{"id":477430,"date":"2023-08-09T09:14:50","date_gmt":"2023-08-09T09:14:50","guid":{"rendered":""},"modified":"2023-09-05T11:14:41","modified_gmt":"2023-09-05T11:14:41","slug":"hash-function","status":"publish","type":"wiki","link":"https:\/\/oneproxy.pro\/vn\/wiki\/hash-function\/","title":{"rendered":"H\u00e0m b\u0103m"},"content":{"rendered":"<p>H\u00e0m b\u0103m l\u00e0 m\u1ed9t lo\u1ea1i h\u00e0m duy nh\u1ea5t \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong khoa h\u1ecdc m\u00e1y t\u00ednh \u0111\u1ec3 \u00e1nh x\u1ea1 d\u1eef li\u1ec7u c\u00f3 k\u00edch th\u01b0\u1edbc t\u00f9y \u00fd th\u00e0nh c\u00e1c gi\u00e1 tr\u1ecb c\u00f3 k\u00edch th\u01b0\u1edbc c\u1ed1 \u0111\u1ecbnh. N\u00f3 \u0111\u00f3ng m\u1ed9t vai tr\u00f2 kh\u00f4ng th\u1ec3 thi\u1ebfu trong nhi\u1ec1u l\u0129nh v\u1ef1c kh\u00e1c nhau, bao g\u1ed3m truy xu\u1ea5t d\u1eef li\u1ec7u, m\u00e3 h\u00f3a, t\u1ed5ng ki\u1ec3m tra v\u00e0 ch\u1eef k\u00fd s\u1ed1, v\u1ec1 c\u01a1 b\u1ea3n \u0111\u00f3ng vai tr\u00f2 l\u00e0 n\u1ec1n t\u1ea3ng c\u1ee7a khoa h\u1ecdc m\u00e1y t\u00ednh v\u00e0 an ninh m\u1ea1ng hi\u1ec7n \u0111\u1ea1i.<\/p>\n<h2>S\u1ef1 ph\u00e1t tri\u1ec3n c\u1ee7a h\u00e0m b\u0103m<\/h2>\n<p>Kh\u00e1i ni\u1ec7m h\u00e0m b\u0103m xu\u1ea5t hi\u1ec7n l\u1ea7n \u0111\u1ea7u ti\u00ean v\u00e0o cu\u1ed1i nh\u1eefng n\u0103m 1950 trong l\u0129nh v\u1ef1c truy xu\u1ea5t th\u00f4ng tin. Hans Peter Luhn, m\u1ed9t nh\u00e0 khoa h\u1ecdc m\u00e1y t\u00ednh c\u1ee7a IBM, \u0111\u00e3 gi\u1edbi thi\u1ec7u ph\u01b0\u01a1ng ph\u00e1p b\u0103m \u0111\u1ec3 truy c\u1eadp d\u1eef li\u1ec7u nhanh ch\u00f3ng. \u00dd t\u01b0\u1edfng l\u00e0 s\u1eed d\u1ee5ng h\u00e0m b\u0103m \u0111\u1ec3 chuy\u1ec3n \u0111\u1ed5i kh\u00f3a th\u00e0nh \u0111\u1ecba ch\u1ec9 n\u01a1i c\u00f3 th\u1ec3 t\u00ecm th\u1ea5y b\u1ea3n ghi t\u01b0\u01a1ng \u1ee9ng.<\/p>\n<p>Trong nh\u1eefng th\u1eadp k\u1ef7 ti\u1ebfp theo, ti\u1ec7n \u00edch c\u1ee7a h\u00e0m b\u0103m \u0111\u00e3 m\u1edf r\u1ed9ng ra ngo\u00e0i vi\u1ec7c truy xu\u1ea5t th\u00f4ng tin \u0111\u01a1n thu\u1ea7n. V\u00e0o nh\u1eefng n\u0103m 1970, h\u00e0m b\u0103m \u0111\u00e3 t\u00ecm th\u1ea5y v\u1ecb tr\u00ed c\u1ee7a n\u00f3 trong m\u1eadt m\u00e3, d\u1eabn \u0111\u1ebfn vi\u1ec7c t\u1ea1o ra c\u00e1c h\u00e0m b\u0103m m\u1eadt m\u00e3, m\u1ed9t lo\u1ea1i h\u00e0m b\u0103m c\u1ee5 th\u1ec3 v\u1edbi c\u00e1c thu\u1ed9c t\u00ednh c\u1ee5 th\u1ec3 khi\u1ebfn n\u00f3 tr\u1edf n\u00ean l\u00fd t\u01b0\u1edfng cho c\u00e1c \u1ee9ng d\u1ee5ng b\u1ea3o m\u1eadt th\u00f4ng tin.