Openssl dsa -in dsaprivatekey.pem -pubout -out dsapublickey.pem To print out the contents of a DSA key pair file openssl dsa -in dsaprivatekey.pem -text -noout Signing the sha-256 hash of a file using RSA private key openssl dgst -sha256 -sign rsakey.key -out signature.data document.pdf Signing the sha3-512 hash of a file using DSA private key. Skip to content; cmdref.net - Cheat Sheet and Example. Cmdref.net is command references/cheat sheets/examples for system engineers. Algorithms and Data Structures Cheatsheet. We summarize the performance characteristics of classic algorithms and data structures for sorting, priority queues, symbol tables, and graph processing.
DSA-LA 2020 Voter Guide 2 Table of Contents Table of Contents Introduction 1 Table of Contents 2 Cheat Sheet 9 Congress 11 CD 23 11 CD 25 11 CD 26 12.
References
Wikipedia Articles
Definitions
- Node - an element containing data that make contain links to one or more parents/children May also be referred to as a vertex
- Edge - a connection between two nodes
- Root - The top node in a tree (a node without a parent)
- Parent - A node connected to another node when moving towards the root
- Child - a node connectd to another node when moving away from root
- Descendant - a node reachable by repeated processing from parent to child
- Ancestor - a node reachable by repeated processing from child to parent
- Leaf - a node without any children
- Degree - the number of sub trees of a node
- Path - a sequence of nodes and edges connecting a node with a descendant
- Depth - the depth of a node is the number of edges from the node to the tree’s root node
- Subtree - of a tree T is a tree consisting of a node in T and all of it’s descendants in T
Tree Types
Binary Tree
A binary tree is a tree data structure in which each node has at most two children.
- Full Binary tree - every node in the tree has 0 or 2 children
- Perfect binary tree - all interior nodes have two children and all leaves have the same depth or level
- Complete binary tree - every level except possibly the last is completely filled, and all nodes in the last level are as far left as possible
Binary Search Tree
A binary search tree (BST) is a data structure that binary tree that keeps it’s keys in sorted order, so that operations can take advantage of the binary search principle (a logarithmic search that takes happens in O(log n) time)
B-tree
A B-tree is a self-balancing tree data structure that keeps data sorted and allows searches, sequential access, insertions, and deletions in logarithmic time.It is a generalization of a binary search tree in that a node can have more than two children. A B-tree is optimized for systems that read and write large blocks of data. B-tree’s are commonly used in databases and file systems.
B+ Tree
A B+ tree is a B-tree in which each node only contains keys (not key-values), and to which an additional level is added at the bottom with linked leaves.
This makes for more efficient retrieval of data in block-oriented storage (once you find the start of the block, you can read sequentially without having to traverse up and down the tree to retrieve data nodes). Additionally, all leave nodes must be the same distance from the root node.
SQL Server & Oracle store table indexes in B+ trees, which are similar to B-trees, except that data is only stored in leaf nodes - all other nodes hold only key valuesand pointers to the next nodes.
AVL Tree
An AVL Tree is a self-balancing binary search tree. The height of the two child subtrees of any node differ at most by one, otherwise the tree is re-balanced.Lookup, insertion, and deletion take O(log n) time. Insertions and deletion may cause a tree rotation
Red-Black Tree
A red-black tree is a self-balancing binary search tree. Each node of the tree has an extra bit, which is interpreted as either black or red. The color bits are used to ensure the tree remains balanced during insertions and deletions. Operations occur in O(log n) time.
Tree Storage
Binary Tree
Pointer-based
Store references to parent and children
Array Based
if a node is at index i, left child is at index (2i + 1), right child is at (2i + 2).
Note that this will result in a lot of wasted space if the tree is not balanced! In other words, a complete binary tree is a good candidate for array-based storage
Tree Rotation
An operation on a binary tree that changes the structure without interfering with the order of the elements.
Tree Traversal
Depth-first search
In a depth-first search, the search is deepened as much as possible on each child before going to the next sibling
Pre-Order
- Display data of root
- Traverse left subtree calling preorder function
- Traverse right subtree calling preorder function
In-Order
- Traverse left subtree calling preorder function
- Display data of root
- Traverse right subtree calling preorder function
An In-Order search will return the sorted contents of a BST (Binary Search Tree)
Post-Order
- Traverse left subtree calling preorder function
- Traverse right subtree calling preorder function
- Display data of root
A stack can be used to perform a depth-first search
Breadth-first search
In a breadth-first search, all nodes on a level are visited before going to a lower level.
A Queue is often used to peform a breadth-first search
Searching a BST
Recursively
Iteratively
BST Insertions
Members of the European Commission appointed in 2019 agreed to put digital policies as one of the cornerstones of EU legislation between 2019-2023. These include the Digital Services Act (DSA), the Digital Markets Act (DMA) and the Data Governance Act (DGA). So, what are the differences between these acts?
Designed by vectorpocket & macrovector/ Freepik
Members of the European Commission appointed in 2019 agreed to put digital policies as one of the cornerstones of EU legislation between 2019-2023. In the Commission’s political agenda, Commission President Ursula Von der Leyen said that “digital technologies should enrich the lives of us all and respect European values”. Among the policies being drafted, ranging from derogations of the ePrivacy Directive, Artificial Intelligence (AI) and others, there are a few “acts” that touch specifically on various aspects of surveillance capitalism. These include the Digital Services Act (DSA), the Digital Markets Act (DMA) and the Data Governance Act (DGA). So, what are the differences between these acts and how can civil society act to improve our digital reality now and in the future?
