AT88RF04C-MY1G View Datasheet(PDF) - Atmel Corporation
Part Name
Description
Manufacturer
AT88RF04C-MY1G Datasheet PDF : 158 Pages
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AT88SC0808/1616/3216/6416CRF, AT88RF04C
K.6.
Key Sets
CryptoRF has four Key Sets. Each Key Set is associated with four registers in the Configuration Memory. The
Authentication Key is stored in the Secret Seed Gi register. The Authentication Attempt Counter for Secret Seed Gi is
stored in the AACi register. The Cryptogram Ci register is used during Authentication Activation and Encryption
Activation procedures to store the response to the Host challenge. The Session Key Si register is used to store the
Encryption Activation key.
Figure 38. Partial Configuration Memory map showing the Key Set Registers.
$0
$1
$2
$3
$4
$5
$6
$7
$50
AAC0
$58
$60
AAC1
$68
$70
AAC2
$78
$80
AAC3
$88
$90
$98
$A0
$A8
Cryptogram C0
Session Encryption Key S0
Cryptogram C1
Session Encryption Key S1
Cryptogram C2
Session Encryption Key S2
Cryptogram C3
Session Encryption Key S3
Secret Seed G0
Secret Seed G1
Secret Seed G2
Secret Seed G3
Cryptography
Secret
Figure 38 shows the portion of the Configuration Memory that contains the Key Set registers. The registers shaded in
green can always be read, but cannot be written after personalization. The registers shaded in blue cannot be written
or read after personalization. Note that all of the Security Fuses must be programmed during personalization for the
device secrets to be secure.
Key Set i uses registers AACi, Ci, Gi and Si. If AACi is locked, the Key Set i is permanently disabled and any User Zone
requiring Key Set i for Authentication or Encryption Activation will no longer be accessible.
K.6.1. Changing Keys
The Secret Seeds cannot be modified after the Security Fuses are programmed during personalization. The AAC
registers cannot be re-written after the Security Fuses are programmed either. This is true even if the SME option in the
DCR register is enabled.
5276C–RFID–3/09
119
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