Duplicate math operations

[code423n4]

Handle

pauliax

Vulnerability details

Impact

First perform the addition and only then check the length to avoid this duplicate math operation:
require(b.length >= index + 32, "BytesLib: length");
// Arrays are prefixed by a 256 bit length parameter
index += 32;
Or if you want to stay with this approach, then at least consider using the 'unchecked' keyword when this addition is performed the second time as then ready know this can't overflow. Also, in function recoverAddrImpl the same operation is performed twice:
sig.length - 33

Recommended Mitigation Steps

Refactor duplicate math operations.

[Ivshti]

resolved in AmbireTech/adex-protocol-eth@67a9bf7

[GalloDaSballo]

As per the require(sig.length >= 1, "SV_SIGLEN"); you can't underflow uint8(sig[sig.length - 1])
Using unchecked does save gas

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