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/**
 * Specifications for keys and per-operation parameters.
 *
 * <p>
 * This package defines lightweight, strongly typed specifications used when
 * creating cryptographic contexts. Key specifications describe how a key should
 * be generated or imported for a particular family, while context
 * specifications supply optional, per-operation parameters (for example,
 * padding or nonce strategy). Algorithms that need no extra parameters use a
 * singleton placeholder.
 * </p>
 *
 * <h2>Key elements</h2>
 * <ul>
 * <li>{@link AlgorithmKeySpec} - marker interface for algorithm-specific key
 * specs used by key builders.</li>
 * <li>{@link ContextSpec} - marker interface for per-operation parameters
 * supplied to context creation.</li>
 * <li>{@link VoidSpec} - singleton context spec used when an algorithm requires
 * no additional parameters.</li>
 * </ul>
 *
 * <h2>Typical usage</h2> <pre>{@code
 * // Algorithm requires no per-operation parameters.
 * zeroecho.core.context.CryptoContext ctx =
 *     algo.createContext(zeroecho.core.KeyUsage.SIGN, privateKey, zeroecho.core.spec.VoidSpec.INSTANCE);
 *
 * // Algorithm with parameters: pass an algorithm-specific ContextSpec implementation.
 * // Example: RSA with OAEP/PSS, AEAD tag length, etc.
 * // zeroecho.core.context.CryptoContext ctx =
 * //     algo.createContext(zeroecho.core.KeyUsage.ENCRYPT, key, someAlgorithmSpecificSpec);
 * }</pre>
 *
 * <h2>Design notes</h2>
 * <ul>
 * <li>Specification types should be immutable and safe to share across
 * operations.</li>
 * <li>Key specifications and context specifications keep configuration separate
 * from runtime state, improving clarity and reuse.</li>
 * <li>Callers should prefer library-provided spec classes and avoid
 * implementing the marker interfaces directly unless extending the library with
 * new families.</li>
 * </ul>
 *
 * @since 1.0
 */
package zeroecho.core.spec;
