The proof-of-concept device hides nano-Morse messages inside tubular DNA structures, then uses molecular keys and AFM imaging to verify and decode them.
Paper: A multiple-encrypted DNA device for secure communication. Image credit: AI-generated image created using ChatGPT/OpenAI
In a recent research article published in the journal Science Advances, researchers developed a laboratory-scale, proof-of-concept multilayer deoxyribonucleic acid (DNA) origami encryption device that integrates multiple cryptographic functions to demonstrate confidentiality, integrity, and authenticity within a molecular communication workflow.
DNA Cryptography and Nano-Morse
The rapid evolution of computing and cryptographic technologies has heightened concerns over conventional data security. Traditional encryption methods, relying largely on complex mathematical problems, could face future threats if sufficiently capable quantum computers and practical quantum algorithms are developed. As a result, alternative molecular-level cryptographic systems have garnered attention.
DNA, with its enormous information storage capacity, programmability, and nanostructural versatility, offers a unique platform for secure communication. DNA nanotechnology, especially DNA origami, enables the precise spatial arrangement of molecular features, presenting an opportunity to encode information not only via DNA sequence but also through structural configurations.
Integrating multiple encryption protocols into a coherent DNA origami-based communication system, however, poses significant challenges.
DNA Origami Encoding Design
At the core of this study is the design of a DNA multilayer encryption (DMLE) device that exploits rectangular DNA origami substrates to encode messages as nano-Morse code. The nano-Morse code is established by spatially mapping Morse symbols onto the origami surface. Dots are represented by paired dumbbell-shaped DNA bulge loops anchored on specific staple strands, spaces by vacant regions, and dashes by double-stranded DNA paths formed through localized hybridization chain reactions (HCRs).
A comprehensive nano-Morse codebook mapping numerical digits and letters of the alphabet to these structural patterns was created. Multiple rectangular DNA origami substrates bearing encoded symbols were interconnected through elongated staples to form higher-order assemblies, such as dimers and pentamers, preserving symbol order and message integrity. In a later experiment, four-character tetramers were used for block-based message normalization to reduce structural side-channel information leakage.
To embed the codes confidentially, the planar DNA origami bearing these codes undergoes a controlled conformational transformation into tubular structures. This switching, mediated by prolonged edge staples that lock strands that bridge them and unlock complementary strands, acts as a physical steganographic layer that conceals the encoded message from direct inspection. The locking strands induce the formation of a tubular structure, producing what the authors termed a signed ciphertext. Unlocking strands then enables reversible reopening to the planar form, supporting a conformation-gated molecular verification mechanism inspired by digital signatures rather than a conventional digital signature system.
The encryption workflow starts with the sender encoding plaintext into nano-Morse code patterns, assembling individual DNA origami monomers with requisite capture staples and dumbbells, combining these into multimer assemblies, and activating HCR to form the dashes.
The ciphertext, stored in a molecular solution, is transmitted to the receiver. The receiver applies atomic force microscopy (AFM) to image and decode the spatial Morse patterns within the DNA origami structures using the shared codebook. The keyed conformational switching was used to verify message origin and detect the specific tampering and counterfeiting scenarios tested.
High-precision AFM imaging and height analysis of the dumbbell loops and HCR-formed paths facilitated error correction and increased encoding accuracy. Ultraviolet (UV) irradiation was employed to reduce structural distortion in DNA origami multimers, improving planar assembly flatness.
Multilayer Encryption and Verification
The authors successfully demonstrated the feasibility of encoding Morse code symbols within DNA origami substrates to produce nano-Morse code. The vacant region representing a Morse-code space measured 23.7 ± 0.3 nm by AFM, providing sufficient separation between neighboring symbols.
For the letter “A,” encoding accuracy was 82.3% across 148 imaged patterns, which was enhanced to 86.4% after height-based error classification and correction. The assembly of connected DNA origami multimers achieved yields of 90.8% for dimers, 84.0% for trimers, 91.9% for tetramers, and 86.4% for pentamers. UV treatment increased the proportion of flat tetramers from 50% to 95% and flat pentamers from 24% to 85%, rather than increasing assembly yield.
The symmetric encryption framework utilized the designed nano-Morse codebook and specified molecular procedures as shared secret information, allowing messages such as “DNA” and rearranged permutations like “AND” and “NAD” to be encoded, transmitted, and decoded. In blind tests, “AND” and “NAD” produced overall structural yields of 77.8% and 76.2%, respectively, and both were successfully decoded.
A pivotal advancement involved the conformational switching between planar and tubular DNA origami nanostructures, mediated by a molecular signing key comprising prolonged edge staples and locking strands, together with a verification key comprising complementary unlocking strands. The tubular configuration encapsulates and physically conceals the encoded nano-Morse code, serving as a steganographic barrier against unauthorized access.
The study achieved a 96.5% yield of tubular DNA origami nanostructures, with 99.7% reopening efficiency, confirming the efficiency of this dynamic process.
The conformation-gated verification mechanism, inspired by digital signatures, was designed to authenticate message origin and detect the counterfeiting and mixed-ciphertext scenarios examined by requiring correct paired molecular keys for morphological verification and subsequent AFM-based message readout.
Integrated DMLE Communication Demonstration
This research advances the field of molecular cryptography by engineering a proof-of-concept DNA origami-based multilayer encryption device capable of secure, authenticated message transmission through nanoscale spatial encoding and structural transformation.
By encoding messages into spatial nano-Morse code patterns on rectangular DNA origami and physically concealing them via conformational switching into tubular structures, the system demonstrated a combination of confidentiality, integrity, and source authentication.
To demonstrate the complete multilayer workflow, the researchers transmitted “JUNE6 INVASION NORMANDY” as six normalized four-character blocks: “JUNE,” “6×××,” “INVA,” “SION,” “NORM,” and “ANDY.” The signed tubular tetramers formed at an 84.7% yield and were verified, reopened, imaged by AFM, and decoded using the molecular verification strands and shared codebook.
While current limitations in information density and throughput exist, the device stores about 8 bits per DNA origami structure and requires several hours to approximately 10 hours for assembly, conformational switching, AFM imaging, and decoding. These laboratory requirements make it more suitable for high-security, low-throughput applications than routine electronic communication. The approach has potential as a complementary component of hybrid cryptographic systems, for example by protecting a conventional symmetric-encryption key rather than an entire dataset.
Future work focusing on enhanced encoding schemes, larger three-dimensional (3D) DNA scaffolds, and automated readout technologies may further broaden practical applications in nanoscale data security.