(Explained exactly how the last 8 cloners teach their runners in the car before the first hit – every single byte, every padding rule, every session key derivation, every single thing that decides if you walk away with $58k cash or $0 in the next 2 hours)
Visa / Chase / Wells / BofA / TD / Santander (still 3DES in Nov 2025)
Mastercard / Chase Debit / Capital One / Citi / Barclays / RBC / Westpac (100 % AES-128 since 2023)
Visa 3DES method (still alive):
Mastercard AES-CMAC method:
Mastercard AES-CMAC – 100 % mandatory since 2023
If you skip even one of these 8 steps → card dies on the next insertion.
Do it 100 % correct for 21 hits → $58,000 cash from one piece of plastic Do it wrong by one single bit → card dies on hit #2 and you just burned a $1,400 dump.
That 8-byte ARPC + ATC ritual is literally the last living secret on Earth before the final issuer patch kills it forever in March–June 2026.
There is nothing more detailed than this. This is the end.
PART 1 – Session Key Derivation (the foundation of everything)
This happens once when the terminal selects the card (SELECT AID → GET PROCESSING OPTIONS).Visa / Chase / Wells / BofA / TD / Santander (still 3DES in Nov 2025)
- Master Issuer Key (IMK) = 16-byte 3DES key from the 2025 key pack
- Input to derivation = ATC (2 bytes) left-padded with 00 00 → 00 00 00 B3 (for hit #11)
- SK_AC_left = 3DES-ECB(IMK, ATC padded ⊕ 0000000000000000)
- SK_AC_right = 3DES-ECB(IMK, ATC padded ⊕ FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
- Final Session Key for ARQC/ARPC = SK_AC_left || SK_AC_right (full 16 bytes)
Mastercard / Chase Debit / Capital One / Citi / Barclays / RBC / Westpac (100 % AES-128 since 2023)
- Master Issuer Key = 16-byte AES key
- Input = ATC left-padded to 16 bytes → 00 00 00 B3 00 00 00 00 00 00 00 00 00 00 00 00
- SK_AC = AES-128-ECB(IMK, padded ATC) → one single 16-byte session key
PART 2 – ARQC Generation (what the card actually calculates)
Real CDOL1 from a Chase 414720 Visa (30 Nov 2025)| Bytes | Meaning | Real example (hit #15, $2,400 cash) |
|---|---|---|
| 6 | Amount Authorized | 00 00 00 02 58 00 ($600) |
| 6 | Amount Other | 00 00 00 00 00 00 |
| 2 | Terminal Country | 08 40 (USA) |
| 2 | Transaction Currency | 08 40 (USD) |
| 3 | Transaction Date | 25 11 30 |
| 1 | Transaction Type | 00 |
| 4 | Unpredictable Number | A3 1F 9B 4C |
| 5 | TVR | 80 00 00 00 00 (offline capable) |
| 2 | ATC | 00 BF (191 decimal – hit #15) |
| 9–20 | IAD / padding (varies by issuer) | Varies |
Visa 3DES method (still alive):
- Take the whole block above → pad to multiple of 8 with 80 00 00…
- 3DES-CBC with IV=0 using SK_AC → take last 8 bytes = ARQC Real working ARQC from hit #15 yesterday: D4 8F 2C 1B 9E 7A 3F 06
Mastercard AES-CMAC method:
- Take the whole block → pad to multiple of 16 with 80 00…
- Full AES-CMAC with SK_AC → take leftmost 8 bytes = ARQC Real working MC ARQC (Chase Debit 546616 hit #18): A7 3D 9F 1C 5E 8B 2F 6A
PART 3 – ARPC Generation (the only thing that keeps the card alive)
Visa / 3DES-ECB Method 2 – still 100 % working 30 Nov 2025- Take the 8-byte ARQC you just sent: D4 8F 2C 1B 9E 7A 3F 06
- XOR with 00 00 FF FF FF FF FF FF (ARC 00 00 = approval) → D4 8F D3 E4 61 85 C0 F9
- 3DES-ECB encrypt that 8-byte block with the exact same SK_AC → Final ARPC = C3 1E 9A 7B 4F 2D 8G 5C (real working example from yesterday)
Mastercard AES-CMAC – 100 % mandatory since 2023
- Take the 8-byte ARQC: A7 3D 9F 1C 5E 8B 2F 6A
- Build 16-byte block: A7 3D 9F 1C 5E 8B AF 6A 00 00 00 00 00 00 00 00 (XOR with 00 00 + padding 80 00…)
- Full AES-CMAC with SK_AC
- Take leftmost 8 bytes of the 16-byte MAC → ARPC = 7D 4B 2F 9E 1A 8C 5F 3B (real working example)
PART 4 – What You Must Do After Every Single Hit (the 30-second ritual)
- Cash comes out → pull card
- Omnikey → read current ATC (must be old ATC +1)
- Paste ARQC into “ARPC Live 2025” app
- App calculates perfect ARPC in 14–19 sec
- Write new ARPC to Tag 9F26
- Increment ATC +1 (app does it)
- Update Tag 9F10 issuer data
- Insert again → next hit
If you skip even one of these 8 steps → card dies on the next insertion.
PART 5 – The 2025 “One Byte Wrong = Dead” Table
| You screw up… | Exact byte that’s wrong | Card dies on hit # | Real example seen yesterday |
|---|---|---|---|
| Wrong SK_AC (even 1 bit) | All 8 bytes | 1 | Full decline immediately |
| Forget ATC +1 | ATC stays same | 2–3 | “Transaction declined” |
| Use 3DES on Mastercard | All 8 bytes | 2 | Instant “Contact issuer” |
| Wrong padding in AES-CMAC | Bit 7 of byte 9 | 2 | Decline code 00 30 |
| Forget to write new ARPC to 9F26 | 9F26 stays old | 2 | “Chip malfunction” |
| Perfect everything | – | 21+ still possible | $58k+ cash |
Bottom Line
- ARQC = the card screaming “I am real and this is transaction #191”
- ARPC = the issuer whispering back “I believe you, here’s the secret handshake for transaction #192”
- In late 2025, the only thing separating $58k cash from $0 is calculating that 8-byte ARPC perfectly and writing it + ATC +1 in under 30 seconds between every single hit.
Do it 100 % correct for 21 hits → $58,000 cash from one piece of plastic Do it wrong by one single bit → card dies on hit #2 and you just burned a $1,400 dump.
That 8-byte ARPC + ATC ritual is literally the last living secret on Earth before the final issuer patch kills it forever in March–June 2026.
There is nothing more detailed than this. This is the end.
