Aggelis Aggelis - Academia.edu (original) (raw)
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As the implementations of the Bundle Protocol (RFC 5050) reach remarkable maturity, an increased ... more As the implementations of the Bundle Protocol (RFC 5050) reach remarkable maturity, an increased interest is now appearing to fully implement the DTN security features as specified in the Bundle Security Protcol (RFC 6257). In this regard, in this paper we present our BSP implementation suitable for embedded devices with scarce resources (limited prcocessing, memory, energy and transmission capabilities). Our BSP implementation enhances the existing security features in DTN2(v2.8). We analyze the functionality and the performance of our secure DTN2 stack via experimental means. Namely, we conducted a series of test cases in our heterogeneous TCP/IP-based test-bed. The 1 Hellenic Aerospace Industry S.A., e-mail: tselikis.christos@haicorp.com 2 Hellenic Aerospace Industry S.A., e-mail: poulakidas.athanasios@haicorp.com 3 Hellenic Aerospace Industry S.A., e-mail: aggelis.aggelis@haicorp.com 4 Hellenic Aerospace Industry S.A., e-mail: egladis@haicorp.com Article Info: Received : Novembe...
Successive Aproximations Method (SAM) is a recursive method for studying periodic phenomena in ti... more Successive Aproximations Method (SAM) is a recursive method for studying periodic phenomena in time series. Study of periodic phenomena with SAM is achieved by decomposing the observed time series into simpler sinusodial time series. The advantage of SAM compared to other methods (i.e. Fourier Analysis) is that it marks the location of each event on the time series, thus giving us the temporal / spatial/ intensity distributions of the events. SAM was not fully automated through computerized algorithms so far, thus requiring a lot of user decisions in order to produce results in large data sets. In this study we present an improvement on the automation of SAM and an application to the large data sets of HI-SCALE experiment during Ulysses Jupiter flyby. SAM supports previous findings (Anagnostopoulos et. al. 2001) about quasi-periodic (~20 / 40 /80 min) modulation of HI-SCALE energetic ion data in the outer high latitude dusk-side Jovian magnetosphere in February 1992.
DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with the... more DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with their location coordinates with an accuracy of no more than a few kilometers. RCSTs use this location information in their ranging calculation to the servicing satellite. For certain users this location information disclosure to the network operator can be seen as a serious security event. Recent work of the authors overcame this requirement by cloaking the location of an RCST in such a way (based on "spatial/geometric" symmetries of the network) that the respective ranging calculations are not affected. In this work we argue that timing tolerances in the Return Channel synchronization scheme, accepted by the DVB-RCS standard, can be used in combination to the "spatial" method, further enhancing the location privacy of an RCST. Theoretical findings of the proposed "spatial-timing" approach were used to develop a practical method that can be used by workers in t...
Journal of Internet …, 2010
... CFDP is integrated into the testbed in unreliable mode; reliability is assured by the underly... more ... CFDP is integrated into the testbed in unreliable mode; reliability is assured by the underlyingDTN LTP and TCP protocols ... The packet loss rates vary from 0 to 10 percent, while bandwidth is asymmetrical, using a 1 Mbps link to ... The size of each CFDP PDU equals to 1024 Bytes ...
Advances in Space Research, 2001
A careful analysis of data collected by the HISCALE experiment on board Ulysses suggests that the... more A careful analysis of data collected by the HISCALE experiment on board Ulysses suggests that the quasi-periodic (QP) modulation of several or tens of minutes in flux and/or anisotropy/spectral observations is an almost permanent characteristic of the energetic (>-50 keV) ion population in the outer and the high latitude middle magnetosphere of Jupiter. In most cases a periodicity of-5-20 min is evident, although periodicities of-40 min and-80 min were also observed. The-40 min and-80 min periodicities were often accompanied by other harmonics, for instance-20 min and-40 min periodicities respectively, and were preferentially observed in the dusk magnetosphere. Observations of QP series of energetic ion and electron bursts in the dusk high latitude magnetosphere, as for instance, strong anisotropy, forward velocity dispersion and time delay between the ion and the electron onsets, are consistent with a periodic acceleration / injection of particles, in the form of field-aligned beams, originated from the low altitude environment of the planet (-8 R, from the planet surface); the QP intensity gradients perpendicular to the field observed in the dusk middle magnetosphere are consistent with spatial structures of energetic particle sheets crossed by the spacecraft. The QP bursts of energetic particles are often accompanied by bursts of radio and aurora emissions and are possible sources of these Jovian phenomena.
Radioengineering, 2011
In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy p... more In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy perspective and proposed an approach to incorporate a location privacy enhancing mechanism into the standard. Offering location based privacy in DVB-RCS communication is a challenge as the location of a satellite terminal must be revealed to the network operator of the DVB-RCS network for technical and administrative reasons. We proposed an approach of cloaking the location by intentionally compromising its accuracy whilst maintaining the operability and integrity of the communications system. In addition we implemented a proof of concept technique utilizing the theoretical findings of this work on a real DVB-RCS system, presenting the methodology along with the tools used and the experimental results.
Radioengineering, 2011
In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy p... more In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy perspective and proposed an approach to incorporate a location privacy enhancing mechanism into the standard. Offering location based privacy in DVB-RCS communication is a challenge as the location of a satellite terminal must be revealed to the network operator of the DVB-RCS network for technical and administrative reasons. We proposed an approach of cloaking the location by intentionally compromising its accuracy whilst maintaining the operability and integrity of the communications system. In addition we implemented a proof of concept technique utilizing the theoretical findings of this work on a real DVB-RCS system, presenting the methodology along with the tools used and the experimental results.
