A-Z: What is a Hash Function?

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Blockchain A – Z covers all of the important topics you need to know if you’re just getting into blockchain! We go letter by letter with each episode defining a specific topic. By the end of the series, you’ll know your blockchain ABCs!

What is a hash function and a hash value?

Hash functions take an input of any length (a message, for example), and returns a fixed-length string of numbers and letters. That is the hash value (also known as a message digest, digital fingerprint, or digest).

The hash value, or digest, is the digital signature. This means that a person who knows the hash value cannot know the original message. On the other hand, the person who knows the original message can prove the hash value is created from that message. When digests are equal, it confirms that the message has not been modified or changed since it was signed.

Cryptographic hashes, such as the SHA-256 computational algorithm used by Bitcoin and others, ensure that any alteration to transaction input, results in a different hash value being computed, which indicates potentially compromised transaction input.

For more blockchain terminology and vocab, head over to our Blockchain Glossaries, where we have a wide range of terms you should definitely know!
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