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 2011-05-15, 02:58 #1 Hian   May 2011 310 Posts Semiprimes Does anyone know where can I get a list of semiprime numbers (>123 decimal digits) with their corresponding prime factors? Can anyone help me to factorise the following 123-digit semiprime? 270670841438652918328457437265155619391032450133463282814465259139067145362144253227993241689950508665789547410822808227577 Many thanks.
2011-05-15, 04:43   #2
R.D. Silverman

Nov 2003

22·5·373 Posts

Quote:
 Originally Posted by Hian Does anyone know where can I get a list of semiprime numbers (>123 decimal digits) with their corresponding prime factors?
I suggest that you estimate the size of such a list......

Quote:
 Can anyone help me to factorise the following 123-digit semiprime? 270670841438652918328457437265155619391032450133463282814465259139067145362144253227993241689950508665789547410822808227577 Many thanks.
Stop posting the same/similar question(s) to multiple forums.

You also need to explain why anyone should want to do your work for you.

2011-05-15, 08:49   #3
xilman
Bamboozled!

"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across

2·3·1,753 Posts

Quote:
 Originally Posted by R.D. Silverman I suggest that you estimate the size of such a list...... Stop posting the same/similar question(s) to multiple forums. You also need to explain why anyone should want to do your work for you.
Bob, you are slipping. Shame on you. Hian asked for a list, not for the complete list.

Hian: here is a list for you:

Code:
13672189887874844830294854600197645512844795863881883253689969830974172409049945718439475079482752818122343529516565272453 = 1496065788071742890012822928063153445784598021413069044090849 * 9138762477482175803233819882492079303177779082384971201704997

27193224269088935025333248735936824028463903074170155941135660729806618027705547104021063592551008779582473241244874916677 = 2975591535078494718909305165623136593204335955651117007329441 * 9138762477482175803233819882492079303177779082384971201704997

83516979619836155805053630304214506559429428372337994908795086403369674908014861010054485048573487229087697485079814770009 = 9138762477482175803233819882492079303177779082384971201704997 * 9138762477482175803233819882492079303177779082384971201704997
(If you ask a silly question, you should expect to get a silly answer.)

Paul

 2011-05-15, 09:16 #4 Hian   May 2011 3 Posts Thank you so much Paul, you are so helpful. Actually, I have been searching for programmes from websites (as suggested by posts in this forum) which can help me to factorise semiprimes. However, I still can't get the answer after running the programmes continuously for almost 2 days. Two good websites I have found so far are: http://www.alpertron.com.ar/ECM.HTM http://sites.google.com/site/bbuhrow/home Is there any better suggestions?
 2011-05-15, 09:47 #5 kar_bon     Mar 2006 Germany 2×1,433 Posts Here is a list of some Semiprimes, too.
2011-05-15, 11:07   #6
R.D. Silverman

Nov 2003

11101001001002 Posts

Quote:
 Originally Posted by Hian Thank you so much Paul, you are so helpful. Actually, I have been searching for programmes from websites (as suggested by posts in this forum) which can help me to factorise semiprimes. However, I still can't get the answer after running the programmes continuously for almost 2 days. Two good websites I have found so far are: http://www.alpertron.com.ar/ECM.HTM http://sites.google.com/site/bbuhrow/home Is there any better suggestions?
Use ggnfs/msieve.

BTW, a simple google search will turn up lots of RSA public keys..........

2011-05-15, 11:15   #7
R.D. Silverman

Nov 2003

746010 Posts

Quote:
 Originally Posted by xilman Bob, you are slipping. Shame on you. Hian asked for a list, not for the complete list. Hian: here is a list for you: Code: 13672189887874844830294854600197645512844795863881883253689969830974172409049945718439475079482752818122343529516565272453 = 1496065788071742890012822928063153445784598021413069044090849 * 9138762477482175803233819882492079303177779082384971201704997 27193224269088935025333248735936824028463903074170155941135660729806618027705547104021063592551008779582473241244874916677 = 2975591535078494718909305165623136593204335955651117007329441 * 9138762477482175803233819882492079303177779082384971201704997 83516979619836155805053630304214506559429428372337994908795086403369674908014861010054485048573487229087697485079814770009 = 9138762477482175803233819882492079303177779082384971201704997 * 9138762477482175803233819882492079303177779082384971201704997 (If you ask a silly question, you should expect to get a silly answer.) The answer to your other question is: yes. Paul
Here's another list:

Code:
2 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
3 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
5 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
7 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
11 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
13 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
17 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
19 * 88625379503308113870163817479116818523025223399242215471800784810025248381387984608067747463864839726134410700901664118330633
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.
.
.
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2011-05-15, 11:39   #8
Christenson

Dec 2010
Monticello

111000000112 Posts

Quote:
 Originally Posted by R.D. Silverman Use ggnfs/msieve. BTW, a simple google search will turn up lots of RSA public keys..........
What's the approximate run-time for the OP's number? (Knowing that the variance could be wide, no proof that it couldn't have a 10-bit factor that could be found in under an hour by TF, ASSUMING its roughly P60*P63 )

2011-05-15, 13:06   #9
wblipp

"William"
May 2003
New Haven

23·5·59 Posts

Quote:
 Originally Posted by Hian Two good websites I have found so far are: http://www.alpertron.com.ar/ECM.HTM http://sites.google.com/site/bbuhrow/home Is there any better suggestions?
Above approximately 100 digits, follow this:

http://gilchrist.ca/jeff/factoring/n...ers_guide.html

2011-05-24, 02:46   #10
lavalamp

Oct 2007
Manchester, UK

2×3×223 Posts

Quote:
 Originally Posted by Hian Can anyone help me to factorise the following 123-digit semiprime? 270670841438652918328457437265155619391032450133463282814465259139067145362144253227993241689950508665789547410822808227577
If you want to factor this number then GNFS is the way to go, you could crack it open with ECM, but it'll take a lot longer since it has two 62 digit factors.

2011-05-29, 07:11   #11
gd_barnes

May 2007
Kansas; USA

7×13×113 Posts

Quote:
 Originally Posted by xilman Bob, you are slipping. Shame on you. Hian asked for a list, not for the complete list. Hian: here is a list for you: Code: 13672189887874844830294854600197645512844795863881883253689969830974172409049945718439475079482752818122343529516565272453 = 1496065788071742890012822928063153445784598021413069044090849 * 9138762477482175803233819882492079303177779082384971201704997 27193224269088935025333248735936824028463903074170155941135660729806618027705547104021063592551008779582473241244874916677 = 2975591535078494718909305165623136593204335955651117007329441 * 9138762477482175803233819882492079303177779082384971201704997 83516979619836155805053630304214506559429428372337994908795086403369674908014861010054485048573487229087697485079814770009 = 9138762477482175803233819882492079303177779082384971201704997 * 9138762477482175803233819882492079303177779082384971201704997 (If you ask a silly question, you should expect to get a silly answer.) The answer to your other question is: yes. Paul

No that isn't a list. He asked for a list of semiprimes > 123 digits. These only have 122 digits. Bob's list is good though.

BTW, the OP hasn't been on the forum since 1 day after his follow up response. I guess he wasn't very serious about learning about factoring. He obviously just wanted his work done for him.

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