ill look into it. in the meantime, if anyone comes across anything genesis ASM related let me know. Hopefully I can figure it out by looking at it
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| [Genesis] Road Rash II Request https://www.kodewerx.org/forum/viewtopic.php?f=2&t=1192 |
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| Author: | kickenchicken57 [ Wed Mar 28, 2007 9:47 pm ] |
| Post subject: | [Genesis] Road Rash II Request |
Normally I don't do this, but I need help. Who can help me crack this one? I would like to know how the checksums in the passwords are calculated so I can make a password generator. http://cheats.ign.com/ob2/068/006/006640.html explains how the passwords are made, but not how to calculate a checksum. I have tried to find the pattern but failed. |
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| Author: | kenobi [ Wed Mar 28, 2007 10:30 pm ] |
| Post subject: | |
Obviously yhey have no clue on how the checksum actually works. They say 'add 2 to a character, remove 2 to another to keep the checksum valid'... They never recalculate the checksum. Then, the only way to find out easily, and for sure, how the checksum is calculated would be to look at the assembly... Also, 'usually' checksums like to xor and bitshift data, so it should be 'almost impossible' to find out the checksum algorithm from scratch. However, if you have time to kill and no access to the checksum assembly, you can still find the checksums when 0 bits are set (0000000), then when only one bit of the data is set (1000000, 2000000, 4000000, 8000000, g000000, ..., 0100000, 0200000, ..., 0000001, 0000002), then for 2 bits (1100000, 1200000...) (then 3 bits?...) until you find a 'pattern' (might not work if the cheksum is 'complicated' : if it not() data, if it adds other fixed data to it, it might be pretty hard to reverse it that way... ; but this road rash checksum seems kinda simple, as adding 2/removing 2 from certain data bytes seems to not change it). |
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| Author: | kickenchicken57 [ Wed Mar 28, 2007 10:35 pm ] |
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it mentions that lower bits of the money is unused but may be used for the chacksum (unless that was another source). O well. I guess tomorrow I will try what you suggested and start over clean. Ill try to take a look at the different bits and how they affect the checksum. Also, what would be a good source to find the tools needed to start looking at Genesis ASM so that I may find a breakpoint on the checksum code and find the ASM that calculates it? |
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| Author: | kenobi [ Wed Mar 28, 2007 10:41 pm ] |
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I wouldn't know, never tried any genesis(/megadrive) emulator in my life. However, google reported some, so there might be one useful for this checksum hacking... |
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| Author: | kickenchicken57 [ Thu Mar 29, 2007 4:27 am ] |
| Post subject: | |
ill look into it. in the meantime, if anyone comes across anything genesis ASM related let me know. Hopefully I can figure it out by looking at it
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