US 6,266,416 B1 · Protection of software against use without permit

Abstract

An arrangement to protect software, particularly freely distributed application software, against utilization without permission of the copyright holder. By encrypting the software employing a key (k1) which is different from that key (k2) which is employed in the decryption, better protection is obtained against unauthorized utilization when the decryption key is kept secret to the user. Further improved security is achieved by additionally executing scrambling-descrambling of the communication between the computer in which the software is utilized and the external unit in which the decryption key is stored. Also, the external unit is arranged such that it returns to the host computer, the result from its processing of data received from the host, the result then being utilized in the further execution of the respective program.

Claims30

Dependent claims

A method of preventing unauthorized utilization of software in a computer, the method comprising the steps of:

encrypting only a part of the software in accordance with a first algorithm (g1), wherein said first algorithm uses a public first key (k1);
and
decrypting said encrypted part of the software in accordance with a second algorithm (g2), said second algorithm (g2) together with a private second key (k2) to be employed in said decryption of said encrypted part of the software being stored in an external unit adapted to be connected to the computer, said external unit comprising at least a computer readable storage medium and a processor of its own, wherein said private second key (k2) is different than said public first key (k1) employed in said encryption.

A method of preparing software for the utilization in a computer only with a corresponding authorization, the method comprising:

encrypting in accordance with a first algorithm (g1) only a part of the software;
transferring the software encrypted using said first algorithm (g1) to an external unit connected to the computer;
decrypting within said external unit the software encrypted using said first algorithm (g1) in accordance with a second algorithm (g2), wherein a key which is employed for said encryption in accordance with said first algorithm (g1), is a public first key (k1) which is different from a private second key (k2) which is employed in the execution of said decryption in accordance with said second algorithm (g2) of that part of the software which is encrypted in accordance with said first algorithm (g1) and said public first key (k1).

A method of making authorized utilization possible in a computer of software prepared for utilization in the computer only with a corresponding authorization, the method comprising:

encrypting in accordance with a first algorithm (g1) only a part of the software which by the utilization in the computer is decrypted in accordance with a second algorithm (g2), wherein
a key which is employed for said encryption in accordance with said first algorithm (g1), is a public first key (k1) which is different from a private second key (k2) which is employed in decryption in accordance with said second algorithm (g2) of said part of the software which is encrypted in accordance with said first algorithm (g1) and said public first key (k1),
said encryption of said part of the software in accordance with said first algorithm (g1) is executed on the source code for the software prior to compiling and linking to an executable program, or in similar processing steps producing an executable program, and at the same time adding an object code to the data library of said executable program associated with an external unit adapted to be connected to the computer, and
said compiling and/or linking of said source code to an executable program, or in similar processing steps producing an executable program, call sequences, or similar instructions, are inserted which in the execution in the computer of said executable program causes a jump to a corresponding entry point to said object code, said object code being used to establish a communication channel between the computer and said external unit in which said decryption takes place in accordance with said second algorithm (g2);
connecting said external unit to the computer, said external unit comprising a computer readable storage medium and a processor, said second algorithm (g2) and a said private second key k2 to be employed in said decryption of said encrypted part of the software being stored in said external unit;
and
when the computer in the execution of said part of the software which is encrypted in accordance with said first algorithm (g1) encounters a call sequence, or a similar instruction, causing a jump to a corresponding entry point to said object code, said object code is utilized by the computer to establish a communication channel to said external unit through which communication channel said encrypted part of the software is transferred in a first transfer session to said external unit to be decrypted by said processor of said external unit in accordance with said second algorithm (g2) and said private second key (k2) both of which being stored in said external unit, said second key (k2) being different from said public first key (k1) employed in the execution of said encryption of said part of the software in accordance with said first algorithm (g1), and said decrypted software part then being processed in said external unit and a result transferred in a second transfer session in the opposite direction through said communication channel for the further utilization in the computer.

4 more elements

A device for the preparation of software to be utilized in a computer only with a corresponding authorization, the device comprising:

crypto means effecting the encryption of only a part of the software in accordance with a first algorithm (g1) and a public first key (k1), and
an external unit adapted to be connected to the computer, said external unit comprising a processor and a computer readable storage medium for storing a second algorithm (g2) and a private second key (k2), and being disposed to execute decryption of said encrypted part of the software in accordance with said second algorithm (g2) and said private second key (k2,)
wherein the device further comprises generator means to provide said second algorithm (g2) and said private second key (k2) intended to be employed in said decryption in accordance with said second algorithm (g2), said private second key (k2) being different from said public first key (k1) employed by said crypto means in the execution of said encryption of said part of the software in accordance with said first algorithm (g1).

A device for making authorized utilization of software in a computer possible comprising:

a device including crypto means for effecting the encryption of only a part of the software in accordance with a first algorithm (g1) and a public first key (k1), and an external unit adapted to be connected to the computer, said external unit comprising a processor and a computer readable storage medium for storing a second algorithm (g2) and a private second key (k2), and being disposed to execute decryption of said encrypted part of the software in accordance with said second algorithm (g2) and said private second key (k2), and
generator means to provide said second algorithm (g2) and said private second key (k2) intended to be employed in said decryption in accordance with said second algorithm (g2), said private second key (k2) being different from said public first key (k1) employed by said crypto means in the execution of said encryption of said part of the software in accordance with said first algorithm (g1), said device comprising a computer adapted to serve as a host computer for said external unit,
wherein said external unit comprises decryption means adapted to execute decryption in accordance with said second algorithm (g2) and said private second key (k2) produced by said generator means.

Dependencies are inferred from the claim text.

Protection of software against use without permit

Life of this patent

Protection of software against use without permit

Life of this patent

Abstract

Claims30