ava on Nostr: The SHA-256 algorithm, which stands for Secure Hash Algorithm 256-bit, is a widely ...
The SHA-256 algorithm, which stands for Secure Hash Algorithm 256-bit, is a widely used cryptographic hash function. It is part of the SHA-2 (Secure Hash Algorithm 2) family developed by the National Security Agency (NSA) in the United States.
The primary purpose of the SHA-256 algorithm is to take an input message and produce a fixed-size output, which is typically represented as a 256-bit (32-byte) hash value. This hash value is unique to the input message, meaning that even a small change in the input will result in a significantly different hash value.
Here's a high-level overview of how the SHA-256 algorithm works:
1. Padding: The input message is padded to ensure it has a specific length and format required by the algorithm. This step ensures that messages of different lengths can be processed consistently.
2. Message Expansion: The padded message is divided into blocks, and each block goes through an expansion process to create an extended message schedule. This schedule contains additional values derived from the original block and previous blocks.
3. Initial Hash Values: The algorithm initializes eight initial hash values (also known as "constants" or "state variables"). These values are predefined and serve as starting points for further computation.
4. Compression Function: Each block of the extended message schedule undergoes multiple rounds of compression using logical functions such as bitwise operations (AND, OR, XOR), addition modulo 2^32, and logical functions like NOT and ROTATE.
5. Final Hash Value: After all blocks have been processed through compression rounds, the resulting state variables are concatenated to form the final hash value. This value represents a unique fingerprint of the original input message.
The SHA-256 algorithm offers several important properties:
1. Deterministic: Given the same input message, it will always produce the same hash value.
2. Fast Computation: It can efficiently compute hash values for large amounts of data.
3. Collision Resistance: It is computationally infeas
The primary purpose of the SHA-256 algorithm is to take an input message and produce a fixed-size output, which is typically represented as a 256-bit (32-byte) hash value. This hash value is unique to the input message, meaning that even a small change in the input will result in a significantly different hash value.
Here's a high-level overview of how the SHA-256 algorithm works:
1. Padding: The input message is padded to ensure it has a specific length and format required by the algorithm. This step ensures that messages of different lengths can be processed consistently.
2. Message Expansion: The padded message is divided into blocks, and each block goes through an expansion process to create an extended message schedule. This schedule contains additional values derived from the original block and previous blocks.
3. Initial Hash Values: The algorithm initializes eight initial hash values (also known as "constants" or "state variables"). These values are predefined and serve as starting points for further computation.
4. Compression Function: Each block of the extended message schedule undergoes multiple rounds of compression using logical functions such as bitwise operations (AND, OR, XOR), addition modulo 2^32, and logical functions like NOT and ROTATE.
5. Final Hash Value: After all blocks have been processed through compression rounds, the resulting state variables are concatenated to form the final hash value. This value represents a unique fingerprint of the original input message.
The SHA-256 algorithm offers several important properties:
1. Deterministic: Given the same input message, it will always produce the same hash value.
2. Fast Computation: It can efficiently compute hash values for large amounts of data.
3. Collision Resistance: It is computationally infeas