Explain the differences as well as the similarities between Checksum vs Hash?
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.
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.
Answer (1)
Checksums and hashes are both cryptographic techniques used to verify data integrity and detect errors or tampering. While they serve similar purposes, they have some differences in terms of their applications and properties.
Similarities:
Data Integrity Verification: Both checksums and hashes are used to verify the integrity of data by generating a fixed-size value (checksum or hash) based on the input data. Any change in the input data is likely to result in a different checksum or hash value.
Fixed Output Size: Both checksums and hashes produce fixed-size output values, regardless of the size of the input data. This allows for efficient comparison and storage of integrity verification data.
Differences:
Purpose:
Checksum: Checksums are primarily used for error detection in data transmission or storage. They are designed to quickly detect accidental errors, such as data corruption during transmission.
Hash: Hash functions are designed for a variety of cryptographic applications, including data integrity verification, digital signatures, password hashing, and more. They provide stronger guarantees of data integrity and security compared to checksums.
Collision Resistance:
Checksum: Checksums are not collision-resistant, meaning that it is possible for two different sets of data to produce the same checksum value (checksum collision). However, they are designed to minimize the likelihood of collisions for typical use cases.
Hash: Hash functions are designed to be collision-resistant, meaning that it should be computationally infeasible to find two different sets of data that produce the same hash value (hash collision). Strong cryptographic hash functions aim to provide a high level of collision resistance.
Security:
Checksum: While checksums provide basic error detection capabilities, they are not suitable for security-sensitive applications due to their vulnerability to intentional manipulation (e.g., malicious tampering).
Hash: Hash functions are designed to provide security properties, such as pre-image resistance (given a hash value, it should be computationally infeasible to find the original input data), second pre-image resistance (given an input, it should be computationally infeasible to find another input that produces the same hash), and collision resistance (as mentioned above).
In summary, while checksums and hashes both serve to verify data integrity, checksums are primarily used for error detection in data transmission, while hash functions are used for a wide range of cryptographic applications, including data integrity verification and security-sensitive tasks. Hash functions provide stronger security guarantees and are designed to be collision-resistant, unlike checksums.