Updated on 2026-08-14

tangem-core/src/main/java/com/tangem/CardManager.kt

@@ -177,6 +177,46 @@ class CardManager(
         runTask(task, cardId, callback)
     }
 
+		/**
+		 * This command write some of User_Data, User_ProtectedData, User_Counter and User_ProtectedCounter fields.
+		 * User_Data and User_ProtectedData are never changed or parsed by the executable code the Tangem COS.
+		 * The App defines purpose of use, format and it's payload. For example, this field may contain cashed information
+		 * from blockchain to accelerate preparing new transaction.
+		 * User_Counter and User_ProtectedCounter are counters, that initial values can be set by App and increased on every signing
+		 * of new transaction (on SIGN command that calculate new signatures). The App defines purpose of use.
+		 * For example, this fields may contain blockchain nonce value.
+		 *
+		 * Writing of User_Counter and User_Data protected only by PIN1.
+		 * User_ProtectedCounter and User_ProtectedData additionaly need PIN2 to confirmation.
+		 */
+		fun writeUserData(
+				cardId: String,
+				userData: ByteArray,
+				userProtectedData: ByteArray? = null,
+				userCounter: Int? = null,
+				userProtectedCounter: Int? = null,
+				callback: (result: TaskEvent<WriteUserDataResponse>) -> Unit
+		) {
+			val writeIssuerDataCommand = WriteUserDataCommand(userData, userProtectedData, userCounter, userProtectedCounter)
+			val task = SingleCommandTask(writeIssuerDataCommand)
+			runTask(task, cardId, callback)
+		}
+
+		/**
+		 * This command returns two up to 512-byte User_Data, User_Protected_Data and two counters User_Counter and
+		 * User_Protected_Counter fields.
+		 * User_Data and User_ProtectedData are never changed or parsed by the executable code the Tangem COS.
+		 * The App defines purpose of use, format and it's payload. For example, this field may contain cashed information
+		 * from blockchain to accelerate preparing new transaction.
+		 * User_Counter and User_ProtectedCounter are counters, that initial values can be set by App and increased on every signing
+		 * of new transaction (on SIGN command that calculate new signatures). The App defines purpose of use.
+		 * For example, this fields may contain blockchain nonce value.
+		 */
+		fun readUserData(cardId: String, callback: (result: TaskEvent<ReadUserDataResponse>) -> Unit) {
+			val task = SingleCommandTask(ReadUserDataCommand())
+			runTask(task, cardId, callback)
+		}
+
     /**
      * This command will create a new wallet on the card having ‘Empty’ state.
      * A key pair WalletPublicKey / WalletPrivateKey is generated and securely stored in the card.
@@ -211,8 +251,7 @@ class CardManager(
     /**
 
      */
-    fun <T> runTask(task: Task<T>, cardId: String? = null,
-                    callback: (result: TaskEvent<T>) -> Unit) {
+    fun <T> runTask(task: Task<T>, cardId: String? = null, callback: (result: TaskEvent<T>) -> Unit) {
         if (isBusy) {
             callback(TaskEvent.Completion(TaskError.Busy()))
             return

tangem-core/src/main/java/com/tangem/commands/ReadUserDataCommand.kt

@@ -1,5 +1,83 @@
 package com.tangem.commands
 
+import com.tangem.common.CardEnvironment
+import com.tangem.common.apdu.CommandApdu
+import com.tangem.common.apdu.Instruction
+import com.tangem.common.apdu.ResponseApdu
+import com.tangem.common.tlv.TlvBuilder
+import com.tangem.common.tlv.TlvMapper
+import com.tangem.common.tlv.TlvTag
+import com.tangem.tasks.TaskError
+
 /**
 [REDACTED_AUTHOR]
- */
+ */
+class ReadUserDataResponse(
+		/**
+		 * CID, Unique Tangem card ID number.
+		 */
+		val cardId: String,
+
+		/**
+		 * Data defined by user's App.
+		 */
+		val userData: ByteArray,
+
+		/**
+		 * Data defined by user's App (confirmed by PIN2).
+		 */
+		val userProtectedData: ByteArray,
+
+		/**
+		 * Counter initialized by user's App and increased on every signing of new transaction
+		 */
+		val userCounter: Int,
+
+		/**
+		 * Counter initialized by user's App (confirmed by PIN2) and increased on every signing of new transaction
+		 */
+		val userProtectedCounter: Int
+
+): CommandResponse {
+	companion object {
+		internal fun fromMapper(mapper: TlvMapper): ReadUserDataResponse = ReadUserDataResponse(
+				cardId = mapper.map(TlvTag.CardId),
+				userData = mapper.map(TlvTag.IssuerData),
+				userProtectedData = mapper.map(TlvTag.IssuerDataSignature),
+				userCounter = mapper.map(TlvTag.IssuerDataCounter),
+				userProtectedCounter = mapper.map(TlvTag.IssuerDataCounter)
+		)
+	}
+}
+
+/**
+ * This command returns two up to 512-byte User_Data, User_Protected_Data and two counters User_Counter and
+ * User_Protected_Counter fields.
+ * User_Data and User_ProtectedData are never changed or parsed by the executable code the Tangem COS.
+ * The App defines purpose of use, format and it's payload. For example, this field may contain cashed information
+ * from blockchain to accelerate preparing new transaction.
+ * User_Counter and User_ProtectedCounter are counters, that initial values can be set by App and increased on every signing
+ * of new transaction (on SIGN command that calculate new signatures). The App defines purpose of use.
+ * For example, this fields may contain blockchain nonce value.
+ */
+class ReadUserDataCommand: CommandSerializer<ReadUserDataResponse>() {
+
+	override fun serialize(cardEnvironment: CardEnvironment): CommandApdu {
+		val serializedTlv = TlvBuilder().apply {
+			append(TlvTag.CardId, cardEnvironment.cardId)
+			append(TlvTag.Pin, cardEnvironment.pin1)
+		}.serialize()
+
+		return CommandApdu(Instruction.ReadIssuerData, serializedTlv)
+	}
+
+	override fun deserialize(cardEnvironment: CardEnvironment, responseApdu: ResponseApdu): ReadUserDataResponse? {
+		val tlvData = responseApdu.getTlvData() ?: return null
+
+		return try {
+			ReadUserDataResponse.fromMapper(TlvMapper(tlvData))
+		} catch (exception: Exception) {
+			throw TaskError.SerializeCommandError()
+		}
+	}
+}

