| 1. |
- Ingemarsson, Ingemar
(författare)
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Encryption in Telefax
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Our standpoint is that the basic need for information security in TELETEX is provided by the data network used together with the possibility to encrypt the messages in the terminals, thereby protecting the messages from information loss. Means for detection of information destruction or change and f or verification at unencrypted data may then be provided for by the user of the TELETEX system.
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| 2. |
- Ahlström, Per
(författare)
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Signalprediktering i vitt gaussiskt brus med hjälp av ett adaptivt signalanpassat filter
- 1976
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ett signalanpassat filter har ett impulssvar som är den exiterandesignalens spegelbild . Ett dylikt filter maximerar vid en viss tidpunkt signalbrusförhållandet på utgången.Ett adaptivt transversalfilter styrt av en gradientkännande algoritm, vilken maximerar signalbrusförhållandet på filterutgången, har studerats. Det spegelvända impulssvaret har använts som prediktion av signalen. Denna prediktion har, vid simulering gjord på dator, ej visat sig vara bättre än en klassisk prediktion med en ren summering av brusstörda upplagor av signalen. Inte ens då dylika summerade upplagor av den brusstörda signalenanvänts som insignal till filtret har signalprediktionen via filtrets impulssvar uppvisat ett lägre kvadratiskt medelfel än d en klassiska.
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| 3. |
- Blom, Rolf, et al.
(författare)
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Data Network Security : Part I Problem Survey and Model
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Data encryption and related methods may be used to preserve information security i n a data network. Here information security is defined as the degree to which the destruction, change or loss of information is presented. Information is defined as the content of the message represented by the data. The information in a block of data is unchanged if the intended result of the transmission of the block is obtained. This means for example that the original message reaches the correct destination where it is interpreted as intended. Undisturbed information does not, in general, require un disturbed data.The network is supposed to be a public network, accessed by many different users. We are interested in a well defined group of users who are communicating mainly among themselves. Different groups, however, are also allowed to communicate in a well defined manner. The logical structure of the communication within a group is star-shaped. The information communicated within the groups hall be protected against threats from other users of the network, from illegitimate users (wiretappers etc) and from members in the group. The structure of the threats is described in section 3 of this paper.The network itself and the requirement it imposes are supposed to be unchanged. Encryption and decryption are taking place outside the network. The encrypted data shall comply with the requirements of the network. The communication process in the group consists of time-limited messages which are essentially transmitted from one point to another in the network. This is the basis for the model of the communication which is described in section 4. The model, although simple, enables us to structure the problems in connection with encryption/decryption. This is done in section 5 and 6. The purpose of the paper is to form a basis for synthesis of security measures by means on cryptological methods. The analysis is general enough to be applied to any data network and any type of user group.
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| 4. |
- Blom, Rolf
(författare)
-
On Pure Ciphers
- 1979
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The algebraic structure of the set of enciphering trans formations of a pure cipher is analysed. An alternative definition of pure ciphers is given and necessary and sufficient conditions for the product of two pure ciphers to be pure is found.
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