The password protection feature enables the host to lock a card while providing a password, which
later will be used for unlocking the card. The password and its size are kept in a 128-bit PWD and 8-bit
PWD_LEN registers, respectively. These registers are non-volatile so that a power cycle will not erase
them. Locked cards respond to (and execute) all commands in the "basic" command class (class 0)
and “lock card” command class. Thus the host is allowed to reset, initialize, select, query for status,
etc., but not to access data on the card. If the password was previously set (the value of PWD_LEN is
not‘0’) will be locked automatically after power on. Similar to the existing CSD and CID register write
commands the lock/unlock command is available in "transfer state" only. This means that it does not
include an address argument and the card has to be selected before using it. The card lock/unlock
command has the structure and bus transaction type of a regular single block write command. The
transferred data block includes all the required information of the command (password setting mode,
PWD itself, card lock/unlock etc.).
4.5.2 Card Identification (CID)
This register contains the card identification information used during the card identification procedure. It
is a 128 bit wide register, one-time programmable by the provider. The CID is divided into eight slices:
The password protection feature enables the host to lock a card while providing a password, which
later will be used for unlocking the card. The password and its size are kept in a 128-bit PWD and 8-bit
PWD_LEN registers, respectively. These registers are non-volatile so that a power cycle will not erase
them. Locked cards respond to (and execute) all commands in the "basic" command class (class 0)
and “lock card” command class. Thus the host is allowed to reset, initialize, select, query for status,
etc., but not to access data on the card. If the password was previously set (the value of PWD_LEN is
not‘0’) will be locked automatically after power on. Similar to the existing CSD and CID register write
commands the lock/unlock command is available in "transfer state" only. This means that it does not
include an address argument and the card has to be selected before using it. The card lock/unlock
command has the structure and bus transaction type of a regular single block write command. The
transferred data block includes all the required information of the command (password setting mode,
PWD itself, card lock/unlock etc.).
This register contains the card identification information used during the card identification procedure. It
is a 128 bit wide register, one-time programmable by the provider. The CID is divided into eight slices: