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Secure IOT (Arduino Server) |
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--------------------------- |
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|
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There are many ways to secure and authenticate a networking communication, but not all solutions will run on a microcontroller, where processing power and memory is a scarce resource. |
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How does it work? |
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~~~~~~~~~~~~~~~~~ |
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|
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+Server -> the iot device that will receive the command+ |
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+Client -> the command sender+ |
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|
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. The Client connects to the Server. |
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. [ Optional: The Client sends a predefined ammount of data for the Server to wake up. (Some libraries need the client to send first data, else they will not recognize that a connection was just made.) ] |
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. The Server sends a challenge to be solved. |
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. The Client send the solved challenge with the command. |
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. The Server extracts the command from the response/solution, executes it [Optional: sends back the response ]. |
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. [ Optional: The Client extracs the execution response from the Server response. ] |
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Implementation |
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~~~~~~~~~~~~~~ |
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Server + Client Requirements |
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
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- set the same initial data length (0-n) |
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- set the same hashing function |
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- set the same symmetric password |
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Data |
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^^^^ |
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. [ Optional: Client Sends: 1-n bytes (wake up packet) ] |
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. Server: Sends Challenge (1-n bytes) |
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. Client: Sends solved challenge ( Len(hash) bytes) |
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. [ Optional: Server: Sends Response ( Len(hash) bytes) ] |
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Methodology |
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^^^^^^^^^^^ |
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. [ Optional: The Client after connection, sends a predefined number of bytes. ] |
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. The Server generates and sends a random number (bigger -> more secure) for each connection. |
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. The Client calculates and sends the HMAC of (random server data + command) using the shared secret password |
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. The Server tries to find what possible command could the Client have sent |
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(calculates HMAC of random server data + possible command, using the shared secret password and compares them) |
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and then calls the corresponding function. [ Optional: The response of that function is then calculated |
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(HMAC of random server data + response, using the shared secret password) and sent to the Client. ] |
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. [ Optional: The Client tries to find what possible response command could the Server have sent |
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(calculates HMAC of random server data + response command, using the shared secret password) ] |
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Considerations |
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~~~~~~~~~~~~~~ |
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Pros |
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^^^^ |
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- Minimalistyc nor verbose |
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- minimal memory usage* |
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- minimal cpu usage* |
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- fast** |
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- authentication |
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- confidentiality |
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- replay protection |
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*with the use of appropriate hashing functions |
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**when a limited ammount of commands is used |
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Cons |
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^^^^ |
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- uses symetric cryptography |
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- is not designed to send multiple bytes (1 byte commands recommended) |
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- requires a random seed |
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Proof of Concept |
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~~~~~~~~~~~~~~~~ |
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Tested and fully working demo is attached! |
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This demo was implemented on a pc (Node.JS Client) and an arduino pro mini with an ethernet shield (Server). |
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" |
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"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> |
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> |
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<head> |
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<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" /> |
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<meta name="generator" content="AsciiDoc 8.6.9" /> |
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<title></title> |
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<style type="text/css"> |
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/* Shared CSS for AsciiDoc xhtml11 and html5 backends */ |
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|
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/* Default font. */ |
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body { |
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font-family: Georgia,serif; |
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} |
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|
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/* Title font. */ |
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h1, h2, h3, h4, h5, h6, |
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div.title, caption.title, |
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thead, p.table.header, |
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#toctitle, |
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#author, #revnumber, #revdate, #revremark, |
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#footer { |
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font-family: Arial,Helvetica,sans-serif; |
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} |
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|
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body { |
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margin: 1em 5% 1em 5%; |
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} |
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|
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a { |
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color: blue; |
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text-decoration: underline; |
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} |
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a:visited { |
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color: fuchsia; |
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} |
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|
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em { |
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font-style: italic; |
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color: navy; |
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} |
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|
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strong { |
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font-weight: bold; |
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color: #083194; |
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} |
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|
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h1, h2, h3, h4, h5, h6 { |
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color: #527bbd; |
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margin-top: 1.2em; |
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margin-bottom: 0.5em; |
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line-height: 1.3; |
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} |
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|
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h1, h2, h3 { |
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border-bottom: 2px solid silver; |
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} |
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h2 { |
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padding-top: 0.5em; |
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} |
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h3 { |
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float: left; |
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} |