<\/p>\n<h2>T\u00ecm hi\u1ec3u s\u00e2u h\u01a1n v\u1ec1 h\u00e0m b\u0103m<\/h2>\n<p>H\u00e0m b\u0103m ho\u1ea1t \u0111\u1ed9ng b\u1eb1ng c\u00e1ch l\u1ea5y \u0111\u1ea7u v\u00e0o (ho\u1eb7c &#039;th\u00f4ng b\u00e1o&#039;) v\u00e0 tr\u1ea3 v\u1ec1 m\u1ed9t chu\u1ed7i byte c\u00f3 k\u00edch th\u01b0\u1edbc c\u1ed1 \u0111\u1ecbnh. \u0110\u1ea7u ra th\u01b0\u1eddng l\u00e0 m\u1ed9t &#039;b\u1ea3n t\u00f3m t\u1eaft&#039; duy nh\u1ea5t cho m\u1ed7i \u0111\u1ea7u v\u00e0o duy nh\u1ea5t. Ngay c\u1ea3 m\u1ed9t thay \u0111\u1ed5i nh\u1ecf \u1edf \u0111\u1ea7u v\u00e0o c\u0169ng s\u1ebd t\u1ea1o ra \u0111\u1ea7u ra kh\u00e1c bi\u1ec7t \u0111\u00e1ng k\u1ec3.<\/p>\n<p>\u0110i\u1ec1u quan tr\u1ecdng l\u00e0 c\u00e1c h\u00e0m b\u0103m c\u00f3 t\u00ednh x\u00e1c \u0111\u1ecbnh, ngh\u0129a l\u00e0 c\u00f9ng m\u1ed9t \u0111\u1ea7u v\u00e0o s\u1ebd lu\u00f4n t\u1ea1o ra c\u00f9ng m\u1ed9t \u0111\u1ea7u ra. C\u00e1c thu\u1ed9c t\u00ednh quan tr\u1ecdng kh\u00e1c bao g\u1ed3m:<\/p>\n<ul>\n<li><strong>Kh\u00e1ng ti\u1ec1n \u1ea3nh:<\/strong> V\u1ec1 m\u1eb7t t\u00ednh to\u00e1n, vi\u1ec7c truy xu\u1ea5t \u0111\u1ea7u v\u00e0o ban \u0111\u1ea7u ch\u1ec9 v\u1edbi gi\u00e1 tr\u1ecb b\u0103m \u0111\u1ea7u ra l\u00e0 kh\u00f4ng th\u1ec3 th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c.<\/li>\n<li><strong>Kh\u00e1ng ti\u1ec1n \u1ea3nh th\u1ee9 hai:<\/strong> G\u1ea7n nh\u01b0 kh\u00f4ng th\u1ec3 t\u00ecm th\u1ea5y \u0111\u1ea7u v\u00e0o th\u1ee9 hai b\u0103m th\u00e0nh c\u00f9ng m\u1ed9t \u0111\u1ea7u ra v\u1edbi \u0111\u1ea7u v\u00e0o \u0111\u1ea7u ti\u00ean nh\u1ea5t \u0111\u1ecbnh.<\/li>\n<li><strong>Ch\u1ed1ng va ch\u1ea1m:<\/strong> S\u1ebd r\u1ea5t kh\u00f3 \u0111\u1ec3 t\u00ecm ra hai \u0111\u1ea7u v\u00e0o kh\u00e1c nhau b\u0103m th\u00e0nh c\u00f9ng m\u1ed9t \u0111\u1ea7u ra.<\/li>\n<\/ul>\n<h2>H\u00e0m b\u0103m ho\u1ea1t \u0111\u1ed9ng nh\u01b0 th\u1ebf n\u00e0o<\/h2>\n<p>Ho\u1ea1t \u0111\u1ed9ng b\u00ean trong c\u1ee7a h\u00e0m b\u0103m ph\u1ee5 thu\u1ed9c v\u00e0o thu\u1eadt to\u00e1n c\u1ee5 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng. Tuy nhi\u00ean, quy tr\u00ecnh c\u01a1 b\u1ea3n v\u1eabn nh\u1ea5t qu\u00e1n tr\u00ean c\u00e1c h\u00e0m b\u0103m kh\u00e1c nhau:<\/p>\n<ol>\n<li>Th\u00f4ng b\u00e1o \u0111\u1ea7u v\u00e0o \u0111\u01b0\u1ee3c x\u1eed l\u00fd theo t\u1eebng kh\u1ed1i c\u00f3 k\u00edch th\u01b0\u1edbc c\u1ed1 \u0111\u1ecbnh (kh\u1ed1i).<\/li>\n<li>M\u1ed7i kh\u1ed1i \u0111\u01b0\u1ee3c x\u1eed l\u00fd b\u1eb1ng m\u1ed9t h\u00e0m to\u00e1n h\u1ecdc ph\u1ee9c t\u1ea1p \u0111\u1ec3 bi\u1ebfn \u0111\u1ed5i \u0111\u1ea7u v\u00e0o.<\/li>\n<li>\u0110\u1ea7u ra t\u1eeb m\u1ed7i kh\u1ed1i \u0111\u01b0\u1ee3c k\u1ebft h\u1ee3p \u0111\u1ec3 t\u1ea1o ra gi\u00e1 tr\u1ecb b\u0103m cu\u1ed1i c\u00f9ng.