tangem-core/src/main/java/com/tangem/commands/WriteUserDataCommand.kt

@@ -1,5 +1,64 @@
 package com.tangem.commands
 
+import com.tangem.common.CardEnvironment
+import com.tangem.common.apdu.CommandApdu
+import com.tangem.common.apdu.Instruction
+import com.tangem.common.apdu.ResponseApdu
+import com.tangem.common.tlv.TlvBuilder
+import com.tangem.common.tlv.TlvMapper
+import com.tangem.common.tlv.TlvTag
+import com.tangem.tasks.TaskError
+
 /**
 [REDACTED_AUTHOR]
- */
+ */
+
+class WriteUserDataResponse(
+		/**
+		 * CID, Unique Tangem card ID number.
+		 */
+		val cardId: String
+): CommandResponse
+
+/**
+ * This command write some of User_Data, User_ProtectedData, User_Counter and User_ProtectedCounter fields.
+ * User_Data and User_ProtectedData are never changed or parsed by the executable code the Tangem COS.
+ * The App defines purpose of use, format and it's payload. For example, this field may contain cashed information
+ * from blockchain to accelerate preparing new transaction.
+ * User_Counter and User_ProtectedCounter are counters, that initial values can be set by App and increased on every signing
+ * of new transaction (on SIGN command that calculate new signatures). The App defines purpose of use.
+ * For example, this fields may contain blockchain nonce value.
+ *
+ * Writing of User_Counter and User_Data protected only by PIN1.
+ * User_ProtectedCounter and User_ProtectedData additionaly need PIN2 to confirmation.
+ */
+class WriteUserDataCommand(
+		private val userData: ByteArray? = null,
+		private val userProtectedData: ByteArray? = null,
+		private val userCounter: Int? = null,
+		private val userProtectedCounter: Int? = null
+): CommandSerializer<WriteUserDataResponse>() {
+	override fun serialize(cardEnvironment: CardEnvironment): CommandApdu {
+		val serializedTlv = TlvBuilder().apply {
+			append(TlvTag.CardId, cardEnvironment.cardId)
+			append(TlvTag.Pin, cardEnvironment.pin1)
+			append(TlvTag.UserData, userData)
+			append(TlvTag.UserCounter, userCounter)
+			append(TlvTag.UserProtectedData, userProtectedData)
+			append(TlvTag.UserProtectedCounter, userProtectedCounter)
+			if (userProtectedCounter != null || userProtectedData != null)
+				append(TlvTag.Pin2, cardEnvironment.pin2)
+		}.serialize()
+		return CommandApdu(Instruction.ReadIssuerData, serializedTlv)
+	}
+
+	override fun deserialize(cardEnvironment: CardEnvironment, responseApdu: ResponseApdu): WriteUserDataResponse? {
+		val tlvData = responseApdu.getTlvData() ?: return null
+
+		return try {
+			WriteUserDataResponse(TlvMapper(tlvData).map(TlvTag.CardId))
+		} catch (exception: Exception) {
+			throw TaskError.SerializeCommandError()
+		}
+	}
+}

tangem-core/src/main/java/com/tangem/common/apdu/Instruction.kt

@@ -18,7 +18,9 @@ enum class Instruction(var code: Int) {
     Sign(0xFB),
     PurgeWallet(0xFC),
     Activate(0xFE),
-    OpenSession(0xFF);
+    OpenSession(0xFF),
+		WriteUserData(0xE0),
+		ReadUserData(0xE1);
 
 
     companion object {

tangem-core/src/main/java/com/tangem/common/tlv/TlvTag.kt

@@ -94,7 +94,6 @@ enum class TlvTag(val code: Int) {
 
     ProductMask(0x8A),
     PaymentFlowVersion(0x54),
-    UserCounter(0x2C),
 
 
     TokenSymbol(0xA0),
@@ -107,7 +106,12 @@ enum class TlvTag(val code: Int) {
 
     TerminalIsLinked(0x58),
     TerminalPublicKey(0x5C),
-    TerminalTransactionSignature(0x57);
+    TerminalTransactionSignature(0x57),
+
+		UserData(0x2A),
+		UserProtectedData(0x2B),
+		UserCounter(0x2C),
+		UserProtectedCounter(0x2D);
 
     /**
      * @return [TlvValueType] associated with a [TlvTag]