{"id":471,"date":"2016-03-14T00:13:21","date_gmt":"2016-03-13T15:13:21","guid":{"rendered":"http:\/\/manatails.net\/blog\/?p=471"},"modified":"2022-04-03T13:48:54","modified_gmt":"2022-04-03T04:48:54","slug":"rar-header","status":"publish","type":"post","link":"https:\/\/manatails.net\/blog\/2016\/03\/rar-header\/","title":{"rendered":"RAR header"},"content":{"rendered":"

\"rar\"<\/a><\/p>\n

From Forensics Wiki:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Field Name<\/th>\nSize (bytes)<\/th>\nDescription<\/th>\n<\/tr>\n
HEAD_CRC<\/td>\n2<\/td>\nCRC of fields from HEAD_TYPE to FILEATTR and file name<\/td>\n<\/tr>\n
HEAD_TYPE<\/td>\n1<\/td>\nHeader Type: 0x74<\/td>\n<\/tr>\n
HEAD_FLAGS<\/td>\n2<\/td>\nBit Flags (Please see ‘Bit Flags for File in Archive’ table for all possibilities)<\/td>\n<\/tr>\n
HEAD_SIZE<\/td>\n2<\/td>\nFile header full size including file name and comments<\/td>\n<\/tr>\n
PACK_SIZE<\/td>\n4<\/td>\nCompressed file size<\/td>\n<\/tr>\n
UNP_SIZE<\/td>\n4<\/td>\nUncompressed file size<\/td>\n<\/tr>\n
HOST_OS<\/td>\n1<\/td>\nOperating system used for archiving (See the ‘Operating System Indicators’ table for the flags used)<\/td>\n<\/tr>\n
FILE_CRC<\/td>\n4<\/td>\nFile CRC<\/td>\n<\/tr>\n
FTIME<\/td>\n4<\/td>\nDate and time in standard MS DOS format<\/td>\n<\/tr>\n
UNP_VER<\/td>\n1<\/td>\nRAR version needed to extract file (Version number is encoded as 10 * Major version + minor version.)<\/td>\n<\/tr>\n
METHOD<\/td>\n1<\/td>\nPacking method (Please see ‘Packing Method’ table for all possibilities<\/td>\n<\/tr>\n
NAME_SIZE<\/td>\n2<\/td>\nFile name size<\/td>\n<\/tr>\n
ATTR<\/td>\n4<\/td>\nFile attributes<\/td>\n<\/tr>\n
HIGH_PACK_SIZE<\/td>\n4<\/td>\nHigh 4 bytes of 64-bit value of compressed file size. Optional value, presents only if bit 0x100 in HEAD_FLAGS is set.<\/td>\n<\/tr>\n
HIGH_UNP_SIZE<\/td>\n4<\/td>\nHigh 4 bytes of 64-bit value of uncompressed file size. Optional value, presents only if bit 0x100 in HEAD_FLAGS is set.<\/td>\n<\/tr>\n
FILE_NAME<\/td>\nNAME_SIZE bytes<\/td>\nFile name – string of NAME_SIZE bytes size<\/td>\n<\/tr>\n
SALT<\/td>\n8<\/td>\npresent if (HEAD_FLAGS & 0x400)\u00a0!= 0<\/td>\n<\/tr>\n
EXT_TIME<\/td>\nvariable size<\/td>\npresent if (HEAD_FLAGS & 0x1000)\u00a0!= 0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

But the actual implementation of HEAD_CRC is the lower bits of CRC32 of header defined as in HEAD_SIZE without HEAD_CRC part calculated with standard polynomial of 0xEDB88320. I write it up here because RAR spec documents are crap. I hope this saves a couple of hours for someone.<\/p>\n","protected":false},"excerpt":{"rendered":"

From Forensics Wiki: Field Name Size (bytes) Description HEAD_CRC 2 CRC of fields from HEAD_TYPE to FILEATTR and file name HEAD_TYPE 1 Header Type: 0x74 HEAD_FLAGS 2 Bit Flags (Please see ‘Bit Flags for File in Archive’ table for all possibilities) HEAD_SIZE 2 File header full size including file name and comments PACK_SIZE 4 Compressed … Continue reading RAR header<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-471","post","type-post","status-publish","format-standard","hentry","category-computer"],"_links":{"self":[{"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/posts\/471","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/comments?post=471"}],"version-history":[{"count":2,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/posts\/471\/revisions"}],"predecessor-version":[{"id":474,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/posts\/471\/revisions\/474"}],"wp:attachment":[{"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/media?parent=471"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/categories?post=471"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/manatails.net\/blog\/wp-json\/wp\/v2\/tags?post=471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}