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h3 + * { |
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clear: left; |
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} |
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h5 { |
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font-size: 1.0em; |
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} |
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|
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div.sectionbody { |
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margin-left: 0; |
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} |
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|
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hr { |
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border: 1px solid silver; |
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} |
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|
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p { |
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margin-top: 0.5em; |
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margin-bottom: 0.5em; |
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} |
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|
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ul, ol, li > p { |
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margin-top: 0; |
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} |
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ul > li { color: #aaa; } |
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ul > li > * { color: black; } |
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|
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.monospaced, code, pre { |
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font-family: "Courier New", Courier, monospace; |
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font-size: inherit; |
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color: navy; |
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padding: 0; |
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margin: 0; |
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} |
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pre { |
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white-space: pre-wrap; |
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} |
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|
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#author { |
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color: #527bbd; |
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font-weight: bold; |
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font-size: 1.1em; |
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} |
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#email { |
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} |
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#revnumber, #revdate, #revremark { |
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} |
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|
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#footer { |
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font-size: small; |
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border-top: 2px solid silver; |
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padding-top: 0.5em; |
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margin-top: 4.0em; |
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} |
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#footer-text { |
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float: left; |
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padding-bottom: 0.5em; |
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} |
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#footer-badges { |
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float: right; |
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padding-bottom: 0.5em; |
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} |
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|
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#preamble { |
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margin-top: 1.5em; |
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margin-bottom: 1.5em; |
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} |
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div.imageblock, div.exampleblock, div.verseblock, |
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div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock, |
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div.admonitionblock { |
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margin-top: 1.0em; |
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margin-bottom: 1.5em; |
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} |
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div.admonitionblock { |
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margin-top: 2.0em; |
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margin-bottom: 2.0em; |
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margin-right: 10%; |
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color: #606060; |
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} |
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|
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div.content { /* Block element content. */ |
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padding: 0; |
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} |
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|
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/* Block element titles. */ |
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div.title, caption.title { |
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color: #527bbd; |
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font-weight: bold; |
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text-align: left; |
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margin-top: 1.0em; |
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margin-bottom: 0.5em; |
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} |
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div.title + * { |
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margin-top: 0; |
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} |
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|
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td div.title:first-child { |
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margin-top: 0.0em; |
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} |
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div.content div.title:first-child { |
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margin-top: 0.0em; |
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} |
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div.content + div.title { |
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margin-top: 0.0em; |
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} |
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|
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div.sidebarblock > div.content { |
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background: #ffffee; |
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border: 1px solid #dddddd; |
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border-left: 4px solid #f0f0f0; |
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padding: 0.5em; |
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} |
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|
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div.listingblock > div.content { |
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border: 1px solid #dddddd; |
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border-left: 5px solid #f0f0f0; |
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background: #f8f8f8; |
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padding: 0.5em; |
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} |
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|
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div.quoteblock, div.verseblock { |
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padding-left: 1.0em; |
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margin-left: 1.0em; |
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margin-right: 10%; |
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border-left: 5px solid #f0f0f0; |
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color: #888; |
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} |
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|
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div.quoteblock > div.attribution { |
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padding-top: 0.5em; |
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text-align: right; |
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} |
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|
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div.verseblock > pre.content { |
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font-family: inherit; |
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font-size: inherit; |
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} |
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div.verseblock > div.attribution { |
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padding-top: 0.75em; |
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text-align: left; |
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} |
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/* DEPRECATED: Pre version 8.2.7 verse style literal block. */ |
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div.verseblock + div.attribution { |
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text-align: left; |
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} |
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|
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div.admonitionblock .icon { |
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vertical-align: top; |
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font-size: 1.1em; |
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font-weight: bold; |
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text-decoration: underline; |
