Magtek eDynamo Programmer's Manual page 196

Appendix B - Examples
Offset Usage Name
854 Track 3 Absolute data length
MagnePrint Absolute data
855
length
To decrypt this data, the host software would first examine the KSN field FFFF9876543210E00008,
and break it down into base key FFFF9876543210E and the key counter is 0x00008 (see section 6.15
DUKPT Key Serial Number for details). The host would use this information to calculate encryption
key 27F66D5244FF621E AA6F6120EDEB427F, which is also provided in the ANSI standard
documentation's examples for convenience.
There are five encrypted values: Track 1 encrypted data, track 2 encrypted data, track 3 encrypted data,
encrypted MagnePrint data, and encrypted session ID. The remainder of this section details the procedure
for decrypting these data values.
The track 1 encrypted data is:
C2 5C 1D 11 97 D3 1C AA
87 28 5D 59 A8 92 04 74
26 D9 18 2E C1 13 53 C0
51 AD D6 D0 F0 72 A6 CB
34 36 56 0B 30 71 FC 1F
D1 1D 9F 7E 74 88 67 42
D9 BE E0 CF D1 EA 10 64
C2 13 BB 55 27 8B 2F 12
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
Because the Track 1 Encrypted Data Length (HID | GATT | SLIP) value in the incoming data says
Track 1 Encrypted data is 64 bytes long, the host software can truncate the trailing blocks:
Block # Content
1 C25C1D1197D31CAA
2 87285D59A8920474
3 26D9182EC11353C0
4 51ADD6D0F072A6CB
5 3436560B3071FC1F
6 D11D9F7E74886742
7 D9BEE0CFD1EA1064
8 C213BB55278B2F12
Section 5 Encryption, Decryption, and Key Management tells us to decrypt the last block first:
C213BB55278B2F12 TDES Decrypt with 27F66D5244FF621E AA6F6120EDEB427F gets
eDynamo| Secure Card Reader Authenticator | Programmer's Manual (COMMANDS)
1F
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Data