initial commit

.gitignore

@@ -0,0 +1 @@
+img

README.md

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+# Attempt to solve the BTC 310 Challenge
+
+https://bitcoinchallenge.codes/
+
+## Solution
+
+https://docs.google.com/document/d/1nUAhlC_n21ZLZcRAHpLw9G--gpk4NUVIJqVp9F68qp4/preview

alpha.b64

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+U2FsdGVkX19Q3I//VCH0U3cVtITZ3ckILJnUcdPX3Gs5qjdF1UjZ3mAftGivtFYDN5ZCSkBynnVqBawl4p8wKO0O8zI6D0A1+VEVCUyEvEeNoUfGcS0El9d93vsPxbg7D5avufQsScgsk3QEtq9/M4Do32OKFeq00/3NrxWOsMmh3AXmDzuuZ0qmZaI7re16FcXIrmPPiQDOHRc7wt0ng6qLiNz7VqESRTdxPOahKFRkWT8sT+Ur2y+2iZ2LEaxNM7UZqcPwYgm6FoKOVjnqdeg30R27jc6AoFPyRZ2g8+EJMp3n/pf94oSCLEWkc0osjH9DqbM6DUptu3HJbAVwXQ==

btc1.py

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+#!/usr/bin/python
+key = "20181002"
+encrypted = "511B2033232841053022B0FE52ED0F7A165B52C7E75112F656FC4B"
+for i in range(len(encrypted)):
+    print(hex((int(encrypted[i],16)-int(key[i%len(key)])) % 16))
+    if i %18 == 0:
+        print("\n")

btc1.txt

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+20181002
+
+310 310 310 310 310
+
+1AA 0FC 32D 544 78F 643
+42C 5C7 490 2F4 36E 43B
+
+
+1AA0FC32D54478F643
+42C5C74902F436E43B
+
+1AA0FC32D54478F64342C5C74902F436E43B

dec

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+#!/bin/sh
+
+DIR="/tmp/btc310"
+[ ! -d $DIR ] && mkdir -p $DIR
+PASSWD="$1";
+FILE="$2";
+for i in $(openssl enc -ciphers 2>&1 | tail -n +2 | xargs | sed 's/ -/ /g' | sed 's/^.//'); do
+	openssl enc -d -$i -md md5 -a -k "$PASSWD" -in "$FILE" -out $DIR/$i.dec 2> /dev/null
+	if [ $? -ne 0 -o ! -s $DIR/$i.dec ]; then
+		rm $DIR/$i.dec
+	else
+		strings $DIR/$i.dec | grep Bitcoin >/dev/null && { echo $DIR/$i.dec; cat $DIR/$i.dec; }
+	fi
+done

go.mod

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+module main

img.go

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+package main
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"image/png"
+	"log"
+	"os"
+	"strconv"
+	"time"
+)
+
+func red(p image.Image) image.Image {
+	bits := ""
+	rect := p.Bounds()
+	n := image.NewRGBA(rect)
+	for i := 0; i < rect.Max.Y; i++ {
+		for j := 0; j < rect.Max.X; j++ {
+			r, g, _, _ := p.At(j, i).RGBA()
+			if i == 310 {
+				//c, _, _, _ := p.(*image.NRGBA).At(j, i).RGBA()
+				//c := color.RGBAModel.Convert(p.At(j, i)).(color.RGBA).R
+				fmt.Fprintf(os.Stderr, "%08b %08b\n", uint8(r), uint8(g))
+				fmt.Fprintf(os.Stderr, "%d %d\n", uint8(r), uint8(g))
+				//bin := strconv.FormatUint(uint64(c.Y), 2)
+				bin := fmt.Sprintf("%08b", uint8(g))
+				bits += string(bin[len(bin)-1])
+				prntln(" 10110101010001\n", bits)
+				time.Sleep(time.Second)
+			}
+			if r != g {
+				n.Set(j, i, color.Black)
+				continue
+			}
+			n.Set(j, i, color.White)
+			// y 1648
+			// x 1538
+		}
+	}
+	prntln(bits)
+	b := bit2bytes(bits)
+	_, a := alpha(p)
+	for i := 0; i < len(a); i++ {
+		a[i] ^= b[i]
+	}
+	bits = ""
+	for _, v := range a {
+		bits += fmt.Sprintf("%08b", ^v)
+	}
+	//prntln(bits)
+	prntln(string(bit2bytes(bits)))
+	return n
+}
+
+func alpha(p image.Image) (image.Image, []byte) {
+	bits := ""
+	rect := p.Bounds()
+	n := image.NewRGBA(rect)
+	for i := 0; i < rect.Max.Y; i++ {
+		for j := 0; j < rect.Max.X; j++ {
+			_, _, _, a := p.At(j, i).RGBA()
+			if a == 65021 {
+				n.Set(j, i, color.White)
+				if i == 310 {
+					bits += "1"
+				}
+				continue
+			}
+			if a == 65278 {
+				n.Set(j, i, color.Black)
+				if i == 310 {
+					bits += "0"
+				}
+				continue
+			}
+			n.Set(j, i, color.White)
+		}
+	}
+	return n, bit2bytes(bits)
+}
+
+func prntln(v ...interface{}) {
+	fmt.Fprintln(os.Stderr, v...)
+}
+
+func bit2bytes(s string) (b []byte) {
+	for i := 0; i < len(s)-8; i += 8 {
+		n, _ := strconv.ParseUint(s[i:i+8], 2, 8)
+		b = append(b, byte(n))
+	}
+	return
+}
+
+func main() {
+	f, err := os.Open("challenge.png")
+	if err != nil {
+		log.Fatal(err)
+	}
+	p, err := png.Decode(f)
+	if err != nil {
+		log.Fatal(err)
+	}
+	n := red(p)
+	//n, bits := alpha(p)
+	//prntln(string(bits))
+
+	err = png.Encode(os.Stdout, n)
+	if err != nil {
+		log.Fatal(err)
+	}
+}

pwd

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+L379F48502 - alpha.b64
+02L3F95847 - red.b64

red.b64

@@ -0,0 +1 @@
+U2FsdGVkX1+WPMJQISUVUvGRg7p4zCX4jIODIGb6b6cAreXFxv0WOxgCeSw9K+imTHiWMkRq45FsPXHs3TjYqcJz7QzQ8HeM340EwWQWXAi0fVy+r6NPmiJRgMgMqLCu4Q9o/WkNyHxvPScNgG9jf8gskggx10FiTcoyF1KE+nxjmRkEuj7uQQsPrrlRP3sjll4KXhAzrGQZi5E4sajQOBGQfaJjei5fHXXO6sxeYsFcuxzo3JdMOF3JFYQtuUDY