Arcium launches Blackthorn AI inference stack in private alpha

Arcium wants you to be able to ask an AI model anything without the model’s operator ever seeing the question. Its new product, Blackthorn, is built around that idea. The company has launched Blackthorn, an AI inference stack that keeps prompts and responses private. It uses secure multi-party computation (MPC) in place of CPU-based trusted execution environments (TEEs). The private alpha opened on October 21, 2026. What Blackthorn actually does Inference is the part of AI most people interact with. You send a prompt, a model processes it, and an answer comes back. Normally, whoever runs the hardware can, in principle, see all of that in plaintext. Blackthorn encrypts the full pipeline end to end. That covers the prompts, the model weights, and the outputs. Under its confidential computing model, no single party can access the plaintext data at any point. A TEE is a sealed, protected zone inside a processor where sensitive code is supposed to run untouched. Arcium’s pitch is that Blackthorn removes reliance on vulnerable hardware TEEs, swapping trust in a chip for cryptography spread across parties. The architecture uses two layers. The inner layer is key-based encryption that user...