> For the complete documentation index, see [llms.txt](https://docs.zama.org/protocol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zama.org/protocol/changelog/zama-protocol-change-log.md).

# Zama Protocol Change Log

### Zama Protocol status

Deployed and planned FHEVM versions on the Testnet and Mainnet.

| Status  | Version     | Details                                                                            |
| ------- | ----------- | ---------------------------------------------------------------------------------- |
| Testnet | FHEVM v0.12 | [Change log ↗](https://docs.zama.org/change-log/release/fhevm-v0.11-february-2026) |
| Mainnet | FHEVM v0.12 | [Change log ↗](https://docs.zama.org/change-log/release/fhevm-v0.11-february-2026) |

See the full version status in the [Zama Protocol Version Dashboard](https://zamablockchain.grafana.net/public-dashboards/4027c482ad1e44ddb1336ec04cc5a1db).

### Product updates

{% updates format="full" %}
{% update date="2026-04-01" tags="preview" %}

## FHEVM v0.12 — April 2026

#### Highlights

The v0.12 release brings multi-chain support, stronger consensus, and tighter resource controls to the Zama Protocol:

* **Multi-chain coprocessor support and multi-coprocessor consensus** with deterministic ciphertext re-randomisation, enabling coprocessors to converge on identical FHE results across chains.
* **KMS context-aware decryptions** introducing epoch IDs and context-state validation across the Gateway, KMS connector, and host contracts.
* **Per-block HCU metering** on the host with configurable per-block, per-transaction, and per-depth Homomorphic Compute Unit limits, plus a whitelist for privileged callers.
* **Simplified ACL (v2)** replacing the MultichainACL contract suite with a single access-control flow on the host chain.
* **Compressed key generation on GPU** in the KMS, lowering key-generation overhead for GPU-backed deployments.

#### New features

* **Multi-chain coprocessor support** (Copro): coprocessors can now serve multiple host chains in a single deployment.
* **Multi-coprocessor consensus** (Copro): independent coprocessors converge on identical FHE results, with deterministic re-randomisation as the foundation.
* **KMS context-aware decryptions** (Gateway, KMS, Host contracts): a new "KMS context" system adds epoch IDs and context state to decryption operations. Decryption requests carry context-aware `extraData`, and the KMS connector validates context state via a new `kms_context` table and Ethereum listener.
* **Per-block HCU limits** (Host contracts): a new `HCULimit` contract enforces configurable per-block, per-transaction, and per-transaction-depth Homomorphic Compute Unit limits, with a whitelist mechanism for privileged callers to bypass block limits.
* **Compressed key generation on GPU** (KMS).
* **Coprocessor state revert tooling** (Copro): new `revert_coprocessor_db_state.sql` script, packaged in the db-migration Docker image, that can revert a coprocessor to a previous block number.
* **Gateway ciphertext drift detection** (Gateway): opt-in detection comparing local ciphertext digests against on-chain consensus, enabled via `--ciphertext-commits-address`.
* **Library-Solidity additions**: `FHE.isPublicDecryptionResultValid` view function for on-chain decryption signature validation; `FHE.fromExternal` returns a trivial-encrypt of `0` for uninitialized handles instead of reverting.
* **relayer-sdk v0.5.x** (Devex): new `extraData` parameter on the relayer SDK.

#### Improvements

* **ACL simplification (v2)** (Host contracts): the MultichainACL contract suite is removed; access control is consolidated on the host chain with simpler validation.
* **New handle format** (Host contracts): handle hashing now includes a `FHE_comp` domain separator and the previous block hash + timestamp, strengthening uniqueness across chains and time.
* **Per-FHE-operation re-randomisation** (Copro): ciphertext inputs are re-randomised per FHE operation using a deterministic seed derived from input ciphertexts and operator.
* **Re-randomisation of input ciphertexts before first compression** (Copro).
* **KMS-connector switched to `eth_getLogs`** (KMS): replaces subscription-based event listening with batched database insertion.
* **tfhe-rs upgraded to v1.5.4** (Copro/MPC).
* **Contract upgrade version check CI**: a new workflow enforces that `REINITIALIZER_VERSION` and version constants are bumped when contract bytecode changes.
* **`ECDSA.sol` renamed to `FhevmECDSA.sol`** to fix naming conflicts.

