core: add ed25519 signature verification precompile

ethereum · Apr 6, 2018 · 9e2cbb9 · 9e2cbb9
1 parent 50dbe8e
commit 9e2cbb9
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Showing 3 changed files with 45 additions and 0 deletions.
diff --git a/core/vm/contracts.go b/core/vm/contracts.go
@@ -26,6 +26,7 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/crypto/bn256"
 	"github.com/ethereum/go-ethereum/params"
+	"golang.org/x/crypto/ed25519"
 	"golang.org/x/crypto/ripemd160"
 )
 
@@ -59,6 +60,20 @@ var PrecompiledContractsByzantium = map[common.Address]PrecompiledContract{
 	common.BytesToAddress([]byte{8}): &bn256Pairing{},
 }
 
+// PrecompiledContractsConstantinople contains the default set of pre-compiled Ethereum
+// contracts used in the Constantinople release.
+var PrecompiledContractsConstantinople = map[common.Address]PrecompiledContract{
+	common.BytesToAddress([]byte{1}): &ecrecover{},
+	common.BytesToAddress([]byte{2}): &sha256hash{},
+	common.BytesToAddress([]byte{3}): &ripemd160hash{},
+	common.BytesToAddress([]byte{4}): &dataCopy{},
+	common.BytesToAddress([]byte{5}): &bigModExp{},
+	common.BytesToAddress([]byte{6}): &bn256Add{},
+	common.BytesToAddress([]byte{7}): &bn256ScalarMul{},
+	common.BytesToAddress([]byte{8}): &bn256Pairing{},
+	common.BytesToAddress([]byte{9}): &ed25519Verify{},
+}
+
 // RunPrecompiledContract runs and evaluates the output of a precompiled contract.
 func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
 	gas := p.RequiredGas(input)
@@ -358,3 +373,26 @@ func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
 	}
 	return false32Byte, nil
 }
+
+// ed25519Verify implements a native Ed25519 signature verification.
+type ed25519Verify struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *ed25519Verify) RequiredGas(input []byte) uint64 {
+	return params.Ed25519VerifyGas
+}
+
+func (c *ed25519Verify) Run(input []byte) ([]byte, error) {
+	// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-665.md#specification
+	message := getData(input, 0, 32)
+	publicKey := getData(input, 32, 32)
+	sig := getData(input, 64, 64)
+
+	// Verify the Ed25519 signature against the public key and message
+	// and return result
+	// https://godoc.org/golang.org/x/crypto/ed25519#Verify
+	if ed25519.Verify(publicKey, message, sig) {
+		return true32Byte, nil
+	}
+	return false32Byte, nil
+}
diff --git a/core/vm/evm.go b/core/vm/evm.go
@@ -45,6 +45,9 @@ func run(evm *EVM, contract *Contract, input []byte) ([]byte, error) {
 		if evm.ChainConfig().IsByzantium(evm.BlockNumber) {
 			precompiles = PrecompiledContractsByzantium
 		}
+		if evm.ChainConfig().IsConstantinople(evm.BlockNumber) {
+			precompiles = PrecompiledContractsConstantinople
+		}
 		if p := precompiles[*contract.CodeAddr]; p != nil {
 			return RunPrecompiledContract(p, input, contract)
 		}
@@ -159,6 +162,9 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 		if evm.ChainConfig().IsByzantium(evm.BlockNumber) {
 			precompiles = PrecompiledContractsByzantium
 		}
+		if evm.ChainConfig().IsConstantinople(evm.BlockNumber) {
+			precompiles = PrecompiledContractsConstantinople
+		}
 		if precompiles[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
 			return nil, gas, nil
 		}

diff --git a/params/protocol_params.go b/params/protocol_params.go
@@ -77,6 +77,7 @@ const (
 	Bn256ScalarMulGas       uint64 = 40000  // Gas needed for an elliptic curve scalar multiplication
 	Bn256PairingBaseGas     uint64 = 100000 // Base price for an elliptic curve pairing check
 	Bn256PairingPerPointGas uint64 = 80000  // Per-point price for an elliptic curve pairing check
+	Ed25519VerifyGas        uint64 = 2000   // Ed25519 signature verification gas price
 )
 
 var (