EMV Tools

Introduction

The EMV & Card Tools group — smart card, EMV and contactless payment tools — is organised by the stage of a transaction it belongs to: offline authentication first (SDA, DDA), then the cryptogram calculators for each scheme, then the issuer-script and token tools that run after authorisation.

Every calculator carries its own activity log on the right, so each intermediate value — derived key, session key, recovered certificate — is visible rather than just the final result.

All tools

Every tool in this group, in the order an EMV transaction reaches them — each card links to the detailed reference below.

SDA Verification

Static Data Authentication: the terminal verifies issuer-signed static data against a CA public key. The tool splits the job into the two steps the terminal performs — recover the issuer public key from its certificate, then use that key to check the signature over the card’s static data.

Retrieve Issuer Public Key

Inputs

• CA PK Modulus and CA PK Exponent — From the Visa / MasterCard CA hierarchy, for the index in tag 8F.
• Issuer PK Certificate — Tag 90.
• Issuer PK Remainder — Tag 92; optional.
• Issuer PK Exponent — Tag 9F32.

Button: Retrieve Key. Every field carries a live character count, and one with an odd number of hex characters is flagged before you run it — the usual cause of a certificate that will not recover.

Verify SSAD

Inputs

• Issuer PK Modulus — The key recovered in the previous step.
• SSAD (Signed Static Data) — Tag 93, built from the AFL records.

Button: Verify SSAD. The log reports the recovered hash alongside the pass/fail result, so a mismatch can be traced to the data rather than the key.

DDA Verification

Dynamic Data Authentication: the card signs terminal-supplied dynamic data, proving it holds the ICC private key. Three tabs walk the chain down — issuer key, then card key, then the signature itself.

Retrieve ICC Public Key

Inputs

• Issuer PK Modulus / Exponent — Recovered on the first tab.
• ICC PK Certificate — Tag 9F46.
• ICC PK Remainder — Tag 9F48; optional.
• ICC PK Exponent — Tag 9F47.
• Static Data To Authenticate — The AFL-built record the certificate hash covers.
• AIP — Tag 82, which the hash includes when the card asks for it.

Button: Retrieve ICC Key.

Verify SDAD

Inputs

• ICC PK Modulus / Exponent — From the previous tab.
• SDAD (Signed Dynamic Data) — Tag 9F4B, returned by INTERNAL AUTHENTICATE.
• Dynamic Data — The terminal’s unpredictable number, e.g. from tag 9F37.

Button: Verify Dynamic Signature.

EMV 4.1 Crypto Calculator

The reference cryptogram calculator, and the one to learn the flow on: five tabs that follow the key hierarchy from the issuer master key down to the response cryptogram — UDK Derivation, Session Keys, Cryptogram, ARPC, Utilities. The scheme-specific calculators below are the same shape with their own derivations.

UDK Derivation

• Master Derivation Key (MDK) — 32 hex characters; the counter turns green at the right length.
• PAN and PAN Sequence — What binds the derived key to one card. The PAN is Luhn-checked, and a failure is a warning rather than a block: the banner reads PAN Luhn checksum failed, but calculation will proceed, which is what you want for test PANs.
• Derivation Option — OPTION_A or OPTION_B.
• Key Parity — ODD, EVEN or none.

Button: Calculate UDK.

Session Keys

• Master Key (UDK) — The card key from the previous tab.
• Initial Vector (IV) — 32 hex characters; zeros for the common case.
• ATC — The transaction counter the session key is diversified on.
• Branch Factor and Height — The EMV tree parameters, defaulting to 50 and 8.
• Key Parity

Button: Generate Session Key.

Cryptogram

• Session Key — From the Session Keys tab.
• Terminal Data — The CDOL-built terminal side of the request.
• ICC Data — AIP, ATC, CVR and the rest of the card side.
• Cryptogram Type — ARQC, TC or AAC. The button label follows the selection.
• Padding Method — e.g. METHOD_1_ISO_9797.

ARPC

• Session Key and Transaction Cryptogram — The ARQC the card produced.
• Response Code — The two-character ARC, e.g. Y3.
• ARPC Method — Method 1 or 2.

Button: Generate ARPC.

Utilities

Key validation helpers that sit alongside the derivation tabs. Paste a Key (Hex) and Calculate KCV returns its check value — the quickest way to confirm the key you loaded is the key you meant.

