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Refactor QR decryption routines to use sjcl. Remove asmcrypto.js dependency.

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May or may not break depending on the build of sjcl and/or minification
options. It remains to be seen.
This commit is contained in:
Arian Kordi 2025-05-04 18:27:47 -04:00
parent 9d247659c7
commit 37df009806
6 changed files with 128 additions and 35 deletions
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3
package.json
View file

@ -17,7 +17,7 @@
"@bprogress/next": "^3.2.12",
"@hello-pangea/dnd": "^18.0.1",
"@prisma/client": "^6.7.0",
"@trafficlunar/asmcrypto.js": "^1.0.2",
"@types/sjcl": "^1.0.34",
"bit-buffer": "^0.2.5",
"canvas-confetti": "^1.9.3",
"dayjs": "^1.11.13",
@ -34,6 +34,7 @@
"react-dropzone": "^14.3.8",
"react-webcam": "^7.2.0",
"sharp": "^0.34.1",
"sjcl-with-all": "1.0.8",
"swr": "^2.3.3",
"zod": "^3.24.3"
},

20
src/lib/constants.ts
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@ -1,4 +1,16 @@
export const MII_DECRYPTION_KEY = new Uint8Array([0x59, 0xfc, 0x81, 0x7e, 0x64, 0x46, 0xea, 0x61, 0x90, 0x34, 0x7b, 0x20, 0xe9, 0xbd, 0xce, 0x52]);
export const TOMODACHI_LIFE_DECRYPTION_KEY = new Uint8Array([
0x30, 0x81, 0x9f, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01,
]);
import type { BitArray } from "sjcl";
/** Length of an encrypted Mii QR code, without extra data. (CFLiWrappedMiiData) */
export const MII_QR_ENCRYPTED_LENGTH = 112;
// Keys are in sjcl.BitArray format.
/** AES-CCM key for Mii QR codes. Original: 59FC817E6446EA6190347B20E9BDCE52 */
export const MII_DECRYPTION_KEY: BitArray = [1509720446, 1682369121, -1875608800, -373436846];
/** AES-CTR key for Tomodachi Life extra data at the end of Mii QR codes. Original: 30819F300D06092A864886F70D010101 */
export const TOMODACHI_LIFE_DECRYPTION_KEY: BitArray = [813801264, 218499370, -2042067209, 218169601];
// Keys as Uint8Array.
// export const MII_DECRYPTION_KEY = new Uint8Array([0x59, 0xfc, 0x81, 0x7e, 0x64, 0x46, 0xea, 0x61, 0x90, 0x34, 0x7b, 0x20, 0xe9, 0xbd, 0xce, 0x52]);
// export const TOMODACHI_LIFE_DECRYPTION_KEY = new Uint8Array([0x30, 0x81, 0x9f, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01]);

11
src/lib/qr-codes.test.ts
View file

@ -30,6 +30,8 @@ const zeroes372 = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
const length32 = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
const badCrc = "ULENrXILeXZooDaJvwHMcFaBjGH7k5pj+DDPDV0irq66c01Fh82TIrZerZX2xiB+TbHBzYIaDHdryA9IbR1uH/slSalGCScmjDiL9zpOXlvh8z38NGkmjtL1fVVrshCcJHKeQApdbZU4S6h+wZd0LA==";
function base64ToUint8Array(base64: string): Uint8Array {
const binary = Buffer.from(base64, "base64");
return new Uint8Array(binary.buffer, binary.byteOffset, binary.byteLength);
@ -53,11 +55,20 @@ describe("convertQrCode", () => {
it("should throw an error on zeroed out data", () => {
const bytes = base64ToUint8Array(zeroes372);
// Will decrypt wrongly, leading to the expected stream
// of zeroes in the decrypted data not being intact.
expect(() => convertQrCode(bytes)).toThrow("QR code is not a valid Mii QR code");
});
it("should throw an error on wrong length", () => {
const bytes = base64ToUint8Array(length32);
// Thrown at the beginning of the function.
expect(() => convertQrCode(bytes)).toThrow("Mii QR code has wrong size (got 32, expected 112 or longer)");
});
it("should throw an error on data with bad CRC-16", () => {
const bytes = base64ToUint8Array(badCrc);
// Verified by new Mii() constructor from mii-js.
expect(() => convertQrCode(bytes)).toThrow("Mii data is not valid");
});
/*

