https://wikiti.brandonw.net/index.php?action=history&feed=atom&title=83Plus%3ABCALLs%3A80C0 2026-04-05T22:56:52Z Revision history for this page on the wiki MediaWiki 1.23.5 https://wikiti.brandonw.net/index.php?title=83Plus:BCALLs:80C0&diff=3505&oldid=prev 2005-03-31T02:02:40Z

<p></p> <p><b>New page</b></p><div>[[Category:83Plus:BCALLs:By_Name:Cryptography|bignumpowermod17]] [[Category:83Plus:BCALLs:By_Name:Math:Big Integer|bignumpowermod17]] [[Category:83Plus:BCALLs:By_Name:Math|bignumpowermod17]] [[Category:83Plus:BCALLs:By_Name|bignumpowermod17]] [[Category:83Plus:BCALLs:By_Address|80C0 - bignumpowermod17]]<br /> == Synopsis ==<br /> '''Official Name:''' bignumpowermod17<br /> <br /> '''BCALL Address:''' 80C0<br /> <br /> Raises a big integer to the 17th power.<br /> <br /> === Inputs ===<br /> * [[83Plus:RAM:8182|8182]] holds the signature<br /> * [[83Plus:RAM:8000|8000]] holds the modulus, another big integer<br /> <br /> === Outputs ===<br /> * [[83Plus:RAM:8478|OP1-OP6]] hold the plaintext, a big integer<br /> * DE points to [[83Plus:RAM:8478|OP1]]<br /> <br /> === Destroys ===<br /> * All registers<br /> * [[83Plus:RAM:8100|8100h]]: 130-byte area which the multiplication routine uses to store its result<br /> * [[83Plus:RAM:8182|8182h]]: 65-byte area used as the first argument to the multiplication routine<br /> * [[83Plus:RAM:81C3|81C3h]]: 65-byte area used as the second argument to the multiplication routine<br /> <br /> == Comments ==<br /> This BCALL takes a large integer pointed at address 8182h and raises it to the 17th power (modulo the current public key.) The OS uses this to decrypt RSA signatures, such as those used for certificate blocks. This differs only from RSAValidate in that this romcall expects the signature to already be copied to 8182h.</div>

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