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Cryptographic Hash Functions: Ensuring Data Integrity

Understanding cryptographic hash functions, their properties, applications in data integrity verification, digital signatures, and password storage systems.

January 15, 2026 1 min read By Scott Weeden cryptographyhash-functionsshamd5data-integritydigital-signatures

Cryptographic Hash Functions: Ensuring Data Integrity

Cryptographic hashes compress arbitrary data to fixed-size digests with preimage resistance, second-preimage resistance, and collision resistance. Those properties underpin integrity checks, commitment schemes, HMAC-style authentication, and Merkle structures used in protocols and blockchains.

In practice, deprecated algorithms (e.g., MD5, SHA-1 for collision-sensitive uses) must be avoided. Modern designs use SHA-256 / SHA-384 / SHA-512 in the SHA-2 family or SHA-3 where policy requires. Password storage requires slow, salted password hashes (e.g., bcrypt, scrypt, Argon2), never raw SHAs.

Hashes also appear inside digital signature and “hash-then-sign” pipelines; pair this note with posts on RSA-PSS, ECDSA, and domain separation so implementation choices stay consistent with your threat model.