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package noise
import (
"crypto/hmac"
"hash"
)
func hkdf(h func() hash.Hash, outputs int, out1, out2, out3, chainingKey, inputKeyMaterial []byte) ([]byte, []byte, []byte) {
if len(out1) > 0 {
panic("len(out1) > 0")
}
if len(out2) > 0 {
panic("len(out2) > 0")
}
if len(out3) > 0 {
panic("len(out3) > 0")
}
if outputs > 3 {
panic("outputs > 3")
}
tempMAC := hmac.New(h, chainingKey)
tempMAC.Write(inputKeyMaterial)
tempKey := tempMAC.Sum(out2)
out1MAC := hmac.New(h, tempKey)
out1MAC.Write([]byte{0x01})
out1 = out1MAC.Sum(out1)
if outputs == 1 {
return out1, nil, nil
}
out2MAC := hmac.New(h, tempKey)
out2MAC.Write(out1)
out2MAC.Write([]byte{0x02})
out2 = out2MAC.Sum(out2)
if outputs == 2 {
return out1, out2, nil
}
out3MAC := hmac.New(h, tempKey)
out3MAC.Write(out2)
out3MAC.Write([]byte{0x03})
out3 = out3MAC.Sum(out3)
return out1, out2, out3
}
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