"use strict";(self.webpackChunkfi=self.webpackChunkfi||[]).push([[7257],{90251:(e,t,n)=>{n.r(t),n.d(t,{assets:()=>a,contentTitle:()=>h,default:()=>d,frontMatter:()=>r,metadata:()=>l,toc:()=>o});vars=n(85893),i=n(11151);constr={id:"python",slug:"/hash-tables/breaking/python",title:"Breaking Python",description:"Actually getting the worst-case time complexity in Python.\n",tags:["cpp","python","hash-tables"],last_update:{date:newDate("2023-11-28T00:00:00.000Z")}},h="Breaking the Hash Table in Python",l={id:"hash-tables/2023-11-28-breaking/python",title:"Breaking Python",description:"Actually getting the worst-case time complexity in Python.\n",source:"@site/algorithms/12-hash-tables/2023-11-28-breaking/01-python.md",sourceDirName:"12-hash-tables/2023-11-28-breaking",slug:"/hash-tables/breaking/python",permalink:"/algorithms/hash-tables/breaking/python",draft:!1,unlisted:!1,editUrl:"https://github.com/mfocko/blog/tree/main/algorithms/12-hash-tables/2023-11-28-breaking/01-python.md",tags:[{label:"cpp",permalink:"/algorithms/tags/cpp"},{label:"python",permalink:"/algorithms/tags/python"},{label:"hash-tables",permalink:"/algorithms/tags/hash-tables"}],version:"current",lastUpdatedAt:1701129600,formattedLastUpdatedAt:"Nov 28, 2023",sidebarPosition:1,frontMatter:{id:"python",slug:"/hash-tables/breaking/python",title:"Breaking Python",description:"Actually getting the worst-case time complexity in Python.\n",tags:["cpp","python","hash-tables"],last_update:{date:"2023-11-28T00:00:00.000Z"}},sidebar:"autogeneratedBar",previous:{title:"Breaking hash table",permalink:"/algorithms/hash-tables/breaking"},next:{title:"Possible Mitigations",permalink:"/algorithms/hash-tables/breaking/mitigations"}},a={},o=[{value:"Preparing the attack",id:"preparing-the-attack",level:2},{value:"Sequences",id:"sequences",level:3},{value:"Results",id:"results",level:2},{value:"Comparing with the tree",id:"comparing-with-the-tree",level:2},{value:"References",id:"references",level:2}];functionc(e){constt={a:"a",admonition:"admonition",code:"code",em:"em",h1:"h1",h2:"h2",h3:"h3",hr:"hr",li:"li",ol:"ol",p:"p",pre:"pre",section:"section",strong:"strong",sup:"sup",table:"table",tbody:"tbody",td:"td",th:"th",thead:"thead",tr:"tr",ul:"ul",...(0,i.a)(),...e.components};return(0,s.jsxs)(s.Fragment,{children:[(0,s.jsx)(t.h1,{id:"breaking-the-hash-table-in-python",children:"Breaking the Hash Table in Python"}),"\n",(0,s.jsxs)(t.p,{children:["Our language of choice for bringing the worst out of the hash table is ",(0,s.jsx)(t.em,{children:"Python"}),"."]}),"\n",(0,s.jsxs)(t.p,{children:["Let's start by talking about the hash function and why we've chosen Python for\nthis. Hash function for integers in Python is simply ",(0,s.jsx)(t.em,{children:"identity"}),", as you might've\nguessed, there's no avalanche effect. Another thing that helps us is the fact\nthat integers in Python are technically ",(0,s.jsx)(t.code,{children:"BigInt"}),"s",(0,s.jsx)(t.sup,{children:(0,s.jsx)(t.a,{href:"#user-content-fn-1",id:"user-content-fnref-1","data-footnote-ref":!0,"aria-describedby":"footnote-label",children:"1"})}),". This allows us to put bit\nmore pressure on the hashing function."]}),"\n",(0,s.jsxs)(t.p,{children:["From the perspective of the implementation, it is a hash table that uses probing\nto resolve conflicts. This also means that it's a contiguous space in memory.\nIndexing works like in the provided example above. When the hash table reaches\na ",(0,s.jsx)(t.em,{children:"breaking point"})," (defined somewhere in the C code), it reallocates the table\nand rehashes everything."]}),"\n",(0,s.jsx)(t.admonition,{type:"tip",children:(0,s.jsx)(t.p,{children:"Resizing and rehashing can reduce the conflicts. That is coming from the fact\nthat the position in the table is determined by the hash and the size of the\ntable itself."})}),"\n",(0,s.jsx)(t.h2,{id:"preparing-the-attack",children:"Preparing the attack"}),"\n",(0,s.jsx)(t.p,{children:"Knowing the things above, it is not that hard to construct a method how to cause\nas many conflicts as possible. Let's go over it:"
