{"id":38635,"date":"2019-10-31T22:24:58","date_gmt":"2019-10-31T19:24:58","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novaya-tehnika-ataki-po-storonnim-kanalam-pozvolyayushhaya-vosstanovit-klyuchi-ecdsa\/"},"modified":"2019-10-31T22:24:58","modified_gmt":"2019-10-31T19:24:58","slug":"novaya-tehnika-ataki-po-storonnim-kanalam-pozvolyayushhaya-vosstanovit-klyuchi-ecdsa","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/novaya-tehnika-ataki-po-storonnim-kanalam-pozvolyayushhaya-vosstanovit-klyuchi-ecdsa","title":{"rendered":"Ny angrebstaktik via sidekanaler, som muligg\u00f8r genopretning af ECDSA n\u00f8gler.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Forskere fra Masaryk Universitet har afsl\u00f8ret<\/a><\/noindex> oplysninger om s\u00e5rbarheder<\/a><\/noindex> i forskellige implementeringer af algoritmen til oprettelse af digitale signaturer ECDSA\/EdDSA, der g\u00f8r det muligt at genoprette v\u00e6rdien af den private n\u00f8gle baseret p\u00e5 analyse af l\u00e6kager af oplysninger om enkelte bits, der opst\u00e5r under brug af metoder til analyse via sidekanaler. S\u00e5rbarhederne har kodeordet Minerva. <\/p>\n

De mest kendte projekter, som den foresl\u00e5ede angrebsmetode omhandler, er OpenJDK\/OracleJDK (CVE-2019-2894) og biblioteket Libgcrypt<\/a><\/noindex> (CVE-2019-13627), der bruges i GnuPG. Problemet ber\u00f8rer ogs\u00e5 MatrixSSL<\/a><\/noindex>, Crypto++<\/a><\/noindex>, wolfCrypt<\/a><\/noindex>, elliptic<\/a><\/noindex>, jsrsasign<\/a><\/noindex>, python-ecdsa<\/a><\/noindex>, ruby_ecdsa<\/a><\/noindex>, fastecdsa<\/a><\/noindex>, easy-ecc<\/a><\/noindex> og smartkortene Athena IDProtect. Ikke testet, men som potentielt s\u00e5rbare er ogs\u00e5 n\u00e6vnt Valid S\/A IDflex V-kort, SafeNet eToken 4300 og TecSec Armored Card, som bruger en standard ECDSA-modul. <\/p>\n

Problemet er allerede blevet l\u00f8st i versionerne libgcrypt 1.8.5 og wolfCrypt 4.1.0, de \u00f8vrige projekter har endnu ikke udgivet opdateringer. For at f\u00f8lge med i rettelsen af s\u00e5rbarheden i libgcrypt-pakken i distributionerne kan man se p\u00e5 disse sider: Debian<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, RHEL<\/a><\/noindex>, Fedora<\/a><\/noindex>, openSUSE\/SUSE<\/a><\/noindex>, FreeBSD<\/a><\/noindex>, Arch<\/a><\/noindex>.<\/p>\n

S\u00e5rbarheder er ikke udsat<\/a><\/noindex> OpenSSL, Botan, mbedTLS og BoringSSL. Der er endnu ikke blevet testet Mozilla NSS, LibreSSL, Nettle, BearSSL, cryptlib, OpenSSL i FIPS-tilstand, Microsoft .NET crypto,
\nlibkcapi fra Linux-kernen, Sodium og GnuTLS.<\/p>\n

Problemet skyldes muligheden for at bestemme v\u00e6rdierne af enkelte bits under udf\u00f8relsen af multiplikation med en skalar ved operationer med elliptiske kurver. For at udtr\u00e6kke oplysninger om bits anvendes indirekte metoder, s\u00e5som vurdering af forsinkelsen ved udf\u00f8relsen af beregninger. For angrebet kr\u00e6ves der ikke-privilegeret adgang til den v\u00e6rt, hvor den digitale signaturgenerering finder sted (ikke udelukket<\/a><\/noindex> og et fjernangreb, men det er betydeligt besv\u00e6rliggjort og kr\u00e6ver et stort datam\u00e6ngde til analyse, s\u00e5 det kan betragtes som usandsynligt). For at downloade tilg\u00e6ngelig<\/a><\/noindex> det v\u00e6rkt\u00f8j, der bruges til angrebet.<\/p>\n

P\u00e5 trods af den lille st\u00f8rrelse p\u00e5 l\u00e6kagen er det for ECDSA tilstr\u00e6kkeligt at bestemme blot nogle f\u00e5 bits af information om initialiseringsvektoren (nonce) for at udf\u00f8re et angreb ved sekventiel genskabelse af hele den private n\u00f8gle. If\u00f8lge forfatterne til metoden er det tilstr\u00e6kkeligt at analysere fra et par hundrede til et par tusinde digitale underskrifter, der er genereret for kendte beskeder af angriberen, for at genskabe n\u00f8gle. For eksempel blev der analyseret 11.000 digitale underskrifter for at bestemme den private n\u00f8gle, der blev anvendt p\u00e5 smartkortet Athena IDProtect baseret p\u00e5 Inside Secure AT90SC chippen, ved brug af den elliptiske kurve secp256r1. Den samlede angrebstid var 30 minutter.<\/p>\n

<\/a><\/noindex><\/p>\n

Kilde: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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\u043f\u0440\u043e\u0435\u043a\u0442\u0430\u043c\u0438, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u0437\u0430\u0442\u0440\u0430\u0433\u0438\u0432\u0430\u0435\u0442 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u043d\u044b\u0439 \u043c\u0435\u0442\u043e\u0434 \u0430\u0442\u0430\u043a\u0438, \u044f\u0432\u043b\u044f\u044e\u0442\u0441\u044f OpenJDK\/OracleJDK (CVE-2019-2894) \u0438 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-38635","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Ny teknik til angreb via 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