/
mojangHash.go
53 lines (44 loc) · 895 Bytes
/
mojangHash.go
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package main
import "encoding/hex"
func McHexDigest(zdata []byte) []byte {
data := make([]byte, len(zdata))
copy(data, zdata)
negative := int8(data[0]) < 0
if negative {
data = performTwosCompliment(data)
}
var digest []byte = make([]byte, 40)
hex.Encode(digest, data)
start := 0
for i := 0; i < len(digest); i++ {
if digest[i] == byte('0') {
start = i + 1
} else {
break
}
}
digest = digest[start:len(digest)]
if negative {
var realDigest []byte = []byte{byte('-')}
realDigest = append(realDigest, digest...)
return realDigest
}
return digest
}
func performTwosCompliment(buf []byte) []byte {
carry := true
var i int = 0
var newByte byte
var value byte
for i = len(buf) - 1; i >= 0; i-- {
value = buf[i]
newByte = ^value & 255
if carry {
carry = newByte == 255
buf[i] = newByte + 1
} else {
buf[i] = newByte
}
}
return buf
}