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color: #527bbd; |
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padding-right: 0.5em; |
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} |
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div.admonitionblock td.content { |
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padding-left: 0.5em; |
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border-left: 3px solid #dddddd; |
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} |
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|
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div.exampleblock > div.content { |
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border-left: 3px solid #dddddd; |
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padding-left: 0.5em; |
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} |
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|
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div.imageblock div.content { padding-left: 0; } |
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span.image img { border-style: none; vertical-align: text-bottom; } |
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a.image:visited { color: white; } |
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|
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dl { |
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margin-top: 0.8em; |
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margin-bottom: 0.8em; |
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} |
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dt { |
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margin-top: 0.5em; |
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margin-bottom: 0; |
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font-style: normal; |
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color: navy; |
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} |
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dd > *:first-child { |
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margin-top: 0.1em; |
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} |
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|
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ul, ol { |
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list-style-position: outside; |
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} |
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ol.arabic { |
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list-style-type: decimal; |
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} |
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ol.loweralpha { |
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list-style-type: lower-alpha; |
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} |
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ol.upperalpha { |
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list-style-type: upper-alpha; |
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} |
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ol.lowerroman { |
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list-style-type: lower-roman; |
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} |
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ol.upperroman { |
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list-style-type: upper-roman; |
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} |
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|
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div.compact ul, div.compact ol, |
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div.compact p, div.compact p, |
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div.compact div, div.compact div { |
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margin-top: 0.1em; |
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margin-bottom: 0.1em; |
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} |
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|
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tfoot { |
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font-weight: bold; |
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} |
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td > div.verse { |
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white-space: pre; |
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} |
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|
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div.hdlist { |
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margin-top: 0.8em; |
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margin-bottom: 0.8em; |
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} |
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div.hdlist tr { |
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padding-bottom: 15px; |
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} |
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dt.hdlist1.strong, td.hdlist1.strong { |
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font-weight: bold; |
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} |
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td.hdlist1 { |
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vertical-align: top; |
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font-style: normal; |
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padding-right: 0.8em; |
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color: navy; |
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} |
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td.hdlist2 { |
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vertical-align: top; |
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} |
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div.hdlist.compact tr { |
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margin: 0; |
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padding-bottom: 0; |
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} |
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|
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.comment { |
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background: yellow; |
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} |
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|
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.footnote, .footnoteref { |
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font-size: 0.8em; |
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} |
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|
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span.footnote, span.footnoteref { |
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vertical-align: super; |
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} |
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|
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#footnotes { |
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margin: 20px 0 20px 0; |
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padding: 7px 0 0 0; |
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} |
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|
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#footnotes div.footnote { |
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margin: 0 0 5px 0; |
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} |
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|
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#footnotes hr { |
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border: none; |
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border-top: 1px solid silver; |
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height: 1px; |
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text-align: left; |
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margin-left: 0; |
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width: 20%; |
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min-width: 100px; |
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} |
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|
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div.colist td { |
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padding-right: 0.5em; |
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padding-bottom: 0.3em; |
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vertical-align: top; |
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} |
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div.colist td img { |
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margin-top: 0.3em; |
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} |
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|
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@media print { |
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#footer-badges { display: none; } |
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} |
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|
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#toc { |
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margin-bottom: 2.5em; |
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} |
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|
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#toctitle { |
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color: #527bbd; |
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font-size: 1.1em; |
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font-weight: bold; |
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margin-top: 1.0em; |
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margin-bottom: 0.1em; |
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} |
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|
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div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 { |
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margin-top: 0; |
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margin-bottom: 0; |
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} |
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div.toclevel2 { |
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margin-left: 2em; |
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font-size: 0.9em; |
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} |
