Chilkat2-Python

PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)

See more SCard Examples

Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Chilkat2-Python

import sys
import chilkat2

success = False

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

scard = chilkat2.SCard()

# First establish a context to the PC/SC Resource Manager
success = scard.EstablishContext("user")
if (success == False):
    print(scard.LastErrorText)
    sys.exit()

# First we'll examine the state of all connected readers to see which have smartcards already inserted..
# Get JSON containing information about the smartcards currently inserted into readers.
# This also includes information about USB security tokens.
json = chilkat2.JsonObject()
success = scard.FindSmartcards(json)
if (success == False):
    print(scard.LastErrorText)
    sys.exit()

# When writing this example, I have 3 smart card readers plugged into my system.
# One of them has a smart card inserted.
# Here's the JSON returned by FindSmartcards...

# {
#   "reader": [
#     {
#       "name": "Alcor Micro USB Smart Card Reader 0",
#       "state": "empty"
#     },
#     {
#       "name": "Generic Smart Card Reader Interface 0",
#       "state": "present",
#       "vendorName": "Generic",
#       "serialNumber": "3230303730383138303030303030303030",
#       "systemName": "Generic Smart Card Reader Interface 0",
#       "card": {
#         "atr": "3BFC180000813180459067464A00641606F2727E00E0",
#         "windows": {
#           "miniDriver": "tagliov70px.dll",
#           "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
#           "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
#         }
#       }
#     },
#     {
#       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
#       "state": "empty"
#     }
#   ]
# }

json.EmitCompact = False
print(json.Emit())
print(" ")

# We can iterate over the JSON to find the readers with a smart card already inserted..

sbState = chilkat2.StringBuilder()

i = 0
count_i = json.SizeOfArray("reader")
while i < count_i :
    json.I = i
    name = json.StringOf("reader[i].name")

    sbState.Clear()
    json.StringOfSb("reader[i].state",sbState)

    if (sbState.Contains("present",True) == True):
        print(name + " has a smart card inserted.")
    else:
        print(name + " does not have a smart card inserted.")

    i = i + 1

print(" ")

# Now let's begin the code to wait for a change (where a smart card gets inserted or removed)

# Get the list of all readers.
stReaders = chilkat2.StringTable()
success = scard.ListReaders(stReaders)
if (success == False):
    print(scard.LastErrorText)
    sys.exit()

# Show the reader names..
numReaders = stReaders.Count
i = 0
while i < numReaders :
    print(str(i) + ": " + stReaders.StringAt(i))
    i = i + 1

# Sample output from the above loop.
# 0: Alcor Micro USB Smart Card Reader 0
# 1: Generic Smart Card Reader Interface 0
# 2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
# 

# Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
json2 = chilkat2.JsonObject()
success = scard.GetStatusChange(30000,stReaders,json2)
if (success == False):
    print(scard.LastErrorText)
    sys.exit()

print(" ")

# Let's see what happened...
json2.EmitCompact = False
print(json2.Emit())
print(" ")

# This is what json2 contains.
# A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
# The "numChanged" indicates that one reader's status changed.  
# The "changed":true indicates the reader that changed.   The state is now "present".

# {
#   "numChanged": 1,
#   "reader": [
#     {
#       "name": "Alcor Micro USB Smart Card Reader 0",
#       "changed": false,
#       "state": "empty"
#     },
#     {
#       "name": "Generic Smart Card Reader Interface 0",
#       "changed": false,
#       "state": "present",
#       "atr": "3BFC180000813180459067464A00641606F2727E00E0"
#     },
#     {
#       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
#       "changed": true,
#       "state": "present",
#       "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
#     }
#   ]
# }

# Find the reader that changed...

numChanged = json2.IntOf("numChanged")
print("number of readers with a changed state: " + str(numChanged))

i = 0
count_i = json2.SizeOfArray("reader")
while i < count_i :
    json2.I = i
    changed = json2.BoolOf("reader[i].changed")
    if (changed == True):
        name = json2.StringOf("reader[i].name")
        state = json2.StringOf("reader[i].state")

        print("Changed: ")
        print("    reader name: " + name)
        print("    new state: " + state)

        # If a card is now in this reader, we should have the ATR of the card..
        if (json2.HasMember("reader[i].atr") == True):
            atr = json2.StringOf("reader[i].atr")
            print("    ATR of card inserted into this reader: " + atr)

    i = i + 1

# The output from the above loop:

# number of readers with a changed state: 1
# Changed: 
#     reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
#     new state: present
#     ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09

# Applications should always release the context when finished.
success = scard.ReleaseContext()
if (success == False):
    print(scard.LastErrorText)