102
src/lib/qr-codes.ts
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@ -1,47 +1,101 @@
import { profanity } from "@2toad/profanity";
import { AES_CCM } from "@trafficlunar/asmcrypto.js";
// import { AES_CCM } from "@trafficlunar/asmcrypto.js";
import sjcl from "sjcl-with-all";
import { MII_DECRYPTION_KEY } from "./constants";
import { MII_DECRYPTION_KEY, MII_QR_ENCRYPTED_LENGTH } from "./constants";
import Mii from "./mii.js/mii";
import TomodachiLifeMii from "./tomodachi-life-mii";
// AES-CCM encrypted Mii QR codes have some errata (https://www.3dbrew.org/wiki/AES_Registers#CCM_mode_pitfall)
// causing them to not be easily decryptable by asmcrypto
// or sjcl, they can't verify the nonce/tag.
// In order to use sjcl's decrypt function without
// verification, a private function needs to be called.
// This private function's name is originally "_ctrMode"
// but its name is minified across builds.
// In "sjcl-with-all" v1.0.8 from npm, the name is "u"
/** Private _ctrMode function defined here: {@link https://github.com/bitwiseshiftleft/sjcl/blob/85caa53c281eeeb502310013312c775d35fe0867/core/ccm.js#L194} */
const sjclCcmCtrMode: ((
prf: sjcl.SjclCipher, data: sjcl.BitArray, iv: sjcl.BitArray,
tag: sjcl.BitArray, tlen: number, L: number
) => { data: sjcl.BitArray; tag: sjcl.BitArray }) | undefined =
// @ts-expect-error -- Referencing a private function that is not in the types.
sjcl.mode.ccm.u; // NOTE: This may need to be changed with a different sjcl build. Read above
export function convertQrCode(bytes: Uint8Array): { mii: Mii; tomodachiLifeMii: TomodachiLifeMii } {
// Decrypt the Mii part of the QR code
// (Credits to kazuki-4ys)
const nonce = bytes.subarray(0, 8);
const content = bytes.subarray(8, 0x70);
// Decrypt 96 byte 3DS/Wii U format Mii data from the QR code.
// References (Credits: jaames, kazuki-4ys):
// - https://gist.github.com/jaames/96ce8daa11b61b758b6b0227b55f9f78
// - https://github.com/kazuki-4ys/kazuki-4ys.github.io/blob/148dc339974f8b7515bfdc1395ec1fc9becb68ab/web_apps/MiiInfoEditorCTR/encode.js#L57
const nonceWithZeros = new Uint8Array(12);
nonceWithZeros.set(nonce, 0);
let decrypted: Uint8Array<ArrayBufferLike> = new Uint8Array();
try {
decrypted = AES_CCM.decrypt(content, MII_DECRYPTION_KEY, nonceWithZeros, undefined, 16);
} catch {
throw new Error("Failed to decrypt QR code. It may be invalid or corrupted");
// Check that the private _ctrMode function is defined.
if (!sjclCcmCtrMode) {
throw new Error("Private sjcl.mode.ccm._ctrMode function cannot be found. The build of sjcl expected may have changed. Read src/lib/qr-codes.ts for more details.");
}
const result = new Uint8Array(96);
result.set(decrypted.subarray(0, 12), 0);
result.set(nonce, 12);
result.set(decrypted.subarray(12), 20);
// Verify that the length is not smaller than expected.
if (bytes.length < MII_QR_ENCRYPTED_LENGTH) {
throw new Error(`Mii QR code has wrong size (got ${bytes.length}, expected ${MII_QR_ENCRYPTED_LENGTH} or longer)`);
}
// Check if QR code is valid (after decryption)
if (result.length !== 0x60 || (result[0x16] !== 0 && result[0x17] !== 0)) throw new Error("QR code is not a valid Mii QR code");
const nonce = bytes.subarray(0, 8); // Extract the AES-CCM nonce.
const encryptedContent = bytes.subarray(8); // Extract the ciphertext.
// Convert to Mii classes
const cipher = new sjcl.cipher.aes(MII_DECRYPTION_KEY); // Construct new sjcl cipher.
// Convert encrypted content and nonce to sjcl.BitArray (toBits expects array)
const encryptedBits = sjcl.codec.bytes.toBits(Array.from(encryptedContent));
const nonceBits = sjcl.codec.bytes.toBits([...nonce, 0, 0, 0, 0]); // Pad to 12 bytes.
// Isolate the actual ciphertext from the tag and adjust IV.
// Copied from sjcl.mode.ccm.decrypt: https://github.com/bitwiseshiftleft/sjcl/blob/85caa53c281eeeb502310013312c775d35fe0867/core/ccm.js#L83
const tlen = 128; // Tag length in bits.
const dataWithoutTag = sjcl.bitArray.clamp(encryptedBits,
// remove tag from out, tag length = 128
sjcl.bitArray.bitLength(encryptedBits) - tlen);
let decryptedBits: { data: sjcl.BitArray };
try {
const buffer = Buffer.from(result);
const mii = new Mii(buffer);
decryptedBits = sjclCcmCtrMode(cipher, dataWithoutTag, nonceBits, [], tlen, 3); // hardcoding 3 as "L" / length
} catch {
// Note that the function above is not likely to fail since it decrypts without verification.
throw new Error("Failed to decrypt QR code. It may be invalid or corrupted");
}
// NOTE: The CBC-MAC within the QR code is NOT verified here.
// Convert the decrypted bytes from sjcl format.
const decryptedBytes = sjcl.codec.bytes.fromBits(decryptedBits.data);
const decryptedSlice = new Uint8Array(decryptedBytes).subarray(0, 88);
// Create the final Mii StoreData from the decrypted bytes.
const result = new Uint8Array([
...decryptedSlice.subarray(0, 12), // First 12 decrypted bytes.
...nonce, // Original nonce from the encrypted bytes.
...decryptedSlice.subarray(12), // Then the rest of the decrypted bytes.
]);
// Check if Mii data is valid by checking always zero "reserved_2" field.
if (result[0x16] !== 0 && result[0x17] !== 0) {
throw new Error("QR code is not a valid Mii QR code");
}
// Construct mii-js Mii and TomodachiLifeMii classes.
try {
const buffer = Buffer.from(result); // Convert to node Buffer.
const mii = new Mii(buffer); // Will verify the Mii data further.
// Decrypt Tomodachi Life Mii data from encrypted QR code bytes.
const tomodachiLifeMii = TomodachiLifeMii.fromBytes(bytes);
// Apply hair dye fields.
if (tomodachiLifeMii.hairDyeEnabled) {
mii.hairColor = tomodachiLifeMii.studioHairColor;
mii.eyebrowColor = tomodachiLifeMii.studioHairColor;
mii.facialHairColor = tomodachiLifeMii.studioHairColor;
}
// Censor potential inappropriate words
// Censor potential inappropriate words.
tomodachiLifeMii.firstName = profanity.censor(tomodachiLifeMii.firstName);
tomodachiLifeMii.lastName = profanity.censor(tomodachiLifeMii.lastName);
tomodachiLifeMii.islandName = profanity.censor(tomodachiLifeMii.islandName);

