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What is hashing?

Hashing is a technique used in computer science and cryptography to convert input data of arbitrary size into a fixed-size output known as a hash value or message digest. The hash function takes the input data, applies a series of mathematical algorithms and operations to it, and produces a unique and fixed-size output that is representative of the input data.

Hashing is used in a variety of applications such as data integrity checking, password storage, digital signatures, and data indexing. In data integrity checking, a hash value of a file is calculated and stored, and the hash value can later be recalculated and compared to the stored value to ensure that the file has not been tampered with or corrupted. In password storage, a hash value of the password is stored instead of the plaintext password, to prevent unauthorized access in case the password database is compromised.

Hash functions should be fast and efficient, while also providing a high level of randomness and uniqueness in their output values. Cryptographic hash functions are designed to be secure and resistant to attacks, while non-cryptographic hash functions are optimized for performance and are used in applications such as hash tables and data partitioning.

What is SHA2/SHA3?

SHA-2 (Secure Hash Algorithm 2) is a family of cryptographic hash functions that includes SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256. SHA-2 is designed to be secure and resistant to attacks, and is widely used in security applications such as digital signatures, password hashing, and message authentication.

SHA-2 works by processing input data in 512-bit blocks and generating a fixed-size hash value of either 224 bits, 256 bits, 384 bits, or 512 bits. The algorithm uses a series of bitwise operations, including XOR, AND, OR, and NOT, as well as modular addition and rotation operations, to process the input data and generate the hash value.

SHA-3 (Secure Hash Algorithm 3) is a family of cryptographic hash functions that is the successor to SHA-2. SHA-3 was developed by the National Institute of Standards and Technology (NIST) and was selected in 2012 as the winner of a public competition to design a new hash function. SHA-3 is designed to provide improved security and resistance to attacks compared to SHA-2.

SHA-3 works by processing input data in 1600-bit blocks and generating a fixed-size hash value of either 224 bits, 256 bits, 384 bits, or 512 bits. The algorithm uses a sponge construction, which involves absorbing the input data into a state, followed by squeezing out the hash value from the state. The sponge construction allows for flexibility in the size of the input data and the hash value, while also providing resistance to certain types of attacks.

What is Murmur2/Murmur3?

Murmur2 is a non-cryptographic hash function that generates 32-bit or 64-bit hash values from input data. It was developed by Austin Appleby in 2008 and is designed to be fast and efficient, making it suitable for use in applications such as hash tables, Bloom filters, and data partitioning. Murmur2 is not suitable for security applications as it is more likely to produce hash collisions than cryptographic hash functions. Murmur2 works by iterating over the input data in 32-bit or 64-bit chunks, performing a series of bitwise operations, and combining the results using a finalization step. The resulting hash value is intended to be uniformly distributed and to have good randomness properties.

MurmurHash3 (also known as Murmur3) is a non-cryptographic hash function that is an updated version of the original MurmurHash algorithm. It was developed by Austin Appleby in 2008 and is designed to be fast and efficient, while also providing improved distribution of hash values and better resistance to certain types of attacks.

MurmurHash3 can generate hash values of varying lengths (32-bit, 64-bit, or 128-bit) from input data of any length. It works by processing the input data in chunks and performing a series of bitwise operations on each chunk, before combining the results using a finalization step. The algorithm uses a mix of multiplication and XOR operations to achieve good distribution of hash values.

MurmurHash3 is widely used in applications such as hash tables, Bloom filters, and data partitioning. It is also used in several programming languages and frameworks, including Apache Cassandra, Apache HBase, and Redis. MurmurHash3 is not suitable for security applications as it is a non-cryptographic hash function and can be vulnerable to certain types of attacks.

| Parameter | Murmur2 Hashing | SHA-2 Hashing | | :-----------: | :-------------------------------------------: | :----------------------------------------------------------: | | Algorithm | Non-cryptographic | Cryptographic | | Hash Size | 32-bit or 64-bit | 224-bit, 256-bit, 384-bit, 512-bit | | Collisions | More likely | Less likely | | Security | Not secure | Secure | | Use Cases | Hash tables, Bloom filters, data partitioning | Digital signatures, password hashing, message authentication |

Summary

Murmur2 and SHA-2 are two different types of hashing algorithms with different characteristics and use cases. Here are some key differences between the two:

Hashing Algorithm: Murmur2 is a non-cryptographic hash function, while SHA-2 is a cryptographic hash function. Non-cryptographic hash functions are designed to be fast and efficient, while cryptographic hash functions are designed to be secure and resistant to attacks.

Hash Size: Murmur2 generates 32-bit or 64-bit hash values, while SHA-2 generates hash values of varying sizes, including 224-bit, 256-bit, 384-bit, and 512-bit.

Collisions: Murmur2 is more likely to produce hash collisions than SHA-2. A hash collision occurs when two different input values produce the same hash value. In non-cryptographic applications where the probability of collisions is acceptable, Murmur2 can be a faster and more efficient choice than SHA-2.

Security: SHA-2 is considered a secure hashing algorithm and is widely used in security applications such as digital signatures and password hashing. Murmur2, on the other hand, is not designed for security applications and should not be used for secure data storage or transmission.

Use Cases: Murmur2 is commonly used in non-security applications such as hash tables, Bloom filters, and data partitioning. SHA-2 is used in security applications such as digital signatures, password hashing, and message authentication.

In summary, the choice between Murmur2 and SHA-2 depends on the specific requirements of the application. If fast performance is a priority and collisions are acceptable, Murmur2 may be a suitable choice. If security is a concern, SHA-2 is a better choice.