<\/li>\n<\/ol>\n<p>Qu\u00e1 tr\u00ecnh n\u00e0y \u0111\u1ea3m b\u1ea3o r\u1eb1ng ngay c\u1ea3 nh\u1eefng thay \u0111\u1ed5i nh\u1ecf trong th\u00f4ng b\u00e1o \u0111\u1ea7u v\u00e0o c\u0169ng s\u1ebd d\u1eabn \u0111\u1ebfn s\u1ef1 kh\u00e1c bi\u1ec7t \u0111\u00e1ng k\u1ec3 trong h\u00e0m b\u0103m cu\u1ed1i c\u00f9ng, t\u1eeb \u0111\u00f3 mang l\u1ea1i kh\u1ea3 n\u0103ng ch\u1ed1ng l\u1ea1i c\u00e1c cu\u1ed9c t\u1ea5n c\u00f4ng m\u1ea1nh m\u1ebd.<\/p>\n<h2>C\u00e1c t\u00ednh n\u0103ng ch\u00ednh c\u1ee7a h\u00e0m b\u0103m<\/h2>\n<p>C\u00e1c t\u00ednh n\u0103ng ch\u00ednh c\u1ee7a h\u00e0m b\u0103m bao g\u1ed3m:<\/p>\n<ul>\n<li><strong>Ch\u1ee7 ngh\u0129a quy\u1ebft \u0111\u1ecbnh:<\/strong> C\u00f9ng m\u1ed9t \u0111\u1ea7u v\u00e0o s\u1ebd lu\u00f4n t\u1ea1o ra c\u00f9ng m\u1ed9t \u0111\u1ea7u ra.<\/li>\n<li><strong>\u0110\u1ed9 d\u00e0i \u0111\u1ea7u ra c\u1ed1 \u0111\u1ecbnh:<\/strong> B\u1ea5t k\u1ec3 k\u00edch th\u01b0\u1edbc c\u1ee7a \u0111\u1ea7u v\u00e0o l\u00e0 bao nhi\u00eau, \u0111\u1ed9 d\u00e0i b\u0103m \u0111\u1ea7u ra v\u1eabn kh\u00f4ng \u0111\u1ed5i.<\/li>\n<li><strong>Hi\u1ec7u qu\u1ea3:<\/strong> Th\u1eddi gian c\u1ea7n thi\u1ebft \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb b\u0103m c\u1ee7a \u0111\u1ea7u v\u00e0o t\u1ef7 l\u1ec7 thu\u1eadn v\u1edbi k\u00edch th\u01b0\u1edbc c\u1ee7a \u0111\u1ea7u v\u00e0o.<\/li>\n<li><strong>Kh\u00e1ng ti\u1ec1n \u1ea3nh:<\/strong> G\u1ea7n nh\u01b0 kh\u00f4ng th\u1ec3 t\u1ea1o \u0111\u1ea7u v\u00e0o ban \u0111\u1ea7u t\u1eeb h\u00e0m b\u0103m \u0111\u1ea7u ra c\u1ee7a n\u00f3.<\/li>\n<li><strong>Hi\u1ec7u \u1ee9ng tuy\u1ebft l\u1edf:<\/strong> Nh\u1eefng thay \u0111\u1ed5i nh\u1ecf \u1edf \u0111\u1ea7u v\u00e0o s\u1ebd d\u1eabn \u0111\u1ebfn nh\u1eefng thay \u0111\u1ed5i m\u1ea1nh m\u1ebd \u1edf \u0111\u1ea7u ra.<\/li>\n<\/ul>\n<h2>C\u00e1c lo\u1ea1i h\u00e0m b\u0103m<\/h2>\n<p>C\u00f3 nhi\u1ec1u lo\u1ea1i h\u00e0m b\u0103m, bao g\u1ed3m c\u1ea3 lo\u1ea1i m\u1eadt m\u00e3 v\u00e0 kh\u00f4ng m\u1eadt m\u00e3. B\u1ea3ng sau li\u1ec7t k\u00ea m\u1ed9t s\u1ed1 v\u00ed d\u1ee5 \u0111\u00e1ng ch\u00fa \u00fd:<\/p>\n<table>\n<thead>\n<tr>\n<th>Ki\u1ec3u<\/th>\n<th style=\"text-align: center;\">m\u1eadt m\u00e3<\/th>\n<th>S\u1ef1 mi\u00eau t\u1ea3<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>MD5<\/td>\n<td style=\"text-align: center;\">\u0110\u00fang<\/td>\n<td>T\u1ea1o gi\u00e1 tr\u1ecb b\u0103m 128 bit, th\u01b0\u1eddng \u0111\u01b0\u1ee3c hi\u1ec3n th\u1ecb d\u01b0\u1edbi d\u1ea1ng s\u1ed1 th\u1eadp l\u1ee5c ph\u00e2n 32 k\u00fd t\u1ef1<\/td>\n<\/tr>\n<tr>\n<td>SHA-1<\/td>\n<td style=\"text-align: center;\">\u0110\u00fang<\/td>\n<td>T\u1ea1o ra gi\u00e1 tr\u1ecb b\u0103m 160 bit, \u0111\u01b0\u1ee3c coi l\u00e0 y\u1ebfu v\u1ec1 kh\u1ea3 n\u0103ng ch\u1ed1ng va