happy-cracking 0.1.0

A fast, comprehensive CTF toolkit for cryptographic encoding/decoding, classic ciphers, hash operations, and analysis tools
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

use anyhow::Result;
use clap::Subcommand;
use std::collections::HashMap;

#[derive(Subcommand)]
pub enum EntropyAction {
    #[command(about = "Calculate Shannon entropy of input")]
    Analyze {
        #[arg(help = "Input text")]
        input: String,
    },
}

pub fn run(action: EntropyAction) -> Result<()> {
    match action {
        EntropyAction::Analyze { input } => {
            let entropy = calculate(&input);
            let classification = classify(entropy);
            println!("Entropy: {:.4} bits/byte", entropy);
            println!("Classification: {}", classification);
        }
    }
    Ok(())
}

// Calculate Shannon entropy in bits per byte.
// H = -Σ p(x) * log2(p(x)), maximum is 8.0 bits/byte.
pub fn calculate(input: &str) -> f64 {
    if input.is_empty() {
        return 0.0;
    }

    let bytes = input.as_bytes();
    let len = bytes.len() as f64;

    let mut counts: HashMap<u8, usize> = HashMap::new();
    for &b in bytes {
        *counts.entry(b).or_insert(0) += 1;
    }

    let mut entropy = 0.0;
    for &count in counts.values() {
        let p = count as f64 / len;
        entropy -= p * p.log2();
    }

    entropy
}

// Classify the entropy value into a human-readable category.
pub fn classify(entropy: f64) -> &'static str {
    if entropy >= 7.5 {
        "High (likely encrypted/compressed)"
    } else if entropy >= 4.0 {
        "Medium (natural language/code)"
    } else {
        "Low (low entropy data)"
    }
}