Glossary

Coprocessor: An off-chain component in fhEVM-native that does the actual FHE computation.
Executor: A component that runs alongside the fhEVM-native blockchain node/validator and does the FHE computation. The node/validator and the Executor communicate over a network connection.
FheLib: A precompiled contract on fhEVM-native that is available on nodes/validators. Exposes functions such as reading FHE ciphertexts from the on-chain storage in fhEVM-native, etc. At the time of writing, it exists at address 0x000000000000000000000000000000000000005d.
fhEVM-coprocessor: An fhEVM configuration where an off-chain Coprocessor component does the actual FHE computation. FHE ciphertexts are stored in an off-chain database local to the Coprocessor and in an off-chain public Data Availablility (DA) layer. No modifications the validator software of the existing chain is required (except for the full-node running for the Coprocessor).
fhEVM-native: An fhEVM configuration where each validator is paired with an Executor. FHE ciphertexts are stored on-chain. fhEVM-native requires modifications to the validator software of an existing chain.
fhevmjs: A JavaScript library that allows dApps to interact with the fhEVM.
handle: A handle refers to (or is a pointer to) a ciphertext in the fhEVM. A handle uniquely refers to a single ciphertext from the user's perspective.
KMS: Key Management Service. Used for managing secret FHE key material.
Symbolic Execution: Onchain execution where inputs to FHE operations are symbolic values (also called handles) that refer to ciphertexts. We check constraints on these handles, but ignore their actual values.
TFHE: An Fully Homomorphic Encryption scheme used in fhEVM and TKMS.
TKMS: Threshold Key Management Service. Uses threshold cryptography and multi-party computation. See KMS.
ZKPoK: Zero-knowledge proof of knowledge of an input FHE ciphertext.

Smart Contracts

fhEVM

ACL Smart Contract: Smart contract deployed on the fhEVM blockchain to manage access control of ciphertexts. dApp contracts use this to persists their own access rights and to delegate access to other contracts.
Gateway Smart Contract: Smart contract deployed on the fhEVM blockchain that is used by a dApp smart contract to request a decrypt. This emits an event that triggers the gateway.
KMS Smart Contract: Smart contract running on the fhEVM blockchain that is used by a dApp contract to verify decryption results from the TKMS. To that end, it contains the identity of the TKMS and is used to verify its signatures.

TKMS

fhEVM ISC: Smart contract which contains all the custom logic needed to validate whether an operation such as decryption, is permitted on a given fhEVM chain. Specifically this involves inclusion proofs of an ACL. Note there is one ISC for each fhEVM.
fhEVM ASC: Smart contract to which transactions from the gateway (connector) are submitted to. This contract contains all logic required to work with any fhEVM blockchain. It handles any fhEVM chain-specific logic (such as ACL validation) by calling the ISC associated with the given fhEVM chain.

PreviousZama's TKMS NextNode and gateway hardware

Last updated 6 months ago

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Smart Contracts

fhEVM

ACL Smart Contract: Smart contract deployed on the fhEVM blockchain to manage access control of ciphertexts. dApp contracts use this to persists their own access rights and to delegate access to other contracts.

Gateway Smart Contract: Smart contract deployed on the fhEVM blockchain that is used by a dApp smart contract to request a decrypt. This emits an event that triggers the gateway.

KMS Smart Contract: Smart contract running on the fhEVM blockchain that is used by a dApp contract to verify decryption results from the TKMS. To that end, it contains the identity of the TKMS and is used to verify its signatures.

TKMS

fhEVM ISC: Smart contract which contains all the custom logic needed to validate whether an operation such as decryption, is permitted on a given fhEVM chain. Specifically this involves inclusion proofs of an ACL. Note there is one ISC for each fhEVM.

fhEVM ASC: Smart contract to which transactions from the gateway (connector) are submitted to. This contract contains all logic required to work with any fhEVM blockchain. It handles any fhEVM chain-specific logic (such as ACL validation) by calling the ISC associated with the given fhEVM chain.