title: I9300 sboot.bin 256-Byte signatures, or checksum?
body: <p>Some time ago I started trying to mod my Samsung Galaxy S3 (International edition (I9300)), and I ended up with the Bootlogo, this is the <strong>FIRST</strong> image that you see when you turn on the Galaxy S3. I wanted to change it, as it is quite easy on other devices.</p>
  
  <p>This is where I ran into troubles, I asked around on XDA-developes [link 1] (<a href="http://forum.xda-developers.com/galaxy-s3/help/removal-bootlogo-t2662444" rel="nofollow">http://forum.xda-developers.com/galaxy-s3/help/removal-bootlogo-t2662444</a>) and [link 2] (<a href="http://forum.xda-developers.com/showthread.php?t=2317694" rel="nofollow">http://forum.xda-developers.com/showthread.php?t=2317694</a>) but most of the answers led me nowhere. I ended up with the sboot.bin which is the secondary boot program (I guess this is how you can call it). To open it was quite difficult for a noob like me, but with hexadecimal editor HxD I opened it and actually found the bootlogo! (I copied the bytes into a jpg and it showed up normally.) I changed the bytes with another jpg image I made myself, and tried to flash it to the phone, but it failed. everything I tried afterwards failed, and I wondered why.</p>
  
  <p>I downloaded a couple of sboot.bin for the i9300, but different countries, and I compared the hex code. There seemed to be subtle changes: one was in the compile date and serie nr. And there rest was a jumble of random character 256 bytes long.</p>
  
  <p>I found that there are 4 sequences of 256 bytes long throughout the sboot.bin. An example of one:</p>
  
  <pre><code>EA E9 0C 62 B0 E0 68 86 5A 7B BD CA 50 3D 21 02 
  17 2C AC 10 09 49 62 E1 DA EB F4 94 B6 74 68 15 
  E6 90 2F CA 2F 75 67 C6 34 AE A3 A0 8F BC 60 62 
  63 87 8C C4 6C 8A 39 AA 7C 8A C7 E1 14 A3 C1 37 
  51 43 85 C0 09 97 05 AF 32 86 32 8C 58 7D C1 8F 
  91 A1 5E F1 9F D7 24 DF 08 82 1B AD FA C7 72 24 
  BC 35 34 6F 0F 42 C9 4E 7F AB FC 72 BC 64 71 84 
  DC 30 BB D5 AD D4 DE 01 9A E9 FB AA 1F 69 6F 52 
  3D E9 2A 52 6B 7E 9B 79 DE BD 7C 55 31 51 D6 99 
  BE 74 4F 22 6F 23 2F BF 7A 81 EF 5B 20 BF 75 03 
  D3 84 61 37 81 50 ED 71 66 4F 3D 34 0E 5A 33 4D 
  86 E2 E7 D0 8F 2B 48 5E 85 B5 E6 3F 56 51 70 74 
  CE 87 52 2D 47 D0 39 F6 CD 50 EE 76 F4 8E 79 7C 
  90 CF 4C 07 D5 47 AF 86 3D 33 3B A1 2A 70 74 4F 
  D1 60 9F 9E 28 96 C9 6E 9D DA 12 CB E1 8C 5B A5 
  CA AC 84 E2 26 1E 6F FD 4E EE B8 53 6E 7B 30 19
  </code></pre>
  
  <p>Maybe because it is helpful: one block is somewhat in the beginning, one is almost in the end, and the last two are at the real end of the file. So maybe the last two blocks are actually one big 512 byte block...</p>
  
  <p>So I have come as far as to think that it might be a checksum or signature. But I am not sure how to find out what kind it is and how to generate one my self. searching for it hasn't helped me, because I cannot seem to find anything this long (256 bytes) only 256 bits long...</p>
  
  <p>I was wondering if maybe someone could see what kind of siganture/checksum this is (Is this possible?) or how I can find out myself. or what I should do next...</p>
  
  <p>[Edit on 25-08]
  <strong>Alright, Since nobody has been able to answer the question yet, I was thinking of offering an incentive. I am willing to pay 1000 USD to whoever can help me alter the BOOTLOGO of the I9300!!!</strong></p>
  
  <p>Frank</p>