Specific APDU error codes from your attempts (e.g., 6985 vs. 05)

[Mutt]

In the context of smart card technology and "carding" (often referring to interactions with smart cards, such as payment cards, SIM cards, or other chip-based cards used in secure systems), APDU (Application Protocol Data Unit) error codes are critical for diagnosing issues during communication between a card reader (or terminal) and a smart card. These error codes, part of the ISO/IEC 7816-4 standard, are returned as two-byte status words (SW1 and SW2) in the response APDU, indicating the success or failure of a command and the specific reason for any failure. The query asks about specific error codes "6985" and "05" in the context of carding, with a request for detailed, educational information. As noted, "05" is ambiguous since APDU status words are always two bytes, so I’ll interpret it as a potential shorthand for a status word like 6905 or a related value, and I’ll provide a comprehensive explanation tailored to carding scenarios, such as payment card transactions (e.g., EMV), SIM card operations, or JavaCard applet interactions.

Below, I’ll break down the error codes 6985 and "05" (assumed as 6905 or a related code), explain their meanings, contexts, causes, and resolutions, and provide educational insights into their relevance in carding. I’ll also include examples, potential debugging steps, and practical considerations for developers, testers, or enthusiasts working with smart cards.

Understanding APDU and Status Words in Carding​

APDUs are the standardized format for commands sent to and responses received from a smart card. A command APDU consists of:

• CLA (Class byte): Indicates the instruction class.
• INS (Instruction byte): Specifies the command (e.g., SELECT, READ RECORD).
• P1, P2 (Parameter bytes): Provide additional command details.
• Lc: Length of the data field (if present).
• Data: Command-specific data (e.g., file identifier, PIN).
• Le: Expected length of the response data (if applicable).

The response APDU includes:

• Data: Returned data (if any).
• SW1, SW2: Status word indicating the command’s outcome (e.g., 9000 for success).

Status words are critical in carding because they reveal why a command failed, guiding developers or testers to fix issues in transaction flows, applet implementations, or card configurations. In carding contexts (e.g., EMV payment cards, SIM cards, or JavaCard applets), errors like 6985 and 6905 are common when commands are sent incorrectly or the card’s state doesn’t permit execution.

Error Code 6985 (SW1=69, SW2=85)​

Meaning​

• Status Word: 0x6985
• Definition: "Command not allowed – Conditions of use not satisfied" (per ISO/IEC 7816-4).
• Explanation: The command is valid and recognized by the card, but it cannot be executed because specific conditions required for its execution are not met. This is a procedural or logical error, often related to the card’s state, incorrect data, or missing prerequisite commands.

Contexts in Carding​

1. EMV Payment Cards:
   • Common during transaction processing, especially with the GET PROCESSING OPTIONS (GPO) command.
   • Example: The terminal sends a GPO command (CLA=80, INS=A8) with a Processing Data Options List (PDOL) that doesn’t match the card’s expectations (e.g., incorrect length, missing tags, or invalid values like a wrong Merchant Type Indicator).
   • Result: The card returns 6985, indicating the data provided doesn’t satisfy the card’s processing conditions.
   • Example APDU:
     • Command: 80 A8 00 00 09 83 07 01 23 45 67 89 00 00 00 00
     • Response: 69 85 (PDOL data invalid, e.g., wrong length or missing required tags like 9F66).
2. JavaCard Applets:
   • Occurs when selecting a file or application with an incorrect identifier or in an invalid context.
   • Example: Sending a SELECT command (CLA=00, INS=A4) with a File Identifier like new byte[]{0002} (incorrect format) instead of new byte[]{0x00, 0x02}.
   • Result: The card returns 6985 because the file or applet cannot be selected due to incorrect parameters or state (e.g., applet not installed or not selectable).
   • Example APDU:
     • Command: 00 A4 04 00 02 00 02
     • Response: 69 85 (Invalid File Identifier or applet not in selectable state).
3. SIM Cards:
   • Seen in commands like EXTERNAL AUTHENTICATE or MANAGE SECURITY ENVIRONMENT (MSE) SET when the card’s state doesn’t allow the operation.
   • Example: Attempting a signature calculation without setting the correct algorithm or security domain reference in a prior MSE SET command.
   • Result: 6985 indicates the card’s security environment isn’t configured correctly.
4. Global Platform (GP) Cards:
   • During applet installation or management, 6985 may occur if an applet cannot be made selectable (e.g., due to card life cycle state or permissions).
   • Example: Issuing a SET STATUS command to make an applet selectable when the card is in a SECURED state but lacks proper privileges.

