IPv4-64: A 64-Bit In-Place Upgrade to IPv4 with Modern Security and Performance: A proposal for extending IPv4 address space

IPv4-64 is a proposed network protocol that extends IPv4 addressing from 32 bits to 64 bits while preserving dotted-decimal notation and full backward compatibility with existing IPv4 addresses. Every current IPv4 address is a valid IPv4-64 address with the upper 32 bits zeroed. The protocol uses a fixed 32-byte IP header with no options and no extension headers, adds a Flow Label field for modern load balancing, and is 8 bytes smaller than the IPv6 header. The design incorporates security fields directly on the wire: a Source Validation Token for anti-spoofing, a Fragment Token for fragment injection prevention, a TCP Retry Cookie for stateless SYN flood protection, and a UDP Validated flag for amplification mitigation. All headers are fixed length. All malformed packets are silently dropped with no error response. The transition model is incremental, requiring no dual-stack operation, no translation gateways, and no changes to existing DNS records, firewall rules, or address notation.