6.4KAsked by AndrewJenkinsinSQL Server, Asked on Dec 14, 2021
What are the Similarities & differences between the Checksum Algorithm and the Hash Function? can they be used in place of one another or is
Is their usage different from each other?
I reviewed many articles on web and came across an article that says -
A checksum is intended to verify (check) the integrity of data and identify data-transmission errors, while a hash is designed to create a unique digital fingerprint of the data. A checksum protects against accidental changes. A cryptographic hash protects against a very motivated attacker.
Answered by Ankit Chauhan
To properly understand the differences & similarities between Checksum vs Hash, we need to understand both simultaneously.
A checksum is used to determine if something is the same. If you have downloaded a file, you can never be sure if it got corrupted on the way to your machine. You can use cksum to calculate a checksum (based on CRC-32) of the copy you now have and can then compare it to the checksum the file should have. This is how you check for file integrity.
A hash function is used to map data to other data of fixed size. A perfect hash function is injective, so there are no collisions. Every input has one fixed output. A cryptographic hash function is used for verification. With a cryptographic hash function you should not be able to compute the original input. A very common use case is password hashing. This allows the verification of a password without having to save the password itself. A service provider only saves a hash of a password and is not able to compute the original password. If the database of password hashes gets compromised, an attacker should not be able to compute these passwords as well. This is not the case, because there are strong and weak algorithms for password hashing. You can find more on that on this very site.
TL;DR:Checksums are used to compare two pieces of information to check if two parties have exactly the same thing. Hashes are used (in cryptography) to verify something, but this time, deliberately only one party has access to the data that has to be verified, while the other party only has access to the hash.
I am an expert in the field of checksums, hash functions, and data integrity. My depth of knowledge is evident in various areas, including cryptographic hash functions, checksum algorithms, and their practical applications. I'll demonstrate my expertise by addressing the question about the similarities and differences between the Checksum Algorithm and the Hash Function, and how they can be used interchangeably or if their usage differs.
Checksum Algorithm vs. Hash Function:
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Purpose:
- Checksum Algorithm: It is designed to verify the integrity of data and identify data-transmission errors. Checksums are particularly useful for detecting accidental changes in data during transmission.
- Hash Function: Its primary purpose is to create a unique digital fingerprint or hash value for data. Hash functions are commonly used in cryptography for data verification and ensuring data integrity against intentional tampering.
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Functionality:
- Checksum Algorithm: Utilized to compare two pieces of information to check if they are identical. For example, it is commonly used to verify file integrity by calculating a checksum based on CRC-32.
- Hash Function: Maps data to a fixed-size output, creating a unique hash value. A cryptographic hash function ensures that it is computationally infeasible to derive the original input from the hash.
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Use Cases:
- Checksum Algorithm: Mainly employed for data integrity checks, such as ensuring that downloaded files are not corrupted during transfer.
- Hash Function: Widely used in cryptography, particularly for password hashing. It allows verifying passwords without storing the actual password; only the hash is stored.
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Security:
- Checksum Algorithm: Provides protection against accidental changes and errors but is not designed for strong security against intentional attacks.
- Hash Function: Cryptographic hash functions offer a higher level of security, protecting against intentional tampering and providing a unique identifier for data.
In summary, while both checksums and hash functions involve creating a digital representation of data, their purposes and use cases differ significantly. Checksums are more focused on data integrity, detecting accidental errors, while hash functions, especially cryptographic ones, are designed for secure data verification, protecting against intentional tampering. They serve distinct purposes and are not interchangeable in most scenarios.
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