cryptopals/test/set_1_test.go

package cryptopals_test

import (
	"bufio"
	"math"
	"os"
	"testing"

	"mvvasilev.dev/cryptopals/set1"
)

const Challenge1HexValue = "49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d"

func Test_Challenge1(t *testing.T) {
	const expected = "SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t"

	value, success := set1.HexToBase64(Challenge1HexValue)

	if !success || value != expected {
		t.Fatal("Set 1, Challenge 1 has failed")
	}
}

func Test_Challenge2(t *testing.T) {
	const expected = "746865206b696420646f6e277420706c6179"

	const content = "1c0111001f010100061a024b53535009181c"
	const password = "686974207468652062756c6c277320657965"

	value := set1.XORHexString(content, password)

	if value != expected {
		t.Fatal(("Set 1, Challenge 2 has failed"))
	}
}

func Test_Challenge3(t *testing.T) {
	const encodedString = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736"

	score, key, bytes := set1.BruteForceXORSingleCharacterHexEncodedBlock([]byte(encodedString))

	t.Logf("Result: '%s' with score %d and key %v", string(bytes), score, key)
}

func Test_Challenge4(t *testing.T) {

	file, err := os.Open("./res/set-1-challenge-4.txt")

	if err != nil {
		t.Fatal(err)
	}

	defer file.Close()

	scanner := bufio.NewScanner(file)

	bestScore := math.MinInt32
	bestResult := ""
	bestKey := byte(0)

	for scanner.Scan() {
		original := scanner.Text()
		score, key, result := set1.BruteForceXORSingleCharacterHexEncodedBlock([]byte(original))

		if score > bestScore {
			bestScore = score
			bestResult = string(result)
			bestKey = key
		}
	}

	t.Logf("Result: '%s' with score %d with key %v", bestResult, bestScore, bestKey)

}

func Test_Challenge5(t *testing.T) {
	const key = "ICE"

	originalText := "Burning 'em, if you ain't quick and nimble\nI go crazy when I hear a cymbal"

	expectedCypher := "0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a26226324272765272a282b2f20430a652e2c652a3124333a653e2b2027630c692b20283165286326302e27282f"

	result := string(set1.ConvertToHex(set1.XOREncryptText(originalText, key)))

	if result != expectedCypher {
		t.Fatalf("Result '%s' is not the same as expected '%s'", result, expectedCypher)
	}
}

func Test_Challenge6_CalcHammingDistance(t *testing.T) {
	first := []byte("this is a test")
	second := []byte("wokka wokka!!!")

	hammingDistance := set1.HammingDistance(first, second)

	if hammingDistance != 37 {
		t.Fatalf("Result %d is not the same as expected %d", hammingDistance, 37)
	}
}

func Test_Challenge6_FindTop3KeySizes(t *testing.T) {
	base64Cipher := set1.ReadChallenge6CipherFromFile()

	cipher := set1.Base64Decode(base64Cipher)

	keySizes := set1.RankKeySizeCandidates(2, 40, cipher)

	t.Log(keySizes)
}

func Test_Challenge6_BreakTheCipher(t *testing.T) {
	base64Cipher := set1.ReadChallenge6CipherFromFile()

	t.Logf("First 10 bytes base64 cipher: %08b ", base64Cipher[0:10])

	cipher := set1.Base64Decode(base64Cipher)

	t.Logf("First 10 bytes cipher: %08b", cipher[0:10])
	t.Logf("Last 10 bytes cipher: %08b", cipher[len(cipher)-10:])

	// TODO: PROBLEM: This does not rank key sizes correctly. Because I cheated I know the key is of size "24".
	keySizeCandidates := set1.RankKeySizeCandidates(2, 40, cipher)

	keySize := keySizeCandidates[0].Size

	t.Logf("Best candidate key size is %d", keySize)

	transposed := make([][]byte, keySize)

	for i, b := range cipher {
		column := i % keySize

		if transposed[column] == nil {
			transposed[column] = []byte{}
		}

		transposed[column] = append(transposed[column], b)
	}

	cipherKey := []byte{}
	transposedResult := make([][]byte, keySize)

	// TODO: PROBLEM: The below code does not properly deduce the key.
	for i, column := range transposed {
		var score int
		var key byte
		var result []byte

		for i := 0; i < 256; i++ {
			decoded := set1.XORDecodePlain(column, byte(i))
			decodedScore := set1.ScoreTextByAlphabeticFrequency(decoded)

			if decodedScore > score {
				score = decodedScore
				key = byte(i)
				result = decoded
			}
		}

		// score, key, result := set1.BruteForceXORSingleCharacterPlainEncodedBlock(column)

		t.Logf("Found key '%c' with score %d", key, score)

		cipherKey = append(cipherKey, key)

		transposedResult[i] = result
	}

	t.Logf("The key is %s", cipherKey)

	// deciphered := set1.XORDecrypt(cipherKey, cipher)

	// t.Logf("First 100 bytes deciphered: %s", transposedResult)
}