ch\u1ea1m<\/td>\n<\/tr>\n<tr>\n<td>SHA-2<\/td>\n<td style=\"text-align: center;\">\u0110\u00fang<\/td>\n<td>Phi\u00ean b\u1ea3n c\u1ea3i ti\u1ebfn c\u1ee7a SHA-1, bao g\u1ed3m c\u00e1c h\u00e0m b\u0103m SHA-224, SHA-256, SHA-384, SHA-512, SHA-512\/224 v\u00e0 SHA-512\/256<\/td>\n<\/tr>\n<tr>\n<td>SHA-3<\/td>\n<td style=\"text-align: center;\">\u0110\u00fang<\/td>\n<td>Th\u00e0nh vi\u00ean m\u1edbi nh\u1ea5t c\u1ee7a d\u00f2ng Thu\u1eadt to\u00e1n b\u0103m an to\u00e0n, hi\u1ec7u qu\u1ea3 h\u01a1n SHA-2<\/td>\n<\/tr>\n<tr>\n<td>L\u1ea9m b\u1ea9mHash<\/td>\n<td style=\"text-align: center;\">KH\u00d4NG<\/td>\n<td>H\u00e0m b\u0103m phi m\u1eadt m\u00e3 t\u1eadp trung v\u00e0o hi\u1ec7u su\u1ea5t, \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong c\u00e1c t\u00e1c v\u1ee5 x\u1eed l\u00fd d\u1eef li\u1ec7u<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>\u1ee8ng d\u1ee5ng v\u00e0 th\u00e1ch th\u1ee9c c\u1ee7a h\u00e0m b\u0103m<\/h2>\n<p>H\u00e0m b\u0103m \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ed9ng r\u00e3i trong nhi\u1ec1u l\u0129nh v\u1ef1c kh\u00e1c nhau, ch\u1eb3ng h\u1ea1n nh\u01b0 truy xu\u1ea5t d\u1eef li\u1ec7u, ch\u1eef k\u00fd s\u1ed1, ki\u1ec3m tra t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 l\u01b0u tr\u1eef m\u1eadt kh\u1ea9u. B\u1ea5t ch\u1ea5p t\u00ednh h\u1eefu d\u1ee5ng c\u1ee7a ch\u00fang, v\u1eabn c\u00f3 m\u1ed9t s\u1ed1 th\u00e1ch th\u1ee9c nh\u1ea5t \u0111\u1ecbnh \u0111i k\u00e8m v\u1edbi h\u00e0m b\u0103m. Ch\u1eb3ng h\u1ea1n, ch\u00fang d\u1ec5 b\u1ecb va ch\u1ea1m b\u0103m, trong \u0111\u00f3 hai \u0111\u1ea7u v\u00e0o kh\u00e1c nhau t\u1ea1o ra c\u00f9ng m\u1ed9t \u0111\u1ea7u ra b\u0103m, c\u00f3 kh\u1ea3 n\u0103ng d\u1eabn \u0111\u1ebfn nh\u1eefng lo ng\u1ea1i v\u1ec1 b\u1ea3o m\u1eadt trong c\u00e1c \u1ee9ng d\u1ee5ng m\u1eadt m\u00e3.<\/p>\n<p>Tuy nhi\u00ean, nh\u1eefng v\u1ea5n \u0111\u1ec1 n\u00e0y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c gi\u1ea3m thi\u1ec3u b\u1eb1ng nhi\u1ec1u c\u00e1ch kh\u00e1c nhau. V\u00ed d\u1ee5: s\u1eed d\u1ee5ng h\u00e0m b\u0103m hi\u1ec7n \u0111\u1ea1i v\u1edbi k\u00edch th\u01b0\u1edbc \u0111\u1ea7u ra l\u1edbn h\u01a1n c\u00f3 th\u1ec3 l\u00e0m gi\u1ea3m kh\u1ea3 n\u0103ng x\u1ea3y ra xung \u0111\u1ed9t. Ngo\u00e0i ra, c\u00e1c k\u1ef9 thu\u1eadt nh\u01b0 th\u00eam mu\u1ed1i (th\u00eam d\u1eef li\u1ec7u ng\u1eabu nhi\u00ean v\u00e0o \u0111\u1ea7u v\u00e0o) c\u00f3 th\u1ec3 t\u0103ng c\u01b0\u1eddng b\u1ea3o m\u1eadt khi b\u0103m m\u1eadt kh\u1ea9u.