager	⚠️ (Some overlap but full support is not currently available).	✅ (Full Support).	⚠️ (Some overlap but full support is not currently available).

Key:

• ✅ for support.
• ⚠️ for partial support or untested (but likely support).
• ❌ for unsupported or untested AND unlikely.