What Are Backup Fragments? The Building Blocks of Threshold Resiliency
A clear technical explanation of cryptographic backup fragments, how they differ from simple file chunks, and why they guarantee zero-knowledge survivability.
What Are Backup Fragments? The Building Blocks of Threshold Resiliency
In modern data resilience engineering, backup fragments represent the fundamental unit of decentralized data protection.
Unlike naive file splitting (such as splitting a large .zip file into parts with split or WinRAR), cryptographic backup fragments are mathematically autonomous, self-describing, and threshold-reconstructible containers.
Simple Split Parts vs. Cryptographic Threshold Fragments
| Feature | Naive Split Parts (e.g. part1.rar, part2.rar) | YourKeep Cryptographic Fragments (.keep) |
|---|---|---|
| Missing Chunk Impact | 1 Missing part = Total restoration failure (100% loss) | Any K fragments restore 100% of the original data |
| Privacy of Individual Parts | May leak filenames, headers, or partial plaintext | Mathematically indistinguishable from pure random noise |
| Metadata Dependency | Requires external index or exact sequential names | Self-describing binary header inside every fragment |
| Tamper Detection | Basic CRC32 checksums (Vulnerable to tampering) | 128-bit GHASH authentication tags (Tamper-evident) |
The Anatomy of a .keep Fragment
Every fragment file produced by YourKeep contains:
- Magic Binary Header: Identifies the file format version and container UUID.
- Fragment Index & Quota: Documents the fragment’s matrix position ($k$) and the required threshold ($K$).
- Cryptographic Tag: Authenticates data integrity using AES-256-GCM AEAD.
- Erasure-Coded Ciphertext: Contains the mathematical payload generated over Galois Fields.
Conclusion
Backup fragments transform rigid, fragile files into fluid, indestructible mathematical objects. Distribute them anywhere with total confidence.