amiga forever rom conversion

whitebird · 24 March 2012, 00:05

Hello,

Is there a tool that can convert an amiga forever encrypted rom file to a normal rom file that can be read by a real amiga or directly by winuae without the rom.key file?

prowler · 24 March 2012, 00:43

Quote:

Originally Posted by whitebird

Hello,

Is there a tool that can convert an amiga forever encrypted rom file to a normal rom file that can be read by a real amiga or directly by winuae without the rom.key file?

Yes, the version of WinUAE included with Amiga Forever will decrypt the ROMs for you if you use a ROM Grabber* and save it to a file.

* http://aminet.net/package/util/sys/SaveROM

whitebird · 24 March 2012, 10:28

Thanks prowler.

I think I understand the method. The only problem is that the rom I want to decrypt is the logica dialoga diagnostic rom, and don't see how I could launch the ROM grabber under this ROM.

prowler · 24 March 2012, 22:41

Do you know for sure that it's encrypted? And why do you wish to decrypt the logica dialoga diagnostic ROM in particular?

If you are looking to burn it to an EPROM, you may be heading for trouble. It is widely believed that Amiga Kickstart ROMs got by decrypting the Amiga Forever versions cannot be used in that way, because they will be found to have been modified, though I have not yet actually verified that for myself.

whitebird · 24 March 2012, 22:59

Yes, I know for sure it is encrypted because without the rom.key file in the folder, winuae cannot run it.

I thank it was only the encryption that makes unusable directly.

I want to burn it to an EPROM. But if it has been modified it will not run. So the best is to ask cloanto for an original rom. Don't know if the dialoga tool can be found elsewhere...

prowler · 24 March 2012, 23:17

Quote:

Originally Posted by whitebird

Yes, I know for sure it is encrypted because without the rom.key file in the folder, winuae cannot run it.

Fair enough, that settles it.

Quote:

Originally Posted by whitebird

I thank it was only the encryption that makes unusable directly.

You may well be right. However, the rumour persists that Amiga Forever ROMS are modified to prevent their piracy.

Quote:

Originally Posted by whitebird

I want to burn it to an EPROM. But if it has been modified it will not run. So the best is to ask cloanto for an original rom.

Try burning it anyway. If it has not been modified, then it will run, but if it has and it does not run, then you can simply overwrite it next time. Or you could simply ask them if it has been modified instead and save yourself some time.

If it has been modified, then I doubt that they would be able to supply you with an unmodified ROM anyway.

robinsonb5 · 25 March 2012, 00:43

Quote:

Originally Posted by prowler

If you are looking to burn it to an EPROM, you may be heading for trouble. It is widely believed that Amiga Kickstart ROMs got by decrypting the Amiga Forever versions cannot be used in that way, because they will be found to have been modified, though I have not yet actually verified that for myself.

I have. I only have Amiga Forever 6 to hand, but of the ROMs supplied with that, the Kickstart 3.0 and 3.1 ROMs are slightly mangled to prevent EPROM burning. It's quite clever actually - there's a "spare" bit in the opcode for the "moveq" instruction which is normally 0. They've changed that bit to 1 throughout the ROM, and programmed UAE's processor emulation to ignore it. Thus it works fine in UAE, but crashes on real hardware. As I say, it's only the 3.0 and 3.1 ROMs - presumably because earlier ones are no commercial threat.

prowler · 25 March 2012, 00:48

Quote:

Originally Posted by robinsonb5

I have. I only have Amiga Forever 6 to hand, but of the ROMs supplied with that, the Kickstart 3.0 and 3.1 ROMs are slightly mangled to prevent EPROM burning. It's quite clever actually - there's a "spare" bit in the opcode for the "moveq" instruction which is normally 0. They've changed that bit to 1 throughout the ROM, and programmed UAE's processor emulation to ignore it. Thus it works fine in UAE, but crashes on real hardware. As I say, it's only the 3.0 and 3.1 ROMs - presumably because earlier ones are no commercial threat.

Thanks for confirming that, and for the explanation.

whitebird · 30 March 2012, 20:49

Hello, I think there are other changes that have been made to the ROMs:

Firstly the size is normally 524288 bytes for a 512K ROM, but there are 524299 bytes in amiga forever version, and after opening the file in a text editor, we can see that it starts with the string "AMIROMTYPE1". If only a bit was toggled the size would have remained unchanged.

