Cryptography
SHA-256
Also known as: Secure Hash Algorithm 256, SHA-2
The 256-bit output variant of the SHA-2 family — the cryptographic hash function LearnCoin uses for leaf hashing, Merkle concatenation, and signature digests.
SHA-256 is a cryptographic hash function in the SHA-2 family, standardized by NIST in FIPS 180-4. It produces a 256-bit (32-byte) digest from any input. As of 2026, SHA-256 remains cryptographically unbroken — preimage, second-preimage, and collision attacks all require infeasible computational resources.
LearnCoin uses SHA-256 throughout the signing pipeline. Credential canonicalization (URDNA2015) produces N-Quads bytes; those bytes get hashed with SHA-256 to produce the Merkle leaf. Leaves are pair-concatenated and hashed with SHA-256 to produce parent nodes, up to the Merkle root. The root itself gets SHA-256'd again as the input to ECDSA signing. Every step uses the same hash function, which simplifies auditing.
SHA-256 is the hash Bitcoin uses, Ethereum uses (alongside Keccak-256), most HSMs support natively, and the W3C Verifiable Credential Data Integrity specification references. It's effectively the default for cryptographic work in 2026 unless a specific context demands otherwise.
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