Adding an ioc calculator

Author: cmbsolver

cmd/calcioc/go.mod

@@ -0,0 +1,3 @@
+module calcioc
+
+go 1.24

cmd/calcioc/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"ioc"
+	"os"
+	"strings"
+)
+
+func main() {
+	// Define command line flags
+	alphabetType := flag.String("alphabet", "english", "Type of alphabet to use (english, runeglish, or rune)")
+	text := flag.String("text", "", "Text to analyze")
+
+	// Parse the flags
+	flag.Parse()
+
+	// Validate that text was provided
+	if *text == "" {
+		fmt.Println("Error: No text provided for analysis")
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	// Get the appropriate alphabet based on the flag
+	var alphabet ioc.AlphabetType
+	switch strings.ToLower(*alphabetType) {
+	case "english":
+		alphabet = ioc.Latin
+		break
+	case "runeglish":
+		alphabet = ioc.Runeglish
+		break
+	case "rune":
+		alphabet = ioc.Rune
+		break
+	default:
+		fmt.Println("Error: Invalid alphabet type")
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	// Calculate the Index of Coincidence
+	result := ioc.CalcIOC(*text, alphabet)
+
+	// Output the result
+	fmt.Printf("IoC: %f\n", result)
+}

go.work

@@ -42,4 +42,6 @@ use (
 	cmd/ipaddressgen
 	cmd/checkmultihash
 	cmd/winchafftext
+	pkg/utility/ioc
+	cmd/calcioc
 )

pkg/utility/ioc/go.mod

@@ -0,0 +1,3 @@
+module ioc
+
+go 1.24

pkg/utility/ioc/iocutil.go

@@ -0,0 +1,75 @@
+package ioc
+
+import "strings"
+
+// AlphabetType represents different types of alphabets that can be used for IOC calculation
+type AlphabetType int
+
+const (
+	// Latin represents the standard 26-letter Latin alphabet (a-z)
+	Latin AlphabetType = iota
+	// Runeglish represents the standard Latin alphabet plus common runes/symbols
+	Runeglish
+	// Rune represents all possible Unicode runes in the text
+	Rune
+)
+
+// GetAlphabet returns the character set corresponding to the specified alphabet type
+func GetAlphabet(alphabetType AlphabetType) []string {
+	var retval string
+
+	switch alphabetType {
+	case Latin:
+		retval = "abcdefghijklmnopqrstuvwxyz"
+	case Runeglish:
+		retval = "abcdefghijlmnoprstuwxy"
+	case Rune:
+		retval = "ᛝᛟᛇᛡᛠᚫᚦᚠᚢᚩᚱᚳᚷᚹᚻᚾᛁᛄᛈᛉᛋᛏᛒᛖᛗᛚᛞᚪᚣ"
+	default:
+		retval = "abcdefghijklmnopqrstuvwxyz"
+	}
+
+	return strings.Split(retval, "")
+}
+
+// CalcIOC calculates the incidence of coincidence for the given text using the provided alphabet.
+// The incidence of coincidence is a measure used in cryptanalysis that
+// reflects the likelihood of randomly selecting the same letter twice from a text.
+// It returns a float64 value between 0 and 1.
+// If an empty alphabet is provided, the function defaults to the standard English alphabet.
+func CalcIOC(text string, alphabetType AlphabetType) float64 {
+	// Get the alphabet
+	alphabet := GetAlphabet(alphabetType)
+
+	// Create a map for faster character lookup
+	validChars := make(map[string]bool)
+	for _, char := range alphabet {
+		validChars[char] = true
+	}
+
+	// Create a map to count occurrences of each letter
+	counts := make(map[string]int)
+
+	// Count only characters in our alphabet
+	totalLetters := 0
+	for _, char := range strings.ToLower(text) {
+		if validChars[string(char)] {
+			counts[string(char)]++
+			totalLetters++
+		}
+	}
+
+	// If there are fewer than 2 letters, return 0
+	if totalLetters <= 1 {
+		return 0.0
+	}
+
+	// Calculate the sum of frequencies squared
+	var sum float64 = 0.0
+	for _, count := range counts {
+		sum += float64(count) * float64(count)
+	}
+
+	// Calculate and return the IOC
+	return sum / (float64(totalLetters) * float64(totalLetters-1))
+}