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 Fraga’s 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 Fraga’s Jewish aljama was first established or the point at which Fraga became accountable to Lleida rather than to Saragossa. In summary, Fraga’s 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 Saragossa’s 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 Fraga’s 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