usigverifier

usigverifier — Universal Signature Verifier Precompile

The only EVM precompile Push Chain ships on top of the cosmos-evm baseline. Verifies Ed25519 signatures inside the EVM so Solidity contracts can authenticate Solana-style signatures (or any other Ed25519 input) without re-implementing the curve in EVM bytecode.

Addresses

Both addresses are registered simultaneously and point at the same implementation. Backward compatibility for previously-deployed contracts is the only reason the legacy address still exists. New code should target 0xEC00000000000000000000000000000000000001.

Wired into app/app.go:781-795:

usigverifierPrecompile, _   := usigverifierprecompile.NewPrecompile()
usigverifierPrecompileV2, _ := usigverifierprecompile.NewPrecompileV2()
corePrecompiles[usigverifierPrecompile.Address()]   = usigverifierPrecompile
corePrecompiles[usigverifierPrecompileV2.Address()] = usigverifierPrecompileV2

Solidity Interface

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.18;

address constant USigVerifier_PRECOMPILE_ADDRESS    = 0x00000000000000000000000000000000000000ca;
address constant USigVerifier_PRECOMPILE_ADDRESS_V2 = 0xEC00000000000000000000000000000000000001;

interface IUSigVerifier {
    /// @notice Verifies an Ed25519 signature.
    /// @param pubKey    The 32-byte Ed25519 public key (Solana address bytes).
    /// @param msg       The message digest that was signed (bytes32).
    /// @param signature The 64-byte Ed25519 signature.
    /// @return isValid  True iff the signature is valid for (pubKey, msg).
    function verifyEd25519(
        bytes calldata pubKey,
        bytes32 msg,
        bytes calldata signature
    ) external view returns (bool);
}

Verification Semantics

The precompile is intentionally narrow. It accepts:

• pubKey — 32 raw Ed25519 public key bytes (a Solana address is exactly this)
• msg — a single bytes32 digest
• signature — 64 raw Ed25519 signature bytes

Internally (query.go:VerifyEd25519), the bytes32 digest is rendered as a 0x-prefixed hex string before being passed to ed25519.Verify:

msgStr := "0x" + hex.EncodeToString(msg)  // 66 ASCII bytes
msgBytes := []byte(msgStr)
ok = ed25519.Verify(pubKeyBytes, msgBytes, signature)

In other words, the signed message that the off-chain signer must sign is the 66-byte ASCII string 0x... of the digest, not the raw 32 bytes. This matches the convention used by Solana wallets when signing arbitrary messages — they prefix-encode the payload — so a normal Solana wallet signature over a Push Chain message hash will verify here without any extra work on the wallet side.

If pubKey is not 32 bytes or signature is not 64 bytes, the precompile reverts with invalid params. Unknown method IDs revert with the standard unknown method error.

Generating the ABI

If USigVerifier.sol is changed, regenerate abi.json with:

cd precompiles/usigverifier
solcjs USigVerifier.sol --abi
mv *.abi abi.json
jq --argjson abi "$(cat abi.json)" \
   '{"_format": "hh-sol-artifact-1", "contractName": "USigVerifier",
     "sourceName": "precompiles/USigVerifier.sol",
     "bytecode": "0x", "deployedBytecode": "0x",
     "linkReferences": {}, "deployedLinkReferences": {},
     "abi": $abi}' <<< '{}' > abi.json

The Go binary embeds abi.json via //go:embed, so a fresh make build will pick up the change.

Testing from the Command Line

# Make sure the precompile is enabled in the EVM params:
# app_state["evm"]["params"]["active_static_precompiles"] must include
# 0x00000000000000000000000000000000000000ca and/or 0xEC00000000000000000000000000000000000001
# (test_node.sh installs the legacy address by default).

cast call 0xEC00000000000000000000000000000000000001 \
    "verifyEd25519(bytes,bytes32,bytes)" \
    "<32-byte pubKey hex>" \
    "<bytes32 digest>" \
    "<64-byte signature hex>"

# Decode the boolean response
cast abi-decode "verifyEd25519(bytes,bytes32,bytes)(bool)" <returndata>

If the call returns 0x (empty), the precompile is not in active_static_precompiles for the current chain — that's a configuration issue, not a verification failure.

Layout

precompiles/usigverifier/
|-- USigVerifier.sol     Solidity interface (the source of truth for the ABI)
|-- abi.json             Embedded into the binary via go:embed
|-- usigverifier.go      Precompile struct, NewPrecompile / NewPrecompileV2, RequiredGas, Run
|-- query.go             VerifyEd25519 method handler
+-- README.md            (this file)