Nový Bitcoin komunikuje přes Tor

24. 2. 2016
Doba čtení: 2 minuty

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Ilustrační obrázek
Autor: Depositphotos – stori
Ilustrační obrázek
Bitcoin Core 0.12, referenční klient protokolu Bitcoin, po delší době přináší větší změny. Týkají se možnosti navýšení poplatků, podpory anonymizační sítě Tor nebo podstatně rychlejšího ověření podpisů.

Bitcoin bylo možné s Torem používat i dříve, ale uživatel to musel nakonfigurovat. Od nové verze 0.12 je Tor použit vždy, kdy je to možné – tedy tehdy, když je Tor dostupný v systému. Ale pozor, použití Toru samozřejmě neřeší problém pseudonymity a tedy možnost spojení bitcoinové adresy se jménem, pouze ztěžuje (prakticky dokonale) možnost vystopování původu transakce v internetu. Bitcoin stále není anonymní a ze své podstaty asi nikdy nebude.

Další velkou změnou je možnost dodatečně navýšit poplatek. Pokud uživatel poslal bitcoiny a kvůli nízkému poplatku bylo potvrzování transakce pomalé, neměl žádnou možnost, jak tuto nepříjemnou situaci řešit. Nově existuje možnost poslat do sítě transakci s vyšším poplatkem, která původní transakci nahradí. Tím pádem se potvrzování urychlí a nehrozí zaseknutí transakce. Použití této možnosti je částečně limitováno kvůli možnému zneužívání. Poctivec to ale řešit nemusí.

Jak je známo, velikost blockchainu se neustále zvyšuje a některých případech už to může představovat problém. Bitcoin Core už proto po klientech nevyžaduje uchovávání kompletního blockchainu. Nová funkce ořezávání zajistí, že klient bude uchovávat jen nejnovějších X megabajtů blockchainu. Nejnižší povolená hodnota je 550 MB, což je oproti plné velikosti blockchainu (cca 60 GB) opravdu rozdíl. Tato možnost potěší hlavně běžné uživatele, kteří chtějí Bitcoin Core používat jen jako osobní peněženku.

Ověřování podpisů je s verzí 0.12 mnohem rychlejší, na 64bitových procesorech až pětinásobně. Namísto používání obecného OpenSSL totiž vývojáři vyvinuli specializovanou knihovnu libsecp256k1. Rychlejší ověřování rovněž trochu sníží náklady na provoz uzlů.

hacking_tip

Klient dále nově umožňuje nastavit maximální velikost paměťového poolu. V praxi to znamená, že takto konfigurované uzly nebude možné zahltit velkým množstvím transakcí – v praxi hlavně cíleným spamem. Výchozí velikost poolu je 300 MB. Pokud jí bude dosaženo, budou z paměti mazány transakce s nejnižší poplatkovou mírou. Potěší také možnost nastavit maximální rychlost uploadu při sdílení blockchainu.

Přestože Bitcoin Core 0.12 přináší hodně novinek a řeší řadu problémů, na které si nejen těžaři stěžovali, ten největší problém zatím zůstává nevyřešen. Diskutuje se o tom, co udělat s velikostí bloku. Současná velikost 1 MB už začíná omezovat. Hlavně v tom, že se protahuje doba ověřování transakcí. Návrhů je několik, ale zatím se nepodařilo dosáhnout konsensu.

Autor článku

Bývalý redaktor serveru Root.cz, dnes produktový manažer a konzultant se zaměřením na Bitcoin a kryptoměny.

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Must be done through a user action on mobile // devices. videoContent.load(); adDisplayContainer.initialize(); // setupDimensions(); try { // Initialize the ads manager. Ad rules playlist will start at this time. adsManager.init(1920, 1080, google.ima.ViewMode.NORMAL); // Call play to start showing the ad. Single video and overlay ads will // start at this time; the call will be ignored for ad rules. adsManager.start(); // window.addEventListener('resize', function (event) { // if (adsManager) { // setupDimensions(); // adsManager.resize(outstreamWidth, outstreamHeight, google.ima.ViewMode.NORMAL); // } // }); } catch (adError) { // An error may be thrown if there was a problem with the VAST response. // videoContent.play(); } } /** * Handles the ad manager loading and sets ad event listeners. * @param { !google.ima.AdsManagerLoadedEvent } adsManagerLoadedEvent */ function onAdsManagerLoaded(adsManagerLoadedEvent) { // Get the ads manager. const adsRenderingSettings = new google.ima.AdsRenderingSettings(); adsRenderingSettings.restoreCustomPlaybackStateOnAdBreakComplete = true; adsRenderingSettings.loadVideoTimeout = 12000; // videoContent should be set to the content video element. adsManager = adsManagerLoadedEvent.getAdsManager(videoContent, adsRenderingSettings); // Add listeners to the required events. adsManager.addEventListener(google.ima.AdErrorEvent.Type.AD_ERROR, onAdError); adsManager.addEventListener( google.ima.AdEvent.Type.CONTENT_PAUSE_REQUESTED, onContentPauseRequested); adsManager.addEventListener( google.ima.AdEvent.Type.CONTENT_RESUME_REQUESTED, onContentResumeRequested); adsManager.addEventListener( google.ima.AdEvent.Type.ALL_ADS_COMPLETED, onAdEvent); // Listen to any additional events, if necessary. adsManager.addEventListener(google.ima.AdEvent.Type.LOADED, onAdEvent); adsManager.addEventListener(google.ima.AdEvent.Type.STARTED, onAdEvent); adsManager.addEventListener(google.ima.AdEvent.Type.COMPLETE, onAdEvent); playAds(); } /** * Handles actions taken in response to ad events. * @param { !google.ima.AdEvent } adEvent */ function onAdEvent(adEvent) { // Retrieve the ad from the event. 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It is the responsibility of the Publisher to // implement this function when necessary. // setupUIForContent(); } function onActiveView() { if (outstreamContainer) { const containerOffset = outstreamContainer.getBoundingClientRect(); const windowHeight = window.innerHeight; if (containerOffset.top < windowHeight/1 && containerOffset.bottom > 0.0) { if (outstreamPaused) { adsManager.resume(); outstreamPaused = false; } return true; } else { if (!outstreamPaused) { adsManager.pause(); outstreamPaused = true; } } } return false; } let outstreamInitInterval; if (typeof cpexPackage !== "undefined") { outstreamInitInterval = setInterval(tryToInitializeOutstream, 100); } else { const wrapper = getWrapper(); if (wrapper) { let outstreamInitialized = false; window.addEventListener('scroll', () => { if (!outstreamInitialized) { const containerOffset = wrapper.getBoundingClientRect(); const windowHeight = window.innerHeight; if (containerOffset.top < windowHeight / 1 && containerOffset.bottom > 0.0) { outstreamInit(); outstreamInitialized = true; } } }); } } function tryToInitializeOutstream() { const wrapper = getWrapper(); if (wrapper) { const containerOffset = wrapper.getBoundingClientRect(); const windowHeight = window.innerHeight; if (containerOffset.top < windowHeight / 1 && containerOffset.bottom > 0.0) { if (cpexPackage.adserver.displayed) { clearInterval(outstreamInitInterval); outstreamInit(); } } } else { clearInterval(outstreamInitInterval); } } }
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