<\/p>\n<h2>So s\u00e1nh v\u00e0 \u0111\u1eb7c \u0111i\u1ec3m c\u1ee7a h\u00e0m b\u0103m<\/h2>\n<p>Vi\u1ec7c so s\u00e1nh c\u00e1c h\u00e0m b\u0103m c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n d\u1ef1a tr\u00ean m\u1ed9t s\u1ed1 y\u1ebfu t\u1ed1 nh\u01b0 \u0111\u1ed9 d\u00e0i h\u00e0m b\u0103m, hi\u1ec7u qu\u1ea3 t\u00ednh to\u00e1n, kh\u1ea3 n\u0103ng ch\u1ed1ng va ch\u1ea1m v\u00e0 m\u1ee9c \u0111\u1ed9 b\u1ea3o m\u1eadt.<\/p>\n<table>\n<thead>\n<tr>\n<th>H\u00e0m b\u0103m<\/th>\n<th style=\"text-align: center;\">\u0110\u1ed9 d\u00e0i b\u0103m (bit)<\/th>\n<th>C\u1ea5p \u0111\u1ed9 b\u1ea3o m\u1eadt<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>MD5<\/td>\n<td style=\"text-align: center;\">128<\/td>\n<td>Th\u1ea5p<\/td>\n<\/tr>\n<tr>\n<td>SHA-1<\/td>\n<td style=\"text-align: center;\">160<\/td>\n<td>Trung b\u00ecnh<\/td>\n<\/tr>\n<tr>\n<td>SHA-256<\/td>\n<td style=\"text-align: center;\">256<\/td>\n<td>Cao<\/td>\n<\/tr>\n<tr>\n<td>L\u1ea9m b\u1ea9mHash<\/td>\n<td style=\"text-align: center;\">32, 128<\/td>\n<td>Th\u1ea5p<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>T\u01b0\u01a1ng lai c\u1ee7a h\u00e0m b\u0103m<\/h2>\n<p>V\u1edbi s\u1ef1 ra \u0111\u1eddi c\u1ee7a \u0111i\u1ec7n to\u00e1n l\u01b0\u1ee3ng t\u1eed, c\u00e1c h\u00e0m b\u0103m ph\u1ea3i \u0111\u1ed1i m\u1eb7t v\u1edbi nh\u1eefng th\u00e1ch th\u1ee9c m\u1edbi, v\u00ec m\u00e1y t\u00ednh l\u01b0\u1ee3ng t\u1eed c\u00f3 kh\u1ea3 n\u0103ng ph\u00e1 v\u1ee1 nhi\u1ec1u h\u00e0m b\u0103m hi\u1ec7n \u0111\u01b0\u1ee3c b\u1ea3o m\u1eadt. \u0110i\u1ec1u n\u00e0y \u0111\u00e3 th\u00fac \u0111\u1ea9y nghi\u00ean c\u1ee9u v\u1ec1 m\u1eadt m\u00e3 h\u1eadu l\u01b0\u1ee3ng t\u1eed, nh\u1eb1m ph\u00e1t tri\u1ec3n c\u00e1c thu\u1eadt to\u00e1n m\u00e3 h\u00f3a an to\u00e0n ch\u1ed1ng l\u1ea1i c\u1ea3 m\u00e1y t\u00ednh c\u1ed5 \u0111i\u1ec3n v\u00e0 l\u01b0\u1ee3ng t\u1eed.<\/p>\n<h2>H\u00e0m b\u0103m v\u00e0 m\u00e1y ch\u1ee7 proxy<\/h2>\n<p>C\u00e1c m\u00e1y ch\u1ee7 proxy, gi\u1ed1ng nh\u01b0 c\u00e1c m\u00e1y ch\u1ee7 do OneProxy cung c\u1ea5p, c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng h\u00e0m b\u0103m cho nhi\u1ec1u m\u1ee5c \u0111\u00edch kh\u00e1c nhau, ch\u1eb3ng h\u1ea1n nh\u01b0 c\u00e2n b\u1eb1ng t\u1ea3i (ph\u00e2n ph\u1ed1i l\u01b0u l\u01b0\u1ee3ng truy c\u1eadp m\u1ea1ng ho\u1eb7c \u1ee9ng d\u1ee5ng tr\u00ean nhi\u1ec1u m\u00e1y ch\u1ee7) v\u00e0 ki\u1ec3m tra t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u. H\u01a1n n\u1eefa, h\u00e0m b\u0103m r\u1ea5t quan tr\u1ecdng trong vi\u1ec7c \u0111\u1ea3m b\u1ea3o li\u00ean l\u1ea1c gi\u1eefa m\u00e1y ch\u1ee7 proxy v\u00e0 m\u00e1y kh\u00e1ch b\u1eb1ng c\u00e1ch t\u1ea1o m\u00e3 x\u00e1c th\u1ef1c tin nh\u1eafn d\u1ef1a tr\u00ean h\u00e0m b\u0103m an to\u00e0n.