SHA-256
SHA-256 is a standardized cryptographic hash function in the SHA-2 family that maps arbitrary input data to a fixed-length 256-bit digest.
Software Security for Developers
SHA-256 is a member of the SHA-2 family of cryptographic hash algorithms that produces a 256-bit digest.
- How it is used
- Detects accidental file corruption before a downstream service processes sensitive operations such as refunds.
- How deep it goes
- Explains repeatable hashing, comparison, rejection behavior, and active-tampering limits, but defers protection against malicious modification to HMAC.
- Examples
- Uses refunds.json and refunds.json.sha256, a warehouse-to-payments workflow, and Java digest computation.
- What you can do after
- Apply it via Java MessageDigest to compute and compare file digests, while recognizing when HMAC is required.
Read how Software Security for Developers explains SHA-256 →
Hacking Cryptography
SHA-256 is a member of the Secure Hash Algorithm 2 family that produces 256-bit cryptographic hash digests.
- How it is used
- Demonstrates how SHA-256-based secret-prefix MACs fail under length-extension attacks in an authenticated transaction API.
- How deep it goes
- Explains Merkle–Damgård state exposure, padding, digest parsing, and HTTP forgery code, stopping short of redesigning authentication.
- Examples
- Uses a bank transaction API, signed query strings, SHA-256 padding, Go code, and an OpenSSL-backed forgery test.
- What you can do after
- Diagnose and reproduce secret-prefix MAC vulnerabilities with Go, cgo, and OpenSSL SHA-256 state manipulation.
Real-World Cryptography
A member of the SHA-2 family of standardized cryptographic hash functions that produces a 256-bit digest.
- How it is used
- Verifies downloaded-file integrity by comparing a computed digest with a trusted published value.
- How deep it goes
- Explains fixed-length hashing, security properties, and high-level SHA-2 construction, stopping short of implementation-level detail.
- Examples
- Uses download verification, OpenSSL commands, repeated inputs, changed inputs, and inputs of different lengths.
- What you can do after
- Apply it via OpenSSL to calculate a file digest and compare that digest against a published verification value.
Effective Data Analysis
SHA-256 is a member of the Secure Hash Algorithm 2 family that produces a 256-bit cryptographic hash.
- How it is used
- Uses SHA-256 to replace sensitive identifiers in analytics data and connect datasets without exposing original values.
- How deep it goes
- Explains deterministic and change-sensitive hashing, demonstrates implementation, and cautions that reversal may become possible; it does not develop cryptographic internals.
- Examples
- Demonstrates hashing email addresses, separating email mappings, and retaining email_hash in a transactions table.
- What you can do after
- Apply it via Python’s hashlib library to create repeatable identifiers and join data while separating original PII.
Related concepts
- hash functionkind of · A hash function deterministically maps input data to a value in a bounded output range, commonly for indexing, lookup, comparison, or integrity checking.
- SHA-2kind of · SHA-2 is a standardized family of cryptographic hash algorithms that produces fixed-length digests, including SHA-224, SHA-256, SHA-384, and SHA-512.
- StandardPasswordEncoderused by · StandardPasswordEncoder is a deprecated Spring Security password encoder that hashes passwords with SHA-256 and an optional secret.
- HMACused by · HMAC is a keyed message authentication code constructed from a cryptographic hash function and a secret key to authenticate data and verify its integrity.
- hmac-sha256used by · HMAC-SHA256 is a keyed message-authentication construction that uses SHA-256 and a shared secret to produce an authentication tag.
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