Simon Willison’s Weblog

Private Cloud Compute: A new frontier for AI privacy in the cloud. Here are the details about Apple's Private Cloud Compute infrastructure, and they are pretty extraordinary.

The goal with PCC is to allow Apple to run larger AI models that won't fit on a device, but in a way that guarantees that private data passed from the device to the cloud cannot leak in any way - not even to Apple engineers with SSH access who are debugging an outage.

This is an extremely challenging problem, and their proposed solution includes a wide range of new innovations in private computing.

The most impressive part is their approach to technically enforceable guarantees and verifiable transparency. How do you ensure that privacy isn't broken by a future code change? And how can you allow external experts to verify that the software running in your data center is the same software that they have independently audited?

When we launch Private Cloud Compute, we’ll take the extraordinary step of making software images of every production build of PCC publicly available for security research. This promise, too, is an enforceable guarantee: user devices will be willing to send data only to PCC nodes that can cryptographically attest to running publicly listed software.

These code releases will be included in an "append-only and cryptographically tamper-proof transparency log" - similar to certificate transparency logs.

# 3:38 pm / apple, certificates, ethics, privacy, security, ai, generative-ai, llms, apple-intelligence

Introducing Apple’s On-Device and Server Foundation Models. Apple Intelligence uses both on-device and in-the-cloud models that were trained from scratch by Apple.

Their on-device model is a 3B model that "outperforms larger models including Phi-3-mini, Mistral-7B, and Gemma-7B", while the larger cloud model is comparable to GPT-3.5.

The language models were trained on unlicensed scraped data - I was hoping they might have managed to avoid that, but sadly not:

We train our foundation models on licensed data, including data selected to enhance specific features, as well as publicly available data collected by our web-crawler, AppleBot.

The most interesting thing here is the way they apply fine-tuning to the local model to specialize it for different tasks. Apple call these "adapters", and they use LoRA for this - a technique first published in 2021. This lets them run multiple on-device models based on a shared foundation, specializing in tasks such as summarization and proof-reading.

Here's the section of the Platforms State of the Union talk that talks about the foundation models and their fine-tuned variants.

As Hamel Husain says:

This talk from Apple is the best ad for fine tuning that probably exists.

The video also describes their approach to quantization:

The next step we took is compressing the model. We leveraged state-of-the-art quantization techniques to take a 16-bit per parameter model down to an average of less than 4 bits per parameter to fit on Apple Intelligence-supported devices, all while maintaining model quality.

Still no news on how their on-device image model was trained. I'd love to find out it was trained exclusively using licensed imagery - Apple struck a deal with Shutterstock a few months ago.

# 3:44 pm / apple, ai, generative-ai, llms, fine-tuning, apple-intelligence

First Came ‘Spam.’ Now, With A.I., We’ve Got ‘Slop’. First the Guardian, now the NYT. I've apparently made a habit of getting quoted by journalists talking about slop!

I got the closing quote in this one:

Society needs concise ways to talk about modern A.I. — both the positives and the negatives. ‘Ignore that email, it’s spam,’ and ‘Ignore that article, it’s slop,’ are both useful lessons.

# 4:12 pm / ethics, new-york-times, ai, generative-ai, slop