Causes​

• Incorrect Data Field: The command’s data (e.g., PDOL in EMV, File Identifier in SELECT) is malformed, has incorrect length, or contains invalid values.
• Card State Mismatch: The card’s current state (e.g., application not selected, file not accessible) doesn’t permit the command.
• Missing Prerequisites: A required prior command (e.g., SELECT application, PIN verification) wasn’t executed or failed.
• Application-Specific Conditions: The card’s application (e.g., EMV, JavaCard applet) has specific requirements (e.g., tag values, key settings) that aren’t met.

Resolution​

1. Verify Command Data:
   • Check the command’s Lc, Le, and data fields against the card’s specification (e.g., EMV Book 3 for PDOL structure).
   • Example: For EMV GPO, ensure the PDOL includes correct tags (e.g., 9F66 for Terminal Transaction Qualifiers) and lengths.
2. Ensure Correct Card State:
   • Execute prerequisite commands (e.g., SELECT AID before GPO in EMV: 00 A4 04 00 07 A0 00 00 00 04 10 10).
   • Verify the card’s life cycle state (e.g., OP_READY, SECURED) for Global Platform operations.
3. Debugging Steps:
   • Log the full APDU sequence (commands and responses) using tools like OpenSCDP, GPShell, or a card reader’s debug mode.
   • Compare against the card’s documentation (e.g., EMV Contactless Specifications, JavaCard API, SIM card AT commands).
   • Test with minimal commands to isolate the issue (e.g., SELECT followed by the failing command).
4. Card-Specific Checks:
   • For EMV: Validate PDOL data against the card’s Application Interchange Profile (AIP) and Application File Locator (AFL).
   • For JavaCard: Ensure the applet is installed, selectable, and in the correct state.
   • For SIM cards: Verify authentication status and key derivation.

Educational Insights​

• Why It Matters in Carding: 6985 is a common roadblock in carding because it often indicates a misunderstanding of the card’s requirements or transaction flow. In EMV transactions, for example, the PDOL is a dynamic data structure that varies by card issuer, and errors here can halt a payment. Understanding 6985 helps developers debug complex transaction flows.
• Learning Tip: Study the card’s Application Identifier (AID) and associated specifications (e.g., EMV, Global Platform) to understand expected data formats and command sequences.
• Practical Example:
  • Scenario: Testing an EMV card with a terminal emulator.
  • Command: GPO with PDOL 83 07 01 23 45 67 89 00 00.
  • Response: 69 85.
  • Fix: Check the card’s PDOL requirements (e.g., via READ RECORD on SFI 1, record 1) and correct the data (e.g., 83 0A 01 23 45 67 89 00 00 00 00 00).

Error Code "05" (Assumed as 6905 or Related)​

Clarification on "05"​

Since APDU status words are always two bytes, "05" is not a valid standalone error code. It’s likely a shorthand, typo, or context-specific value. Possible interpretations include:

• 6905: SW1=69, SW2=05 ("Command not allowed – Security status not satisfied").
• Data Field Value: "05" could be a value in the command’s data field or a custom error code in a specific application.
• Other Status Words: Less likely, but could relate to codes like 9405 ("Problems in the data field") or a proprietary code.

For educational purposes, I’ll assume "05" refers to 6905, as it’s a common error in carding contexts and aligns with the security-related issues often encountered. If "05" refers to something else (e.g., a data field value or custom code), please clarify for a more precise analysis.

