PunchCard Key Backup is an open-source tool that allows you to physically back up cryptographic keys, like PGP or SSH keys, onto durable, punch-out cards. It encodes the key as a grid of punched holes, readable by a webcam and decodable by the software. This provides a low-tech, offline backup method resistant to digital threats and EMP attacks, ideal for long-term storage or situations where digital backups are unavailable or unreliable. The cards are designed to be easily reproducible and verifiable, and the project includes templates for printing your own cards.
This Hacker News post introduces "PunchCard Key Backup," a novel approach to securing cryptographic keys using physical, punched cards. The project, hosted on GitHub under the username "volution," provides a method for encoding a cryptographic key onto a standard 80-column punch card. The system leverages the physical presence and absence of holes in the card to represent the binary data of the key. This allows for offline, cold storage of sensitive cryptographic information, mitigating the risks associated with digital storage vulnerabilities like hacking or data breaches.
The system facilitates the translation of a hexadecimal representation of a key into a series of punch positions on the card. Conversely, it also allows for the decoding of a punched card back into its corresponding hexadecimal key. This bidirectional functionality enables users to generate punch cards from their existing keys and later retrieve those keys from the cards. The process avoids storing the key digitally at any point during encoding or decoding, further enhancing security.
While the exact cryptographic algorithms supported aren't explicitly mentioned in the post title or GitHub repository description, the system is designed to be algorithm-agnostic. It simply acts as a physical medium for storing the binary representation of the key, irrespective of the algorithm it's intended for. This flexibility allows for the storage of keys used in various cryptographic systems. The project potentially provides an added layer of resilience against key compromise by storing the key in a physical format that requires specialized equipment (a punch card reader) to retrieve. This makes it considerably more difficult for an attacker to acquire the key compared to accessing digitally stored key material. The GitHub repository presumably contains the necessary software to facilitate the encoding and decoding processes along with instructions on how to use the system.
Summary of Comments ( 23 )
https://news.ycombinator.com/item?id=44145202
HN users generally praised the project for its cleverness and simplicity, viewing it as a fun and robust offline backup method. Some discussed the practicality, pointing out limitations like the 255-bit key size being smaller than modern standards. Others suggested improvements such as using a different encoding scheme for greater density or incorporating error correction. Durability of the cards was also a topic, with users considering lamination or metal stamping for longevity. The overall sentiment was positive, appreciating the project as a novel approach to cold storage.
The Hacker News post titled "Show HN: PunchCard Key Backup" generated a moderate discussion with several interesting comments. Many commenters expressed appreciation for the novelty and physicality of the punchcard backup system, contrasting it with the more abstract and digital nature of typical key backup methods.
One commenter highlighted the advantage of this system being resistant to electromagnetic pulses (EMPs), a concern for some individuals preparing for disaster scenarios. They further elaborated on the potential longevity of punchcards, pointing out their durability and resistance to data degradation over time compared to electronic storage media. Another commenter echoed this sentiment, emphasizing the robustness and simplicity of the punchcard approach.
Several commenters discussed the practicality of the system. One questioned the number of keys that could be reasonably stored on a punchcard, while another suggested potential improvements like using a more robust material than card stock for the punchcards. The discussion also touched upon the potential for errors during the punching process and the possibility of developing tools to assist with accurate punching.
One user jokingly compared the method to storing secrets on bananas, alluding to the unusual nature of using fruit for data storage, while acknowledging the cleverness of the punchcard concept.
Some commenters explored the historical context of punchcards, drawing parallels to their use in early computing. One mentioned the potential for using existing punchcard readers to interface with the backup system, bridging the gap between this modern application and its historical roots.
The security aspect was also addressed. A commenter raised the concern that punchcards might not be as secure as other backup methods if not stored carefully, as they are visually decipherable. This led to a discussion about the importance of physical security in any backup strategy, regardless of the medium.
Overall, the comments reflected a mixture of amusement, appreciation for the ingenuity, and practical considerations regarding the punchcard key backup system. The discussion highlighted the trade-offs between simplicity, durability, security, and practicality inherent in this unconventional approach.