What does hash value mean? Understand the concept, common algorithms, principles and applications of hash value in one article

The hash value is the digital fingerprint of the input data. It is a fixed-length value generated by digesting the document content and is collision-resistant. It is calculated by applying mathematical operations to the input data through a hash algorithm (such as MD5, SHA-1, SHA-256, bcrypt), dividing the data into equal-sized blocks, operating block by block to generate intermediate values, and finally generating a hash value. . Hash values ​​are widely used, including data integrity verification, digital signatures, cryptography, blockchain, hash tables, etc.

Hash value: understand its concepts, algorithms, principles and applications

What is hash value?

A hash value is a fixed-length value calculated from input data (such as a string, file, or any other type of binary data) through a hash function. It is a digital fingerprint of the input data and is collision-resistant, i.e. it is extremely unlikely that different input data will produce the same hash value.

Hash algorithm

Common hashing algorithms include:

• MD5 (Message Digest 5)
• SHA-1 (Secure Hash Algorithm 1)
• SHA-256 (Secure Hash Algorithm 256)
• bcrypt

Principle

The hash function divides the input data into equal-sized chunks and applies a specific mathematical operation to each chunk. These operations produce an intermediate value, which is then further processed through other iterative operations, ultimately producing a hash value.

Applications

Hash values ​​are widely used in various applications, including:

• Data Integrity Verification: Hash values ​​can be used to verify the integrity of data and ensure that data is transmitted or has not been tampered with during storage.
• Digital signature: Hash values ​​can be used to create digital signatures, which are cryptographic authentications of data.
• Cryptography: Hashes can be used to store secure versions of passwords to prevent them from being cracked.
• Blockchain: Hash plays a vital role in the blockchain to verify new blocks and ensure that the data cannot be tampered with.
• Hash table: Hash values ​​can be used to quickly find data in a hash table, which is a structure that organizes data according to key values.

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