CRC64 ECMA182

This package can be used as verify Ali-OSS file.

Installation

$ npm install --save crc64-ecma182

Usage

Calculate a Buffer

You can calculate the CRC64-ECMA182 value for a Node.js buffer or string:

crc64.crc64(buff[, prev]);

• Parameters:
  • buff: the buffer or string to be calculated;
  • [prev]: if exists, prev indicates the previous CRC64-ECMA182 value and the result of this function will strict equal to prev; (optional)
• Returns: the result buffer that calculated.

const crc64 = require("crc64-ecma182");
const ret1 = crc64.crc64("123456789");
const ret2 = crc64.crc64(new Buffer("123456789"));
const ret3 = crc64.crc64("123456789", Buffer.alloc(8));
const ret4 = crc64.crc64(new Buffer("123456789"), Buffer.alloc(8));

// ret1 ~ ret2 all equals to:
//
//   [ 0xfa, 0x39, 0x19, 0xdf, 0xbb, 0xc9, 0x5d, 0x99 ]

Calculate a file

You can calculate the CRC64-ECMA182 value for a file:

crc64.crc64File(filename[, toString], callback);

• Parameters:
  • filename: the file's name that to be calculated;
  • toString: to decide wether the result should be a buffer or a UInt64 string, default to true; (optional)
  • callback: the callback function which receives two arguments err and ret.

crc64.crc64File(path.join(__dirname, "pic.png"), function(err, ret) {
    console.log(err, ret);

    // a possible result:
    //
    //   undefined 5178350320981835788
});

Convert Result Buffer to String

If you get a CRC64-ECMA182 result in Buffer, you could convert it to a UInt64 string via function:

crc64.toUInt64String(buff);

• Parameters:
  • buff: the CRC64-ECMA182 buffer result;
• Returns: the UInt64 string.

const ret1 = crc64.crc64("123456789");
const str = crc64.toUInt64String(ret1); // 11051210869376104954

Contribution

You're welcome to make pull-requests.