P5DF081_SDS

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Objective short data sheet

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Rev. 1 — 12 August 2010

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NXP Semiconductors

P5DF081

MIFARE SAM AV2

8.6.2 SAM key management commands

Table 7.

SAM key management commands

Command

Description

AV1 compatibility mode

SAM_ChangeKeyEntry

This command updates any key entry of the KST.

The complete data set of the full key entry must always be sent, and it will be programmed to the

non-volatile memory of the MIFARE SAM AV2 as defined in the non-volatile ProMas.

SAM_GetKeyEntry

The SAM_GetKeyEntry command allows reading the contents of the key entry specified in the

parameter KeyNo.

Instead of the full keys on positions a, b and c, only their key version will be returned, each

packed in one byte.

This command can be issued without valid (host) authentication.

SAM_ChangeKUCEntry

This command updates any key usage counter entry stored in the MIFARE SAM AV2.

Always limit, KeyNoCKUC and KeyVCKUC have to be sent; the parameter ProMas defines which

properties are programmed into the MIFARE SAM AV2 non-volatile memory.

Successful host authentication with the key specified in KeyNoCKUC of the current KUC entry is

required.

SAM_GetKUCEntry

The SAM_GetKUCEntry command allows reading the data of the key usage counter entry

specified within the Parameter RefNoKUC.

This command can be issued without valid (host) authentication.

SAM_DumpSessionKey

The command SAM_DumpSessionKey can be used to retrieve the session key generated by the

MIFARE SAM AV2.

The session key could be retrieved either in plain or encrypted with the session key of any logical

channel. A CRC is appended before encryption as usual.

This feature is necessary if cryptographic operations like en-/decipher should be handled by the

terminal microcontroller instead of the MIFARE SAM AV2.

As this feature can be seen as a

potential security risk if not used in the correct way, it can be en-/disabled using the

configuration settings of every key entry.

SAM_DisableKeyEntry

The SAM_DisableKeyEntry command disables a key entry. After executing this command, the

corresponding disable flag in the key entry is set and the key entry cannot be used anymore for

authentication and key change procedures. The key entry can still be read by a

SAM_GetKeyEntry command. To reactivate the entry, a SAM_ChangeKeyEntry command has to

be issued. All fields in the key entry can still be changed by this command even if the entry has

been disabled.

AV2 Mode

The following rows give an outlook of the changes compared to the AV1 compatibility mode. All commands except

SAM_GetKUCEntry got partially or completely redefined for the AV2 mode. For more information see Ref. 1.

SAM_ChangeKeyEntry

and

SAM_ChangeKUCEntry

In the AV1 version, there are two possibilities for changing key and KUC entries via the

SAM_ChangeKeyEntry and SAM_ChangeKUCEntry respectively. Which possibility is used,

depends on whether the "allow crypto with secret key" of the change key, i.e. the key referenced

by KeyNoCEK or KeyNoCKUC respectively, was set. If set, this allowed for offline preparation of

the key/KUC changing cryptogram.

In the new MIFARE SAM AV2 mode, these two possibilities are still supported, but which

possibility is used depends on the key class of the change key. Change keys are either Host Keys

or OfflineChange Keys. The second class will allow offline command generation.

SAM_GetKeyEntry

The SAM_GetKeyEntry command allows reading the contents of the key entry specified in the

parameter KeyNo.

Instead of the full keys on positions a, b and c, only their key version will be returned, each

packed in one byte.

This command can be issued without valid (host) authentication.