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Key

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The format of the PAN cryptogram is:

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E(card-data) = ID(Kpan-pub)|| IVpan-session ||ERSA-OAEP-SHA-1(Kpan-pub, Kpan-session)||Eaes-ecb(Kpan-session, IVpan-session, card-data)

With:

  • ID(Kpan-pub) is the public key identifier.

Which translates into:

Note

Cryptogram format changed starting secure client v1.0.9

Object

Length (bytes)

Comments

RSA Key ID length

12

Length of the RSA key ID (MSB)

RSA Key ID

var

RSA key ID used for the session key encryption

Encrypted KEK length

2

Length of the encrypted KEK block (MSB - should be 256)

Encrypted KEK

256

Encrypted KEK block:

  • encrypted with RSA key (RSA/ECB/OAEPWithSHA-256AndMGF1Padding)

  • cleartext contains the KEK (16 bytes) and the IV (16 bytes)

Encrypted card data length

2

Length of the encrypted card data block (MSB )

Encrypted sensitive card data

var

Encrypted sensitive card data:

  • encrypted with KEK key (AES/CBC/NoPadding)

  • cleartext which can contain the following tags :(as TLV)

    • ‘56’ (Track1)

    • ‘57’ (Track2)

    • ‘5A’ (PAN)

    • ‘90’ (Issuer Public Key Certificate)

    • ‘9F46’ (ICC Public Key Certificate)

    • ‘9F6B’ (Track2 data - MasterCard)

The sensitive card data are organized in a simple TLV stream before being encrypted.

Example

Below is an example of data received after a successful card data export:

Code Block
053cb9dd2f509ead9d7d203cf268e9df4f61b88ccf4a7cf25e62c19099088689a7098309be3ed7d3e61c3a7
26d56a45124f1ce7f1551db784d4452e8da020bf7732e9365e9092643d5ebde4fb6a8706d83fc46fab5f0
7d0729abd11604207565f6c513d81ebbae3d81a4f131b5ff1eef45b06febc2d49ffd37956f418c61322c5
df44552170af975f1a35dfda7dce7304a3637dcce962e4a466cf77d9374af8400f1cc029c037f37e3bcbf
2279adba8383145b226d4c4be4fa95381f66845ccd56a3b98fe933fac5b9e379ad55ce46b997a62ff1455
0719421f8891d49396f9b7ee203493bc140958081d1525857e1df74ff3fb6d367577cf2dd1636e4961cce
391a2943f79035e1e076d4f210a3b3c657d79cbda1c22ee1e4f28dbe71679b9fd14ea01645209825507cc
161522f505524279b3379aaa45dfd3e697c79024b28523b9ba2f267cc477413cb87b57ba5696d2983599d
ccbcd08ab9cd15d36f2507022a81e4f1f684089e9679ab5e8f06bb8efbe66e78500fb0187e142cce11499
76c5aec2b1b6b

Which can be split into:

  • The key ID:

Code Block
3cb9dd2f50

  • The encrypted KEK:

Code Block
9ead9d7d203cf268e9df4f61b88ccf4a7cf25e62c19099088689a7098309be3ed7d3e61c3a726d56a4512
4f1ce7f1551db784d4452e8da020bf7732e9365e9092643d5ebde4fb6a8706d83fc46fab5f07d0729abd1
1604207565f6c513d81ebbae3d81a4f131b5ff1eef45b06febc2d49ffd37956f418c61322c5df44552170
af975f1a35dfda7dce7304a3637dcce962e4a466cf77d9374af8400f1cc029c037f37e3bcbf2279adba83
83145b226d4c4be4fa95381f66845ccd56a3b98fe933fac5b9e379ad55ce46b997a62ff14550719421f88
91d49396f9b7ee203493bc140958081d1525857e1df74ff3fb6d367577cf2dd1636e4961cce391a2943f7
90

  • The encrypted card data:

Code Block
35e1e076d4f210a3b3c657d79cbda1c22ee1e4f28dbe71679b9fd14ea01645209825507cc161522f50552
4279b3379aaa45dfd3e697c79024b28523b9ba2f267cc477413cb87b57ba5696d2983599dccbcd08ab9cd
15d36f2507022a81e4f1f684089e9679ab5e8f06bb8efbe66e78500fb0187e142cce1149976c5aec2b1b6
b

Applying an RSA decryption (RSA/ECB/OAEPWithSHA-256AndMGF1Padding) on the “encrypted KEK” block will lead to:

  • The KEK:

Code Block
68bd9a24627d8a40f64d7a365d6bfd07

  • The IV:

Code Block
b7edc9e4625c73bd2fcbdb9b2cc77672

Applying a AES decryption (AES/CBC/NoPadding) on the “encrypted card data” block will provide the following data:

Code Block
563342353431333333303035373030343036325e4355535420494d50204d43203430362f5e32353132323
03130323234303038373057115413330057004062d2512201022400870f5a0854133300570040629f6b11
5413330057004062d2512201022400870f000000000000000000000000000000000000000000000000000
0

Which can be split into:

  • Tag ‘56’ (Track1)

Code Block
42353431333333303035373030343036325e4355535420494d50204d43203430362f5e32353132323
031303232343030383730

  • Tag ‘57’ (Track2)

Code Block
5413330057004062d2512201022400870f

  • Tag ‘5A’ (PAN)

Code Block
5413330057004062

  • Tag ‘9F6B’ (Track2 data)

Code Block
5413330057004062d2512201022400870f

  • Padding

...

HMAC Key ID length

2

Length of the HMAC key ID (MSB)

HMAC Key ID

var

HMAC key ID used for the checksum calculation

HMAC length

2

Length of the HMAC checksum (MSB - should be 32)

HMAC

32

AES-CBC-256 checksum