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The Internet checksum, [1] [2] also called the IPv4 header checksum is a checksum used in version 4 of the Internet Protocol (IPv4) to detect corruption in the header of IPv4 packets. It is carried in the IPv4 packet header , and represents the 16-bit result of the summation of the header words.
BSD checksum (Unix) 16 bits sum with circular rotation SYSV checksum (Unix) 16 bits sum with circular rotation sum8 8 bits sum Internet Checksum: 16 bits sum (ones' complement) sum24 24 bits sum sum32 32 bits sum fletcher-4: 4 bits sum fletcher-8: 8 bits sum fletcher-16: 16 bits sum fletcher-32: 32 bits sum Adler-32: 32 bits sum xor8: 8 bits ...
The first weakness of the simple checksum is that it is insensitive to the order of the blocks (bytes) in the data word (message). If the order is changed, the checksum value will be the same and the change will not be detected. The second weakness is that the universe of checksum values is small, being equal to the chosen modulus.
The simplest checksum algorithm is the so-called longitudinal parity check, which breaks the data into "words" with a fixed number n of bits, and then computes the bitwise exclusive or (XOR) of all those words. The result is appended to the message as an extra word.
Adler-32 is a checksum algorithm written by Mark Adler in 1995, [1] modifying Fletcher's checksum. Compared to a cyclic redundancy check of the same length, it trades reliability for speed. Adler-32 is more reliable than Fletcher-16, and slightly less reliable than Fletcher-32. [2]
The FNV_offset_basis is the 64-bit value: 14695981039346656037 (in hex, 0xcbf29ce484222325). The FNV_prime is the 64-bit value 1099511628211 (in hex, 0x100000001b3). The multiply returns the lower 64 bits of the product. The XOR is an 8-bit operation that modifies only the lower 8-bits of the hash value. The hash value returned is a 64-bit ...
The ".sha1" file extension indicates a checksum file containing 160-bit SHA-1 hashes in sha1sum format. The ".md5" file extension, or a file named "MD5SUMS", indicates a checksum file containing 128-bit MD5 hashes in md5sum format. The ".sfv" file extension indicates a checksum file containing 32-bit CRC32 checksums in simple file verification ...
HxD is a freeware hex editor, disk editor, and memory editor developed by Maël Hörz for Windows. It can open files larger than 4 GiB and open and edit the raw contents of disk drives, as well as display and edit the memory used by running processes. Among other features, it can calculate various checksums, compare files, or shred files. [1]