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Pad precompiled EC recover input and add validations

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This commit is contained in:
Gustav Simonsson 2015-06-09 15:41:15 +02:00
parent d8e55a5cc3
commit ad5b5a4895
1 changed files with 14 additions and 8 deletions
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22
core/vm/contracts.go
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@ -67,21 +67,27 @@ func ripemd160Func(in []byte) []byte {
const ecRecoverInputLength = 128
func ecrecoverFunc(in []byte) []byte {
if len(in) < ecRecoverInputLength {
in = common.RightPadBytes(in, 128)
}
// "in" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
if len(in) < ecRecoverInputLength {
return nil
}
r := common.BytesToBig(in[64:96])
s := common.BytesToBig(in[96:128])
// Treat V as a 256bit integer
v := new(big.Int).Sub(common.Bytes2Big(in[32:64]), big.NewInt(27))
// Ethereum requires V to be either 0 or 1 => (27 || 28)
if !(v.Cmp(Zero) == 0 || v.Cmp(One) == 0) {
vbig := common.Bytes2Big(in[32:64])
v := byte(vbig.Uint64())
if !crypto.ValidateSignatureValues(v, r, s) {
glog.V(logger.Error).Infof("EC RECOVER FAIL: v, r or s value invalid")
return nil
}
// v needs to be moved to the end
rsv := append(in[64:128], byte(v.Uint64()))
// v needs to be at the end and normalized for libsecp256k1
vbignormal := new(big.Int).Sub(vbig, big.NewInt(27))
vnormal := byte(vbignormal.Uint64())
rsv := append(in[64:128], vnormal)
pubKey, err := crypto.Ecrecover(in[:32], rsv)
// make sure the public key is a valid one
if err != nil {