583 research outputs found
Citadel: Self-Sovereign Identities on Dusk Network
The amount of sensitive information that service providers handle about their
users has become a concerning fact in many use cases, where users have no other
option but to trust that those companies will not misuse their personal
information. To solve that, Self-Sovereign Identity (SSI) systems have become a
hot topic of research in recent years: SSI systems allow users to manage their
identities transparently. Recent solutions represent the rights of users to use
services as Non-Fungible Tokens (NFTs) stored on Blockchains, and users prove
possession of these rights using Zero-Knowledge Proofs (ZKPs). However, even
when ZKPs do not leak any information about the rights, the NFTs are stored as
public values linked to known accounts, and thus, they can be traced. In this
paper, we design a native privacy-preserving NFT model for the Dusk Network
Blockchain, and on top of it, we deploy Citadel: our novel
full-privacy-preserving SSI system, where the rights of the users are privately
stored on the Dusk Network Blockchain, and users can prove their ownership in a
fully private manner
L'Aljama de jueus de Fraga
While there is no clear evidence of Jews having been present in the town of
Fraga when the Count of Barcelona Ramon Berenguer IV reconquered it in
1149, the possibility cannot be dismissed out of hand.
The first documentary reference to the Jews of Fraga appears in a letter that King
James I of Catalonia-Aragon sent to the Jews living in the town in around 1237.
Another reference can be found in a document dated 8 October 1264, in which the
king acknowledged that every aljama in Aragon had paid his eldest son, Peter, the
annual tax for the Christmas celebrations. It should be noted that Fraga contributed
to the coffers of Saragossa at the time in question, as did Lleida [Lérida].
In 1282, King Peter the Great ordered Fragas Jewish aljama to submit its
account books corresponding to the last 15 years for inspection in order to clear
up a matter related to tax payment. Counting back 15 years from 1282 gives
1267-1268 as possibly either the time at which Fragas Jewish aljama was first
established or the point at which Fraga became accountable to Lleida rather
than to Saragossa.
In summary, Fragas Jewish aljama was already established in the 13th century,
under the jurisdiction of that of Lleida. There had been Jews in the town
since 1237, and a Jewish community since 1267-1268, when the Jews of both
Fraga and Lleida ceased to have ties with Saragossas Jewish community. The
Jewish aljama in Fraga spanned carrer Barranco and La Collada, encompassing
the present-day passageways of San Julián, Santa Irene, Aitona and Santa Margarita.
Accessible via a gate on carrer Barranco, the Jewish quarter had a bakery,
stores, wells or storage pits, wine cellars, workshops and shops looking out onto
the street. However, there are now no traces of any of them, nor of the synagogue.
The authorities that represented the Jewish community comprised a
secretary, a rabbi or teacher, a treasurer, an almoner, a town crier and a gatekeeper
or area guard, one of whom would also have acted as a judge. The rabbi
oversaw religious celebrations and feast days. The Jews of Fraga came to enjoy
genuine privileges as a result of a series of decrees issued in 1328.
The Jews contributed to standard royal expenditure through taxes known as
the cena (a hospitality tax paid to the royal court) and the quèstia (an irregular
tax usually levied in response to specific needs). Queen Maria de Luna exempted
them from the cena tax in 1396, but it was reinstated following restoration work on the aljama in 1436. The Jews contributions to the extraordinary
charges imposed by the king were unusual in that they could be made in an individual
capacity, i. e. directly to the Crown. The Jews made such contributions
when princes and princesses married, when members of the royal family were
born, when kings were crowned and when funding was required for military
campaigns, as well as through the morabatí tax (paid to the king in exchange for
a royal promise to refrain from altering the coinage), such as that of 1397, etc.
In 1408, an attempt was made to reduce the size of the Jews debt corresponding
to annual fees levied on property, at which point they owed varying amounts to Fragas
Augustinian monastery (outstanding since 1397), to Queen Violante de Bar and
to the priest of the Corpus Christi Chapel of the Church of Saint John of Lleida.
The Jewish quarter was abandoned until 1436, after which time it apparently
made a successful recovery. Information on the period in question is very
scarce, however.
The Jews were granted many specific privileges, notably including measures
to help them increase their earnings through sales of products such as wine
(1309, 1322, 1324), taxes, called cises, on food products (1389, 1399, 1409)
and a 10-year exemption from the cena tax (1400); exemption from fees, called
lluïsme and fadiga, payable to landowners as a result of transfer of landed property
(1384, 1389); waived debts (1389); exemption from fines and penalties
(1399); the right not to be disturbed (1399); the privilege of not being the subject
of accusations (1409); the right to represent themselves in court (1391);
exemption from contributions payable upon slaughtering animals (1409); protection
for aljama officials involved in crimes (1453); the right to establish an
aljama with up to 100 households (1413); the right to receive pledges from
Christians (1413); free transport of belongings (1413); the right to have a house
in any part of the town (1436); exemption from the morabatí tax (1398, 1451);
and the privilege of not being prosecuted by Christian courts.
There are no records of any deaths having occurred in Fraga in the disturbances
that took place in August 1391. As of that time, the town council included
two representatives of the aljama. The conversion of Jews in 1414-1415
led to more problems, possibly similar in all the aljamas along the banks of the
Cinca River. The problems in question basically consisted of the conversions
giving rise to a cultural change, a break with tradition and the abandonment of
the aljama, whose inhabitants moved to another part of the town. The neophytes
did not see why charges applicable to the Jews should also apply to them,
and were forced to contribute thereto against their will. Some neophytes encountered
problems in terms of obtaining annual payments levied on property
due to them as Jews or the heirs of Jews. After 1436, the Jewish quarter was restored and its synagogue reopened, and as many as 50 families lived there until
the expulsion of the Jews in 1492
The Geopolitics of Deplatforming:A Study of Suspensions of Politically-Interested Iranian Accounts on Twitter
Social media companies increasingly play a role in regulating freedom of speech. Debates over ideological motivations behind suspension policies of major platforms are on the rise. This study contributes to this ongoing debate by looking at content moderation from a geopolitical perspective. The starting premise is that US-based social media companies may be inclined to moderate content on their platforms in compliance with US sanctions laws, especially those concerned with the Specially Designated Nationals and Blocked Persons List. Despite the release of transparency reports by social media companies, we know little about the scope of the problem and the impact of suspensions on political conversations. I tracked 600,000 users who follow Iranian elites on Twitter. After accounting for alternative explanations, the results show that Principlist (conservative) users and those supportive of the Iranian government are significantly more likely to be suspended. Further analyses uncover the types of discussions that are being suppressed as a result of these suspensions. Although the exact mechanism at hand cannot be decisively isolated, this paper contributes to building a better understanding of how governments can influence conversations of geopolitical relevance, and how social media suspensions shape political conversations online
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