Isibali sekhodi sehashi CRC-32

I-Cyclic Redundancy Check (CRC) ikhodi yokuthola iphutha evame ukusetshenziswa ukuthola izinguquko zephutha kudatha eluhlaza. Yize ingewona umsebenzi we-cryptographic hash, i-CRC-32 ivamise ukubizwa ngokuthi i-hashi ngenxa yekhono layo lokukhiqiza okukhiphayo okunosayizi ogxilile (amabhithi angu-32) kusukela ekufakweni kobude obuguquguqukayo. Inguqulo evezwe kuleli khasi iwuhlobo lwe-CRC-32B, okuyindida nje olimini lwe-PHP eshintshashintsha kancane (i-little-endian vs big-endian ku-CRC-32 yoqobo).

Ukudalulwa okuphelele: Angibhalanga ukusetshenziswa okuqondile komsebenzi we-hashi osetshenziswe kuleli khasi. Kungumsebenzi ojwayelekile ofakwe nolimi lokuhlela lwe-PHP. Ngenze isixhumi esibonakalayo sewebhu kuphela ukuze ngisenze sitholakale esidlangalaleni lapha ukuze kube lula.

Mayelana ne-CRC-32B Hash Algorithm

Angisona isazi sezibalo, kodwa ngizozama ukuchaza lo msebenzi we-hashi ngesifaniso esilula. Ngokungafani nemisebenzi eminingi ye-cryptographic hash, akuyona i-algorithm eyinkimbinkimbi, ngakho-ke kuzolunga ;-)

Cabanga ukuthi uthumela incwadi ngemeyili, kodwa ukhathazekile ukuthi ingase yonakale ngaphambi kokuba ifike kumamukeli. Ngokusekelwe kokuqukethwe yincwadi, ubala isheke le-CRC-32 bese ubhala lokho emvilophini. Lapho umemukeli ethola incwadi, angakwazi futhi ukubala isheke futhi abone ukuthi liyahambisana yini nalokhu okubhalile. Uma kwenzeka, incwadi ayizange yonakaliswe noma ishintshwe endleleni.

Indlela i-CRC-32 eyenza ngayo lokhu kuyisinyathelo sezinyathelo ezine:

Isinyathelo 1: Engeza Isikhala Esingeziwe (Ukuphequlula)

• I-CRC yengeza igumbi elengeziwe elincane ekugcineni komlayezo (njengokupakisha amakinati ebhokisini).
• Lokhu kuyisiza ukuthi ibone amaphutha kalula.

Isinyathelo sesi-2: I-Magic Ruler (I-Polynomial)

• I-CRC-32 isebenzisa "irula eliwumlingo" ukukala idatha.
  • Cabanga ngalo mbusi njengephethini yamaqhuqhuva nemisele (lena i-polynomial, kodwa ungakhathazeki ngalelo gama).
  • "Irula" elivame kakhulu le-CRC-32 iphethini engashintshi.

Isinyathelo sesi-3: Ukuslayida irula (Inqubo Yesigaba)

• Manje i-CRC islayida irula kuwo wonke umlayezo.
  • Endaweni ngayinye, ihlola ukuthi amaqhubu nemifantu kukleliswe yini.
  • Uma zingalayini, i-CRC yenza inothi (lokhu kwenziwa kusetshenziswa i-XOR elula, njengokuvula noma ukuvala amaswishi).
  • Ilokhu ishelela futhi inyakazisa amaswishi ize ifike ekugcineni.

Isinyathelo sesi-4: Umphumela wokugcina (I-Checksum)

• Ngemva kokuslayida irula kuwo wonke umlayezo, usala nenombolo encane (amabhithi angu-32 ubude) emele idatha yoqobo.
  • Le nombolo ifana nezigxivizo zeminwe ezihlukile zomlayezo.
  • Lena isheke ye-CRC-32.

Inguqulo eyethulwe ekhasini iwuhlobo lwe-CRC-32B, ngokuvamile okuyi-PHP quirk eshintsha i-bit order nxazonke (i-little-endian vs big-endian). Kufanele usebenzise le nguqulo kuphela uma udinga ngokukhethekile ukuhambisana nolunye uhlelo lokusebenza lwe-PHP oluyisebenzisayo.

Nginazo izibali zezinye izinhlobo futhi:

• Isibali sekhodi sehashi CRC-32
• Isibali sekhodi sehashi CRC-32C