System and apparatus for blockwise encryption/decryption of data
First Claim
1. A system for encrypting and decrypting digital data, wherein the data is divided into packets of N blocks (X(1) . . . X(N)) of 2m bits, said system comprising:
- an encryption device having encryption means for performing a XOR operation (+) and then an encryption operation by means of an encryption algorithm (E) on each block of a packet, wherein encrypted blocks (Y(1) . . . Y(N)) are obtained according to
space="preserve" listing-type="equation">Y(1)=E X(N)+IV!
space="preserve" listing-type="equation">Y(i)=E X(N-i+1)+Y(i-1)! for i>
1 and i≦
N,where IV is an initial vector, and wherein said encryption means reverses the sequence of the blocks (X(1) . . . X(N)) before carrying out the encryption and XOR operations, and wherein said encryption device includes means for reversing the encrypted blocks (Y(1) . . . Y(N)) before transferring the encrypted blocks (Y(1) . . . Y(N)); and
a decryption device having means for performing a decryption algorithm (D) and then the XOR operation on each encrypted block (Y(1) . . . Y(N)), wherein the original blocks (X(1) . . . X(N)) are obtained according to
space="preserve" listing-type="equation">X(i)=D Y(N-i+1)!+Y(N-1) for i=1, 2 . . . , N-1
space="preserve" listing-type="equation">X(N)=D Y(1)!+IV.
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Abstract
A system for encrypting and decrypting digital data wherein the data is divided in packets of N blocks X(1) . . . X(N) of 2m bits, comprises an encryption device and a decryption device. The encryption device reverses the sequence of the blocks X(1) . . . X(N) before a XOR operation and next an encryption operation by means of an encryption algorithm E is carried out on each block of a packet. Thereby the following encrypted blocks Y(1) . . . Y(N) are formed: Y(1)=E X(N)+IV!, Y(i)=E X(N-i+1)+Y(i-1)! for i>1 and i≦N. The encrypted blocks Y(1) . . . Y(N) are transferred by a sender in reversed sequence Y(N) . . . Y(1) to a receiver. The decryption device at the receiver obtains the original blocks X(1) . . . X(N) by carrying out a decryption operation by means of a decryption algorithm D and next a XOR operation on each block Y(N) . . . Y(l) received. Thereby the original blocks are obtained as follows: X(i)=D Y(N-i+1)!+Y(N-i) for i=1, 2, . . . , N-1; X(N)=D Y(1)!+IV.
111 Citations
12 Claims
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1. A system for encrypting and decrypting digital data, wherein the data is divided into packets of N blocks (X(1) . . . X(N)) of 2m bits, said system comprising:
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an encryption device having encryption means for performing a XOR operation (+) and then an encryption operation by means of an encryption algorithm (E) on each block of a packet, wherein encrypted blocks (Y(1) . . . Y(N)) are obtained according to
space="preserve" listing-type="equation">Y(1)=E X(N)+IV!
space="preserve" listing-type="equation">Y(i)=E X(N-i+1)+Y(i-1)! for i>
1 and i≦
N,where IV is an initial vector, and wherein said encryption means reverses the sequence of the blocks (X(1) . . . X(N)) before carrying out the encryption and XOR operations, and wherein said encryption device includes means for reversing the encrypted blocks (Y(1) . . . Y(N)) before transferring the encrypted blocks (Y(1) . . . Y(N)); and a decryption device having means for performing a decryption algorithm (D) and then the XOR operation on each encrypted block (Y(1) . . . Y(N)), wherein the original blocks (X(1) . . . X(N)) are obtained according to
space="preserve" listing-type="equation">X(i)=D Y(N-i+1)!+Y(N-1) for i=1, 2 . . . , N-1
space="preserve" listing-type="equation">X(N)=D Y(1)!+IV. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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- 10. An encryption device for a system for encrypting and decrypting digital data, wherein the data is divided into packets of N blocks (X(1) . . . X(N)) of 2m bits, the encryption device having encryption means for performing a XOR operation (+) and then an encryption operation by means of an encryption algorithm (E) on each block of a packet, wherein encrypted blocks (Y(1) . . . Y(N)) are obtained according to
- space="preserve" listing-type="equation">Y(1)=E X(N)+IV!
space="preserve" listing-type="equation">Y(i)=E X(N-i+1)+Y(i-1)! for i>
1 and i≦
N,where IV is an initial vector, and wherein said encryption means reverses the sequence of the blocks (X(1) . . . X(N)) before carrying out the encryption and XOR operations.
- 11. A decryption device for a system for encrypting and decrypting digital data, wherein the data is divided into packets of N blocks (X(1) . . . X(N)) of 2m bits and encrypted into packets of N blocks (Y(1) . . . Y(N)), the decryption device having means for performing a decryption algorithm (D) and then a XOR operation (+) on each encrypted block (Y(1) . . . Y(N)), wherein the original blocks (X(1) . . . X(N)) are obtained according to
- space="preserve" listing-type="equation">X(i)=D Y(N-i+1)!+Y(N-i) for i=1, 2 . . . , N-1
space="preserve" listing-type="equation">X(N)=D Y(1)!+IVwhere IV is an initial vector.
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12. A method for encrypting and decrypting digital data, wherein the data is divided into packets of N blocks (X(1) . . . X(N)) of 2m bits, said system comprising:
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reversing the blocks (X(1) . . . X(N)) of a packet; encrypting the blocks (X(1) . . . X(N)), the step of encrypting including performing a XOR operation (+) and then an encryption operation by means of an encryption algorithm (E) on each block of a packet, wherein encrypted blocks (Y(1) . . . Y(N)) are obtained according to
space="preserve" listing-type="equation">Y(1)=E X(N)+IV!
space="preserve" listing-type="equation">Y(i)=E X(N-i+1)+Y(i-1)! for i>
1 and i≦
N,where IV is an initial vector; reversing the encrypted blocks (Y(1) . . . Y(N)); transferring the encrypted blocks (Y(1) . . . Y(N)) to a receiver; and decrypting the encrypted blocks (Y(1) . . . Y(N), the step of decrypting including performing a decryption algorithm (D) and then the XOR operation on each encrypted block (Y(1) . . . Y(N)), wherein the original blocks (X(1) . . . X(N)) are obtained according to
space="preserve" listing-type="equation">X(i)=D Y(N-i+1)!+Y(N-i) for i=1, 2 . . . , N-1
space="preserve" listing-type="equation">X(N)=D Y(1)!+IV.
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Specification