As the implementations of the Bundle Protocol (RFC 5050) reach remarkable maturity, an increased ... more As the implementations of the Bundle Protocol (RFC 5050) reach remarkable maturity, an increased interest is now appearing to fully implement the DTN security features as specified in the Bundle Security Protcol (RFC 6257). In this regard, in this paper we present our BSP implementation suitable for embedded devices with scarce resources (limited prcocessing, memory, energy and transmission capabilities). Our BSP implementation enhances the existing security features in DTN2(v2.8). We analyze the functionality and the performance of our secure DTN2 stack via experimental means. Namely, we conducted a series of test cases in our heterogeneous TCP/IP-based test-bed. The 1 Hellenic Aerospace Industry S.A., e-mail: tselikis.christos@haicorp.com 2 Hellenic Aerospace Industry S.A., e-mail: poulakidas.athanasios@haicorp.com 3 Hellenic Aerospace Industry S.A., e-mail: aggelis.aggelis@haicorp.com 4 Hellenic Aerospace Industry S.A., e-mail: egladis@haicorp.com Article Info: Received : Novembe...
Successive Aproximations Method (SAM) is a recursive method for studying periodic phenomena in ti... more Successive Aproximations Method (SAM) is a recursive method for studying periodic phenomena in time series. Study of periodic phenomena with SAM is achieved by decomposing the observed time series into simpler sinusodial time series. The advantage of SAM compared to other methods (i.e. Fourier Analysis) is that it marks the location of each event on the time series, thus giving us the temporal / spatial/ intensity distributions of the events. SAM was not fully automated through computerized algorithms so far, thus requiring a lot of user decisions in order to produce results in large data sets. In this study we present an improvement on the automation of SAM and an application to the large data sets of HI-SCALE experiment during Ulysses Jupiter flyby. SAM supports previous findings (Anagnostopoulos et. al. 2001) about quasi-periodic (~20 / 40 /80 min) modulation of HI-SCALE energetic ion data in the outer high latitude dusk-side Jovian magnetosphere in February 1992.
DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with the... more DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with their location coordinates with an accuracy of no more than a few kilometers. RCSTs use this location information in their ranging calculation to the servicing satellite. For certain users this location information disclosure to the network operator can be seen as a serious security event. Recent work of the authors overcame this requirement by cloaking the location of an RCST in such a way (based on "spatial/geometric" symmetries of the network) that the respective ranging calculations are not affected. In this work we argue that timing tolerances in the Return Channel synchronization scheme, accepted by the DVB-RCS standard, can be used in combination to the "spatial" method, further enhancing the location privacy of an RCST. Theoretical findings of the proposed "spatial-timing" approach were used to develop a practical method that can be used by workers in t...
Journal of Internet …, 2010
... CFDP is integrated into the testbed in unreliable mode; reliability is assured by the underly... more ... CFDP is integrated into the testbed in unreliable mode; reliability is assured by the underlyingDTN LTP and TCP protocols ... The packet loss rates vary from 0 to 10 percent, while bandwidth is asymmetrical, using a 1 Mbps link to ... The size of each CFDP PDU equals to 1024 Bytes ...
Advances in Space Research, 2001
A careful analysis of data collected by the HISCALE experiment on board Ulysses suggests that the... more A careful analysis of data collected by the HISCALE experiment on board Ulysses suggests that the quasi-periodic (QP) modulation of several or tens of minutes in flux and/or anisotropy/spectral observations is an almost permanent characteristic of the energetic (>-50 keV) ion population in the outer and the high latitude middle magnetosphere of Jupiter. In most cases a periodicity of-5-20 min is evident, although periodicities of-40 min and-80 min were also observed. The-40 min and-80 min periodicities were often accompanied by other harmonics, for instance-20 min and-40 min periodicities respectively, and were preferentially observed in the dusk magnetosphere. Observations of QP series of energetic ion and electron bursts in the dusk high latitude magnetosphere, as for instance, strong anisotropy, forward velocity dispersion and time delay between the ion and the electron onsets, are consistent with a periodic acceleration / injection of particles, in the form of field-aligned beams, originated from the low altitude environment of the planet (-8 R, from the planet surface); the QP intensity gradients perpendicular to the field observed in the dusk middle magnetosphere are consistent with spatial structures of energetic particle sheets crossed by the spacecraft. The QP bursts of energetic particles are often accompanied by bursts of radio and aurora emissions and are possible sources of these Jovian phenomena.
Radioengineering, 2011
In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy p... more In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy perspective and proposed an approach to incorporate a location privacy enhancing mechanism into the standard. Offering location based privacy in DVB-RCS communication is a challenge as the location of a satellite terminal must be revealed to the network operator of the DVB-RCS network for technical and administrative reasons. We proposed an approach of cloaking the location by intentionally compromising its accuracy whilst maintaining the operability and integrity of the communications system. In addition we implemented a proof of concept technique utilizing the theoretical findings of this work on a real DVB-RCS system, presenting the methodology along with the tools used and the experimental results.
Radioengineering, 2011
In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy p... more In this paper we studied the DVB-RCS (Return Channel through Satellite) standard from a privacy perspective and proposed an approach to incorporate a location privacy enhancing mechanism into the standard. Offering location based privacy in DVB-RCS communication is a challenge as the location of a satellite terminal must be revealed to the network operator of the DVB-RCS network for technical and administrative reasons. We proposed an approach of cloaking the location by intentionally compromising its accuracy whilst maintaining the operability and integrity of the communications system. In addition we implemented a proof of concept technique utilizing the theoretical findings of this work on a real DVB-RCS system, presenting the methodology along with the tools used and the experimental results.