DoD Seeks Software-Only Encryption for Post-Quantum Migration
In late August 2026, the U.S. Department of Defense (DoD) issued a Request for Information (RFI) seeking software-only encryption technologies capable of protecting military communications and data systems during the transition to Post-Quantum Cryptography (PQC).
The initiative reflects a practical challenge facing large defense networks: replacing vulnerable cryptographic infrastructure across thousands of systems can be significantly more difficult than deploying a new algorithm.
Rather than requiring new cryptographic hardware, the RFI seeks solutions that can operate within existing software stacks and protect communications at a granular level.
The effort follows the DoD Post-Quantum Cryptography Strategy published by the DoD Chief Information Officer in June 2026 and forms part of a broader U.S. government effort to prepare critical infrastructure for the eventual emergence of cryptographically relevant quantum computers.
🔐 The Core Requirement: Zero Hardware Changes #
The most restrictive aspect of the RFI is its requirement for a 100% software-based implementation.
The proposed technology must operate without modifying, replacing, or physically adding components to existing systems.
That excludes changes involving:
- Custom cryptographic processors
- Dedicated crypto cards
- Radios
- Hardware Security Modules (HSMs)
- Network appliances
- Peripheral cryptographic devices
- Other physical hardware components
The objective is straightforward: deploy quantum-resistant protection without requiring a hardware modernization program.
This is particularly important for defense environments where hardware replacement can involve lengthy procurement cycles, certification requirements, field deployment, interoperability testing, and operational downtime.
Software-Defined Cryptographic Migration #
A software-only architecture could potentially be integrated above existing networking and communications infrastructure:
┌──────────────────────────────────────────────┐
│ Military Application │
├──────────────────────────────────────────────┤
│ Software Cryptography Layer │
│ │
│ PQC Key Exchange / Authentication / AEAD │
├──────────────────────────────────────────────┤
│ Existing Network Stack │
├──────────────────────────────────────────────┤
│ Existing Hardware Infrastructure │
│ │
│ Servers • Radios • Routers • Endpoints │
└──────────────────────────────────────────────┘
The key architectural requirement is that the PQC capability must be introduced without changing the underlying hardware platform.
📦 Packet-Level Cryptographic Protection #
The RFI also emphasizes granular protection rather than treating encryption as a single monolithic network function.
The desired system should provide packet-level cryptographic protection across relevant defense communications.
A simplified architecture could look like:
Application Data
│
▼
┌───────────────┐
│ Packetization │
└───────┬───────┘
│
▼
┌─────────────────────────┐
│ PQC Cryptographic Layer │
│ │
│ Key Exchange │
│ Authentication │
│ Encryption │
│ Integrity Protection │
└───────────┬─────────────┘
│
▼
Network Packet
│
▼
Existing Network
Packet-level protection provides a mechanism for applying cryptographic controls without requiring every underlying network component to understand the new PQC algorithms.
For large heterogeneous environments, this abstraction can be valuable because legacy infrastructure may include equipment with dramatically different capabilities and software lifecycles.
Sovereign Key Management #
The RFI also places emphasis on data sovereignty and cryptographic key control.
A suitable implementation must allow the DoD to retain control over:
- Cryptographic keys
- Protected data
- Key-generation processes
- Security policies
- Cryptographic configuration
- Operational data
This requirement is particularly important for defense applications where outsourcing cryptographic control could introduce unacceptable dependency or supply-chain risks.
📅 Aggressive PQC Migration Timeline #
The RFI establishes a relatively compressed schedule for evaluating and deploying post-quantum protection.
┌─────────────────────────────────────────────────────────────┐
│ U.S. DoD PQC MIGRATION TIMELINE │
├─────────────────────────────────────────────────────────────┤
│ │
│ September 27, 2026 │
│ │ │
│ ▼ │
│ Industry RFI submission deadline │
│ │ │
│ ▼ │
│ December 31, 2029 │
│ Initial software PQC migration target │
│ │ │
│ ▼ │
│ December 31, 2030 │
│ PQC support readiness across all DoD systems │
│ │ │
│ ▼ │
│ December 31, 2031 │
│ PQC operational protection enabled by default │
│ │
└─────────────────────────────────────────────────────────────┘
The sequence effectively separates migration into three phases:
- Initial deployment and modernization
- System-wide readiness
- Operational enforcement
This approach recognizes that cryptographic migration is not simply an algorithm replacement exercise.
🧮 Why PQC Migration Is Urgent #
The primary concern is the future availability of Cryptographically Relevant Quantum Computers (CRQCs).
Large-scale quantum computers could threaten widely deployed public-key cryptography based on mathematical problems that are difficult for classical computers but potentially tractable with quantum algorithms.
The affected technologies include widely deployed families such as:
- RSA
- Elliptic Curve Cryptography (ECC)
- Diffie-Hellman-style public-key mechanisms
The fundamental concern is that cryptographic systems need to be upgraded before sufficiently capable quantum hardware becomes operational.
Harvest Now, Decrypt Later #
One of the most important reasons to migrate early is the Harvest Now, Decrypt Later (HNDL) threat.
An adversary does not necessarily need a quantum computer today to benefit from future quantum capabilities.
The basic attack model is:
Today
│
▼
Capture Encrypted Traffic
│
▼
Store Long-Term
│
▼
Quantum Computer Becomes Capable
│
▼
Attempt Decryption
│
▼
Recover Previously Protected Data
This is especially concerning for defense information with long operational lifetimes.
