{"id":2718,"date":"2025-10-15T12:07:54","date_gmt":"2025-10-15T04:07:54","guid":{"rendered":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/?p=2718"},"modified":"2025-10-15T12:07:54","modified_gmt":"2025-10-15T04:07:54","slug":"%e8%ae%a1%e7%ae%97-iv","status":"publish","type":"post","link":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/2025\/10\/15\/%e8%ae%a1%e7%ae%97-iv\/","title":{"rendered":"\u8ba1\u7b97 IV"},"content":{"rendered":"\n<p>\u5728 SRTP \u5bf9\u8d1f\u8377\u8fdb\u884c\u52a0\u5bc6\uff08\u6216\u8005\u89e3\u5bc6\uff09\u65f6\u9700\u8981\u5148\u8ba1\u7b97 IV \uff08Initialization vector, \u521d\u59cb\u5316\u5411\u91cf\uff09\uff0cRFC3711\u5b9a\u4e49\u4e86\u8be5\u503c\u7684\u8ba1\u7b97\u65b9\u6cd5\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">IV = (k_s * 2^16) XOR (SSRC * 2^64) XOR (i * 2^16)<\/pre>\n\n\n\n<p>\u770b\u8d77\u6765\u4f3c\u4e4e\u5f88\u666e\u901a\u3001\u4e5f\u5f88\u5bb9\u6613\u7406\u89e3\uff0c\u65e0\u975e\u5c31\u662f\u4e09\u4e2a\u53c2\u6570\u7684\u5f02\u6216\u8ba1\u7b97\uff1a\uff081\uff09k_s\uff0c\uff082\uff09SSRC \u4ee5\u53ca\uff083\uff09i\u3002<\/p>\n\n\n\n<p>IV \u662f 16 \u5b57\u8282\u7684\u6570\u636e\u6d41\uff1bk_s \u662f session salt\uff08\u5927\u5c0f14\u5b57\u8282\uff09\uff0c\u8981\u6c42\u5de6\u79fb2\u5b57\u8282\uff1bSSRC \u662f RTP \u4e2d\u7684\u6e90\u6807\u8bc6\u53c2\u6570\uff0c\u8981\u6c42\u5de6\u79fb8\u5b57\u8282\u3002<\/p>\n\n\n\n<p>i \u53c2\u6570\u6709\u70b9\u7279\u6b8a\uff0c\u5b9a\u4e49\u4e3a\u300c\u5305\u7d22\u5f15\u300d\uff0c\u5b83\u662f 48 \u6bd4\u7279\u7684\u503c\uff0c\u89c4\u8303\u4e2d\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">i = 2^16 * ROC + SEQ.<\/pre>\n\n\n\n<p>ROC \u662f rollover counter\uff0c RTP \u5305\u4e2d\u6ca1\u6709\u8fd9\u4e2a\u53c2\u6570\uff0c\u9700\u8981\u6839\u636e SEQ \u7684\u503c\u6765\u5224\u65ad\u662f\u5426\u9700\u8981\u8bbe\u7f6e ROC\u3002\u8fd9\u91cc\u63d0\u4e00\u4e0b\uff0c RTP \u534f\u8bae\u975e\u5e38\u5c71\u70ae\u5730\u7528 2 \u5b57\u8282\u5b9a\u4e49 SEQ \u503c\uff0c\u53ef\u60f3\u800c\u77e5\u5b83\u5b8c\u5168\u4e0d\u591f\u7528\u3002\u56e0\u6b64\u5e94\u7528\u5c42\u4e0d\u5f97\u4e0d\u81ea\u5df1\u8ba1\u7b97ROC\u503c\uff0c\u7ec4\u5408 ROC \u503c\u548c SEQ \u503c \u624d\u80fd\u5b8c\u6574\u5224\u65ad RTP \u5305\u7684\u771f\u5b9e\u5e8f\u5217\u53f7\u3002<\/p>\n\n\n\n<p>\u7ec4\u5408\u51fa\u4e09\u4e2a 16 \u5b57\u8282\u7684\u6570\u636e\u6d41\u540e\uff0c\u5f02\u6216\u8ba1\u7b97\u5f97\u51fa IV \u503c\uff0c\u8bf7\u53c2\u8003\u4ee5\u4e0b\u56fe\u8868\u793a\u610f\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"670\" height=\"106\" src=\"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-content\/uploads\/2025\/10\/image.png\" alt=\"IV \u5f02\u6216\u8ba1\u7b97\" class=\"wp-image-2719\" srcset=\"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-content\/uploads\/2025\/10\/image.png 670w, https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-content\/uploads\/2025\/10\/image-300x47.png 