<\/p>\n<h2>Li\u00ean k\u1ebft li\u00ean quan<\/h2>\n<p>\u0110\u1ec3 bi\u1ebft th\u00eam th\u00f4ng tin v\u1ec1 h\u00e0m b\u0103m, c\u00e1c t\u00e0i nguy\u00ean sau c\u00f3 th\u1ec3 h\u1eefu \u00edch:<\/p>\n<ol>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Hash_function\" target=\"_new\" rel=\"noopener nofollow\">B\u00e0i vi\u1ebft tr\u00ean Wikipedia v\u1ec1 H\u00e0m b\u0103m<\/a><\/li>\n<li><a href=\"https:\/\/www.khanacademy.org\/computing\/computer-science\/cryptography\" target=\"_new\" rel=\"noopener nofollow\">Kh\u00f3a h\u1ecdc v\u1ec1 m\u1eadt m\u00e3 c\u1ee7a Khan Academy<\/a><\/li>\n<li><a href=\"https:\/\/www.coursera.org\/learn\/crypto\" target=\"_new\" rel=\"noopener nofollow\">Kh\u00f3a h\u1ecdc Coursera v\u1ec1 M\u1eadt m\u00e3 h\u1ecdc<\/a><\/li>\n<li><a href=\"https:\/\/www.geeksforgeeks.org\/hashing-data-structure\/\" target=\"_new\" rel=\"noopener nofollow\">Gi\u1edbi thi\u1ec7u v\u1ec1 b\u0103m<\/a> tr\u00ean GeekforGeeks<\/li>\n<li><a href=\"https:\/\/csrc.nist.gov\/projects\/hash-functions\" target=\"_new\" rel=\"noopener nofollow\">Ch\u00ednh s\u00e1ch c\u1ee7a NIST v\u1ec1 H\u00e0m b\u0103m<\/a><\/li>\n<\/ol>","protected":false},"featured_media":468520,"menu_order":0,"template":"","meta":{"_acf_changed":false,"content-type":"","inline_featured_image":false,"footnotes":""},"class_list":["post-477430","wiki","type-wiki","status-publish","has-post-thumbnail","hentry"],"acf":{"faq_title":"Frequently Asked Questions about <mark>Hash Function: The Foundation of Data Integrity and Security<\/mark>","faq_items":[{"question":"What is a hash function?","answer":"<p>A hash function is a special type of function used in computer science that takes an input (or 'message') and returns a fixed-size string of bytes, typically a 'digest' that is unique to each unique input. Hash functions are widely used in various domains, including data retrieval, encryption, checksums, and digital signatures.<\/p>"},{"question":"Who first introduced the concept of hash functions?","answer":"<p>The concept of hash functions was first introduced by Hans Peter Luhn, a computer scientist at IBM, in the late 1950s. He proposed hashing for rapid access to data in the field of information retrieval.<\/p>"},{"question":"What are the main features of a hash function?","answer":"<p>Key features of hash functions include determinism (the same input will always produce the same output), fixed output length, efficiency (time taken to compute the hash is proportional to the input size), preimage resistance (it's near-impossible to generate the original input from its output hash), and the avalanche effect (small changes in the input result in drastic changes in the output).