Package zeroecho.core.alg.digest

package zeroecho.core.alg.digest
Digest algorithms (SHA-2, SHA-3, SHAKE) and their streaming contexts.

This package provides the core unkeyed hash functions of the ZeroEcho library. It integrates JCA MessageDigest engines into the framework’s streaming context model, allowing digests to be applied as pipeline stages with produce/verify modes. It also defines immutable specifications for selecting digest variants and output lengths for extendable-output functions.

Scope and responsibilities

  • Expose a single algorithm descriptor under id "DIGEST" that covers SHA-2, SHA-3, and SHAKE variants.
  • Provide a JCA-backed DigestContext for streaming input through a MessageDigest engine.
  • Support both fixed-length digests and extendable-output functions (XOFs) with configurable output size.
  • Ensure interoperability with JCA provider implementations.

Components

  • Sha2Sha3Algorithm: registers the algorithm, declares its digest capability, and creates contexts bound to the appropriate JCA MessageDigest.
  • DigestSpec: immutable specification of digest variant and output length (for XOFs); provides static factories for common cases.
  • JcaDigestContext: streaming digest context that adapts MessageDigest to the core SPI, supporting produce (append digest) and verify (check expected tag) modes.

Design notes

  • Algorithm instances are immutable and thread-safe for reuse.
  • Context instances are stateful and not thread-safe; create a new context for each pipeline.
  • Verification policies integrate with the tagging engine to either throw on mismatch or set a flag in the context.
  • Extendable-output functions require explicit output lengths; fixed digests derive their size from the algorithm.
Since:
1.0
  • Class
    Description
    DigestSpec
    Digest parameters for SHA-2, SHA-3, and SHAKE
    DigestSpec.Algorithm
    Enumeration of supported digest algorithms.
    JcaDigestContext
    Digest context that adapts a JCA MessageDigest to a pull-based streaming pipeline.
    Sha2Sha3Algorithm
    SHA-2, SHA-3, and SHAKE digest algorithms