如何从解码缓冲区中编码CBOR

Question

当对CBOR进行解码、编码和解码时，缓冲器不返回相同的值。

const greenpassData = cbor.decodeAllSync(cbor_data);

// --------------------------------
//Want the CBOR data after decoding  CBOR Data

const greenpassDataEncode = cbor.encode(greenpassData);

console.log(greenpassDataEncode);
console.log(cbor_data);

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/**
 * Simple green pass decoder inspired by https://git.gir.st/greenpass.git/blob_plain/master:/greenpass.py
 *
 * 2021 Lorenzo Millucci
 * 
 * Before usage install following dependecies `npm install base45 cbor jpeg-js jsqr pako`
 */

const base45 = require('base45');
const cbor = require('cbor');
const fs = require('fs');
const jpeg = require('jpeg-js');
const jsQR = require("jsqr");
const pako = require('pako');

// Set the path to the green pass QR
const FILE_PATH = __dirname + '/greenpass.jpeg';

// Read image file
const greenpassJpeg = fs.readFileSync(FILE_PATH);
const greenpassImageData = jpeg.decode(greenpassJpeg, { useTArray: true });

// Decode QR
const decodedGreenpass = jsQR(greenpassImageData.data, greenpassImageData.width, greenpassImageData.height);

// Remove `HC1:` from the string
const greenpassBody = decodedGreenpass.data.substr(4);
console.log(greenpassBody)

// Data is Base45 encoded
const decodedData = base45.decode(greenpassBody);

// And zipped
const output = pako.inflate(decodedData);
const results = cbor.decodeAllSync(output);
[headers1, headers2, cbor_data, signature] = results[0].value;

const greenpassData = cbor.decodeAllSync(cbor_data);

// --------------------------------
//Want the cbor data after decoding  cbor Data

const greenpassDataEncode = cbor.encode(greenpassData);

console.log(greenpassDataEncode);
console.log(cbor_data);
// --------------------------------

var josnString = JSON.stringify(greenpassData[0].get(-260).get(1), null, 2);
//new Encoded Array
const ecodeArrayGreenPassData = cbor.encode(greenpassData);
const greenpassData2 = cbor.decodeAllSync(ecodeArrayGreenPassData);

Answer 1

也许因为..。

呃..。

让控制台记录Pako创建的内容，如下所示：

 Uint8Array(350) [
  210, 132,  67, 
   ....
   35,  68,  98,  99,
  ... 250 more items
]

..while平原cbor.encode()是从decodeAllSync结果生成的，如下所示：

<Buffer 11 21 31 41 51 61 ... 302 more bytes>

..you遗漏了这一点：

const build = new Uint8Array(cbor.encode(my-decode-result))

玩得开心!

(..but老实说:我也花了一段时间..。然而，回来的其他部分应该更容易。)

Answer 2

我的朋友，这是cbor.decodeAllSync()的原型

static decodeAllSync(input: BufferLike, options?: DecoderOptions | string): Array<ExtendedResults> | Array<any>;

它返回一个数组。因此，您要将一个数组传递给cbor.encode()，该数组使用0x81头(因此是额外的字节)进行编码。

您的代码将像预期的那样工作：

const greenpassDataEncode = cbor.encode(greenpassData[0]);

代替：

const greenpassDataEncode = cbor.encode(greenpassData);