Disable Trezor support

Trezor support has been broken since Sept 2018
( https://github.com/rfjakob/gocryptfs/issues/261 ).

Disable trezor.go by renaming to trezor.go.broken.
This keeps "dep" from having to pull in A LOT OF dependencies:

Before:

  $ du -sh vendor/
  49M	vendor/

After:

  $ du -sh vendor/
  16M	vendor/

1 files changed, 119 insertions, 0 deletions

diff --git a/internal/readpassword/trezor.go.broken b/internal/readpassword/trezor.go.broken
new file mode 100644
index 0000000..a4d32cf
--- /dev/null
+++ b/internal/readpassword/trezor.go.broken
@@ -0,0 +1,119 @@
+// +build enable_trezor
+
+package readpassword
+
+import (
+	"bytes"
+	"log"
+	"os"
+
+	"github.com/rfjakob/gocryptfs/internal/exitcodes"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
+
+	"github.com/xaionaro-go/cryptoWallet"
+	"github.com/xaionaro-go/cryptoWallet/vendors"
+)
+
+const (
+	// TrezorPayloadLen is the length of the payload data passed to Trezor's
+	// CipherKeyValue function.
+	TrezorPayloadLen        = 32
+	trezorNonce             = "" // the "nonce" is optional and has no use in here
+	trezorKeyName           = "gocryptfs"
+	trezorKeyDerivationPath = `m/10019'/0'`
+	// TrezorSupport is true when gocryptfs has been compile with -tags enable_trezor
+	TrezorSupport = true
+)
+
+func trezorGetPin(title, description, ok, cancel string) ([]byte, error) {
+	return Once("", title), nil
+}
+func trezorGetConfirm(title, description, ok, cancel string) (bool, error) {
+	return false, nil // do not retry on connection failure
+}
+
+// Trezor reads 32 deterministically derived bytes from a
+// SatoshiLabs Trezor USB security module.
+// The bytes are pseudorandom binary data and may contain null bytes.
+// This function either succeeds and returns 32 bytes or calls os.Exit to end
+// the application.
+func Trezor(payload []byte) []byte {
+	if len(payload) != TrezorPayloadLen {
+		tlog.Fatal.Printf("Invalid TrezorPayload length: wanted %d, got %d bytes\n", TrezorPayloadLen, len(payload))
+		os.Exit(exitcodes.LoadConf)
+	}
+
+	// Find all trezor devices
+	trezors := cryptoWallet.Find(cryptoWallet.Filter{
+		VendorID:   &[]uint16{vendors.GetVendorID("satoshilabs")}[0],
+		ProductIDs: []uint16{1 /* Trezor One */},
+	})
+
+	// ATM, we require to one and only one trezor device to be connected.
+	// The support of multiple trezor devices is not implemented, yet.
+	if len(trezors) == 0 {
+		tlog.Fatal.Printf("Trezor device is not found. Check the connection.")
+		os.Exit(exitcodes.TrezorError)
+	}
+	if len(trezors) > 1 {
+		tlog.Fatal.Printf("It's more than one Trezor device connected. This case is not implemented, yet. The number of currently connected devices: %v.", len(trezors))
+		os.Exit(exitcodes.TrezorError)
+	}
+
+	// Using the first found device
+	trezor := trezors[0]
+
+	// Trezor may ask for PIN or Passphrase. Setting the handler for this case.
+	trezor.SetGetPinFunc(trezorGetPin)
+
+	// In some cases (like lost connection to the Trezor device and cannot
+	// reconnect) it's required to get a confirmation from the user to
+	// retry to reconnect. Setting the handler for this case.
+	trezor.SetGetConfirmFunc(trezorGetConfirm)
+
+	// To reset the state of the device and check if it's initialized.
+	// If device is not initialized then trezor.Reset() will return an
+	// error.
+	err := trezor.Reset()
+	if err != nil {
+		tlog.Fatal.Printf("Cannot reset the Trezor device. Error: %v", err.Error())
+		os.Exit(exitcodes.TrezorError)
+	}
+
+	// To generate a deterministic key we trying to decrypt our
+	// predefined constant key using the Trezor device. The resulting key
+	// will depend on next variables:
+	// * the Trezor master key;
+	// * the passphrase (passed to the Trezor).
+	//
+	// The right key will be received only if both values (mentioned
+	// above) are correct.
+	//
+	// Note:
+	// Also the resulting key depends on this values (that we defined as
+	// constants above):
+	// * the key derivation path;
+	// * the "encrypted" payload;
+	// * the nonce;
+	// * the key name.
+	key, err := trezor.DecryptKey(trezorKeyDerivationPath, payload, []byte(trezorNonce), trezorKeyName)
+	if err != nil {
+		tlog.Fatal.Printf("Cannot get the key from the Trezor device. Error description:\n\t%v", err.Error())
+		os.Exit(exitcodes.TrezorError)
+	}
+
+	// Sanity checks
+	if len(key) != TrezorPayloadLen {
+		log.Panicf("BUG: decrypted value has wrong length %d", len(key))
+	}
+	if bytes.Equal(key, payload) {
+		log.Panicf("BUG: payload and decrypted value are identical")
+	}
+	zero := make([]byte, TrezorPayloadLen)
+	if bytes.Equal(key, zero) {
+		log.Panicf("BUG: decrypted value is all-zero")
+	}
+
+	// Everything ok
+	return key
+}