EMV 4.2 Crypto Calculator

The same five tabs against the EMV 4.2 rules. The UDK tab states its derivation in the panel subtitle — EMV 4.2 Option A — and drops the separate parity selector, so the form is just the master key and the card identifiers.

• Master Derivation Key (MDK) — 32 characters.
• Primary Account Number (PAN)
• PAN Sequence Number

Button: Calculate UDK. Session key, cryptogram and ARPC follow on their own tabs exactly as in 4.1.

MasterCard M/Chip Crypto Calculator

M/Chip’s own derivation, with a fifth tab that 4.1 and 4.2 do not have: Session Key (EMV 2000), kept for cards personalised against the older scheme.

• MDK, PAN, PAN Sequence No.
• UDK Derivation Option — Option A or Option B.
• Key Parity — NONE by default here, unlike the EMV 4.1 tool.

Button: Generate UDK. The cryptogram tab is labelled AAC/ARQC/TC — one tab covering all three types.

VSDC Crypto Calculator

Visa Smart Debit/Credit, in four tabs: UDK, Session Keys, AAC/ARQC/TC, ARPC.

• MDK, PAN, PAN Sequence No.
• UDK Derivation Option — Option A by default.
• Key Parity — Odd by default.

Button: Generate UDK.

Secure Messaging

Issuer scripts reach the card after authorisation, and Secure Messaging is what protects them: SMI for integrity, SMC for confidentiality. Three tabs cover the sequence — derive the session keys, build the encrypted PIN block a PIN-change script carries, then MAC the command.

Session Key

• Input Key Type — MK to start from the master keys.
• MK-SMI and MK-SMC — The integrity and confidentiality master keys, 32 characters each.
• Application Cryptogram (AC) — Diversifies the session keys onto this transaction.
• Command Number — Advances with each script command in the sequence.

Button: Generate Session Keys.

PIN Block

• Output PIN Block Format — Standard EMV PIN Block by default.
• SK-ENC — The encryption session key from the previous tab.
• New PIN — The value the script will set.

Button: Generate PIN Block.

MAC

The MAC covers the command as the card will see it, so the form takes the APDU apart rather than asking for one hex blob:

• SK-MAC — The integrity session key.
• Class, INS, P1, P2, Lc, Le — The APDU header and lengths.
• ARC and AC — Authorisation response code and application cryptogram.
• Payload — The script data itself.

CAP Token Computation

Computes the Chip Authentication Programme token some banks ask for as an online-banking second factor — the number a customer reads off a handheld reader and types into the website.

Inputs

• IPB — Issuer Processing Base, the mask that selects which bits reach the token.
• IAF — Issuer Action Format.
• PAN + SN — PAN with its sequence number appended.
• CID — Cryptogram Information Data.
• ATC — Application Transaction Counter.
• AC — The application cryptogram the card generated.
• IAD — Issuer Application Data.

Button: Generate Token.

HCE (Host Card Emulation)

Host Card Emulation puts the card credential in a phone instead of a chip, so the key that signs a tap is short-lived by design. The Visa HCE calculator follows that chain across four tabs: card key, then the Limited-Use Key it produces, then the two contactless cryptograms an HCE wallet can present.

LUK Key

The Limited-Use Key is bound to a point in time, which is what limits it:

• UDK — The card key from the first tab.
• Current Year (YY) and Current Hours (HH) — The window the key belongs to.
• Hourly Counter — Which key within that hour.

Button: Generate LUK.

MSD

Magnetic Stripe Data mode — the legacy contactless path, where the phone presents a dynamic value in a magstripe-shaped message.

• LUK_ATC — The limited-use key with its counter.
• MSD Device Type — Drop-down.

qVSDC

The full contactless cryptogram. Each field is labelled with the EMV tag it comes from, so a capture can be transcribed straight in:

• LUK
• Amount (9F02), Amount, Other (9F03)
• Country Code (9F1A), Currency Code (5F2A)
• TVR (95), AIP (82), CVR (from 9F10)
• Transaction Date (9A), Transaction Type (9C)
• Unpredictable No. (9F37), ATC (9F36)

Tips

• For SDA / DDA work, double-check the CA public key index in tag 8F matches the CA you supply — mismatched indices is the most common SDA failure.
• Cryptogram versions vary by issuer, and the CVN is encoded inside the IAD (tag 9F10) — read it before picking a calculator, because the derivation differs.
• Work the tabs left to right. Each one consumes what the previous produced, and the activity log keeps every intermediate key so you can restart mid-chain rather than from the master key.