{% hint style="danger" %}

#### Breaking changes

* **MultichainACL contracts deleted**: `MultichainACL.sol`, `MultichainACLChecks.sol`, and `IMultichainACL.sol` are removed entirely.
* **`isUserDecryptionReady` signature changed**: the `address userAddress` parameter was removed. The old signature is preserved via a backward-compatibility overload but is deprecated.
* **New handle format**: `FHEVMExecutor` handle hashing now prepends `COMPUTATION_DOMAIN_SEPARATOR` (`"FHE_comp"`) and appends `blockhash(block.number-1)` + `block.timestamp`.
* **`HCULimit` contract required**: `FHEVMExecutor` `REINITIALIZER_VERSION` bumped to 3; initialization requires `hcuCapPerBlock`, `maxHCUDepthPerTx`, and `maxHCUPerTx`. Integrators must sync to get whitelisted contracts.
* **ACL `REINITIALIZER_VERSION` bumped to 4**: `ExpirationDateBeforeOneHour` error replaced by `ExpirationDateInThePast`. Validation now only checks `expirationDate > block.timestamp`.
* **`KMSVerifier` upgraded** for context-aware decryption with epoch / context support.
* **`ECDSA.sol` renamed to `FhevmECDSA.sol`**: import path changes from `cryptography/ECDSA.sol` to `cryptography/FhevmECDSA.sol`; library renamed from `ECDSA` to `FhevmECDSA`.
* **Coprocessor**: `tenants` table removed from the DB; legacy `tfhe-worker` gRPC endpoint removed.
  {% endhint %}

#### Bug fixes

* Backport of `prepareUpgrade` flows to the 0.12.x line.
* Reduced coprocessor migration lock time during the 0.12 migration.
* Coprocessor no longer reads key blobs from the database on key cache hits.

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.12.0)
* [Documentation](https://docs.zama.org/protocol/solidity-guides/v0.12)
  {% endupdate %}

{% update date="2026-02-01" tags="new-features,improvements,fixes" %}

## FHEVM v0.11 — February 2026

This release brings major performance and security improvements to the Zama Protocol.

#### Highlights

* **tfhe-rs v1.5.0 upgrade** across Coprocessor and KMS for improved FHE performance
* **ACL checks on host chain** for direct access control enforcement through the relayer and KMS connector
* **Delegated decryption** with a complete end-to-end flow
* **FHE statistics for TFHE-rs** for better observability into Coprocessor FHE operations

#### New features

* **GPU acceleration:** Optional GPU backends for ZK proof verification, Switch-and-Squash (SnS), and re-randomization. CPU-only deployments remain fully supported.
* **Delegated decryption:** Complete end-to-end support for delegated user decryption, allowing authorized addresses to decrypt on behalf of users.
* **Operator staking system:** New ERC-4626-based staking contracts with UUPS upgradeability, permit support, and Operator Rewarder contracts for fee management.
* **Confidential Tokens Registry:** Added a Confidential Tokens Registry and ERC-7984 upgradeable wrapper contracts for encrypted token assets.
* **CLI tool:** Added a new command-line tool for common FHEVM workflows.
* **BNB chain support:** Added configurations for BNB chain deployments.

#### Improvements

* **tfhe-rs upgrade to v1.5.0:** Updated across the Coprocessor and KMS, while FHE keys and serialized ciphertexts remain generally compatible.
* **ACL checks on host chain:** Decryption ACL checks now run directly on the host chain through the relayer and KMS connector, reducing trust assumptions.
* **FHE statistics:** Added FHE operation statistics and decryption performance metrics in the Coprocessor.
* **Dependence-chain processing:** Improved the Coprocessor scheduler for better parallelism.
* **Host-listener poller mode:** Added an alternative polling mode that replaces WebSocket-based event listening.
* **KMS garbage collection:** Added garbage collection for KMS operations.
* **Database optimizations:** Improved indexing for the `ciphertext_digest` table.

#### Fixes

* Overflow prevention in the `ProtocolStaking` cooldown mechanism
* ERC-4626 inflation attack mitigation using decimal offset
* Better handling of cyclic dependence errors in the Coprocessor
* Improved `eth_getLogs` timeout management in the host-listener

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.11.0)
* [Documentation](https://docs.zama.org/protocol/solidity-guides)
  {% endupdate %}

{% update date="2025-10-01" tags="preview,new-features,improvements" %}

## FHEVM v0.10 — October 2025

This preview introduces a dedicated payment contract in the Gateway and flexible delegation of decryption rights through smart contracts.

These changes improve fee management, access control, and the usability of encrypted operations.

