Securing Data¶
According NIST requirements, secrets must be salted and hashed
| Meaning | Reversible | Limitation | |
|---|---|---|---|
| One-way Hashing | Converting credential into fixed-length hash value | ❌ | - multiple credentials can have the same hash value; which is also good because adversary cannot easily get the credential even with hashes - multiple people can have the same credential and hence, the same hash - adversary will use this information to find patterns between the people and crack the credentials |
| Salting | Private key perturbs the hash value | N/A | |
| Encryption | ✅ |
The hashing algorithm need not be private; reputed hashing functions are nearly impossible to reverse-engineer
Problems¶
| Rainbow Table | Adversaries may have already hashed all the words in the dictionary But very unlikely for reputed hashing functions |
If an online service directly emails your password - that means they know your password, and hence it is stored unencrypted - do not use that service anymore
Encryption¶
| Type | Encryption | Decryption | Application | Algorithms |
|---|---|---|---|---|
| Secret-Key/ Symmetric | Private key | Private key | AES Triple DES | |
| Assymetric Public-Key | Public key | Private key | Messaging data transfer and storage | Diffie-Hellman MQV RSA |
| Assymetric Private-Key | Private key | Public key | Digital signatures Message source verification | |
| End-to-End | ||||
| ## Deleting Data |
Deleting from storage device does not actually physically delete the files; it just frees up the pointer
- Secure deletion: just turn all the bits to 0s/1s/random
- Full-disk encryption/Encryption at rest
- Data only decrypted when the device is on
- Important to enable this at the start of using storage device
- Over time, device may wear out and encryption may not happen
Ransomeware¶
Adversary encrypts the victim's storage for payment
Quantum Computing¶
If adversaries get more computing power, all systems will become insecure
2024-12-26