Stego 15
From Kyle's Wiki
This mission has some 24 odd pixels at:
98,0 106,0 69,1 121,1 98,2 109,2 70,3 105,3 73,4 87,4 57,5 115,5 101,6 109,6 112,6 114,6 75,7 67,8 111,8 118,8 78,9 71,10 70,11 122,11
Assuming starting from in the upper left hand corner. What mysteries to these numbers hold? The ascii values of the x components of each is: </pre> You must cat out the last two chars. The solution is: easy findable with the codes listed down
Some decoding Code:
<? require_once("imagefrombmp.php"); $im = ImageCreateFromjpeg("stego15b.jpg"); $x= imagesx($im); $y= imagesy($im); $hely=-1; $elozo=0; $s=$s2=""; $bv=$bv2=""; $db=0; for($i=0; $i<=$y-1; ++$i){ for($j=0; $j<=$x-1; ++$j){ ++$hely; $rgb = imagecolorat($im, $j, $i); $rgb=imagecolorsforindex($im,$rgb); if(!($rgb["red"]>=240 || $rgb["green"]>=240 || $rgb["blue"]>=240)){ $s.="$j,$i "; $s2.=$j%6; $s2.=","; $s2.=$i%6; $s2.=" "; $bv.=chr($j); $bv2.=chr($j+$i); $db++; }; }; }; echo "$s<br>$s2<br>$bv<br>$bv2<br>".base64_decode($bv)."<br>$db"; ?>
Imagecreate from BMP
<?php /*********************************************/ /* Fonction: ImageCreateFromBMP */ /* Author: DHKold */ /* Contact: admin@dhkold.com */ /* Date: The 15th of June 2005 */ /* Version: 2.0B */ /*********************************************/ function ImageCreateFromBMP($filename) { //Ouverture du fichier en mode binaire if (! $f1 = fopen($filename,"rb")) return FALSE; //1 : Chargement des ent?tes FICHIER $FILE = unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread($f1,14)); if ($FILE['file_type'] != 19778) return FALSE; //2 : Chargement des ent?tes BMP $BMP = unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel'. '/Vcompression/Vsize_bitmap/Vhoriz_resolution'. '/Vvert_resolution/Vcolors_used/Vcolors_important', fread($f1,40)); $BMP['colors'] = pow(2,$BMP['bits_per_pixel']); if ($BMP['size_bitmap'] == 0) $BMP['size_bitmap'] = $FILE['file_size'] - $FILE['bitmap_offset']; $BMP['bytes_per_pixel'] = $BMP['bits_per_pixel']/8; $BMP['bytes_per_pixel2'] = ceil($BMP['bytes_per_pixel']); $BMP['decal'] = ($BMP['width']*$BMP['bytes_per_pixel']/4); $BMP['decal'] -= floor($BMP['width']*$BMP['bytes_per_pixel']/4); $BMP['decal'] = 4-(4*$BMP['decal']); if ($BMP['decal'] == 4) $BMP['decal'] = 0; //3 : Chargement des couleurs de la palette $PALETTE = array(); if ($BMP['colors'] < 16777216) { $PALETTE = unpack('V'.$BMP['colors'], fread($f1,$BMP['colors']*4)); } //4 : Cr?ation de l'image $IMG = fread($f1,$BMP['size_bitmap']); $VIDE = chr(0); $res = imagecreatetruecolor($BMP['width'],$BMP['height']); $P = 0; $Y = $BMP['height']-1; while ($Y >= 0) { $X=0; while ($X < $BMP['width']) { if ($BMP['bits_per_pixel'] == 24) $COLOR = unpack("V",substr($IMG,$P,3).$VIDE); elseif ($BMP['bits_per_pixel'] == 16) { $COLOR = unpack("n",substr($IMG,$P,2)); $COLOR[1] = $PALETTE[$COLOR[1]+1]; } elseif ($BMP['bits_per_pixel'] == 8) { $COLOR = unpack("n",$VIDE.substr($IMG,$P,1)); $COLOR[1] = $PALETTE[$COLOR[1]+1]; } elseif ($BMP['bits_per_pixel'] == 4) { $COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1)); if (($P*2)%2 == 0) $COLOR[1] = ($COLOR[1] >> 4) ; else $COLOR[1] = ($COLOR[1] & 0x0F); $COLOR[1] = $PALETTE[$COLOR[1]+1]; } elseif ($BMP['bits_per_pixel'] == 1) { $COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1)); if (($P*8)%8 == 0) $COLOR[1] = $COLOR[1] >>7; elseif (($P*8)%8 == 1) $COLOR[1] = ($COLOR[1] & 0x40)>>6; elseif (($P*8)%8 == 2) $COLOR[1] = ($COLOR[1] & 0x20)>>5; elseif (($P*8)%8 == 3) $COLOR[1] = ($COLOR[1] & 0x10)>>4; elseif (($P*8)%8 == 4) $COLOR[1] = ($COLOR[1] & 0x8)>>3; elseif (($P*8)%8 == 5) $COLOR[1] = ($COLOR[1] & 0x4)>>2; elseif (($P*8)%8 == 6) $COLOR[1] = ($COLOR[1] & 0x2)>>1; elseif (($P*8)%8 == 7) $COLOR[1] = ($COLOR[1] & 0x1); $COLOR[1] = $PALETTE[$COLOR[1]+1]; } else return FALSE; imagesetpixel($res,$X,$Y,$COLOR[1]); $X++; $P += $BMP['bytes_per_pixel']; } $Y--; $P+=$BMP['decal']; } //Fermeture du fichier fclose($f1); return $res; } ?>