#### Preview

* **Gateway payment contract** for Coprocessor and KMS fee management
* **Delegation through smart contracts** for controlled decryption access
* **Time-scoped permissions** for temporary or session-based access
* **Contract-scoped permissions** for stricter access control

#### New features

* **Gateway payment contract:** Adds a dedicated payment contract within the Gateway to manage fees for Coprocessor and KMS operations, including input and decryption flows.
* **Delegation via smart contracts:** Users can delegate decryption rights to other addresses with fine-grained control over scope and duration:
  * Explicit authorization for another address to generate EIP-712 signatures and run `userDecrypt` operations
  * Delegation validity defined by timestamp for temporary or session-based access
  * Delegation scoped to specific contract addresses for context-aware access control

#### Improvements

* More flexible encrypted data access through delegation
* More transparent fee management with a dedicated Gateway payment flow

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.10.0)
* [Documentation](https://docs.zama.org/protocol/solidity-guides/v0.10)
  {% endupdate %}

{% update date="2025-10-01" tags="new-features,improvements,breaking-changes" %}

## FHEVM v0.9 — October 2025

This release adds new key generation capabilities, dynamic coprocessor management, and a redesigned decryption event flow.

These changes improve flexibility, scalability, and consensus handling while deprecating older event formats.

{% hint style="danger" %}

#### Breaking changes

The methods `FHE.requestDecryption` and `FHE.setDecryptionOracle` are now deprecated and must be removed.

Update your contracts to use the new decryption flow through the relayer.
{% endhint %}

#### Highlights

* **On-chain FHE key and CRS generation**
* **Dynamic pauser management**
* **Transaction input re-randomization**
* **Redesigned user decryption events**
* **Gateway API cleanup and renaming**

#### New features

* **Support generation of FHE key and CRS on-chain:**
  * Request FHE key and CRS generation directly through the Gateway.
  * New environment variables for gateway contracts:
    * `KMS_GENERATION_THRESHOLD` — threshold used to validate consensus on FHE key or CRS generation
    * `KMS_NODE_STORAGE_URL_[0-N]` — storage base URL for public materials for each KMS node
  * New environment variable for the coprocessor (`gw-listener`):
    * `KMS_GENERATION_ADDRESS` — address of the `KMSGeneration` gateway contract
  * New environment variable for the connector:
    * `KMS_GENERATION_ADDRESS` — address of the `KMSGeneration` gateway contract

{% hint style="info" %}

#### Obsolete environment variables

These variables are no longer used:

* `FHE_PARAMS_NAME`

* `FHE_PARAMS_DIGEST`
  {% endhint %}

* **New `PauserSet` immutable contract:**
  * Host and Gateway contracts can now be paused by any address added in `PauserSet`.
  * New environment variables for gateway contracts:
    * `NUM_PAUSERS` — number of pauser addresses to add. Set this to `n_kms + n_copro`.
    * `PAUSER_ADDRESS_[0-N]` — pauser addresses
  * New environment variables for host contracts:
    * `NUM_PAUSERS` — number of pauser addresses to add. Set this to `n_kms + n_copro`.
    * `PAUSER_ADDRESS_[0-N]` — pauser addresses

{% hint style="info" %}

#### Obsolete environment variable

This variable is no longer used:

* `PAUSER_ADDRESS`
  {% endhint %}

* **Re-randomization of transaction inputs:**
  * All transaction inputs, including state inputs, are re-encrypted before FHE evaluation.
  * This provides [sIND-CPAD security](https://www.zama.ai/post/drifting-towards-better-error-probabilities-in-fully-homomorphic-encryption).
  * This feature is transparent to users.

#### Improvements

* **User decryption response:**
  * Encrypted shares and signatures are no longer aggregated on-chain in the Gateway.
  * Each KMS response now emits its own event.
  * New events in the `Decryption` contract:
    * `UserDecryptionResponse(uint256 indexed decryptionId, uint256 indexShare, bytes userDecryptedShare, bytes signature, bytes extraData);`
    * `UserDecryptionResponseThresholdReached(uint256 indexed decryptionId);`

{% hint style="danger" %}

#### Breaking changes

This event is deprecated from the Gateway `Decryption` contract:

* `PublicDecryptionResponse(uint256 indexed decryptionId, bytes decryptedResult, bytes[] signatures, bytes extraData)`
  {% endhint %}

* **User decryption request:**
  * User EIP-712 signature verification is simplified in the Gateway `Decryption` contract.

