Digimon: ASR

"
Security:
-> Checksum32 (Signed)
   -> Offset: 20
   -> Calculation Start: 0
   -> Calculation Length: 0x185E

Additional:
Before the checksum is calculated, the last checksum is overwritten with 0.
"

private int CalculateSignedChecksum32(byte[] data, int offset, int size) {
    int sum = 0;

    while (size-- > 0)
        sum += (sbyte) data[offset++];

    return sum;
}