One can adapt certain checksum or fingerprinting algorithms for use as hash functions.

This method may produce a sufficiently uniform distribution of hash values, as long as the hash range size n is small compared to the range of the checksum or fingerprint function.

Moreover, each bit of the input has a deterministic effect on each bit of the CRC32, that is one can tell without looking at the rest of the input, which bits of the output will flip if the input bit is flipped ; so care must be taken to use all 32 bits when computing the hash from the checksum.

* Cyclic redundancy check, a type of hash function used to produce a checksum in order to detect errors in data storage or transmission

* Redundancy check, Error detection realized using a hash function or checksum algorithm

In computer science, a collision or clash is a situation that occurs when two distinct pieces of data have the same hash value, checksum, fingerprint, or cryptographic digest.

* Forensic imaging or acquisition is the process where the entire drive contents are imaged to a file and checksum values are calculated to verify the integrity ( in court cases ) of the image file ( often referred to as a " hash value ").

The recipient splits its copy of the file into fixed-size non-overlapping chunks and computes two checksums for each chunk: the MD5 hash, and a weaker ' rolling checksum '.

This requires a simultaneous hash collision in MD5 and the rolling checksum.

With 128 bits from MD5 plus 32 bits from the rolling checksum, and assuming maximum entropy in these bits, the probability of a hash collision with this combined checksum is 2 < sup >−( 128 + 32 )</ sup > = 2 < sup >− 160 </ sup >.

Common methods for verifying that operating system patches have not been altered include the use of cryptographic hash, such as an MD5 based checksum, or the use of read-only media.

The MD5 hash ( or checksum ) functions as a compact digital fingerprint of a file.

This weakness makes it trivial to create a hash collision, allowing large sections to be completely altered without altering the checksum.

UUHash will hash the first 300 kilobytes using MD5 and then apply a smallhash function ( identical to the CRC32 checksum used by PNG ) to 300 KB blocks at file offsets 2 < sup > n </ sup > MB with n being an integer incremented from 0 until the offset reaches end of file.

The 128-bit hash value of any message is formed by padding it to a multiple of the block length on the computer ( 128 bits or 16 bytes ) and adding a 16-byte checksum to it.

* Speed of Computation-As a hash designed primarily for hashtable and checksum use, FNV-1 and 1a were designed to be fast to compute.

For each object in question a HIDS will usually remember its attributes ( permissions, size, modifications dates ) and create a checksum of some kind ( an MD5, SHA1 hash or similar ) for the contents, if any.

* Data corruption problems have led to most programs using segmented downloading using some sort of checksum or hash algorithm to ensure file integrity ( to receive file intact ) and uniqueness ( to not receive bits of other similar files ).

In cryptographic terms, the list of MD4 checksums is a hash list, and the file identification checksum is the root hash, also called top hash or master hash.

* < tt > sum </ tt >, a Unix command ( also ported to Win32 ) that generates order-independent sums ; uses two different algorithms for calculating, the SYSV checksum algorithm and the BSD checksum ( default ) algorithm.

* A checksum based on the formation of the sum of the digits of a numeral.

The check digit provides a checksum test using a position-weighted sum of each of the digits.

As with simpler checksum algorithms, the Fletcher checksum involves dividing the binary data word to be protected from errors into short " blocks " of bits and computing the modular sum of those blocks.

This is the modular sum of the values taken by the simple checksum as each block of the data word is added to it.

Usually, the second sum will be multiplied by 256 and added to the simple checksum, effectively stacking the sums side-by-side in a 16-bit word with the simple checksum at the least significant end.

Usually, the second sum will be multiplied by 2 < sup > 16 </ sup > and added to the simple checksum, effectively stacking the sums side-by-side in a 32-bit word with the simple checksum at the least significant end.

Usually, the second sum will be multiplied by 2 < sup > 32 </ sup > and added to the simple checksum, effectively stacking the sums side-by-side in a 64-bit word with the simple checksum at the least significant end.

* checksum: 1 byte, sum modulo 256 of bytes in the packet

One common method used to prevent cheating is for a checksum ( such as an MD5 sum ) to be calculated against each game datafile on the client computer, and for these checksums to be reported to the server before the client can join the game.

The checksum was the sum of all bytes in the packet modulo 256.

When hex dumps are intended to be manually entered into a computer, such as was the case with print magazine articles of home computer era a checksum byte ( or two ) would be added at the end of each row, commonly calculated as simple 256 modulo of sum of all values in the row or a more sophisticated CRC.

The procedure that yields the checksum from the data is called a checksum function or checksum algorithm.

A good checksum algorithm will yield a different result with high probability when the data is accidentally corrupted ; if the checksums match, the data is very likely to be free of accidental errors.

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 exclusive or of all those words.

To check the integrity of a message, the receiver computes the exclusive or of all its words, including the checksum ; if the result is not a word with n zeros, the receiver knows that a transmission error occurred.

A variant of the previous algorithm is to add all the " words " as unsigned binary numbers, discarding any overflow bits, and append the two's complement of the total as the checksum.

To validate a message, the receiver adds all the words in the same manner, including the checksum ; if the result is not a word full of zeros, an error must have occurred.

The goal of a good checksum algorithm is to spread the valid corners as far from each other as possible, so as to increase the likelihood that " typical " transmission errors will end up in an invalid corner.

This schema is also used in many text checksum and fingerprint algorithms.

* The IPv6 header is not protected by a checksum ; integrity protection is assumed to be assured by both link-layer and higher-layer ( TCP, UDP, etc.

This improvement may have been made less necessary by the development of routers that perform checksum computation at link speed using dedicated hardware, but it is still relevant for software-based routers.

If the checksum is bad, the routing node discards the packet.

Each of these smaller problems is then encoded as a relation between a checksum and a packet such that whether the checksum is accurate or not is also the answer to that smaller problem.