Digital Services Act (DSA)
The EDRi network has been working actively to help mould the DSA. The DSA aims to re-shape the internet by altering the power imbalances between big dominant platforms and people using them. It is an update of the eCommerce Directive.
Why is this important?
The DSA includes key concepts that would give back control to the people using these Big Tech services. It would also help ensure an open environment where the likes of Google and Facebook are made accountable and where credible alternatives to their services that respect fundamental rights and are people-centric exist and are interoperable. The DSA could also ensure access to justice when people seek remedy for unjust situations (for example, wrongful take-downs of legal content).
What should you look at specifically?
Ideally, an additional tool to kill surveillance capitalism. Specifically, for a meaningful DSA to come to fruition, general rules such as a ban on general monitoring of content obligations towards platforms must remain, while at the same time bringing systemic changes to the current business models based on absorbing people’s data and experiences, making them addictive to their services, and instead enabling de-centralised, local, user/workers owned, and privacy-friendly alternatives allowing people to escape from the data-hungry digital silos where they are now stuck. The DSA is being finalised and the proposal will be published before the end of 2020. If you want your voice to be heard in drafting the DSA you might want to talk to them on what is important for you (cheat sheet here) or wait until it is published (scheduled for 9 December) and then stay tuned to engage with your elected Members of the European Parliament and your national representatives in Brussels (see our Brussels activist guide here!)
Digital Markets Act (DMA)
The DMA aims at opening digital market by establishing limits to current digital gatekeepers (aka big tech monopolies). This is an initiative by European Commissioner Vestagger. The DMA is, as the DSA, also expected to be published on 9 December.
Why is this important?
Because of the power imbalance between individuals and companies and the impact this has on freedom of expression, association, etc.., the Commission is aiming at also considering the structural problems of such a concentrated industry. Competition law is often referred to as one of the tools that could address this power imbalance, because it controls and regulates market power, including in the digital economy. For a better overview on the relevance of competition law and digital rights, read our series of competition law blogposts here.
What should you look at specifically?
The DMA will be based on two pillars: (1) “a clear list of dos and don’ts for giant digital gatekeepers” and (2) a harmonised market investigation framework across the single market to tackle market failures and prevent future gatekeeping threats from happening. This will be done by, for example, letting users move between interoperable services and by harmonising rules so that the application of competition polices are coherent throughout the European Union.
Data Governance Act (DGA)
Perhaps the least well known of these acts is the DGA. The DGA allegedly aims at “foster[ing] the availability of data for use by increasing trust in data intermediaries and by strengthening data sharing mechanisms across the EU”. The DGA builds on the consultations for the European strategy for data. See EDRi’s response to the consultation here. The DGA is expected to be presented on 25 November but published only on 2 December.
Why is this important?
The main goal of the DGA is to “benefit” from the expected “economic value” (for companies, we assume) of sharing personal data and to build “alternatives to the current business model for Big Tech platforms”. Framing everything in terms of theoretical economic benefits, this puts aside the civil society’s goals of walking towards a people’s centric internet, all in favour of private companies. However, the DGA may end up undermining protections ensured by the General Data Protection Regulation (GDPR) by creating a “lex specialis” which private entities and public institutions could use to avoid protections in place for personal data. The DGA (in the leaked document) requires the creation of an expert group called the “European Data Innovation Board” consisting of Member States representatives and the European Commission.
What should you look at specifically?
The draft DGA proposal includes proposals to make sensitive data in the hands of public sector data available for re-use, allow the re-use of personal data with the help of a data-sharing intermediary, allow sharing data among businesses, and making data reusable on “altruistic” grounds that as Estelle Massé from Access Now says “threaten people’s ability to control how their personal information is being used”. The leaked document states that the re-use of personal data will need to be based on one of the GDPR’s legal basis and in general be compliant with the GDPR. However, it should be emphasised that the GDPR does not permit public authorities to rely on the legal basis of “legitimate interests”, and the data user shall also not be permitted to rely on it. A potential but resource-intensive to look at this problem could be to closely scrutinise each of these re-uses and require the competent authorities monitoring the DGA to supervise these re-uses case by case before they occur. However, given the existing problems with the implementation of the GDPR this is not likely to work too well. And regarding these competent authorities, it seems coherent with the GDPR that data protection authorities should be the competent authorities monitoring its enforcement, rather than leaving up Member States the freedom to designate “one or more competent authorities” as the draft proposal suggests.
Contribution by:
Diego Naranjo
Head of Policy
Dsa Cheat Sheet Pdf
Twitter: @DNBSevilla
Everything you need to know about the DSA (29.04.2020)
Commissioner Vestagger speech on the Digital Markets Act (29.19.2020)
Access Now: New EU laws could erase its legacy of world-leading data protection (20.11.2020)
Ds Cheat Sheet
Leaked draft proposal for a Data Governance Act (October 2020)
Dsa Ada Cheat Sheet
Commission proposes measures to boost data sharing and support European data spaces (November 2020)