Table of Contents

Iso7064Mod11_2 Class

Definition

Namespace
Bodu.IO.Hashing.CheckDigits
Assembly
Bodu.IO.Hashing.dll
Package
Bodu.IO.Hashing 1.0.0
Source
Iso7064Mod11_2.cs

Computes the single-character check of a decimal string using the ISO 7064 MOD 11-2 pure algorithm. This class cannot be inherited.

public sealed class Iso7064Mod11_2 : AlphanumericCheckDigitAlgorithm
Inheritance
Iso7064Mod11_2
Inherited Members
Extension Methods

Examples

// Single-call computation against a decimal body.
char check = Iso7064Mod11_2.Compute("0794");   // '0'

// Full-sequence validation.
bool ok = Iso7064Mod11_2.IsValid("07940");     // true

// Streaming use when the body is built up incrementally.
var algo = new Iso7064Mod11_2();
algo.Append("0794");
char d = algo.GetCurrentCheckDigit();          // '0'

Remarks

MOD 11-2 is the pure ISO 7064 system that uses modulus eleven with radix two. It operates on an arbitrary sequence of decimal digits and emits a single check character drawn from the alphabet '0'-'9' plus the sentinel 'X' used to represent the value ten.

The working digit is initialized to zero, and for each body digit a it is updated as p ← ((p + a) × 2) mod 11. The check character is chosen so that (p + c) mod 11 = 1, i.e. c = (12 - p) mod 11; the sequence body + c is valid when the same identity holds.

Worked example. For the body "0794", the computed check character is '0', and the resulting sequence "07940" is therefore valid under MOD 11-2.

important

This algorithm is not cryptographically secure and should not be used for password hashing, digital signatures, or integrity validation in security-sensitive applications.

Constructors

Iso7064Mod11_2()

Initializes a new instance of the Iso7064Mod11_2 class.

public Iso7064Mod11_2()

Properties

AlgorithmName

Gets the canonical name of the algorithm, suitable for diagnostic output and logging.

public override string AlgorithmName { get; }

Property Value

string

A short, stable identifier such as "Luhn", "IBAN", or "ISO 7064 MOD 97-10".

InputAlphabet

Gets the subset of ASCII from which this algorithm accepts body characters.

public override CheckDigitInputAlphabet InputAlphabet { get; }

Property Value

CheckDigitInputAlphabet

The declared input alphabet.

OutputAlphabet

Gets the subset of ASCII from which this algorithm may emit its check character.

public override CheckDigitOutputAlphabet OutputAlphabet { get; }

Property Value

CheckDigitOutputAlphabet

The declared output alphabet.

Methods

Append(ReadOnlySpan<char>)

Absorbs the supplied characters into the running check-value state.

public override void Append(ReadOnlySpan<char> body)

Parameters

body ReadOnlySpan<char>

The characters to append. Each element must belong to the algorithm's accepted input alphabet. An empty span is a permitted no-op.

Exceptions

ArgumentOutOfRangeException

Thrown when body contains any character outside the algorithm's accepted input alphabet.

Compute(ReadOnlySpan<char>)

Computes the ISO 7064 MOD 11-2 check character for the supplied body of decimal digits without allocating a streaming instance.

public static char Compute(ReadOnlySpan<char> digits)

Parameters

digits ReadOnlySpan<char>

The body characters. Each must be an ASCII decimal digit ('0' to '9').

Returns

char

The check character, either an ASCII decimal digit or the sentinel 'X'.

Exceptions

ArgumentOutOfRangeException

Thrown when digits contains any character outside the range '0' to '9'.

GetCurrentCheckDigit()

Returns the check character computed for the body absorbed since the last Reset() (or since construction).

public override char GetCurrentCheckDigit()

Returns

char

The check character as an ASCII character drawn from OutputAlphabet.

Remarks

This call is non-destructive; the running state is unaffected and the method may be invoked any number of times with identical results between appends.

IsValid(ReadOnlySpan<char>)

Determines whether the supplied sequence, comprising a body followed by a trailing ISO 7064 MOD 11-2 check character, is consistent.

public static bool IsValid(ReadOnlySpan<char> valueIncludingCheck)

Parameters

valueIncludingCheck ReadOnlySpan<char>

The complete sequence including the trailing check character.

Returns

bool

true if the sequence evaluates as valid under MOD 11-2; otherwise, false - including the case where valueIncludingCheck is empty, any non-final character is not a decimal digit, or the final character is neither a decimal digit nor 'X'.

Reset()

Resets the algorithm to its initial state, discarding any characters previously absorbed.

public override void Reset()

Remarks

Equivalent in behavior to constructing a fresh instance of the same concrete type.

Applies to

ProductVersions
.NET8, 10