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Title: How to get in Python, result same in cpp ? Post by: COBRAS on May 10, 2022, 04:16:27 PM Hello
Then I divide in modmath I get: ./modmath 0x60f4d11574f5deee49961d9609ac / 2 Result: 307a688aba7aef7724cb0ecb04d6 in Python: He =0x60f4d11574f5deee49961d9609ac h2 = int(He / 2) % n print(hex(h2)) result 0x307a688aba7af000000000000000 [Program finished] HOW TO GET IN PYTHON result = af55fc59c335c8ec67ed24827 ? ------ /modmath 0x60f4d11574f5deee49961d9609ac / 8 Result: 7fffffffffffffffffffffffffffffff5d577a91f1c6febc9bc6f8792bcde1d6 python: n = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 He =0x60f4d11574f5deee49961d9609ac h2 = int(He / 8 ) % n print(hex(h2)) 0xc1e9a22ae9ebc00000000000000 [Program finished HOW TO GET IN PYTHON result = 7fffffffffffffffffffffffffffffff5d577a91f1c6febc9bc6f8792bcde1d6 ??? thanks !!! ASAP PLEASE Title: Re: How to get in Python, result same in cpp ? Post by: n0nce on May 10, 2022, 07:55:46 PM This happens because the division operator gives you a float which can only have so many bits of accuracy. You circumvent it by using //.
Example: Code: >>> 1966507701910865760267104647776684/2 As you correctly noticed, all those trailing zeroes are wrong and due to the rounding done by Python floats. By dividing with //, you force it to stay in the integer realm and you get the correct result. Code: >>> 1966507701910865760267104647776684//2 The second division is mathematically wrong (the modmath output, that is), it seems to have overflown. I don't know how many bits a modmath number has, so I can't tell you how to replicate the result in Python. But the method from above (with double //) will give you mathematically correct results no matter what. Title: Re: How to get in Python, result same in cpp ? Post by: NotATether on May 11, 2022, 04:09:27 AM ./modmath 0x60f4d11574f5deee49961d9609ac / 2 ... h2 = int(He / 2) % n ... HOW TO GET IN PYTHON result = af55fc59c335c8ec67ed24827 ? [I have trimmed your code and cmdline above] Apparently, the first line is for a c++ program (did you write it?), the other is for a custom script that you made. If you did not write the modmath program then you ought to take a look at its code on Github to see how it's getting the correct results. Maybe there are some ANDs being done there which you thought weren't necessary in Python because of its lack of overflow. (and while you're at the codebase, drop us a link to it please). Title: Re: How to get in Python, result same in cpp ? Post by: iceland2k14 on May 11, 2022, 04:51:27 AM If you did not write the modmath program then you ought to take a look at its code on Github to see how it's getting the correct results. Maybe there are some ANDs being done there which you thought weren't necessary in Python because of its lack of overflow. (and while you're at the codebase, drop us a link to it please). He is Talking about https://github.com/albertobsd/ecctools (https://github.com/albertobsd/ecctools) I think. Title: Re: How to get in Python, result same in cpp ? Post by: mausuv on May 11, 2022, 06:12:11 AM Hello @COBRASThen I divide in modmath I get: ./modmath 0x60f4d11574f5deee49961d9609ac / 2 Result: 307a688aba7aef7724cb0ecb04d6 you need this ( 0x60f4d11574f5deee49961d9609ac / 2 = 307a688aba7aef7724cb0ecb04d6) result run python2, its working Code: user@0d3aad1851b1:~/Downloads$ python2 1.py Code: user@0d3aad1851b1:~/Downloads$ python2 1.py edit: @COBRAS share your ./modemath ideas thinkeasy123@protonmail.com answer me https://bitcointalk.org/index.php?topic=5395858.msg60039035#msg60039035 Title: Re: How to get in Python, result same in cpp ? Post by: fxsniper on May 11, 2022, 07:54:20 AM I think modmath.c it is not a division number by simple math
but modmath.c it is division by use function Elliptic curve point division Code: case '/': Code: def ECdiv(Qx,Qy,Scalar): # EC point division try to use Elliptic curve point division function on python I am not sure I am correct, wait programmer/expert coder to help confirm Title: Re: How to get in Python, result same in cpp ? Post by: COBRAS on May 11, 2022, 01:32:21 PM Hello @COBRASThen I divide in modmath I get: ./modmath 0x60f4d11574f5deee49961d9609ac / 2 Result: 307a688aba7aef7724cb0ecb04d6 you need this ( 0x60f4d11574f5deee49961d9609ac / 2 = 307a688aba7aef7724cb0ecb04d6) result run python2, its working Code: user@0d3aad1851b1:~/Downloads$ python2 1.py Code: user@0d3aad1851b1:~/Downloads$ python2 1.py edit: @COBRAS share your ./modemath ideas thinkeasy123@protonmail.com answer me https://bitcointalk.org/index.php?topic=5395858.msg60039035#msg60039035 Hi Bro. Yes, I need this. pm me we are talk. I not agree what 0xfffff... is wrang. because then I div for ex 10 to 9 (10 / 9) 0xfff....... is ok, result without floating part not good for dividing... Title: Re: How to get in Python, result same in cpp ? Post by: COBRAS on May 11, 2022, 01:33:32 PM If you did not write the modmath program then you ought to take a look at its code on Github to see how it's getting the correct results. Maybe there are some ANDs being done there which you thought weren't necessary in Python because of its lack of overflow. (and while you're at the codebase, drop us a link to it please). He is Talking about https://github.com/albertobsd/ecctools (https://github.com/albertobsd/ecctools) I think. yes Title: Re: How to get in Python, result same in cpp ? Post by: COBRAS on May 12, 2022, 04:08:59 PM example of dividing
./md 1 / 3 Result: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0242b81 (let it be 1/3) 10000 x 1/3: ./md 10000 x 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0242b81 Result: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0243886 1000*1/3 - 1/3=3333: ./md 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0243886 - 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0242b81 Result: d05 search range: 1/3 to 1/3*10000 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0242b81 : 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa9d1c9e899ca306ad27fe1945de0243886 = 3333 3 times smale then 10000.You can play with ecctools for making your methods based on this example. Use pubkeys from start privkeys and you get pubkey in range 3 time smaler too !!! I looking for python programmer who know good simplest math operation in python for work on code for dividing pubksys. ASAP. YOU MAST KNOW HOW TO GET THIS RESULT, IF YOU CAN MESSAGE ME YOUR TELEGRAMM FOR TALK: Hello @COBRASThen I divide in modmath I get: ./modmath 0x60f4d11574f5deee49961d9609ac / 2 Result: 307a688aba7aef7724cb0ecb04d6 you need this ( 0x60f4d11574f5deee49961d9609ac / 2 = 307a688aba7aef7724cb0ecb04d6) result run python2, its working Code: user@0d3aad1851b1:~/Downloads$ python2 1.py Code: user@0d3aad1851b1:~/Downloads$ python2 1.py edit: |