(also hash sum)
A checksum is a numerical value that is computed from a data set. It acts as a unique identifier, often used to verify the integrity of data sent through transmission. By comparing the checksum values of the original and received data, a person can detect errors or corruption that may have occurred during transmission. If even a single bit in the data set is changed, the checksum will also change, indicating that the data has been tampered with or corrupted.
- MD5 checksum: A widely used cryptographic hash function that produces a 128-bit (16-byte) hash value. It is commonly used to verify data integrity.
- SHA-1 checksum: A cryptographic hash function that takes an input and produces a 160-bit (20-byte) hash value. It is used in various security applications and protocols, including TLS and SSL, PGP, SSH, and IPsec.
Ensuring data integrity with checksums
- Always compare checksum values when downloading files from the internet to ensure they haven’t been tampered with.
- Use checksums when transmitting data over a network to detect errors or corruption.
- Keep in mind that while checksums can verify data integrity, they cannot protect against malicious tampering. For that, cryptographic techniques are needed.