Enhanced HKDF-based key derivation with improved security features

- Implemented proper RFC 5869 compliant HKDF key derivation process
- Added Perfect Forward Secrecy (PFS) key for enhanced session security
- Improved key separation using unique info parameters for each derived key
- Enhanced salt size from 32 to 64 bytes for increased entropy
- Added comprehensive key validation and error handling
- Implemented proper ECDH + HKDF integration following Web Crypto API best practices
- Added metadata encryption key for enhanced data protection
- Improved compatibility with modern cryptographic standards (RFC 7748, NIST SP 800-56A)
 -Enhanced logging and debugging capabilities for cryptographic operations
- Maintained backward compatibility while upgrading security infrastructure
Security improvements:
- Cryptographic isolation between different key purposes
- Enhanced protection against cross-key attacks
- Improved resistance to future key compromise scenarios
- Better compliance with OWASP cryptographic storage guidelines
Technical details:
- Refactored deriveSharedKeys() method for proper HKDF implementation
- Updated WebRTC manager to use new messageKey API
- Added comprehensive error handling and validation
- Improved browser compatibility with standardized cryptographic operations
- This update strengthens the existing security foundation with modern cryptographic practices while maintaining full system compatibility.

SECURITY.md

@@ -19,6 +19,7 @@ SecureBit.chat is built with security-first principles and implements **military
 - **Enhanced Replay Protection:** Multi-factor protection with sequence numbers, message IDs, and timestamps
 - **Secure Key Storage:** WeakMap-based isolation preventing direct access to sensitive keys
 - **Key Security Monitoring:** Automatic validation, rotation, and emergency wipe capabilities
+- **HKDF Key Derivation:** RFC 5869 compliant key separation with proper salt and info parameters
 
 ### Advanced Traffic Obfuscation
 - **Packet Padding:** Random padding (64-512 bytes) to hide real message sizes
@@ -116,7 +117,7 @@ We maintain a hall of fame for security researchers who help improve SecureBit.c
 ## 📊 Security Architecture (Stage 5)
 
 ```
-18-Layer Security Architecture:
+19-Layer Security Architecture:
 ├── Layer 1: Enhanced Authentication (ECDSA P-384 + SHA-384)
 ├── Layer 2: Key Exchange (ECDH P-384, non-extractable keys)
 ├── Layer 3: Metadata Protection (AES-256-GCM + 64-byte salt)
@@ -134,7 +135,8 @@ We maintain a hall of fame for security researchers who help improve SecureBit.c
 ├── Layer 15: Production Logging (Data sanitization)
 ├── Layer 16: ASN.1 Validation (Complete key structure verification)
 ├── Layer 17: OID Validation (Algorithm and curve verification)
-└── Layer 18: EC Point Validation (Format and structure verification)
+├── Layer 18: EC Point Validation (Format and structure verification)
+└── Layer 19: HKDF Key Derivation (RFC 5869 compliant key separation)
 ```
 
 ### Security Metrics
@@ -202,7 +204,7 @@ We maintain a hall of fame for security researchers who help improve SecureBit.c
 ## 🔄 Recent Security Updates (Version 4.02)
 
 ### Major Security Enhancements:
-- ✅ **Implemented 18-layer security architecture**
+- ✅ **Implemented 19-layer security architecture**
 - ✅ **Added complete ASN.1 DER parser for key validation**
 - ✅ **Enhanced key security with OID and EC point verification**
 - ✅ **Fixed high-risk vulnerability in key structure validation**
@@ -210,6 +212,8 @@ We maintain a hall of fame for security researchers who help improve SecureBit.c
 - ✅ **Implemented key size limits to prevent DoS attacks**
 - ✅ **Added BIT STRING validation ensuring unused bits are 0**
 - ✅ **Enhanced fallback support from P-384 to P-256**
+- ✅ **Implemented RFC 5869 compliant HKDF key derivation**
+- ✅ **Enhanced key separation with proper salt and info parameters**
 
 ### Previous Enhancements (Version 4.01):
 - ✅ **Implemented 15-layer security architecture**
@@ -266,13 +270,14 @@ cryptoManager.getASN1ValidationStatus()
 ## 🏅 Security Achievements
 
 SecureBit.chat v4.02 provides:
-- **🥇 Military-Grade Security:** 18-layer protection system
+- **🥇 Military-Grade Security:** 19-layer protection system
 - **🥇 Government-Level Encryption:** Triple AES-256-GCM + P-384 ECDH/ECDSA
 - **🥇 Perfect Forward Secrecy:** Complete with automatic key rotation
 - **🥇 Traffic Analysis Protection:** Maximum with 6-layer obfuscation
 - **🥇 Zero-Trust Architecture:** No central points of failure
 - **🥇 Complete ASN.1 Validation:** Full structural verification of all cryptographic keys
 - **🥇 PKCS Compliance:** Complete adherence to cryptographic standards
+- **🥇 HKDF Key Derivation:** RFC 5869 compliant key separation and derivation
 
 **Security Rating: MAXIMUM** - Exceeds most government and military communication standards with complete key structure validation.