Secondly, bytes n°4 to number 7 are the reset vector which is 00 F8 00 D2, and this sequence does not appear in the beginning, so there may be other changes to prevent burning...

prowler · 30 March 2012, 21:04

Granted, the size of the encrypted ROM is 524299 bytes, but after using a ROM grabber to decrypt the file you'll find it will have the expected size.

whitebird · 30 March 2012, 22:17

OK, and do we find the sequence 00 F8 00 D2 at the beginning of the grabbed ROM?

Unfortunately, as already said I cannot use a rom grabber to save the logica rom because there is now ay to lauch the grabber in the diagnostic environment.

prowler · 30 March 2012, 22:29

Quote:

Originally Posted by whitebird

OK, and do we find the sequence 00 F8 00 D2 at the beginning of the grabbed ROM?

As I said somewhere above, I have never got around to verifying the rumoured modifications to the AF ROMs, so I couldn't say.

Quote:

Originally Posted by whitebird

Unfortunately, as already said I cannot use a rom grabber to save the logica rom because there is now ay to lauch the grabber in the diagnostic environment.

Well it looks like you're stumped for the moment. The only way I can see you achieving your goal is with a custom ROM grabbing tool suitable for backing up the logica dialoga diagnostic ROM.

thomas · 31 March 2012, 08:58

At least the A4000 3.1 ROM is not modified. WinUAE identifies it as normal A4000 ROM and it works perfectly with Blizkick in a real A4000.

The rom.key file ist just EOR'ed into the encrypted file as often as it fits. Should be easy to write your own decryption program. Or find the relevant section in UAE's source code.

robinsonb5 · 31 March 2012, 09:51

Quote:

Originally Posted by whitebird

Firstly the size is normally 524288 bytes for a 512K ROM, but there are 524299 bytes in amiga forever version, and after opening the file in a text editor, we can see that it starts with the string "AMIROMTYPE1".
If only a bit was toggled the size would have remained unchanged.

Yes, that's just a header.

Quote:

Secondly, bytes n°4 to number 7 are the reset vector which is 00 F8 00 D2, and this sequence does not appear in the beginning.

After you've exclusive-ored it with the keyfile to decrypt it, the reset vector should be present and correct - unless they did something more drastic for newer versions; I've only tried it with AF6's ROMs.

whitebird · 02 April 2012, 23:24

I followed the methods given in the posts and wrote a small C++ decryption program. Now Winuae can run the ROM directly, without the need of the key.

The reset vector clearly appears and is 00 F8 04 8C for the dialoga ROM.

Many thanks for the help you gave me which made me solve the problem.

12 January 2014, 11:35

Quote:

Originally Posted by whitebird

I followed the methods given in the posts and wrote a small C++ decryption program. Now Winuae can run the ROM directly, without the need of the key.

The reset vector clearly appears and is 00 F8 04 8C for the dialoga ROM.

Many thanks for the help you gave me which made me solve the problem.

< Edit: Request for Kickstart ROM and reverse-engineering aid removed - prowler>

Arnie · 12 January 2014, 12:08

Why don't you just buy a copy of AF?

I thought this sort of piracy was banned on EAB?

prowler · 12 January 2014, 22:55

Quote:

Originally Posted by Arnie

I thought this sort of piracy was banned on EAB?

Quite right. Distributing Kickstart ROM images is against the EAB rules, and it is likely that distributing a tool specifically designed to reverse-engineer the copyrighted files included in Amiga Forever is in violation of the terms and conditions of purchasing it.

Offending post above edited.

Hewitson · 13 January 2014, 08:24

I don't see the difference between WinUAE and a stand alone kickstart decrypter. Why should one be allowed and the other is not?

thomas · 13 January 2014, 10:14

As long as you still need the .key file along with the encrypted .rom, it should be legal to share the decrypting program.

Sharing the .key and .rom files surely is illegal.

And actually I don't see a reason why one would like to decrypt a ROM for WinUAE because WinUAE can handle encrypted ROMs quite well.

Using Amiga Forever ROMs with products like MiniMig which cannot use encrypted ROMs is a reason for decrypting them.