24
src/lib/tomodachi-life-mii.ts
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@ -1,12 +1,17 @@
import { TOMODACHI_LIFE_DECRYPTION_KEY } from "../lib/constants";
import { AES_CTR } from "@trafficlunar/asmcrypto.js";
import sjcl from "sjcl-with-all";
// @ts-expect-error - This is not in the types, but it's a function needed to enable CTR mode.
sjcl.beware["CTR mode is dangerous because it doesn't protect message integrity."]();
// Converts hair dye to studio color
// Reference: https://github.com/ariankordi/nwf-mii-cemu-toy/blob/9906440c1dafbe3f40ac8b95e10a22ebd85b441e/assets/data-conversion.js#L282
// (Credits to kat21)
const hairDyeConverter = [
55, 51, 50, 12, 16, 12, 67, 61, 51, 64, 69, 66, 65, 86, 85, 93, 92, 19, 20, 20, 15, 32, 35, 26, 38, 41, 43, 18, 95, 97, 97, 99,
];
// Reference: https://github.com/ariankordi/nwf-mii-cemu-toy/blob/ffl-renderer-proto-integrate/assets/kaitai-structs/tomodachi_life_qr_code.ksy
// (Credits to ariankordi for the byte locations)
export default class TomodachiLifeMii {
firstName: string;
@ -16,7 +21,7 @@ export default class TomodachiLifeMii {
hairDye: number;
hairDyeEnabled: boolean;
// There is more properties but I don't plan to add them *yet*
// There are more properties but I don't plan to add them *yet*
// Property below is not located in the bytes
studioHairColor: number;
@ -63,9 +68,18 @@ export default class TomodachiLifeMii {
}
static fromBytes(bytes: Uint8Array): TomodachiLifeMii {
const iv = bytes.slice(0x70, 128);
const encryptedExtraData = bytes.slice(128, -4);
const decryptedExtraData = AES_CTR.decrypt(encryptedExtraData, TOMODACHI_LIFE_DECRYPTION_KEY, iv);
const iv = bytes.subarray(0x70, 128);
const encryptedExtraData = bytes.subarray(128, -4);
const cipher = new sjcl.cipher.aes(TOMODACHI_LIFE_DECRYPTION_KEY);
// Convert nonce and encrypted content to sjcl.BitArray.
const encryptedBits = sjcl.codec.bytes.toBits(Array.from(encryptedExtraData));
const ivBits = sjcl.codec.bytes.toBits(Array.from(iv));
// Perform decryption.
const decryptedBits = sjcl.mode.ctr.decrypt(cipher, encryptedBits, ivBits);
// Convert from sjcl format.
const decryptedExtraData = sjcl.codec.bytes.fromBits(decryptedBits);
const data = new Uint8Array(decryptedExtraData);
return new TomodachiLifeMii(data.buffer);

3
tsconfig.json
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@ -19,7 +19,8 @@
}
],
"paths": {
"@/*": ["./src/*"]
"@/*": ["./src/*"],
"sjcl-with-all": ["./node_modules/@types/sjcl"]
}
},
"include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],