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div.toclevel3 { |
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margin-left: 4em; |
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font-size: 0.9em; |
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} |
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div.toclevel4 { |
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margin-left: 6em; |
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font-size: 0.9em; |
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} |
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|
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span.aqua { color: aqua; } |
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span.black { color: black; } |
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span.blue { color: blue; } |
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span.fuchsia { color: fuchsia; } |
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span.gray { color: gray; } |
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span.green { color: green; } |
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span.lime { color: lime; } |
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span.maroon { color: maroon; } |
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span.navy { color: navy; } |
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span.olive { color: olive; } |
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span.purple { color: purple; } |
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span.red { color: red; } |
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span.silver { color: silver; } |
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span.teal { color: teal; } |
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span.white { color: white; } |
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span.yellow { color: yellow; } |
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|
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span.aqua-background { background: aqua; } |
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span.black-background { background: black; } |
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span.blue-background { background: blue; } |
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span.fuchsia-background { background: fuchsia; } |
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span.gray-background { background: gray; } |
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span.green-background { background: green; } |
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span.lime-background { background: lime; } |
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span.maroon-background { background: maroon; } |
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span.navy-background { background: navy; } |
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span.olive-background { background: olive; } |
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span.purple-background { background: purple; } |
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span.red-background { background: red; } |
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span.silver-background { background: silver; } |
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span.teal-background { background: teal; } |
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span.white-background { background: white; } |
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span.yellow-background { background: yellow; } |
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|
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span.big { font-size: 2em; } |
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span.small { font-size: 0.6em; } |
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|
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span.underline { text-decoration: underline; } |
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span.overline { text-decoration: overline; } |
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span.line-through { text-decoration: line-through; } |
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|
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div.unbreakable { page-break-inside: avoid; } |
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|
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|
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/* |
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* xhtml11 specific |
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* |
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* */ |
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|
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div.tableblock { |
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margin-top: 1.0em; |
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margin-bottom: 1.5em; |
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} |
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div.tableblock > table { |
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border: 3px solid #527bbd; |
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} |
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thead, p.table.header { |
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font-weight: bold; |
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color: #527bbd; |
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} |
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p.table { |
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margin-top: 0; |
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} |
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/* Because the table frame attribute is overriden by CSS in most browsers. */ |
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div.tableblock > table[frame="void"] { |
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border-style: none; |
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} |
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div.tableblock > table[frame="hsides"] { |
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border-left-style: none; |
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border-right-style: none; |
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} |
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div.tableblock > table[frame="vsides"] { |
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border-top-style: none; |
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border-bottom-style: none; |
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} |
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|
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|
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/* |
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* html5 specific |
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* |
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* */ |
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|
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table.tableblock { |
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margin-top: 1.0em; |
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margin-bottom: 1.5em; |
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} |
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thead, p.tableblock.header { |
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font-weight: bold; |
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color: #527bbd; |
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} |
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p.tableblock { |
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margin-top: 0; |
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} |
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table.tableblock { |
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border-width: 3px; |
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border-spacing: 0px; |
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border-style: solid; |
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border-color: #527bbd; |
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border-collapse: collapse; |
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} |
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th.tableblock, td.tableblock { |
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border-width: 1px; |
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padding: 4px; |
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border-style: solid; |
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border-color: #527bbd; |
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} |
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|
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table.tableblock.frame-topbot { |
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border-left-style: hidden; |
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border-right-style: hidden; |
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} |
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table.tableblock.frame-sides { |
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border-top-style: hidden; |
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border-bottom-style: hidden; |
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} |
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table.tableblock.frame-none { |
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border-style: hidden; |
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} |
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|
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th.tableblock.halign-left, td.tableblock.halign-left { |
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text-align: left; |
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} |
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th.tableblock.halign-center, td.tableblock.halign-center { |
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text-align: center; |
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} |
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th.tableblock.halign-right, td.tableblock.halign-right { |
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text-align: right; |
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} |
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|
