{"action":"closed","issue":{"url":"https://api.github.com/repos/joearms/crypto_tutorial/issues/10","labels_url":"https://api.github.com/repos/joearms/crypto_tutorial/issues/10/labels{/name}","comments_url":"https://api.github.com/repos/joearms/crypto_tutorial/issues/10/comments","events_url":"https://api.github.com/repos/joearms/crypto_tutorial/issues/10/events","html_url":"https://github.com/joearms/crypto_tutorial/issues/10","id":104546812,"number":10,"title":"about 10.6 How big RSA keys","user":{"login":"byronhe","id":1394332,"avatar_url":"https://avatars.githubusercontent.com/u/1394332?v=3","gravatar_id":"","url":"https://api.github.com/users/byronhe","html_url":"https://github.com/byronhe","followers_url":"https://api.github.com/users/byronhe/followers","following_url":"https://api.github.com/users/byronhe/following{/other_user}","gists_url":"https://api.github.com/users/byronhe/gists{/gist_id}","starred_url":"https://api.github.com/users/byronhe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/byronhe/subscriptions","organizations_url":"https://api.github.com/users/byronhe/orgs","repos_url":"https://api.github.com/users/byronhe/repos","events_url":"https://api.github.com/users/byronhe/events{/privacy}","received_events_url":"https://api.github.com/users/byronhe/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-09-02T18:44:04Z","updated_at":"2015-09-04T09:56:00Z","closed_at":"2015-09-04T09:56:00Z","body":"\r\n> 10.6 How big RSA keys?\r\n> How large should an RSA key be? The WikiPedia says the world record was\r\n> set for RSA-76825 and has stood since 2009. This took the equivalent of 2000\r\n> years on a single-core 2.2 GHZ AMD Operon.\r\n> Now each additional bit doubles the complexity of the problem So RSA 1024\r\n> bits are 10110 time more difficult to crack than the world record26 - despite\r\n> this I’ve often seen recommendations for 2048 bits (ie 10883 times more difficult\r\n> than RSA 1024).\r\n> I guess we’re expecting aliens real soon ...\r\n\r\n\r\naccording to my understanding, this calculation is wrong.\r\n\r\nsince the most powerfull algorithm to crack RSA is NFS (number field sieve) , NFS is a sub-exponential  time complex algorithm , so add one bit to the key size will not result in a double of secret level, it is less than double in factor. \r\n\r\nhttps://en.wikipedia.org/wiki/General_number_field_sieve\r\n\r\nhttp://crypto.stackexchange.com/questions/8687/security-strength-of-rsa-in-relation-with-the-modulus-size\r\n"}}