refactor: reorganize capsula-crypto module with enhanced hash API

- Restructure crypto module into functional categories:
  * asymmetric/ - Ed25519 signatures and X25519 key exchange
  * symmetric/ - AES-256-GCM and ChaCha20-Poly1305 encryption
  * hash/ - SHA-256 and SHA-512 hash functions with flexible API
  * kdf/ - HKDF key derivation with cleaner API

- Enhance hash module with algorithm selection:
  * Add HashAlgorithm enum for SHA-256/SHA-512 selection
  * Implement generic hash() function with algorithm parameter
  * Add quick_hash() convenience functions using default algorithm
  * Maintain backward compatibility with existing sha256/sha512 functions

- Improve KDF module:
  * Rename functions to derive_key32() and derive_many()
  * Keep legacy names as deprecated aliases for compatibility

- Update all imports and examples to use new module structure
- All 25 tests passing with enhanced test coverage

BREAKING CHANGE: Module paths have changed, but all exports are maintained at crate root for backward compatibility

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: atlas-form

Cargo.toml

@@ -103,6 +103,7 @@ getrandom = "0.3"
 sha2 = "0.10"
 signature = "2.2"
 base64 = "0.22.1"
+hkdf = "0.12.4"
 
 # 证书相关
 rcgen = { version = "0.14", features = ["pem"] }

crates/capsula-crypto/Cargo.toml

@@ -20,6 +20,7 @@ ed25519-dalek = { workspace = true, features = [
 x25519-dalek = { workspace = true, features = ["static_secrets", "zeroize"] }
 p256 = { workspace = true, features = ["ecdsa"] }
 pkcs8 = { workspace = true }
+hkdf = { workspace = true }
 
 # PEM encoding
 pem = { workspace = true }

crates/capsula-crypto/src/ed25519.rs …capsula-crypto/src/asymmetric/ed25519.rscrates/capsula-crypto/src/ed25519.rs renamed to crates/capsula-crypto/src/asymmetric/ed25519.rs crates/capsula-crypto/src/ed25519.rs renamed to crates/capsula-crypto/src/asymmetric/ed25519.rs

@@ -0,0 +1,10 @@
+//! Asymmetric cryptography algorithms
+//! 
+//! This module provides implementations of asymmetric cryptographic algorithms
+//! including digital signatures and key exchange.
+
+pub mod ed25519;
+pub mod x25519;
+
+pub use ed25519::Ed25519;
+pub use x25519::X25519;

crates/capsula-crypto/src/asymmetric/mod.rs

@@ -0,0 +1,19 @@
+//! Cryptographic hash functions
+//!
+//! This module provides cryptographic hash functions for data integrity
+//! and key derivation purposes, including SHA-256 and SHA-512.
+
+pub mod sha;
+
+// Re-export the hash algorithm enum
+pub use sha::HashAlgorithm;
+// Re-export generic hash functions
+pub use sha::{hash, hash_hex, verify};
+// Re-export convenience functions
+pub use sha::{quick_hash, quick_hash_hex};
+// Re-export SHA-256 specific functions
+pub use sha::{sha256, sha256_hex, sha256_verify};
+// Re-export SHA-512 specific functions
+pub use sha::{sha512, sha512_hex, sha512_verify};
+// Re-export SHA types from sha2 crate for convenience
+pub use sha2::{Sha256, Sha512};