87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package globalplatform
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import (
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"bytes"
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"encoding/binary"
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"github.com/status-im/status-go/smartcard/apdu"
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"github.com/status-im/status-go/smartcard/globalplatform/crypto"
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)
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// APDUWrapper is a wrapper for apdu commands inside a global platform secure channel.
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type APDUWrapper struct {
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macKey []byte
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icv []byte
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}
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// NewAPDUWrapper returns a new APDUWrapper using the specified key for MAC generation.
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func NewAPDUWrapper(macKey []byte) *APDUWrapper {
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return &APDUWrapper{
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macKey: macKey,
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icv: crypto.NullBytes8,
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}
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}
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// Wrap wraps the apdu command adding the MAC to the end of the command.
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// Future implementations will encrypt the message when needed.
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func (w *APDUWrapper) Wrap(cmd *apdu.Command) (*apdu.Command, error) {
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macData := new(bytes.Buffer)
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cla := cmd.Cla | 0x04
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if err := binary.Write(macData, binary.BigEndian, cla); err != nil {
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return nil, err
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}
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if err := binary.Write(macData, binary.BigEndian, cmd.Ins); err != nil {
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return nil, err
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}
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if err := binary.Write(macData, binary.BigEndian, cmd.P1); err != nil {
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return nil, err
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}
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if err := binary.Write(macData, binary.BigEndian, cmd.P2); err != nil {
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return nil, err
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}
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if err := binary.Write(macData, binary.BigEndian, uint8(len(cmd.Data)+8)); err != nil {
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return nil, err
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}
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if err := binary.Write(macData, binary.BigEndian, cmd.Data); err != nil {
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return nil, err
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}
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var (
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icv []byte
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err error
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)
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if bytes.Equal(w.icv, crypto.NullBytes8) {
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icv = w.icv
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} else {
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icv, err = crypto.EncryptICV(w.macKey, w.icv)
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if err != nil {
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return nil, err
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}
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}
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mac, err := crypto.MacFull3DES(w.macKey, macData.Bytes(), icv)
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if err != nil {
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return nil, err
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}
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newData := make([]byte, 0)
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newData = append(newData, cmd.Data...)
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newData = append(newData, mac...)
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w.icv = mac
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newCmd := apdu.NewCommand(cla, cmd.Ins, cmd.P1, cmd.P2, newData)
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if ok, le := cmd.Le(); ok {
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newCmd.SetLe(le)
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}
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return newCmd, nil
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}
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