arnaucube / go-blindsecp256k1 Goto Github PK

Looks like this check should be removed or modified:

The big.Int type can have less than 32 bytes if the number starts with "0x00" (we've found this issue in a working code)

The following code

    h := "001ec8a5ac7b6f30f24582a1cc7a99714162d9f73d5b5b1d64c3df0b53914320"
    b, _ := hex.DecodeString(h)
    bi := new(big.Int).SetBytes(b)
    fmt.Printf("%s | %x | %d\n", bi.String(), bi.Bytes(), len(bi.Bytes()))

produces this output, thus the big.Int is of 31 bytes (but still válid).

54390227768401831994291737067988167540000774869646691930140901779484787488 | 1ec8a5ac7b6f30f24582a1cc7a99714162d9f73d5b5b1d64c3df0b53914320 | 31

If the signature requires 32 bytes but a big.Int type is used as input, I think the function should build the padding

Change the current 'custom' types & methods, and use the Go standard types https://pkg.go.dev/crypto/ecdsa#PublicKey