Compatibility - Fhevm

Github

kms: https://github.com/zama-ai/kms tfhe-rs: https://github.com/zama-ai/tfhe-rs

Limitations

There is no on-chain or relayer-side signal that tells the SDK the minimum tfhe.wasm version required to deserialize a given PubKey/CRS pair, and the format is not forward-compatible across minor versions:

[email protected] cannot parse a PubKey/CRS produced by [email protected].

Heuristic

Lacking a direct signal, the SDK derives the right tfhe.wasm version from a protocol context:

Read ACL.version on the host chain and map it to a protocol version.
Resolve the PubKey/CRS version from what this SDK knows at the time it is written:
- for known public relayers, use the PubKey/CRS version they are known to serve at SDK release time;
- otherwise, use the PubKey/CRS version expected when fresh key material is generated for that protocol line.
Map (protocol version, PubKey/CRS version) to a wasm version:
- Protocol < v0.13.0 with PubKey/CRS < v1.6.0 → [email protected]
- Protocol ≥ v0.13.0 with PubKey/CRS < v1.6.0 → [email protected] by default, while v1.5.3 remains compatible for the current legacy public PubKey/CRS.
- Protocol ≥ v0.13.0 with PubKey/CRS ≥ v1.6.0 → [email protected]

The PubKey/CRS part is a release-time snapshot, not a future-proof signal. After the SDK is published, key rotation or CRS removal can change the material served by a relayer. The SDK cannot guess those future changes without a direct on-chain or relayer-side version signal.

The protocol-version part works as long as every protocol release bumps at least one host-contract version. See the open question on this assumption below if it ever breaks.

In the future: add view functions in InputVerifier.sol and KMSVerifier.sol or ProtocolConfig.sol

KMS

KMS releases pin an exact tfhe-rs crate version via tfhe = "=X.Y.Z" in the workspace Cargo.toml.

KMS version	`tfhe-rs` crate	Notes
`0.12.4` – `0.12.7`	`1.4.0-alpha.3`	initial line, prerelease alpha
`0.13.0` – `0.13.3`	`1.5.1`	tfhe minor bump (`1.4` → `1.5`)
`0.13.10`	`1.5.4`	tfhe patch bump within `1.5.x`
`0.13.20-0`	`1.6.1`	tfhe minor bump (`1.5` → `1.6`)

Chains

KMS 0.12.7 generated the PubKey/CRS in December 2025

Chain	Protocol	PubKey/CRS
Mainnet	`0.11.0`	`1.4.0-alpha.3`
Testnet	`0.13.0`	`1.4.0-alpha.3`
Devnet	`0.13.0`	`1.4.0-alpha.3`
Polygon-Amoy (Devnet)	`0.13.0`	`1.4.0-alpha.3`

Contract and components versions

On-chain contracts

Protocol	ACL	FHEVMExecutor	KMSVerifier	InputVerifier	HCULimit	ProtocolConfig	PauserSet
`0.10.0`	`0.2.0`	`0.1.0`	`0.1.0`	`0.2.0`	`0.1.0`	-	`0.1.0`
`0.11.0`	`0.2.0`	`0.2.0`	`0.1.0`	`0.2.0`	`0.1.0`	-	`0.1.0`
`0.12.0`	`0.3.0`	`0.3.0`	`0.2.0`	`0.2.0`	`0.2.0`	-	`0.1.0`
`0.13.0`	`0.4.0`	`0.4.0`	`0.3.0`	`0.2.0`	`0.3.0`	`0.1.0`	`0.1.0`
`0.14.0`	`0.5.0`	?	`0.4.0`	?	?	`0.2.0`	?

Off-chain components

Protocol	TFHE	KMS	Extra data
`0.10.0`	`1.4.0-alpha.3`	`0.12.4`	`v0`
`0.11.0`	`1.5.1`	`0.13.3`	`v0`
`0.12.0`	`1.5.4`	`0.13.10`	`v1`
`0.13.0`	`1.6.1`	`0.13.20-0`	`v1`
`0.14.0`	?	?	`v2`

PubKey/Crs versions on existing chains and compatibility with other TFHE versions

Chain	Protocol	PubKey/CRS (TFHE)	TFHE 1.5.3	TFHE 1.6.1
Mainnet	`0.11.0`	`1.4.0-alpha.3`	✅	❌
Testnet	`0.13.0`	`1.4.0-alpha.3`	✅	✅
Devnet	`0.13.0`	`1.4.0-alpha.3`	✅	✅

Localstack

Protocol	PubKey/CRS (TFHE)	Readable by TFHE 1.5.3	Readable by TFHE 1.6.1
`0.11.0`	`1.5.1`	✅	✅
`0.12.0`	`1.5.4`	✅	✅
`0.13.0`	`1.6.1`	❌	✅
`0.14.0`	?	❌	?

TFHE API

Protocol	TFHE	Types	Functions
`v0.11.0`
`v0.12.0`
`v0.13.0`
`v0.14.0`
`v1.5.3`
`v1.6.1`	`CompactCiphertextList.builder`
`CompactCiphertextListBuilder.push_boolean`
`CompactCiphertextListBuilder.push_u8`
`CompactCiphertextListBuilder.push_u16`
`CompactCiphertextListBuilder.push_u32`
`CompactCiphertextListBuilder.push_u64`
`CompactCiphertextListBuilder.push_u128`
`CompactCiphertextListBuilder.push_u160`
`CompactCiphertextListBuilder.push_u256`
`CompactCiphertextListBuilder.build_with_proof_packed`
`CompactCiphertextListBuilder.free`
`CompactPkeCrs.safe_serialize`
`CompactPkeCrs.safe_deserialize`
`ProvenCompactCiphertextList.safe_serialize`
`ProvenCompactCiphertextList.safe_deserialize`
`ProvenCompactCiphertextList.free`
`ProvenCompactCiphertextList.len`
`ProvenCompactCiphertextList.get_kind_of`
`TfheCompactPublicKey.safe_serialize`
`TfheCompactPublicKey.safe_deserialize`
`ZkComputeLoad`	`init_panic_hook`
`initThreadPool`
`setWorkerUrlConfig`
`getWasmInfo`

KMS API

Protocol	KMS	Types	Functions
`v0.11.0`
`v0.12.0`
`v0.13.0`
`v0.14.0`
`v0.13.x`
`v0.14.0`	`Client`
`PrivateEncKeyMlKem512`
`PublicEncKeyMlKem512`
`ServerIdAddr`
`TypedPlaintext`	`new_client`
`new_server_id_addr`
`ml_kem_pke_keygen`
`ml_kem_pke_get_pk`
`ml_kem_pke_pk_to_u8vec`
`ml_kem_pke_sk_to_u8vec`
`u8vec_to_ml_kem_pke_sk`
`process_user_decryption_resp_from_js`