<\/p>"},{"question":"Can you name some types of hash functions?","answer":"<p>There are several types of hash functions, including both cryptographic and non-cryptographic ones. Some notable examples are MD5, SHA-1, SHA-2, SHA-3, and MurmurHash.<\/p>"},{"question":"What are the applications and challenges of hash functions?","answer":"<p>Hash functions have various applications in fields like data retrieval, digital signatures, data integrity checks, and password storage. Despite their utility, they face certain challenges like hash collisions, where two different inputs produce the same hash output. This can lead to security concerns in cryptographic applications.<\/p>"},{"question":"How are hash functions used in proxy servers?","answer":"<p>In the context of proxy servers like OneProxy, hash functions can be used for several purposes. They can assist in load balancing by evenly distributing network or application traffic across multiple servers. Hash functions also play a crucial role in data integrity checks and securing communications between proxy servers and clients through the creation of secure hash-based message authentication codes.<\/p>"},{"question":"What is the future perspective of hash functions?","answer":"<p>The advent of quantum computing has introduced new challenges to hash functions, as these powerful machines could potentially break many currently secure hash functions. This scenario has led to the development of post-quantum cryptography, aiming to construct cryptographic algorithms that are secure against both classical and quantum computers.<\/p>"},{"question":"What are some resources to learn more about hash functions?","answer":"<p>Several resources can provide more in-depth knowledge about hash functions. These include the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Hash_function\" target=\"_new\">Wikipedia article on Hash Functions<\/a>, the <a href=\"https:\/\/www.khanacademy.org\/computing\/computer-science\/cryptography\" target=\"_new\">Khan Academy course on Cryptography<\/a>, the <a href=\"https:\/\/www.coursera.org\/learn\/crypto\" target=\"_new\">Coursera course on Cryptography<\/a>, the <a href=\"https:\/\/www.geeksforgeeks.org\/hashing-data-structure\/\" target=\"_new\">Introduction to Hashing<\/a> on GeeksforGeeks, and the <a href=\"https:\/\/csrc.nist.gov\/projects\/hash-functions\" target=\"_new\">NIST\u2019s policy on Hash Functions<\/a>.<\/p>"}]},"_links":{"self":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/477430","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/477430\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media\/468520"}],"wp:attachment":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media?parent=477430"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}