300w, https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-content\/uploads\/2025\/10\/image-604x96.png 604w\" sizes=\"auto, (max-width: 670px) 100vw, 670px\" \/><\/figure>\n\n\n\n<p>\u4ece\u56fe\u4e2d\u4e5f\u53ef\u4ee5\u770b\u51fa\uff0cIV \u867d\u7136\u6709 16 \u4e2a\u5b57\u8282\uff0c\u4f46\u662f\u5b9e\u9645\u4e0a\u6700\u540e\u4e24\u4e2a\u5b57\u8282\u6839\u672c\u6ca1\u7528\uff0c\u56e0\u6b64\u9ed8\u8ba4\u8bbe\u7f6e\u4e3a 0 \u5373\u53ef\u3002<\/p>\n\n\n\n<p>roc + seq \u7684\u8bbe\u7f6e\u53ef\u4ee5\u53d6\u5de7\u4e00\u4e0b\u3002\u867d\u7136\u5b8c\u6574\u5b9a\u4e49\u662f 48-bits\uff0c\u4f46\u752832-bits\u4e5f\u8db3\u591f\u4e86\uff08\u8003\u8651\u5230 VoIP \u5bf9\u8bdd\u4e2d\u4e00\u822c 20ms \u4e00\u4e2a\u5305\uff0c\u5e8f\u5217\u53f7\u8981\u6ea2\u51fa32bits\u7684\u503c\u9700\u8981\u8d85\u8fc7990\u5929\uff09\u3002\u800c\u7b80\u5316\u6210 32-bits \u7684\u6700\u5927\u597d\u5904\u5c31\u662f\u76f4\u63a5\u8c03\u7528 C \u51fd\u6570\uff08htonl\uff09\u8fdb\u884c\u7f51\u7edc\u5b57\u8282\u5e8f\u8f6c\u6362\u5373\u53ef\uff0c\u53ea\u9700\u8981\u586b\u5145\u7b2c10\u4e2a\u5b57\u8282\u5230\u7b2c13\u4e2a\u5b57\u8282\u3002<\/p>\n\n\n\n<p>SSRC \u662f 32-bits \u6574\u6570\uff0c\u56e0\u6b64\u4e5f\u9700\u8981\u8f6c\u6362\u6210\u7f51\u7edc\u5b57\u8282\u5e8f\uff1b\u800c session salt \u672c\u8eab\u662f 14 \u5b57\u8282\u7684\u6570\u636e\u6d41\uff0c\u65e0\u9700\u8f6c\u6362\u5b57\u8282\u5e8f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728 SRTP \u5bf9\u8d1f\u8377\u8fdb\u884c\u52a0\u5bc6\uff08\u6216\u8005\u89e3\u5bc6\uff09\u65f6\u9700\u8981\u5148\u8ba1\u7b97 IV \uff08Initialization vector, \u521d\u59cb\u5316\u5411\u91cf\uff09\uff0cRFC3711\u5b9a\u4e49\u4e86\u8be5\u503c\u7684\u8ba1\u7b97\u65b9\u6cd5\uff1a &#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.myvoipapp.com\/blogs\/yxh\/2025\/10\/15\/%e8%ae%a1%e7%ae%97-iv\/\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[53,27],"tags":[928,927,931,929,930,300],"class_list":["post-2718","post","type-post","status-publish","format-standard","hentry","category-53","category-27","tag-iv","tag-openssl","tag-rfc3711","tag-roc","tag-seq","tag-srtp"],"_links":{"self":[{"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/posts\/2718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/comments?post=2718"}],"version-history":[{"count":1,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/posts\/2718\/revisions"}],"predecessor-version":[{"id":2720,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/posts\/2718\/revisions\/2720"}],"wp:attachment":[{"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/media?parent=2718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/categories?post=2718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.myvoipapp.com\/blogs\/yxh\/wp-json\/wp\/v2\/tags?post=2718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}