Nonvolatile semiconductor memory and method of managing information in information distribution system
View Patent ↗There is provided semiconductor memory capable of reconfiguring an area to be given an authentication key and access limitation, and there is implemented an information distribution system having an advanced security function using the semiconductor memory. Part of a storage area in the semiconductor memory stores information about the area to be given the authentication key and the access limitation. Alternatively, the authentication key is stored in units of data to be authenticated for limiting an access to stored information. Information is protected doubly by storing encrypted information in the area provided with the access limitation according to the above-mentioned method.
1. A nonvolatile semiconductor memory formed on a semiconductor substrate comprising:
a memory cell array containing a plurality of nonvolatile memory cells;
a decoder driver to select a nonvolatile memory cell addressed from the memory cell array; and
an access right check circuit supplied with an input command and an input address, the access right check circuit being provided in the nonvolatile semiconductor memory, wherein
the access right check circuit compares access control information about an access control area limiting a specified access in the memory cell array with the input command and the input address supplied to the access right check circuit, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input command and the input address do not comply with an access limited for an address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input command and the input address comply with an access limited for the address control area;
the access control information includes address information about an access-limited area and a limited access mode; and
information included in the access control information is specifiable by means of a command.
2. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 1 , wherein
the limited access mode includes any of writing, reading, and erasing.
3. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 1 , wherein
the access control information has a first key provided in correspondence with the access-limited area;
the access right check circuit further compares the first key with an input key input together with the input command and the input address, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key matches the first key or the input command and the input address do not comply with an access limited for the address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key does not match the first key and the input command and the input address comply with an access limited for the address control area; and
the first key included in the access control information is specifiable by means of a command.
4. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 3 , wherein
a first access control area and a second access control area are included as the access control area; and
the second access control area can be specified including an area overlapping with the first access control area.
5. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 3 , wherein
a plurality of first keys can be specified for the access control area.
6. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 5 , wherein
the plurality of first keys has a predetermined relationship.
7. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 1 , further comprising:
a plurality of access control areas, wherein
the access right check circuit stores a table that stores address information about the access-limited area out of a plurality of access control areas and the limited access mode.
8. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 1 , wherein
the access control information is stored each time a read operation is performed.
9. A nonvolatile semiconductor memory formed on a semiconductor substrate comprising:
a memory cell array containing a plurality of nonvolatile memory cells;
a decoder driver to select a nonvolatile memory cell addressed from the memory cell array; and
an access right check circuit supplied with an input command and an input address,
wherein
the access right check circuit compares access control information about an access control area limiting a specified access in the memory cell array with the input command and the input address supplied to the access right check circuit, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input command and the input address do not comply with an access limited for an address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input command and the input address comply with an access limited for the address control area;
the access control information includes address information about an access-limited area and a limited access mode; and
information included in the access control information is specifiable by means of a command,
wherein
the access right check control information has a first key provided in correspondence with the access-limited area;
the access right check circuit further compares the first key with an input key input together with the input command and the input address, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key matches the first key or the input command and the input address do not comply with an access limited for the address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key does not match the first key and the input command and the input address comply with an access limited for the address control area;
the first key included in the access control information is specifiable by means of a command, and
wherein
the access control information has a permitted access mode allowed when the input key does not match the first key; and
the access right check circuit provides control to select a nonvolatile memory cell specified by the input address via the decoder driver even if the input key and the first key do not match and if the input command is included in the permitted access mode.
10. A nonvolatile semiconductor memory formed on a semiconductor substrate comprising:
a memory cell array containing a plurality of nonvolatile memory cells;
a decoder driver to select a nonvolatile memory cell addressed from the memory cell array; and
an access right check circuit supplied with an input command, an input address and an input key, the access right check circuit being provided in the nonvolatile semiconductor memory,
wherein a specified area in the memory cell array is an access limitation area limiting a specified access and stores access control information including an access mode limited for the access limitation area and a first key;
wherein the access right check circuit compares the access control information with the input command, the input address and the input key, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key matches the first key or the input command and the input address do not comply with an access limited for the address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key does not match the first key and the input command and the input address comply with an access limited for the address control area; and
wherein the access limitation area stores data encrypted with a second key.
11. The nonvolatile semiconductor memory formed on the semiconductor substrate according to claim 10 , wherein
a person who specifies the first key differs from a person who specifies the second key.
12. A nonvolatile semiconductor memory formed on a semiconductor substrate comprising:
a memory cell array containing a plurality of nonvolatile memory cells;
a decoder driver to select a nonvolatile memory cell addressed from the memory cell array; and
an access right check circuit supplied with an input command, an input address and an input key,
wherein a specified area in the memory cell array is an access limitation area limiting a specified access and stores access control information including an access mode limited for the access limitation area and a first key;
wherein the access right check circuit compares the access control information with the input command, the input address and the input key, provides control to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key matches the first key or the input command and the input address do not comply with an access limited for the address control area, and provides control not to select a nonvolatile memory cell specified by the input address via the decoder driver when the input key does not match the first key and the input command and the input address comply with an access limited for the address control area;
wherein the access limitation area stores data encrypted with a second key, and
wherein
the access control information has a permitted access mode allowed when the input key does not match the first key; and
the access right control circuit provides control to select a nonvolatile memory cell specified by the input address via the decoder driver even if the input key and the first key do not match and if the input command is included in the permitted access mode.