SCard B4X (B4A / B4J) Reference Documentation
ChilkatSCard
Current Version: 11.6.0
Chilkat.SCard
Enumerate available PC/SC smart card readers and identify the reader the
application should use.
Connect to a reader/card, check card presence and status, and manage the
active PC/SC connection.
Send APDU commands directly to the card and receive the raw response
bytes and status words.
Issue lower-level reader control commands when supported by the reader
driver and PC/SC environment.
Monitor reader or card status changes so applications can detect card
insertion, removal, or state changes.
Use PC/SC transactions for coordinated card access and inspect detailed
error information when reader or card operations fail.
For an extended overview, see
SCard Class Overview.
Communicate directly with smart card readers and cards through PC/SC.
Chilkat.SCard is the low-level PC/SC smart card interface for
applications that need direct reader and card communication. It supports
reader discovery, reader connection, card status checking, APDU transmission,
reader-control commands, status-change monitoring, transactions, and
diagnostic access to underlying PC/SC errors. Use this class when the
application needs APDU-level control rather than a higher-level certificate,
minidriver, or PKCS#11 abstraction.
Reader discovery
Connect to cards
Transmit APDUs
Reader-control commands
Status monitoring
Transactions and diagnostics
Chilkat.SCard for direct PC/SC
reader and APDU-level work; use Chilkat.ScMinidriver for
card-minidriver certificate and key-container operations, and
Chilkat.Pkcs11 for PKCS#11 token or HSM sessions.
Declare / Initialize / Dispose
Sub Process_Globals
Private obj As ChilkatSCard
End Sub
' Call Initialize before first use -- typically in AppStart (B4J)
' or Activity_Create (B4A):
obj.Initialize ' classes without events
obj.Initialize("evt") ' classes with events: "evt" becomes the
' prefix of event Subs such as evt_PercentDone
Creates the underlying native Chilkat object. Classes that support events take an EventName argument: it becomes the prefix of the event Subs (<EventName>_AbortCheck, <EventName>_PercentDone, <EventName>_ProgressInfo); classes without events take no arguments. The native Chilkat library loads automatically on the first Initialize — from the APK on Android, or extracted from ChilkatB4J.jar on Windows/Linux/macOS.
True if Initialize has been called and the native object exists.
Explicitly frees the underlying native object. Calling Dispose is optional — every ChilkatSCard is also freed automatically when garbage-collected — but is recommended for long-lived objects holding sockets, sessions, or large buffers. A disposed object can be re-Initialized.
Properties
ActiveProtocol
ActiveProtocol As String
The name of the active protocol if connected smart card reader, or an empty string if not connected. Possible values are T0, T1, raw, undefined, or if not connected to a reader.
CardAtr
CardAtr As String
This is the Current ATR of a card in the connected reader.
topConnectedReader
ConnectedReader As String
The name of the currently connected smart card reader, or an empty string if not connected.
topContext
Context As String
Contains the string user or system if this object has established a context (by calling EstablishContext). Contains the empty string if no context is established.
DebugLogFilePath
DebugLogFilePath As String
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastErrorHtml
LastErrorHtml As String
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
LastErrorText As String
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
LastErrorXml As String
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
LastMethodSuccess As Boolean
Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
PcscLibPath
PcscLibPath As String
For Linux systems only. Specifies the full path of the libpcsclite.so shared lib. This property should only be used if the libpcsclite.so is in a non-standard location or if Chilkat cannot automatically located it.
topReaderStatus
ReaderStatus As String
The current status of the connected reader. Possible values are:
absent- There is no card in the reader.present- There is a card in the reader, but it has not been moved into position for use.swallowed- There is a card in the reader in position for use. The card is not powered.powered- Power is being provided to the card, but the reader driver is unaware of the mode of the card.negotiable- The card has been reset and is awaiting PTS negotiation.specific- The card has been reset and specific communication protocols have been established.
ScardError
ScardError As String
The last error returned by an underlying PC/SC function. Can be one of the following:
SCARD_W_REMOVED_CARD- The smart card has been removed, so that further communication is not possible.SCARD_W_RESET_CARD- The smart card has been reset, so any shared state information is invalid.
...
VerboseLogging
VerboseLogging As Boolean
If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
Version As String
Methods
BeginTransaction
Establishes a temporary exclusive access mode for doing a series of commands in a transaction.
Returns True for success, False for failure.
topCheckStatus
Check the current status of the currently connected reader. Calling this method updates the ReaderStatus, ActiveProtocol, and CardAtr properties. If this method returns False, none of the properties are updated.
Returns True for success, False for failure.
Connect
Establish a connection to a reader. The reader is the name of a reader returned from ListReaders. The shareMode can be shared, exclusive, or direct. The preferredProtocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.)
If successful, the state of this object instance is that it's connected to the reader.
Returns True for success, False for failure.
Disconnect
Terminates a connection with a reader. The disposition can be one of the following values:
leave: Do nothing.reset: Reset the card (warm reset).unpower: Power down the card (cold reset).eject: Eject the card.
Returns True for success, False for failure.
EndTransaction
Ends a previously begun transaction. The disposition is the action to be taken on the reader, and can be leave which is to do nothing, reset, unpower, or eject.
Returns True for success, False for failure.
topEstablishContext
Creates an Application Context to the PC/SC Resource Manager. This must be the first WinSCard function called in a PC/SC application. The scope can be user or system. After calling, this object will have context and all other methods will use the established context. The Context property will hold the value user or system if context was established, or will be empty if no context was established.
Returns True for success, False for failure.
topFindSmartcards
Returns JSON containing information about the smartcards currently inserted into readers.
Returns True for success, False for failure.
GetAttrib
Get an attribute from the IFD Handler (reader driver).
The attr can be one of the following:
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
The attribute data is returned in bd.
Returns True for success, False for failure.
topGetAttribStr
Get a string typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return string values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns Null on failure
GetAttribUint
Get an unsigned integer typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return unsigned integer values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns 0xFFFFFFFF on failure.
topGetStatusChange
Blocks execution until the current availability of the cards in a specific set of readers changes.
This function receives a list of reader names in stReaderNames. It then blocks waiting for a change in state to occur for a maximum blocking time of maxWaitMs (in milliseconds) or forever if 0 is used.
Information about the current reader states and which reader(s) changed is returned in json. See the example below for more information.
To wait for a reader event (reader added or removed) you may use the special reader name \\?PnP?\Notification.
To cancel the ongoing call, call Cancel().
The stReaderNames contains the reader names to check. The json is empty on input, and if the call returns success contains information about the state (after the event change) of each reader.
Returns True for success, False for failure.
GetStatusChangeCancel
Cancels an ongoing GetStatusChange method call. This would be called from a separate thread in your application if GetStatusChange was called synchronously.
Returns True for success, False for failure.
topListReaderGroups
Returns a list of currently available reader groups on the system. The reader groups are returned in readerGroups.
Returns True for success, False for failure.
topListReaders
Returns a list of currently available readers on the system.
Returns True for success, False for failure.
Reconnect
Reestablishes a connection to a reader that was previously connected to using Connect().
In a multi application environment it is possible for an application to reset the card in shared mode. When this occurs any other application trying to access certain commands will be returned the value SCARD_W_RESET_CARD. When this occurs Reconnect() must be called in order to acknowledge that the card was reset and allow it to change its state accordingly.
The shareMode can be shared, exclusive, or direct. The preferredProtocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.) The action is the desired action taken on the card/reader. It can be leave, reset, unpower, or eject.
If successful, the state of this object instance is that it's connected to the reader.
Returns True for success, False for failure.
topReleaseContext
Destroys a communication context to the PC/SC Resource Manager. This must be the last function called in a PC/SC application.
Returns True for success, False for failure.
topSendControl
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is sent in bdSend. The response is written to bdRecv.
Returns True for success, False for failure.
topSendControlHex
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is provided as a hex string in sendData. The response is written to bdRecv.
Returns True for success, False for failure.
topTransmit
Sends an APDU to the smart card contained in the currently connected reader. The protocol can be T0, T1, or raw. The APDU to be sent is contained in bdSend. The response from the card is contained in bdRecv. The maxRecvLen is the maximum response size (in bytes) willing to be accepted.
Returns True for success, False for failure.
topTransmitHex
Sends an APDU to the smart card contained in the currently connected reader. The protocol can be T0, T1, or raw. The APDU (in hexadecimal) to be sent is passed in apduHex. The response from the card is contained in bdRecv. The maxRecvLen is the maximum response size (in bytes) willing to be accepted.
Returns True for success, False for failure.
topEvents
All Chilkat methods are synchronous: the call returns when the work is done. During a call, ChilkatSCard raises three events so your application can show progress and offer a way out. The event-name prefix is the string passed to Initialize:
scard.Initialize("evt") ' event Subs are named evt_AbortCheck, evt_PercentDone, evt_ProgressInfo
scard.HeartbeatMs = 250 ' raise evt_AbortCheck 4 times per second during Chilkat callsAbortCheck fires at regular intervals controlled by the HeartbeatMs property (0, the default, disables it); PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values. Returning True from an AbortCheck or PercentDone Sub aborts the running method. Implement only the Subs you need — events are skipped entirely when no matching Sub exists.
If a Chilkat call runs on a separate thread (e.g. via the Threading library), its events are automatically queued to the main thread. Events raised that way cannot abort by return value; set the object's AbortCurrent property to True instead.
AbortCheck
' Return True to abort the Chilkat method in progress.
Sub evt_AbortCheck As Boolean
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example (object initialized with scard.Initialize("evt")):
scard.HeartbeatMs = 250 ' fire evt_AbortCheck 4 times per second
Sub evt_AbortCheck As Boolean
' Called every HeartbeatMs milliseconds while a Chilkat method is running.
Return False ' Return True to abort the method in progress
End SubPercentDone
' Return True to abort the Chilkat method in progress.
Sub evt_PercentDone (PctDone As Int) As Boolean
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to True. This will cause the method to terminate and return a failure status or corresponding failure value.
Example (object initialized with scard.Initialize("evt")):
Sub evt_PercentDone (PctDone As Int) As Boolean
' PctDone ranges from 1 to 100.
Log("Percent done: " & PctDone)
Return False ' Return True to abort the method in progress
End SubProgressInfo
Sub evt_ProgressInfo (Name As String, Value As String)
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example (object initialized with scard.Initialize("evt")):
Sub evt_ProgressInfo (Name As String, Value As String)
Log(Name & ": " & Value)
End Sub