The windows NT registry has 2 different blocks, where one can occur many times... the "regf"-Block ================ "regf" is obviosly the abbreviation for "Registry file". "regf" is the signature of the header-block which is always 4kb in size, although only the first 64 bytes seem to be used and a checksum is calculated over the first 0x200 bytes only! Offset Size Contents 0x00000000 D-Word ID: ASCII-"regf" = 0x66676572 0x00000004 D-Word ???? //see struct REGF 0x00000008 D-Word ???? Always the same value as at 0x00000004 0x0000000C Q-Word last modify date in WinNT date-format 0x00000014 D-Word 1 0x00000018 D-Word 3 0x0000001C D-Word 0 0x00000020 D-Word 1 0x00000024 D-Word Offset of 1st key record 0x00000028 D-Word Size of the data-blocks (Filesize-4kb) 0x0000002C D-Word 1 0x000001FC D-Word Sum of all D-Words from 0x00000000 to 0x000001FB //XOR of all words. Nigel I have analyzed more registry files (from multiple machines running NT 4.0 german version) and could not find an explanation for the values marked with ???? the rest of the first 4kb page is not important... the "hbin"-Block ================ I dont know what "hbin" stands for, but this block is always a multiple of 4kb in size. Inside these hbin-blocks the different records are placed. The memory- management looks like a C-compiler heap management to me... hbin-Header =========== Offset Size Contents 0x0000 D-Word ID: ASCII-"hbin" = 0x6E696268 0x0004 D-Word Offset from the 1st hbin-Block 0x0008 D-Word Offset to the next hbin-Block 0x001C D-Word Block-size The values in 0x0008 and 0x001C should be the same, so I dont know if they are correct or swapped... From offset 0x0020 inside a hbin-block data is stored with the following format: Offset Size Contents 0x0000 D-Word Data-block size //this size must be a multiple of 8. Nigel 0x0004 ???? Data If the size field is negative (bit 31 set), the corresponding block is free and has a size of -blocksize! That does not seem to be true. All block lengths seem to be negative! (Richard Sharpe) The data is stored as one record per block. Block size is a multiple of 4 and the last block reaches the next hbin-block, leaving no room. (That also seems incorrect, in that the block size if a multiple of 8. That is, the block, including the 4 byte header, is always a multiple of 8 bytes. Richard Sharpe.) Records in the hbin-blocks ========================== nk-Record The nk-record can be treated as a kombination of tree-record and key-record of the win 95 registry. lf-Record The lf-record is the counterpart to the RGKN-record (the hash-function) vk-Record The vk-record consists information to a single value. sk-Record sk (? Security Key ?) is the ACL of the registry. Value-Lists The value-lists contain information about which values are inside a sub-key and dont have a header. Datas The datas of the registry are (like the value-list) stored without a header. All offset-values are relative to the first hbin-block and point to the block-size field of the record-entry. to get the file offset, you have to add the header size (4kb) and the size field (4 bytes)... the nk-Record ============= Offset Size Contents 0x0000 Word ID: ASCII-"nk" = 0x6B6E 0x0002 Word for the root-key: 0x2C, otherwise 0x20 //key symbolic links 0x10. Nigel 0x0004 Q-Word write-date/time in windows nt notation 0x000C D-Word UNKNOWN // added by TDM 0x0010 D-Word Offset of Owner/Parent key 0x0014 D-Word number of sub-Keys 0x0018 D-Word UNKNOWN // added by TDM 0x001C D-Word Offset of the sub-key lf-Records 0x0020 D-Word UNKNOWN // added by TDM 0x0024 D-Word number of values 0x0028 D-Word Offset of the Value-List 0x002C D-Word Offset of the sk-Record 0x0030 D-Word Offset of the Class-Name //see NK structure for the use of these fields. Nigel 0x0044 D-Word Unused (data-trash) //some kind of run time index. Does not appear to be important. Nigel 0x0048 Word name-length 0x004A Word class-name length 0x004C ???? key-name the Value-List ============== Offset Size Contents 0x0000 D-Word Offset 1st Value 0x0004 D-Word Offset 2nd Value 0x???? D-Word Offset nth Value To determine the number of values, you have to look at the owner-nk-record! Der vk-Record ============= Offset Size Contents 0x0000 Word ID: ASCII-"vk" = 0x6B76 0x0002 Word name length 0x0004 D-Word length of the data //if top bit is set when offset contains data. Nigel 0x0008 D-Word Offset of Data 0x000C D-Word Type of value 0x0010 Word Flag 0x0012 Word Unused (data-trash) 0x0014 ???? Name If bit 0 of the flag-word is set, a name is present, otherwise the value has no name (=default) If the data-size is lower 5, the data-offset value is used to store the data itself! The data-types ============== Wert Beteutung 0x0001 RegSZ: character string (in UNICODE!) 