Meaning (6905)​

• Status Word: 0x6905
• Definition: "Command not allowed – Security status not satisfied" (per ISO/IEC 7816-4).
• Explanation: The command requires specific security conditions (e.g., authentication, secure messaging, or a secure channel) that are not met. This is a security-related error, distinct from 6985’s procedural focus.

Contexts in Carding​

1. EMV Payment Cards:
   • Occurs when a command (e.g., GENERATE AC for Application Cryptogram) requires prior authentication or secure conditions.
   • Example: Attempting GENERATE AC (CLA=80, INS=AE) without completing cardholder verification (e.g., PIN entry) or issuer authentication.
   • Result: The card returns 6905 because the security context (e.g., Cardholder Verification Method or ARQC generation) isn’t established.
   • Example APDU:
     • Command: 80 AE 00 00 09 80 00 00 00 00 00 00 00 00
     • Response: 69 05 (Missing PIN verification or issuer authentication).
2. SIM Cards:
   • Common during authentication commands like EXTERNAL AUTHENTICATE or RUN GSM ALGORITHM.
   • Example: Sending EXTERNAL AUTHENTICATE (CLA=00, INS=88) without a successful RUN GSM ALGORITHM to derive session keys.
   • Result: 6905 indicates the card’s security state (e.g., no authenticated session) doesn’t allow the command.
   • Example APDU:
     • Command: 00 88 00 00 10 [encrypted challenge]
     • Response: 69 05 (No prior authentication or incorrect keys).
3. JavaCard Applets:
   • Seen when a command requires secure messaging or applet-specific authentication.
   • Example: An applet implementing a custom protocol requires a secure channel (e.g., SCP02/SCP03 per Global Platform). Sending a command without initializing the secure channel results in 6905.
   • Example APDU:
     • Command: 00 22 41 B6 00 (MSE SET without secure channel).
     • Response: 69 05 (Secure channel not established).
4. Global Platform Cards:
   • Occurs during card management operations (e.g., INSTALL, LOAD) if the card manager’s security domain isn’t authenticated.
   • Example: Attempting to load an applet without authenticating with the card manager’s keys (e.g., via INITIALIZE UPDATE and EXTERNAL AUTHENTICATE).
   • Result: 6905 indicates missing security privileges.

Causes​

• Missing Authentication: The command requires prior authentication (e.g., PIN verification, mutual authentication with keys) that hasn’t been performed.
• Secure Channel Not Established: Global Platform cards or applets requiring SCP02/SCP03 secure messaging return 6905 if the channel isn’t initialized.
• Incorrect Security Context: The card’s security environment (e.g., key set, algorithm) isn’t configured correctly for the command.
• Application-Specific Security: The card’s application (e.g., SIM, EMV applet) enforces security policies that aren’t satisfied.

Resolution​

1. Perform Authentication:
   • For EMV: Complete cardholder verification (e.g., VERIFY PIN: 00 20 00 80 08 [PIN data]) or issuer authentication (e.g., EXTERNAL AUTHENTICATE with ARPC).
   • For SIM cards: Run prerequisite commands like RUN GSM ALGORITHM to derive session keys before EXTERNAL AUTHENTICATE.
   • For JavaCard/Global Platform: Initialize a secure channel using INITIALIZE UPDATE (80 50 00 00 08 [host challenge]) and EXTERNAL AUTHENTICATE.
2. Verify Secure Messaging:
   • Ensure commands use the correct secure messaging format (e.g., SCP02/SCP03 with MAC and encryption) as required by the card.
   • Example: For Global Platform, append a MAC to commands after establishing a secure channel.
3. Check Card Documentation:
   • Review the card’s security requirements (e.g., EMV Book 2 for security flows, 3GPP for SIM authentication, Global Platform for secure channel protocols).
   • Confirm key sets, algorithm IDs, and security levels match the card’s expectations.
4. Debugging Steps:
   • Use tools like PyAPDU, OpenSCDP, or a card reader’s logging feature to capture the full command-response sequence.
   • Test authentication commands independently to ensure they succeed (e.g., 9000 response).
   • Simulate the transaction flow in a controlled environment to isolate the security issue.

Educational Insights​

• Why It Matters in Carding: 6905 is critical in secure carding scenarios because it protects against unauthorized access or command execution. In EMV, it ensures transactions are authenticated, preventing fraud. In SIM cards, it secures network authentication. Understanding 6905 helps developers implement secure command flows.
• Learning Tip: Study security protocols like EMV’s ARQC-ARPC flow, Global Platform’s SCP02/SCP03, or 3GPP’s MILENAGE algorithm to grasp authentication requirements.
• Practical Example:
  • Scenario: Authenticating a SIM card for network access.
  • Command: EXTERNAL AUTHENTICATE without prior RUN GSM ALGORITHM.
  • Response: 69 05.
  • Fix: Send RUN GSM ALGORITHM (00 88 00 00 10 [RAND]) to derive keys, then retry EXTERNAL AUTHENTICATE with the correct response.

Comparison: 6985 vs. 6905​

Aspect	6985 (Conditions Not Satisfied)	6905 (Security Status Not Satisfied)
SW1-SW2	69 85	69 05
Meaning	Command valid but cannot execute due to logical conditions	Command requires unmet security conditions
Typical Cause	Invalid data (e.g., PDOL, File Identifier), wrong card state	Missing authentication, secure channel, or key setup
Carding Context	EMV GPO, JavaCard SELECT, SIM MSE SET	EMV GENERATE AC, SIM EXTERNAL AUTHENTICATE, GP INSTALL
Fix	Correct data fields, ensure proper command sequence	Perform authentication, establish secure channel
Example	GPO with wrong PDOL → 69 85	GENERATE AC without PIN verification → 69 05

Key Differences​

• 6985: Focuses on procedural errors (e.g., wrong data, missing prerequisites, incorrect card state). It’s about the command’s logical validity.
• 6905: Focuses on security errors (e.g., missing authentication, secure channel, or key setup). It’s about the command’s security context.
• Carding Implication: 6985 often requires fixing data or sequence, while 6905 requires implementing or correcting security protocols.

If "05" Refers to Something Else​

If "05" isn’t 6905 but a data field value, custom error, or typo, here are alternative interpretations:

1. Data Field Value:
   • In some carding applications, "05" could be a value in the command’s data field (e.g., a tag, parameter, or error code returned in the response data).
   • Example: In EMV, a card might return a proprietary error code in the response data (not SW1-SW2) indicating an issue like "invalid parameter = 05."
   • Resolution: Check the card’s documentation for proprietary error codes or data field meanings.
2. Custom or Proprietary Code:
   • Some cards (e.g., vendor-specific JavaCard applets) use non-standard status words or data values like "05" to indicate application-specific errors.
   • Resolution: Consult the card or applet’s technical specification.
3. Typo or Shorthand:
   • If "05" was meant to be part of a larger code (e.g., 9405, "Problems in the data field"), it could indicate issues like incorrect TLV (Tag-Length-Value) data in EMV or SIM commands.
   • Example: 94 05 might occur if a READ RECORD command references a non-existent record.
   • Resolution: Verify the command’s data structure (e.g., correct SFI and record number).

To confirm the meaning of "05," please provide:

• The full status word (e.g., SW1-SW2).
• The command sent (e.g., CLA, INS, P1, P2, data).
• The card type (e.g., EMV, SIM, JavaCard) and context (e.g., transaction, authentication).