And intended piracy is another reason.

24 March 2012, 00:05	#1
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	amiga forever rom conversion Hello, Is there a tool that can convert an amiga forever encrypted rom file to a normal rom file that can be read by a real amiga or directly by winuae without the rom.key file? Last edited by prowler; 24 March 2012 at 00:44. Reason: Oops! Hit 'Edit' instead of 'Quote'. :O

13 January 2014, 08:24	#19
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	I don't see the difference between WinUAE and a stand alone kickstart decrypter. Why should one be allowed and the other is not? Last edited by Hewitson; 13 January 2014 at 08:31.

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24 March 2012, 10:28	#3
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	Thanks prowler. I think I understand the method. The only problem is that the rom I want to decrypt is the logica dialoga diagnostic rom, and don't see how I could launch the ROM grabber under this ROM.

24 March 2012, 22:41	#4
prowler Global Moderator Join Date: Aug 2008 Location: Sidcup, England Posts: 10,300	Do you know for sure that it's encrypted? And why do you wish to decrypt the logica dialoga diagnostic ROM in particular? If you are looking to burn it to an EPROM, you may be heading for trouble. It is widely believed that Amiga Kickstart ROMs got by decrypting the Amiga Forever versions cannot be used in that way, because they will be found to have been modified, though I have not yet actually verified that for myself.

24 March 2012, 22:59	#5
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	Yes, I know for sure it is encrypted because without the rom.key file in the folder, winuae cannot run it. I thank it was only the encryption that makes unusable directly. I want to burn it to an EPROM. But if it has been modified it will not run. So the best is to ask cloanto for an original rom. Don't know if the dialoga tool can be found elsewhere...

30 March 2012, 20:49	#9
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	Hello, I think there are other changes that have been made to the ROMs: Firstly the size is normally 524288 bytes for a 512K ROM, but there are 524299 bytes in amiga forever version, and after opening the file in a text editor, we can see that it starts with the string "AMIROMTYPE1". If only a bit was toggled the size would have remained unchanged. Secondly, bytes n°4 to number 7 are the reset vector which is 00 F8 00 D2, and this sequence does not appear in the beginning, so there may be other changes to prevent burning...

30 March 2012, 21:04	#10
prowler Global Moderator Join Date: Aug 2008 Location: Sidcup, England Posts: 10,300	Granted, the size of the encrypted ROM is 524299 bytes, but after using a ROM grabber to decrypt the file you'll find it will have the expected size.

30 March 2012, 22:17	#11
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	OK, and do we find the sequence 00 F8 00 D2 at the beginning of the grabbed ROM? Unfortunately, as already said I cannot use a rom grabber to save the logica rom because there is now ay to lauch the grabber in the diagnostic environment.

31 March 2012, 08:58	#13
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 7,001	At least the A4000 3.1 ROM is not modified. WinUAE identifies it as normal A4000 ROM and it works perfectly with Blizkick in a real A4000. The rom.key file ist just EOR'ed into the encrypted file as often as it fits. Should be easy to write your own decryption program. Or find the relevant section in UAE's source code.

02 April 2012, 23:24	#15
whitebird Registered User Join Date: May 2006 Location: France Age: 48 Posts: 211	I followed the methods given in the posts and wrote a small C++ decryption program. Now Winuae can run the ROM directly, without the need of the key. The reset vector clearly appears and is 00 F8 04 8C for the dialoga ROM. Many thanks for the help you gave me which made me solve the problem.

12 January 2014, 12:08	#17
Arnie R.I.P Smudge 18-08-16 Join Date: Aug 2005 Location: Leicester/UK Age: 66 Posts: 3,968	Why don't you just buy a copy of AF? I thought this sort of piracy was banned on EAB?

13 January 2014, 10:14	#20
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 7,001	As long as you still need the .key file along with the encrypted .rom, it should be legal to share the decrypting program. Sharing the .key and .rom files surely is illegal. And actually I don't see a reason why one would like to decrypt a ROM for WinUAE because WinUAE can handle encrypted ROMs quite well. Using Amiga Forever ROMs with products like MiniMig which cannot use encrypted ROMs is a reason for decrypting them. And intended piracy is another reason.

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