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deadprogram
103 lines
2.6 KiB
Go
103 lines
2.6 KiB
Go
package lorawan
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import (
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"bytes"
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"crypto/aes"
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"errors"
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)
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// Otaa is used to store Over The Air Activation data of a LoRaWAN session
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type Otaa struct {
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DevEUI [8]uint8
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AppEUI [8]uint8
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AppKey [16]uint8
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DevNonce [2]uint8
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AppNonce [3]uint8
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NetID [3]uint8
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}
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// Set configures the Otaa AppEUI, DevEUI, AppKey for the device
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func (o *Otaa) Set(appEUI [8]uint8, devEUI [8]uint8, appKey [16]uint8) {
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o.AppEUI = appEUI
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o.DevEUI = devEUI
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o.AppKey = appKey
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}
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// GenerateJoinRequest Generates a LoraWAN Join request
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func (o *Otaa) GenerateJoinRequest(buf []uint8) error {
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// TODO: Add checks
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buf = append(buf, 0x00)
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buf = append(buf, revertByteArray(o.AppEUI[:])...)
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buf = append(buf, revertByteArray(o.DevEUI[:])...)
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buf = append(buf, revertByteArray(o.DevNonce[:])...)
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mic := genPayloadMIC(buf, o.AppKey)
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buf = append(buf, mic[:]...)
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return nil
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}
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// DecodeJoinAccept Decodes a Lora Join Accept packet
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func (o *Otaa) DecodeJoinAccept(phyPload []uint8, s *Session) error {
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if len(phyPload) < 12 {
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return errors.New("Bad packet")
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}
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data := phyPload[1:] // Remove trailing 0x20
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// Prepare AES Cipher
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block, err := aes.NewCipher(o.AppKey[:])
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if err != nil {
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return errors.New("Lora Cipher error 1")
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}
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buf := make([]byte, len(data))
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for k := 0; k < len(data)/aes.BlockSize; k++ {
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block.Encrypt(buf[k*aes.BlockSize:], data[k*aes.BlockSize:])
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}
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copy(o.AppNonce[:], buf[0:3])
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copy(o.NetID[:], buf[3:6])
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copy(s.DevAddr[:], buf[6:10])
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s.DLSettings = buf[10]
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s.RXDelay = buf[11]
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if len(buf) > 16 {
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copy(s.CFList[:], buf[12:28])
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}
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rxMic := buf[len(buf)-4:]
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dataMic := []byte{}
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dataMic = append(dataMic, phyPload[0])
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dataMic = append(dataMic, o.AppNonce[:]...)
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dataMic = append(dataMic, o.NetID[:]...)
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dataMic = append(dataMic, s.DevAddr[:]...)
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dataMic = append(dataMic, s.DLSettings)
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dataMic = append(dataMic, s.RXDelay)
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dataMic = append(dataMic, s.CFList[:]...)
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computedMic := genPayloadMIC(dataMic[:], o.AppKey)
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if !bytes.Equal(computedMic[:], rxMic[:]) {
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return errors.New("invalid Mic")
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}
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// Generate NwkSKey
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// NwkSKey = aes128_encrypt(AppKey, 0x01|AppNonce|NetID|DevNonce|pad16)
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sKey := []byte{}
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sKey = append(sKey, 0x01)
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sKey = append(sKey, o.AppNonce[:]...)
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sKey = append(sKey, o.NetID[:]...)
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sKey = append(sKey, o.DevNonce[:]...)
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for i := 0; i < 7; i++ {
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sKey = append(sKey, 0x00) // PAD to 16
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}
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block.Encrypt(buf, sKey)
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copy(s.NwkSKey[:], buf[0:16])
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// Generate AppSKey
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// AppSKey = aes128_encrypt(AppKey, 0x02|AppNonce|NetID|DevNonce|pad16)
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sKey[0] = 0x02
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block.Encrypt(buf, sKey)
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copy(s.AppSKey[:], buf[0:16])
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// Reset counters
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s.FCntDown = 0
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s.FCntUp = 0
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return nil
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}
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