I'm just playing arround with encrypting/decrypting. After creating some strong passwords I asked myself how to transmit passwords in a anonymous way.
First idea was Bluetooth but in that case the other device has to be in reach. Sending it via mail or other platforms will (at least) leave traces.
So why not use a picture you took?
1. Send/share this pic to another device (take care it will not abe modified)
2. Store it in the gallery
3. in your app call ContentChooser to let the user select that image
4. Get the bytes of the image
5. From a known position get f.e. 100 bytes
6. You can use this string as a password (same pic - same password on all devices)
7. or use it for further encryption, etc.
Add this permission to your manifest:
First idea was Bluetooth but in that case the other device has to be in reach. Sending it via mail or other platforms will (at least) leave traces.
So why not use a picture you took?
1. Send/share this pic to another device (take care it will not abe modified)
2. Store it in the gallery
3. in your app call ContentChooser to let the user select that image
4. Get the bytes of the image
5. From a known position get f.e. 100 bytes
6. You can use this string as a password (same pic - same password on all devices)
7. or use it for further encryption, etc.
B4X:
Sub choose_pic
Dim chooser As ContentChooser
If chooser.IsInitialized = False Then
chooser.Initialize("chooser")
End If
chooser.Show("image/*", "Choose image")
End Sub
Sub chooser_Result(Success As Boolean, Dir As String, FileName As String)
If Success Then
Dim pwpic As String
Dim InputStream1 As InputStream
InputStream1 = File.OpenInput(Dir, FileName)
Dim OutputStream1 As OutputStream
OutputStream1.InitializeToBytesArray(1000)
File.Copy2(InputStream1, OutputStream1)
Dim buffer() As Byte 'declares an empty array
buffer = OutputStream1.ToBytesArray
Log (buffer.Length)
If buffer.Length<400 Then
Msgbox("Please choose a pic with a size >=400 bytes","")
Else
For i=1 To 100
pwpic=pwpic&Chr(buffer(i+buffer.Length/2)+128) '+128 -> to get positive values
Next
End If
Dim buffer() As Byte
Else
ToastMessageShow("No image selected", True)
End If
End SubAdd this permission to your manifest:
B4X:
AddPermission(android.permission.READ_EXTERNAL_STORAGE)