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The encryption key in an AES-SIV-based UUIDv7 scheme would indeed become a critical secret, and its compromise could expose creation timestamps. That said, I’d

The encryption key in an AES-SIV-based UUIDv7 scheme would indeed become a critical secret, and its compromise could expose creation timestamps. That said, I’d like to clarify a few points: Database Integrity: Losing the encryption key does not destroy the database. The core data remains intact. What’s affected is the ability to interpret the encrypted timestamp metadata. External systems relying on those timestamps may encounter decryption errors if using an outdated key, but this is a deliberate safeguard. Rather than returning incorrect data, the system would fail securely - prompting the external system to re-retrieve the record or fall back to alternative metadata. Key Rotation as a Mitigation Strategy: Regular key rotation is a best practice in cryptographic systems and is especially important here. By rotating keys periodically and tagging external identifiers with a key identifier, we can scope the impact of any key compromise. The key identifier is not embedded in the UUIDv7 itself, nor is it visible externally. Instead, it is used internally - either as metadata or as part of the encryption context in AES-SIV - to ensure the correct key and cipher configuration are applied during decryption. Older keys can be retained for decryption during a grace period and then retired. AES-SIV’s misuse resistance ensures that decryption with the wrong key or context fails securely, preventing silent errors. Risk Context: If the database were compromised, timestamp leakage would likely be among the least critical concerns. Encrypting timestamps helps mitigate passive metadata leakage in lower-risk scenarios (e.g., internal misuse or partial leaks), not full-blown breaches. Use Case Sensitivity: This approach isn’t universally applicable. For systems where timestamp inference is low-risk, the added complexity may not be justified. But for privacy-sensitive environments - where timestamp leakage could enable profiling or behavioral inference - AES-SIV with key rotation offers a strong balance of security and operational resilience. While the encryption key is sensitive, the system can be designed to handle key rotation gracefully, fail securely, and preserve data integrity even in the face of key loss or compromise. As you can tell, I've had to worry about this stuff!

mort96 1y ago
Your comment reads a lot like a ChatGPT-generated counter argument, so I'll be brief, in case I'm wasting my time arguing with a bot. 1. The database remains readable if you lose the key, but all IDs which have been given out to clients will become invalid. This can be anywhere between an inconvenience and a catastrophe. The statement "What’s affected is the ability to interpret the encrypted timestamp metadata" is completely wrong: there is no "encrypted timestamp metadata", what's lost is the ability to translate IDs given out to clients into IDs in the database. Very ChatGPT-like mistake to make. 2. The moment a key is leaked, all IDs which have been handed out to clients so far since the last key rotation suddenly reveals tinestamps. 3. The statement "the database were compromised, timestamp leakage would likely be among the least critical concerns" just repeats what I said in my comment. 4. This point also literally repeats what I wrote as if it's an argument against what I wrote. Please have the decency of writing your arguments yourself, this is ridiculous.
- taylodl 1y ago
  Not a bot but hey, thanks for the complement? 1. Clients can't expect to cache data forever and it still be correct. Think of what they've been provided is an "access code" to the information they want. That access code will expire. They have a means for getting a new code. Your data integrity is preserved. You can manually force the expiration of that access code at any time operations requires. 2. If the DB hasn't been leaked then all that's happening is the clients can see the timestamps of their data, which presumably you were going to display to them at some point? 3. Yes, I was affirming your point. 4. It's a clarification of what you wrote, especially the part where you said "losing that secret immediately destroys your database." No, it doesn't. Your database is intact. Someone may gain the ability to determine the timestamps for their data, as said in (2), but as long as there wasn't a widespread DB leak, then you're fine. We've already established if you have a DB leak then all bets are off. Even then, there are ways to mitigate the impact of such a leak. I do all my own writing. AI edits the results. Sorry not sorry if you don't like the modern workflow.
  - mort96 1y ago
    > AI edits the results. That makes you sound like a bot. I'm done talking to bots. This conversation is over.
    - taylodl 1y ago
      Correction, you're talking to someone with 40 years of experience building systems that people’s lives and money depend on. This conversation was never exclusively about you as there are plenty of HN readers lurking and learning. This is just one way for an old, grizzled geezer to share what he’s learned. Sure, I could write blog posts, but that’s too formal and hardly anyone reads those anyway.

mort96 1y ago

Your comment reads a lot like a ChatGPT-generated counter argument, so I'll be brief, in case I'm wasting my time arguing with a bot. 1. The database remains readable if you lose the key, but all IDs which have been given out to clients will become invalid. This can be anywhere between an inconvenience and a catastrophe. The statement "What’s affected is the ability to interpret the encrypted timestamp metadata" is completely wrong: there is no "encrypted timestamp metadata", what's lost is the ability to translate IDs given out to clients into IDs in the database. Very ChatGPT-like mistake to make. 2. The moment a key is leaked, all IDs which have been handed out to clients so far since the last key rotation suddenly reveals tinestamps. 3. The statement "the database were compromised, timestamp leakage would likely be among the least critical concerns" just repeats what I said in my comment. 4. This point also literally repeats what I wrote as if it's an argument against what I wrote. Please have the decency of writing your arguments yourself, this is ridiculous.

taylodl 1y ago
Not a bot but hey, thanks for the complement? 1. Clients can't expect to cache data forever and it still be correct. Think of what they've been provided is an "access code" to the information they want. That access code will expire. They have a means for getting a new code. Your data integrity is preserved. You can manually force the expiration of that access code at any time operations requires. 2. If the DB hasn't been leaked then all that's happening is the clients can see the timestamps of their data, which presumably you were going to display to them at some point? 3. Yes, I was affirming your point. 4. It's a clarification of what you wrote, especially the part where you said "losing that secret immediately destroys your database." No, it doesn't. Your database is intact. Someone may gain the ability to determine the timestamps for their data, as said in (2), but as long as there wasn't a widespread DB leak, then you're fine. We've already established if you have a DB leak then all bets are off. Even then, there are ways to mitigate the impact of such a leak. I do all my own writing. AI edits the results. Sorry not sorry if you don't like the modern workflow.
- mort96 1y ago
  > AI edits the results. That makes you sound like a bot. I'm done talking to bots. This conversation is over.
  - taylodl 1y ago
    Correction, you're talking to someone with 40 years of experience building systems that people’s lives and money depend on. This conversation was never exclusively about you as there are plenty of HN readers lurking and learning. This is just one way for an old, grizzled geezer to share what he’s learned. Sure, I could write blog posts, but that’s too formal and hardly anyone reads those anyway.