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--- ac:laboratoare:09 [2024/12/15 05:09]
dimitrie.valu [3. Card verification method (2p)]
+++ ac:laboratoare:09 [2024/12/15 06:42] (current)
dimitrie.valu
@@ Line 82: / Line 82: @@
 Note that the following CV Rule that would be applied in the case of PIN failure is ''%%0b00000000%%'', i.e. **Fail CVM processing**.
+The only cardholder verification method allowed is, hence, plaintext PIN verification.
 </solution>
@@ Line 105: / Line 107: @@
 <solution -hidden>
+''%%T->C: 80CA9F1700%%''
+Command APDU Format: ''%%CLA INS P1 P2 Le%%''
 <code>
-T->C: 80CA9F1700
+= (CLA) (class) proprietary class of commands, not ISO 7816-standard.
-CA = GET DATA
+CA = (INS) (instruction) GET DATA.
+From here, we know to look into Book 3, 6.5.7 - GET DATA Command-Response APDUs.
+F17 = (P1+P2) (parameters 1/2) Tag of data that the terminal is requesting.
+In this case, it's PIN Try Counter.
+= (Le) Length of command data, 0=no data is being sent with this command.
 </code>
+''%%C->T: 6C04%%''
+Status Bytes Format: ''%%SW1 SW2%%'' (Status Bytes 1 and 2)
+<code>
+C = (SW1) Wrong length Le.
+= (SW2) The correct, exact length.
+</code>
+''%%T->C: 80CA9F1704%%''
+Command APDU Format: ''%%CLA INS P1 P2 Le%%''
+<code>
+Same as the first command, but with a correct length:
+= (Le) Length of command data, i.e. PIN is 4-bytes long.
+</code>
+''%%C->T: CA9F1701069000%%''
+Response APDU Format: ''%%Data SW1 SW2%%''
+<code>
+CA = Echo of the INS byte (GET DATA).
+F17 = The tag for the data object being returned (PIN Try Counter).
+= Length of the value being returned, in bytes.
+= Value of the data object (i.e. 6 remaining PIN attempts).
+= Operation successful.
+</code>
 </solution>
 ==== 4. Card-holder verification (2p) ====
@@ Line 129: / Line 172: @@
 </note>
+<solution -hidden>
+''%%T->C: 0020008008241111FFFFFFFFFF%%''
+Command APDU Format: ''%%CLA INS P1 P2 Lc Data%%''
+<code>
+= (CLA) ISO 7816 class of instructions for standard commands.
+= (INS) VERIFY. Used for Cardholder Verification, such as PIN verification
+= (P1) PIN verification applies to the currently selected application.
+= (P2) Specifies the PIN type and format (plaintext data for 80).
+= (Lc) (Length of data) Data field is 8 bytes long.
+FFFFFFFFFF = (Data) Of which:
+= The PIN to be verified.
+FFFFFFFFFF = Padding (used to fill until 8 bytes).
+</code>
+''%%C->T: 9000%%''
+Status Bytes Format: ''%%SW1 SW2%%''
+<code>
+= Operation successful.
+= No additional information.
+</code>
+**The card successfully verified the PIN sent by the terminal.**
+</solution>
 ==== 5. Transaction authentication (2p) ====
@@ Line 149: / Line 220: @@
 </note>
+<solution -hidden>
+''%%T->C: 80AE80002B00000000000000000000000000008000000000000000000000000000003400000000000000000000410002%%''
+Command APDU Format: ''%%CLA INS P1 P2 Lc Data%%''
+**The terminal is sending a Generate Application Cryptogram (GEN AC) command to request an ARQC (Authorisation Request Cryptogram) for transaction authentication.**
+<code>
+= (CLA) Proprietary command.
+AE = (INS) GEN AC (Generate Application Cryptogram). This is used for transaction authentication.
+It requests the card to generate a cryptogram to verify the integrity of the transaction.
+= (P1) Terminal is requesting an Authorisation Request Cryptogram (ARQC).
+= (P2) RFU.
+B = (Lc) (Length of Data) 43 bytes.
+The data itself follows. It is broken into:
+000000000000 = Amount Authorized
+000000000000 = Amount Other
+= Terminal Country Code
+= Transaction Currency Code
+= Transaction Date
+= Transaction Type
+0000000000000000 = Unpredictable Number (randomly generated)
+= Data Authentication Code (ARQC input)
+</code>
+''%%C->T: 612B%%''
+Status Bytes Format: ''%%SW1 SW2%%''
+<code>
+= Card has more data to send.