0x0002 ExpandSZ: string with "%var%" expanding (UNICODE!) 0x0003 RegBin: raw-binary value 0x0004 RegDWord: Dword 0x0007 RegMultiSZ: multiple strings, seperated with 0 (UNICODE!) The "lf"/"lh"/"ri"-record (hash list header) =============== Offset Size Contents 0x0000 Word ID: ASCII-"lf" = 0x666C (or "lh" or "ri") 0x0002 Word number of keys 0x0004 ???? Hash-Records Hash-Record =========== Offset Size Contents 0x0000 D-Word Offset of corresponding "nk"-Record 0x0004 D-Word ASCII: the first 4 characters of the key-name, padded with 0-s. Case sensitive! (the hash value may be computed differently for the various header types "lf"/"lh"/"ri"/etc) Keep in mind, that the value at 0x0004 is used for checking the data-consistency! If you change the key-name you have to change the hash-value too! //These hashrecords must be sorted low to high within the lf record. Nigel. The "sk"-block ============== (due to the complexity of the SAM-info, not clear jet) (This is just a self-relative security descriptor in the data. R Sharpe.) Offset Size Contents 0x0000 Word ID: ASCII-"sk" = 0x6B73 0x0002 Word Unused 0x0004 D-Word Offset of previous "sk"-Record 0x0008 D-Word Offset of next "sk"-Record 0x000C D-Word usage-counter 0x0010 D-Word Size of "sk"-record in bytes ???? //standard self relative security desciptor. Nigel ???? ???? Security and auditing settings... ???? The usage counter counts the number of references to this "sk"-record. You can use one "sk"-record for the entire registry! Windows nt date/time format =========================== The time-format is a 64-bit integer which is incremented every 0,0000001 seconds by 1 (I dont know how accurate it really is!) It starts with 0 at the 1st of january 1601 0:00! All values are stored in GMT time! The time-zone is important to get the real time! Common values for win95 and win-nt ================================== Offset values marking an "end of list", are either 0 or -1 (0xFFFFFFFF). If a value has no name (length=0, flag(bit 0)=0), it is treated as the "Default" entry... If a value has no data (length=0), it is displayed as empty. simplyfied win-3.?? registry: ============================= +-----------+ | next rec. |---+ +----->+------------+ | first sub | | | | Usage cnt. | | name | | +-->+------------+ | | length | | value | | | | next rec. | | | text |------->+-------+ +-----------+ | | | name rec. |--+ +------------+ | xxxxx | +------------+ | | value rec. |-------->+------------+ +-------+ v | +------------+ | Usage cnt. | +-----------+ | | length | | next rec. | | | text |------->+-------+ | first sub |------+ +------------+ | xxxxx | | name | +-------+ | value | +-----------+ Greatly simplyfied structure of the nt-registry: ================================================ +---------------------------------------------------------------+ | | v | +---------+ +---------->+-----------+ +----->+---------+ | | "nk" | | | lf-rec. | | | nk-rec. | | | ID | | | # of keys | | | parent |---+ | Date | | | 1st key |--+ | .... | | parent | | +-----------+ +---------+ | suk-keys|-----+ | values |--------------------->+----------+ | SK-rec. |---------------+ | 1. value |--> +----------+ | class |--+ | +----------+ | vk-rec. | +---------+ | | | .... | v | | data |--> +-------+ +------------+ | +----------+ | xxxxx | | Class name | | +-------+ +------------+ | v +---------+ +---------+ +----->| next sk |--->| Next sk |--+ | +---| prev sk |<---| prev sk | | | | | .... | | ... | | | | +---------+ +---------+ | | | ^ | | | | | | +--------------------+ | +----------------------------------+ --------------------------------------------------------------------------- Hope this helps.... (Although it was *fun* for me to uncover this things, it took me several sleepless nights ;) B.D.