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Fix sum32 checksum

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This commit is contained in:
Andrew Gutekanst
2020-01-14 11:23:27 -05:00
parent 5f1d429c12
commit e6d7b7b9c2
1 changed files with 5 additions and 6 deletions
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11
server/entranceserver/crypto.go
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@@ -6,23 +6,22 @@ import (
var ( var (
_bin8Key = []byte{0x01, 0x23, 0x34, 0x45, 0x56, 0xAB, 0xCD, 0xEF} _bin8Key = []byte{0x01, 0x23, 0x34, 0x45, 0x56, 0xAB, 0xCD, 0xEF}
_sum32Table0 = []byte{0x7A, 0xAA, 0x97, 0x53, 0x66, 0x12, 0xDE, 0xDE, 0x35} _sum32Table0 = []byte{0x35, 0x7A, 0xAA, 0x97, 0x53, 0x66, 0x12}
_sum32Table1 = []byte{0x35, 0x7A, 0xAA, 0x97, 0x53, 0x66, 0x12} _sum32Table1 = []byte{0x7A, 0xAA, 0x97, 0x53, 0x66, 0x12, 0xDE, 0xDE, 0x35}
) )
// CalcSum32 calculates the custom MHF "sum32" checksum of the given data. // CalcSum32 calculates the custom MHF "sum32" checksum of the given data.
func CalcSum32(data []byte) uint32 { func CalcSum32(data []byte) uint32 {
tableIdx0 := byte(len(data) & 0xFF) tableIdx0 := int(len(data) & 0xFF)
tableIdx1 := byte(data[len(data)>>1]) tableIdx1 := int(data[len(data)>>1] & 0xFF)
out := make([]byte, 4) out := make([]byte, 4)
for i := 0; i < len(data); i++ { for i := 0; i < len(data); i++ {
tableIdx0++ tableIdx0++
tableIdx1++ tableIdx1++
tmp := byte((_sum32Table0[tableIdx1%9] ^ _sum32Table1[tableIdx0%7]) ^ data[i]) tmp := byte((_sum32Table1[tableIdx1%9] ^ _sum32Table0[tableIdx0%7]) ^ data[i])
out[i&3] = (out[i&3] + tmp) & 0xFF out[i&3] = (out[i&3] + tmp) & 0xFF
} }
return binary.BigEndian.Uint32(out) return binary.BigEndian.Uint32(out)