Some sensitive data may remain valuable for decades. Encryption that is secure today may therefore need to remain confidential long after the original communication has occurred.
⚔️ Quantum Computing as Both Threat and Strategic Capability #
Quantum Information Science creates a dual strategic problem.
On one side, quantum computing could provide significant capabilities in areas such as:
- Scientific simulation
- Optimization
- Materials research
- Cryptanalysis
- Advanced sensing
On the other side, sufficiently capable quantum computers could undermine portions of today’s public-key cryptographic infrastructure.
For defense organizations, the result is a race between:
Quantum Computing Capability
│
▼
Potential Cryptanalytic Advantage
│
▼
PQC Migration
│
▼
Quantum-Resistant Infrastructure
The migration therefore needs to occur before cryptographically relevant quantum systems become operationally mature.
🏗️ Why Software-Only Deployment Matters #
A software-only requirement changes the economics and logistics of PQC migration.
A hardware replacement program typically requires:
Hardware Design
↓
Procurement
↓
Manufacturing
↓
Certification
↓
Deployment
↓
Integration Testing
↓
Operational Rollout
A software migration can potentially compress the process:
PQC Software
↓
Integration
↓
Testing
↓
Certification
↓
Software Deployment
↓
Fleet-Wide Update
The actual process is still complex in a defense environment, particularly where systems require security certification and strict configuration control.
Nevertheless, software deployment provides a potentially faster path for legacy platforms that cannot realistically be replaced before the required migration deadlines.
🔧 Engineering Challenges of Software PQC #
Software-only PQC does not eliminate the engineering challenges associated with cryptographic modernization.
Performance Overhead #
Post-quantum algorithms can have substantially different computational and bandwidth characteristics from classical public-key cryptography.
Depending on the algorithm and protocol, systems may need to handle:
- Larger public keys
- Larger ciphertexts
- Larger signatures
- Additional computation
- Increased memory requirements
- More complex key-management workflows
These effects matter particularly in bandwidth-constrained military communications.
Legacy Protocol Integration #
Existing applications may have cryptographic assumptions deeply embedded within their communication stacks.
Replacing the cryptographic primitive may therefore require changes to:
Application
↓
Security Protocol
↓
Key Management
↓
Network Stack
↓
Transport
↓
Hardware
A software-only solution needs to integrate with this stack while minimizing disruption to existing applications and hardware.
Operational Availability #
Military systems often operate in environments where downtime is unacceptable.
A PQC migration system must therefore support controlled deployment, rollback strategies, interoperability testing, and potentially mixed classical/PQC environments during the transition period.
The migration path cannot simply assume that every system will be upgraded simultaneously.
🛡️ Cryptographic Agility Becomes Critical #
The DoD initiative also reinforces the importance of cryptographic agility.
A modern security architecture should avoid hard-coding a single cryptographic algorithm into every layer of an application.
Instead, algorithms should be replaceable through well-defined interfaces:
Application
│
▼
Cryptographic API
│
├── Classical Algorithm
├── PQC Algorithm
└── Future Algorithm
This architecture allows organizations to respond to new cryptographic threats without redesigning entire systems.
For defense networks with extremely long equipment lifecycles, cryptographic agility may ultimately be as important as the immediate migration to PQC.
📡 Spectrum and Operational Readiness #
The RFI also connects cryptographic modernization with broader operational requirements, including the ability to maintain spectrum superiority.
Military communications operate under constraints that extend beyond cryptographic correctness.
Encryption mechanisms must coexist with:
- Bandwidth limitations
- Variable network conditions
- Tactical communications
- Radio systems
- Distributed infrastructure
- Intermittent connectivity
- Real-time operational requirements
A PQC solution that is theoretically secure but imposes unacceptable latency, bandwidth, or compute overhead may not be suitable for every operational environment.
The challenge is therefore to achieve quantum-resistant security without compromising mission-critical communications.
🔍 What the RFI Signals for the Security Industry #
The software-only requirement could create demand for a new class of cryptographic products focused on retrofit deployment.
Instead of selling another dedicated encryption appliance, vendors may compete around:
- Transparent software integration
- Low-overhead packet protection
- Centralized key management
- Cryptographic agility
- Legacy compatibility
- Automated fleet deployment
- Hardware-independent PQC acceleration
- High-assurance software implementations
The winning technologies will likely need to demonstrate not only cryptographic security but also operational scalability across heterogeneous legacy environments.
📌 Conclusion #
The DoD’s software-only encryption RFI highlights a fundamental reality of post-quantum migration: the hardest problem may not be selecting a quantum-resistant algorithm, but deploying it across enormous amounts of existing infrastructure.
By prohibiting hardware modifications, the initiative focuses industry attention on software architectures capable of protecting existing systems without requiring widespread equipment replacement.
The strategic motivation is equally clear. The emergence of cryptographically relevant quantum computers could threaten classical public-key cryptography, while the Harvest Now, Decrypt Later model creates risks for sensitive data that must remain confidential for years or decades.
The reported timeline targets initial software migration by December 31, 2029, system-wide PQC readiness by December 31, 2030, and operational PQC protection by default by December 31, 2031.
For defense infrastructure, this makes software-defined cryptography, packet-level protection, sovereign key management, and cryptographic agility increasingly important engineering requirements.
The September 27, 2026 industry response deadline marks the next major milestone in what could become one of the largest cryptographic infrastructure migrations in the history of the U.S. defense ecosystem.