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EP0137995A2
Expired / Lapsed
EP
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Single-chip microcomputer with encryptable function on program memory
Assignee: Toshiba Corp
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Filing: 1984-08-28
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Granted: —
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Expires: 2004-08-28
Abstract
Abstract A single-chip microcomputer (19) with an encryptable function on program memory encrypts the contents of the memory for protection of secrecy when the data stored in read only memory (ROM) (21) are read to the outside. An encrypting code generator (37) is provided to execute the ancrypting and the encrypting code is stored in an instruc- ion decoder (27), which decodes the encrypting code and sends it to the arithmetic and logic unit (ALU) (33). The ALU encryptes the data from the ROM based on the encrypting code from the decoder, and outputs the result to the outside on an input/output port (25).
Inventors
- 👤 Masafumi C/O Patent Division Watanabe
- 👤 Toshitune C/O Patent Division Ozaki
- 👤 Jiro C/O Patent Division Hirahara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 15:42
CPC Classifications
G; G06; G06F; G06F21/00; G06F21/70; G06F21/71; G06F21/72; G06F21/10; G06F21/101; G06F21/12; G06F21/121; G06F21/125; G06F2221/00; G06F2221/21; G06F2221/2107
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
72 words
A single-chip microcomputer with an encryptable function on program memory, comprising: a program memory (21) which stores a program;, a central processing unit (27, 29, 31, 33) which executes the program read out from said program memory; an input/output port (25) which inputs and outputs from/to the outside data; and means (37, 107, 43, 108, 39) for encrypting the contents of said program memory when the contents are output to the outside.
Claim 2
Dependent Claim
72 words
A single-chip microcomputer with an encryptable function on program memory, comprising: a program memory (21) which stores a program;, a central processing unit (27, 29, 31, 33) which executes the program read out from said program memory; an input/output port (25) which inputs and outputs from/to the outside data; and means (37, 107, 43, 108, 39) for encrypting the contents of said program memory when the contents are output to the outside.
Claim 3
Dependent Claim
33 words
A single-chip microcomputer according to claim 1, characterized in that said means (37, 107, 43, 108) for encrypting is provided at the output port (39) for outputting the contents of said program memory.
Claim 4
Dependent Claim
48 words
A single-chip microcomputer according to claim 1, characterized in that said means (37) for encrypting generates an encrypting code, said central processing unit encrypting data based on the encrypting code from said encrypting means when the program read out of said program memory is output to the outside.
Claim 5
Dependent Claim
31 words
A single-chip microcomputer according to claim 3, characterized in that said means (37) for generating an encrypting code is set in the same process as for setting of said program memory.
Claim 6
Dependent Claim
25 words
A single-chip microcomputer according to claim 3, characterized in that said encrypting rotates the data read out from said program memory by a predetermined value.
Claim 7
Dependent Claim
25 words
A single-chip microcomputer according to claim 3, characterized in that said encrypting inverts a predetermined bit of the data read out from said program memory.
Claim 8
Dependent Claim
25 words
A single-chip microcomputer according to claim 3, characterized in that said encrypting shifts the data read out from said program memory by a predetermined value.
Claim 9
Dependent Claim
87 words
A single-chip microcomputer according to claim 1, characterized in that said central processing unit includes an arithmetic logic unit (33), and said means (37, 107, 43, 108, 39) for encrypting is a data generation means (43) which stores preset encrypting data, said arithmetic and logic unit, and said arithmetic and logic unit performs predetermined logic operations on the data supplied from said data generating means (43) and on the data read out from said program memory, and outputs the result to the outside on said input/output port.
Claim 10
Dependent Claim
28 words
A single-chip microcomputer according to claim 8, characterized in that said data generating means (43) is set in the same process as the setting of said program memory.
Claim 11
Dependent Claim
86 words
A single-chip microcomputer according to claim 1, characterized in that said central processing unit includes an arithmetic and logic unit, said means for encrypting comprises means for generating data (43), in which a predetermined code is stored and means (37) for generating an encrypting code which shows the contents of the encrypted data, said arithmetic and logic unit operates the data read out from said program memory and the code data from said data generator based on the encrypting data from said encrypting data generating means.
Claim 12
Dependent Claim
30 words
A single-chip microcomputer according to claim 10, characterized in that said data generator and said encrypting code generating means (37) are set in the same process as said program memory.
Claim 13
Dependent Claim
33 words
A single-chip microcomputer according to claim 8, characterized in that the values of the encrypting data output from said data generating means (43) are different for every fixed area of said program memory.
Claim 14
Dependent Claim
29 words
A single-chip microcomputer according to claim 8, characterized in that the encrypting data from said data generating means (43) is provided corresponding to every bit in said program memory.
Claim 15
Dependent Claim
33 words
A single-chip microcomputer according to claim 10, characterized in that the values of the encrypting data output from said data generating means (43) are different for every fixed area of said program memory.
Claim 16
Dependent Claim
29 words
A single-chip microcomputer according to claim 10, characterized in that the encrypting data from said data generating means (43) is provided corresponding to every bit in said program memory.
References Cited (Backward Citations)
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