+B = 43 bytes of data are available for retrieval.
+</code>
+''%%T->C: 00C000002B%%''
+Command APDU Format: ''%%CLA INS P1 P2 Le%%''
+**Here, the terminal is requesting 43 bytes of data from the card.**
+<code>
+= ISO 7816 standard.
+C0 = GET RESPONSE.
+= RFU.
+= RFU.
+B = 43 bytes.
+</code>
+''%%C->T: C077299F2701809F360201349F2608817C3AAB208BE0659F10120310A00006250400000000000000000000FF9000%%''
+Response APDU Format: ''%%Data SW1 SW2%%''
+<code>
+Data is broken into:
+C0 = Proprietary or issuer-specific data.
+= Template for cryptogram-related data (EMV tag 77).
+Following data is TLV-encoded:
+F27 = Cryptogram Information Data (CID).
+= Length of CID data.
+= Cryptogram type: ARQC (Authorisation Request Cryptogram).
+F36 = Application Transaction Counter (ATC).
+= ATC value length.
+= ATC value (Counter = 308).
+F26 = Application Cryptogram.
+= Length of cryptogram.
+C3AAB208BE065 = The actual cryptogram generated by the card.
+F10 = Issuer Application Data (IAD).
+= Length of IAD.
+A00006250400000000000000000000FF = Encrypted issuer-specific data (used for ARQC verification).
+= Operation successful, no more information.
+</code>
+**The response is concluded with 9000, meaning the operation was successful. This data will be sent to the issuer for further authentication.**
+</solution>
 ==== MAC generation (Bonus) (2p) ====
@@ Line 167: / Line 321: @@
 </note>
-<hidden>
+<solution -hidden>
-==== Getting data from your card ====
+We should allow students to select the data somewhat arbitrarily as it's not **entirely** provided in the exercises above, as per the minimum spec mentioned in EMV Book 2, page 87, section 8.1.1, table 28.
-First, get pyscard from
+<code python>
-[[https://pypi.python.org/pypi/pyscard|here]].
+from Crypto.Cipher import DES3
+from Crypto.Util.Padding import pad
-Then, install pyscard (check the readme). Do the following (as root):
+master_key = bytes.fromhex("79610497EFCB67E5546EF8CEBCB05D85")
-  * Install pcsclite-dev:
+aip = bytes.fromhex("1000")
-<code>
-sudo apt-get install libpcsclite-dev
-</code>
-  * Only if the above doesn't work, then install these packages:
-<code>
-#apt-get install swig libudev-dev git autoconf libtool libsystemd-dev flex
-</code>
-  * Get and install Pyscard from [[https://pypi.python.org/pypi/pyscard|here]]
-<code>
-#python setup.py build_ext install
-</code>
-  * Install Pyserial
-<code>
-#sudo pip install pyserial
-</code>
-If this doesn't work, then get pyserial from [[https://pypi.python.org/pypi/pyserial#downloads|here]]
-  * Install pcsc related libs:
-<code>
-sudo apt-get install libusb-dev libusb++-0.1-4v5 libccid pcscd libpcsclite1
-</code>
-  * Only if desired, additional tools can be installed from here:
-<code>
-#apt-get install libpcsc-perl
-#apt-get install pcsc-tools
-</code>
-See details [[http://support.gemalto.com/fileadmin/user_upload/IAM/FAQ/How_to_install_the_PC-Link_reader_on_Linux.pdf|here]].
+# concatenation of amount authorised and amount other,
+# terminal country code, transaction currency code,
+# transaction date, transaction type,
+# unpredictable number, given AIP and the ATC
+# we aren't given the terminal verification results,
+# so I assumed that it's gonna be 5 * b'00'
+transaction_data = bytes.fromhex(
+        "00000000000000000000000008000000000000000000000034000000000000000010000134"
+        ) # from task 5
+# 3DES block size is 8 bytes
+padded_data = pad(transaction_data, 8)
-Files for accessing card data [[https://ocw.cs.pub.ro/courses/_media/ac/laboratoare/sclink.zip|here]].
+# 3DES encryption
-</hidden>
+cipher = DES3.new(master_key, DES3.MODE_ECB)
+mac = cipher.encrypt(padded_data)
+mac = mac.hex()
+print(mac)
+</code>
+</solution>

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ac/laboratoare/09.1734232147.txt.gz · Last modified: 2024/12/15 05:09 by dimitrie.valu

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