Debugging APDU Errors in Carding​

To effectively troubleshoot 6985, 6905, or ambiguous codes like "05" in carding:

1. Use Proper Tools:
   • Card Readers: ACR122U, HID Omnikey, or similar for sending APDUs.
   • Software: OpenSCDP, GPShell, PyAPDU, or card-specific SDKs (e.g., EMV test tools).
   • Logging: Capture full APDU traces (command and response) for analysis.
2. Follow Standards:
   • ISO/IEC 7816-4: Defines standard APDU commands and status words.
   • EMV Specifications: Books 1–4 for payment card transactions.
   • Global Platform: For JavaCard and applet management.
   • 3GPP/ETSI: For SIM/USIM authentication protocols.
3. Test Incrementally:
   • Start with basic commands (e.g., SELECT AID: 00 A4 04 00 [AID]) to confirm card accessibility.
   • Add commands one at a time (e.g., READ RECORD, GPO, VERIFY PIN) to isolate the failing step.
   • Check SW1-SW2 after each command to ensure 9000 (success) or handle errors.
4. Common Carding Scenarios:
   • EMV Transaction:
     • Sequence: SELECT AID → READ RECORD → GPO → VERIFY PIN → GENERATE AC.
     • 6985: Likely at GPO due to PDOL issues.
     • 6905: Likely at GENERATE AC due to missing verification.
   • SIM Authentication:
     • Sequence: SELECT AID → RUN GSM ALGORITHM → EXTERNAL AUTHENTICATE.
     • 6985: Incorrect algorithm setup.
     • 6905: Missing or failed authentication.
   • JavaCard Applet:
     • Sequence: SELECT AID → Custom command (e.g., GET DATA).
     • 6985: Wrong AID or applet state.
     • 6905: Missing secure channel.
5. Error Logging Example:
   • Command: 80 A8 00 00 09 83 07 01 23 45 67 89 00 00
   • Response: 69 85
   • Action: Check PDOL structure in card’s documentation, correct data field (e.g., 83 0A ...).
   • Command: 80 AE 00 00 09 80 00 00 00 00 00 00 00 00
   • Response: 69 05
   • Action: Perform VERIFY PIN (00 20 00 80 08 [PIN]) first.

Educational Takeaways for Carding​

1. APDU Structure Mastery:
   • Understand the roles of CLA, INS, P1, P2, Lc, Data, and Le in commands.
   • Learn response formats: Data + SW1-SW2.
   • Practice crafting APDUs manually or with libraries like javax.smartcardio (Java) or PC/SC APIs.
2. Card-Specific Protocols:
   • EMV: Focus on transaction flows (AID selection, PDOL, cryptograms).
   • SIM/USIM: Study 3GPP authentication (MILENAGE, TUAK algorithms).
   • JavaCard/Global Platform: Learn applet life cycle and secure channel setup.
3. Error Code Interpretation:
   • SW1=69 indicates "Command not allowed," with SW2 specifying why (85 = conditions, 05 = security).
   • Use ISO/IEC 7816-4 as a reference, supplemented by card-specific standards.
4. Security Awareness:
   • Errors like 6905 highlight the importance of authentication and secure channels in carding.
   • Always implement security protocols (e.g., PIN verification, mutual authentication) to avoid 6905.
5. Practical Learning:
   • Set up a test environment with a card reader and sample cards (e.g., EMV test cards, JavaCard dev kits).
   • Experiment with tools like OpenSC or cardpeek to send APDUs and analyze responses.
   • Simulate real-world scenarios (e.g., EMV payment, SIM authentication) to understand error triggers.

Conclusion​

• 6985: Indicates a procedural issue (e.g., invalid PDOL in EMV, wrong File Identifier in JavaCard, or incorrect card state). Fix by correcting data or command sequence.
• 6905 (assumed for "05"): Indicates a security issue (e.g., missing PIN verification, authentication, or secure channel). Fix by implementing required security steps.
• Ambiguous "05": Could be a data field value, custom code, or typo. Clarify the full status word or context for precise analysis.

For further assistance, please provide:

• The exact APDU command sent (e.g., CLA, INS, P1, P2, data).
• The card type (e.g., EMV, SIM, JavaCard).
• The full status word for "05" (e.g., SW1-SW2).
• The carding context (e.g., payment transaction, applet development, SIM authentication).

This will allow a more targeted diagnosis and additional examples tailored to your scenario. For hands-on learning, consider experimenting with a card reader and open-source tools to replicate and resolve these errors in a controlled environment.