[操作疑難] 請教 Cyclic Redundancy Check (CRC)

Mr.K

最近研究緊 FPS qrcode
佢個 format 所有都冇咩問題
但 CRC 2-byte 4個位點計出黎？

https://ffo.hkma.gov.hk/download ... ents_in_HK_v1_0.pdf
The CRC (ID “63”) shall be calculated according to [ISO/IEC 13239] using the
polynomial '1021' (hex) and initial value 'FFFF' (hex). The data over which the
checksum is calculated shall cover all data objects, including their ID, Length and
Value, to be included in the QR Code, in their respective order, as well as the ID and
Length of the CRC itself (but excluding its Value). Following the calculation of the
checksum, the resulting 2-byte hexadecimal value shall be encoded as a 4-character
Alphanumeric Special value by converting each nibble to an Alphanumeric Special
character. For example, a CRC with a two-byte hexadecimal value of '007B' is
included in the QR Code as "6304007B".

7h1r733n

ISO/IEC 13239係CRC16既standard... 點計網上大把code sample.. 搵一搵就有...

http://srecord.sourceforge.net/crc16-ccitt.html

Mr.K

ISO/IEC 13239係CRC16既standard... 點計網上大把code sample.. 搵一搵就有...
7h1r733n 發表於 2019-1-17 00:30

    原來係 16, 我奇怪點解搵唔倒 crc2

Mr.K

計極都同hsbc個fps crc 唔同

Mr.K

解決左, 原來連 id 63 length 04 都要入埋
麻煩哂巴打, 多謝提點, 馬上通左

xiao

0x6304007B, 直接BCD數就是ASCII STRING

ati16800

crc16算唔算史前動物, 咁新既fps點解仲用?

燕飛

crc16算唔算史前動物, 咁新既fps點解仲用?
ati16800 發表於 2019-1-17 13:06

唔用crc可以用咩？
唔通用2百幾bit 既hash 塞落個QR code?

via HKEPC Reader for Android

Mr.K

其實qrcode加呢個hash個作用係咩?

Mr.K

原來依家基本上所有都唔支援FPS qrcode
就算用hkma 整合左都冇咩用
得hsbc認倒