Composition
Anycodewithacheckcodeiscomposedoftwoparts:thebodycodeandthecheckcode(suchastheorganizationcode).Thebodycodeisthenumberthatrepresentsthecodeobject.Theverificationcodeisanumberattachedtothebodycodetoverifytheaccuracyofthebodycodeduringtheinputprocess.Eachbodycodecanonlyhaveonecheckcode,andthecheckcodeisobtainedthroughaprescribedmathematicalrelationship.
Principleofverification
Thesystemispresetwithaverificationprogramcompiledaccordingtotheverificationformuladerivedfromtheverificationmethod.Whenthecodewiththeverificationcodeisinputintothesystem,Thesystemusestheverificationprogramtocalculatetheinputbodycodetoobtaintheverificationresult,andthencomparestheverificationresultwiththeverificationcodeoftheinputcodetocheckwhethertheinputiscorrectornot.Ifthetwoareconsistent,itmeansthatthecodeisenteredcorrectlyandthesystemallowsentry;iftheyareinconsistent,itmeansthatthecodeisenteredincorrectly,andthesystemrefusestoenterandrequiresthecodetobere-entered.
Checksumalgorithm
Differentchecksumalgorithmsareoftendifferent.Commoncheckcodealgorithmsinclude:codedistance,paritycheck,Hammingcheck,cyclicredundancycheck,etc.
Algorithmexample
IDcardcheckcode
AccordingtothenationalstandardGB11643-1999ofthePeople’sRepublicofChina,thecalculationmethodfortheverificationcodeofthecitizen’sidentitynumberofthePeople’sRepublicofChinaistheISO7064:1983.MOD11-2verificationcodecalculationmethod.
Assuminga17-digitnumberis
17-digitnumber | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
Weightingfactor | 7 | 9 | 10 | 5 | 8 | 4 | 2 | 1 | 6 | 3 | 7 | 9 | 10 | 5 | 8 | 4 | 2 |
368
Calculatethesumoftheproductofthe17-digitnumberandthecorrespondingweightingfactorS:1×7+2×9+3×10+4×5+5×8+6×4+7×2+8×1+9×6+0×3+1×7+2×9+3×10+4×5+5×8+6×4+7×2=368;CalculatetheremainderTofS÷11:368mod11=5;CalculatetheremainderRof(12-T)÷11,ifR=10,thecheckcodeisaletter"X";ifR≠10,thecheckcodeisthenumber"R":(12-5)mod11=7.The17-digitcheckcodeis7,whichisaggregatedinto123456789012345677.
TheformulaoftheweightingfactorisWi=2^(n-1)(mod11),wherenisthenumbersequencestartingfrom1fromrighttoleft.
Sequence
ai12345678901234567?
Wi79105842163791058421
OrganizationCheckCode
Thenationalorganizationcodeconsistsofeightdigits(oruppercaseLatinletters)bodycodeandonedigit(OruppercaseLatinletters)checkcode.Thecheckcodeiscalculatedaccordingtothefollowingformula:
8 |
C9=11-MOD(∑Ci×Wi,11) |
i=1 |
MOD-representingtheremainderfunction;i-representingthepositionnumberofthecodecharacterfromlefttoright;
Ci-representingthevalueofthecodecharacteratthei-thposition,listedinthefollowing"codecharacterset"Characters;
C9-indicatingcheckcode;
Wi-indicatingtheweightingfactoratthei-thposition,thevaluesareasfollows:
weightingfactor
p>i | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Wi | 3 | 7 | 9 | 10 | 5 | 8 | 4 | 2 |
WhentheMODfunctionvalueWhenitis1(ieC9=10),thecheckcodeshouldberepresentedbythecapitalLatinletter“X”;whentheMODfunctionvalueis0(ieC9=11),thecheckcodeisstillrepresentedby“0”;whenthevalueofC9Whenitis1to9,thecheckcodeisdirectlyrepresentedbythevalueofC9.
See
Checkcodesystem
Redundancycheck