{% hint style="danger" %}

#### Breaking changes

The `uint256 contractsChainId` field is no longer part of the `UserDecryptRequestVerification` struct used for EIP-712 signature verification.
{% endhint %}

* **Gateway contract renaming:**
  * `MultichainAcl` is renamed to `MultichainACL`.
  * `KmsManagement` is renamed to `KMSGeneration`.

{% hint style="danger" %}

#### Breaking changes

These Gateway contracts are renamed:

* `MultichainAcl` → `MultichainACL`
* `KmsManagement` → `KMSGeneration`

These environment variables are renamed:

* `KMS_MANAGEMENT_ADDRESS` → `KMS_GENERATION_ADDRESS`
* `KMS_CONNECTOR_KMS_MANAGEMENT_CONTRACT__ADDRESS` → `KMS_CONNECTOR_KMS_GENERATION_CONTRACT__ADDRESS`

In the KMS Connector Helm chart `values.yaml`, this field is renamed:

* `kmsManagement` → `kmsGeneration`
  {% endhint %}

* **Gateway check functions replaced:**
  * All external `check...` view functions are removed from the Gateway contracts.
  * Associated errors are moved to other contracts or removed.
  * Equivalent `is...` view functions now return a boolean instead of reverting.

{% hint style="danger" %}

#### Breaking changes

All `check...` view functions are removed from the Gateway contracts.

For example:

* `checkPublicDecryptAllowed` is replaced by `isPublicDecryptAllowed`
* `PublicDecryptNotAllowed` is moved to the `Decryption` contract
  {% endhint %}

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.9.0)
* [Documentation](https://docs.zama.org/protocol/solidity-guides/v0.9)
  {% endupdate %}

{% update date="2025-09-01" tags="new-features,improvements,breaking-changes" %}

## FHEVM v0.8 — September 2025

This release makes FHEVM more scalable, secure, and developer-friendly.

#### Highlights

* **New KMS connector** for modular integration
* **Compressed ciphertexts** for lighter payloads
* **Flexible `extraData` field** for richer apps
* **Post-quantum ML-KEM512** for faster, smaller decrypts
* **Stronger chain resilience and ERC-7995 compliance**

#### New features

* **New KMS connector:** Added a new Key Management System connector to improve modularity and integration.
* **Compressed ciphertext support:** Added support for compressed ciphertexts in both the SnS worker and KMS, reducing payload sizes.
* **Generic `extraData` field:** Gateway functions, events, and signed structs now include a generic `extraData` field for extensibility and custom data support.
* **`SepoliaConfig` update:** Added the `protocolId()` function to support protocol identification.

#### Improvements

* **ERC-7995 compatibility:** Updated the Oracle callback interface for compliance, following [ERC-7995](https://github.com/ethereum/ERCs/pull/1143).
* **Reduced user decrypt payload size:** Migrated to **ML-KEM512** for 128-bit equivalent post-quantum security. This reduces decrypt response sizes and allows more responses per block.
* **Host listener:** Added reorganization handling in the host listener for stronger chain resilience.
* **Library storage layout:** Adjusted the storage layout to align with the standard guidelines.

{% hint style="danger" %}

#### Breaking changes

**Oracle callback function signature** now requires this format:

```solidity
function callbackExample(
  uint256 requestID,
  bytes memory cleartexts,
  bytes memory decryptionProof
) external;
```

{% endhint %}

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.8.0)
* [Documentation](https://docs.zama.ai/protocol/solidity-guides/v0.8)
  {% endupdate %}

{% update date="2025-07-01" tags="new-features,breaking-changes" %}

## FHEVM v0.7 — July 2025

This release introduces the first iteration of the Zama Protocol.

#### Highlights

* **Gateway** is now a core component for protocol orchestration.
* **Coprocessor input verification** is now enforced on the coprocessor side.
* **Decryption pipeline** now prepares ciphertexts for decryption on coprocessors.
* **Solidity library** is restructured to match the new protocol architecture.

{% hint style="danger" %}

#### Breaking changes

* Renamed the library from `TFHE` to `FHE`
* Introduced `FHE.requestDecryption` with support for `msg.value`, deprecating `GatewayCaller`
* Removed `ebytesXXX` types
* Replaced `einput` with `externalEuintXXX`, `externalEbool`, and `externalEaddress`
* Introduced per-transaction operation limits, replacing the previous per-block limit
  {% endhint %}

#### Resources

* [GitHub release](https://github.com/zama-ai/fhevm/releases/tag/v0.7.0)
* [Documentation](https://docs.zama.ai/protocol/solidity-guides/v0.7)
  {% endupdate %}
  {% endupdates %}


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