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vm: explicit error checks in ecrecover. closes #505

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This commit is contained in:
Ethan Buchman 2015-03-18 20:56:06 -07:00
parent 8ed4f226d1
commit d2fa6e7753
1 changed files with 21 additions and 7 deletions
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28
vm/address.go
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@ -3,8 +3,8 @@ package vm
import (
"math/big"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
)
type Address interface {
@ -61,15 +61,29 @@ func ripemd160Func(in []byte) []byte {
return common.LeftPadBytes(crypto.Ripemd160(in), 32)
}
const EcRecoverInputLength = 128
func ecrecoverFunc(in []byte) []byte {
// In case of an invalid sig. Defaults to return nil
defer func() { recover() }()
// "in" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
if len(in) < EcRecoverInputLength {
return nil
}
hash := in[:32]
v := common.BigD(in[32:64]).Bytes()[0] - 27
// v is only a bit, but comes as 32 bytes from vm. We only need least significant byte
encodedV := in[32:64]
v := encodedV[31] - 27
if !(v == 0 || v == 1) {
return nil
}
sig := append(in[64:], v)
return common.LeftPadBytes(crypto.Sha3(crypto.Ecrecover(append(hash, sig...))[1:])[12:], 32)
pubKey := crypto.Ecrecover(append(hash, sig...))
// secp256.go returns either nil or 65 bytes
if pubKey == nil || len(pubKey) != 65 {
return nil
}
// the first byte of pubkey is bitcoin heritage
return common.LeftPadBytes(crypto.Sha3(pubKey[1:])[12:], 32)
}
func memCpy(in []byte) []byte {