# Encryption & Key Management

Model Vault Encrypted protects your data across its full lifecycle, in transit, at rest, and in use.
This page describes the encryption model and how keys are generated, held, and rotated.

The most important property to keep in mind: the keys that protect your data are generated **inside**
the trusted execution environment (TEE) and are **never shared with Cohere**.

## Data in transit

Requests are end-to-end encrypted from your client all the way into the TEE using Oblivious HTTP
(OHTTP):

- Your client encrypts each request to the vault's OHTTP public key, which is cryptographically bound to the attested environment (see [Remote Attestation](/guides/model-vault-encrypted-attestation)).
- The encrypted request travels through the untrusted load balancer and network, which only ever see ciphertext. In OHTTP the payload stays encrypted while routing headers remain in the clear.
- Only a genuine, attested TEE holds the matching private key, so only it can decrypt the request. The response is encrypted the same way back to your client.

Because the client verifies attestation before encrypting, it will only ever encrypt to a verified
environment, never to the host or a man-in-the-middle.

## Data in use

This is what sets Encrypted Vaults apart from standard transport security. While the model runs, your
prompts and responses stay protected inside the TEE:

- **CPU**: the confidential VM (for example, Intel TDX or AMD SEV-SNP) encrypts memory using keys that are generated inside the processor and never leave it. The host operating system, hypervisor, and operators cannot read VM memory.
- **GPU**: the NVIDIA GPU runs in confidential-computing mode, and the link between the CPU TEE and the GPU is authenticated and encrypted over an SPDM-based secure session, so data moving to and from GPU memory is never exposed in plaintext to the host.

See the [Confidential Computing Primer](/guides/model-vault-encrypted-confidential-computing) for the
underlying concepts.

## Data at rest

The vault image is integrity-protected: it boots from a read-only root filesystem whose measurements
are verified at boot and checked during attestation, so the running software cannot be silently
modified. Combined with Zero Data Retention (below), your prompts and responses are not written to
durable storage in plaintext.

## Key management

Several distinct keys protect a vault, and they are all managed within the confidential environment:

- **Memory-encryption keys** (CPU and GPU): generated inside the processor, never exposed to software outside the TEE, and destroyed when the environment shuts down.
- **OHTTP keys**: each confidential VM generates its OHTTP key pair locally at boot. The private key stays inside TEE-protected memory, and the public key is bound into the attestation evidence. Keys are rotated periodically.
- **Attestation-gated key sharing**: a VM only shares its OHTTP keys with peers that have passed attestation, so possessing a shared key is itself proof of having been verified. This lets any replica decrypt a request and lets the fleet scale, without your data leaving the protected boundary. See [Remote Attestation](/guides/model-vault-encrypted-attestation) for the full key-sharing flow.

Cohere operates the infrastructure but is outside this boundary: it cannot read the private keys or the
data they protect.

## Zero Data Retention (ZDR)

When Zero Data Retention (ZDR) is enabled, Cohere processes inputs and outputs for inference but does
not retain any prompts or responses. Combined with confidential computing, this means your inference
data is only ever present, in plaintext, inside the TEE for the duration of the request, and is not
persisted afterward.

## Related pages

- [Security Model](/guides/model-vault-encrypted-security-model)
- [Remote Attestation](/guides/model-vault-encrypted-attestation)
- [Compliance](/guides/model-vault-encrypted-compliance)

## Related pages

- [Confidential Computing Primer](./model-vault-encrypted-confidential-computing.md)
- [Security Model](./model-vault-encrypted-security-model.md)
- [Remote Attestation](./model-vault-encrypted-attestation.md)
- [Verifying Your Deployment](./model-vault-encrypted-verifying-deployment.md)
- [Compliance](./model-vault-encrypted-compliance.md)

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