Max Hillebrand on Nostr: The SHA-256 algorithm processes input data to produce a 256-bit hash value. Here's a ...
The SHA-256 algorithm processes input data to produce a 256-bit hash value. Here's a step-by-step walkthrough of the algorithm:
1. Padding: The input message is padded to make its length a multiple of 512 bits. This is done by appending a single '1' bit, followed by '0' bits, and then a 64-bit representation of the original message length.
2. Initialization: Eight 32-bit buffers (A to H) are initialized with specific hexadecimal values derived from the first 32 bits of the fractional parts of the square roots of the first 8 prime numbers.
3. Message schedule: The padded message is divided into 512-bit blocks. Each block is further divided into 16 32-bit words. These words are expanded into 64 32-bit words using a specific formula.
4. Compression function: This is the core of the algorithm, consisting of 64 rounds of operations. In each round:
The current state (A to H) is mixed with the message schedule word and a constant K[i].
Bitwise operations (AND, XOR, rotations) are performed.
The state is updated for the next round.
5. Final addition: After processing all blocks, the final values of A to H are added to their initial values.
Output: The final state of the eight 32-bit words (A to H) is concatenated to produce the 256-bit hash value.
This process ensures that any change in the input, no matter how small, results in a completely different hash value, making SHA-256 useful for integrity verification and digital signatures.
Published at
2024-07-07 16:55:24Event JSON
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"pubkey": "b7ed68b062de6b4a12e51fd5285c1e1e0ed0e5128cda93ab11b4150b55ed32fc",
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"kind": 1,
"tags": [],
"content": "The SHA-256 algorithm processes input data to produce a 256-bit hash value. Here's a step-by-step walkthrough of the algorithm:\n\n1. Padding: The input message is padded to make its length a multiple of 512 bits. This is done by appending a single '1' bit, followed by '0' bits, and then a 64-bit representation of the original message length.\n\n2. Initialization: Eight 32-bit buffers (A to H) are initialized with specific hexadecimal values derived from the first 32 bits of the fractional parts of the square roots of the first 8 prime numbers.\n\n3. Message schedule: The padded message is divided into 512-bit blocks. Each block is further divided into 16 32-bit words. These words are expanded into 64 32-bit words using a specific formula.\n\n4. Compression function: This is the core of the algorithm, consisting of 64 rounds of operations. In each round:\nThe current state (A to H) is mixed with the message schedule word and a constant K[i].\nBitwise operations (AND, XOR, rotations) are performed.\nThe state is updated for the next round.\n\n5. Final addition: After processing all blocks, the final values of A to H are added to their initial values.\nOutput: The final state of the eight 32-bit words (A to H) is concatenated to produce the 256-bit hash value.\n\nThis process ensures that any change in the input, no matter how small, results in a completely different hash value, making SHA-256 useful for integrity verification and digital signatures.",
"sig": "cdd7095c02abeedd2b7a18672ab1715c45ece4bcb31cda21c1503773829c8107fb5942686973a042827a7ba66be63d4b91b54297bd860d1fdfcde7eb8c5c4b06"
}