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th.tableblock.valign-top, td.tableblock.valign-top { |
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vertical-align: top; |
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} |
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th.tableblock.valign-middle, td.tableblock.valign-middle { |
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vertical-align: middle; |
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} |
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th.tableblock.valign-bottom, td.tableblock.valign-bottom { |
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vertical-align: bottom; |
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} |
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|
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|
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/* |
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* manpage specific |
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* |
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* */ |
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|
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body.manpage h1 { |
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padding-top: 0.5em; |
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padding-bottom: 0.5em; |
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border-top: 2px solid silver; |
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border-bottom: 2px solid silver; |
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} |
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body.manpage h2 { |
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border-style: none; |
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} |
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body.manpage div.sectionbody { |
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margin-left: 3em; |
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} |
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@media print { |
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body.manpage div#toc { display: none; } |
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} |
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</style> |
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<script type="text/javascript"> |
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/*<+'])'); |
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// Function that scans the DOM tree for header elements (the DOM2 |
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// nodeIterator API would be a better technique but not supported by all |
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// browsers). |
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var iterate = function (el) { |
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for (var i = el.firstChild; i != null; i = i.nextSibling) { |
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if (i.nodeType == 1 /* Node.ELEMENT_NODE */) { |
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var mo = re.exec(i.tagName); |
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if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") { |
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result[result.length] = new TocEntry(i, getText(i), mo[1]-1); |
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} |
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iterate(i); |
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} |
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iterate(el); |
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return result; |
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var toc = document.getElementById("toc"); |
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var i; |
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if (entry.nodeName.toLowerCase() == 'div' |
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&& entry.getAttribute("class").match(/^toclevel/)) |
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// Rebuild TOC entries. |
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if (entry.element.id == "") |
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toc.parentNode.removeChild(toc); |
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///////////////////////////////////////////////////////////////////// |
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// Footnotes generator |
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///////////////////////////////////////////////////////////////////// |
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|
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/* Based on footnote generation code from: |
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* http://www.brandspankingnew.net/archive/2005/07/format_footnote.html |
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*/ |
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footnotes: function () { |
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// Delete existing footnote entries in case we're reloading the footnodes. |
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var i; |
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// Because JavaScript has no s (dotall) regex flag. |
|||
note = spans[i].innerHTML.match(/\s*\[([\s\S]*)]\s*/)[1]; |
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|||
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|||
"' title='View footnote' class='footnote'>" + n + "</a>]"; |
|||
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|||
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|||
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|||
"<a href='#_footnoteref_" + n + "' title='Return to text'>" + |
|||
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|||
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|||
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|||
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|||
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|||
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|||
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|||
"[<a href='#_footnote_" + n + |
|||
"' title='View footnote' class='footnote'>" + n + "</a>]"; |
|||
} |
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} |
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} |
|||
}, |
|||
|
|||
install: function(toclevels) { |
|||
var timerId; |
|||
|
|||
function reinstall() { |
|||
asciidoc.footnotes(); |
|||
if (toclevels) { |
|||
asciidoc.toc(toclevels); |
|||
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|||
} |
|||
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|||
function reinstallAndRemoveTimer() { |
|||
clearInterval(timerId); |
|||
reinstall(); |
|||
} |
|||
|
|||
timerId = setInterval(reinstall, 500); |
|||
if (document.addEventListener) |
|||
document.addEventListener("DOMContentLoaded", reinstallAndRemoveTimer, false); |
|||
else |
|||
window.onload = reinstallAndRemoveTimer; |
|||
} |
|||
|
|||
} |
|||
asciidoc.install(); |
|||
/*]]>*/ |
|||
</script> |
|||
</head> |
|||
<body class="article"> |
|||
<div id="header"> |
|||
</div> |
|||
<div id="content"> |
|||
<div class="sect1"> |
|||
<h2 id="_secure_iot">Secure IOT (Arduino Server)</h2> |
|||
<div class="sectionbody"> |
|||
<div class="paragraph"><p>There are many ways to secure and authenticate a networking communication, but not all solutions will run on a microcontroller, where processing power and memory is a scarce resource.</p></div> |
|||
<div class="sect2"> |
|||
<h3 id="_how_does_it_work">How does it work?</h3> |
|||
<div class="paragraph"><p><code>Server → the iot device that will receive the command</code></p></div> |
|||
<div class="paragraph"><p><code>Client → the command sender</code></p></div> |
|||
<div class="olist arabic"><ol class="arabic"> |
|||
<li> |
|||
<p> |
|||
The Client connects to the Server. |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
[ Optional: The Client sends a predefined ammount of data for the Server to wake up. (Some libraries need the client to send first data, else they will not recognize that a connection was just made.) ] |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Server sends a challenge to be solved. |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Client send the solved challenge with the command. |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Server extracts the command from the response/solution, executes it [Optional: sends back the response ]. |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
[ Optional: The Client extracs the execution response from the Server response. ] |
|||
</p> |
|||
</li> |
|||
</ol></div> |
|||
</div> |
|||
<div class="sect2"> |
|||
<h3 id="_implementation">Implementation</h3> |
|||
<div class="sect3"> |
|||
<h4 id="_server_client_requirements">Server + Client Requirements</h4> |
|||
<div class="ulist"><ul> |
|||
<li> |
|||
<p> |
|||
set the same initial data length (0-n) |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
set the same hashing function |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
set the same symmetric password |
|||
</p> |
|||
</li> |
|||
</ul></div> |
|||
</div> |
|||
<div class="sect3"> |
|||
<h4 id="_data">Data</h4> |
|||
<div class="olist arabic"><ol class="arabic"> |
|||
<li> |
|||
<p> |
|||
[ Optional: Client Sends: 1-n bytes (wake up packet) ] |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
Server: Sends Challenge (1-n bytes) |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
Client: Sends solved challenge ( Len(hash) bytes) |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
[ Optional: Server: Sends Response ( Len(hash) bytes) ] |
|||
</p> |
|||
</li> |
|||
</ol></div> |
|||
</div> |
|||
<div class="sect3"> |
|||
<h4 id="_methodology">Methodology</h4> |
|||
<div class="olist arabic"><ol class="arabic"> |
|||
<li> |
|||
<p> |
|||
[ Optional: The Client after connection, sends a predefined number of bytes. ] |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Server generates and sends a random number (bigger → more secure) for each connection. |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Client calculates and sends the HMAC of (random server data + command) using the shared secret password |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
The Server tries to find what possible command could the Client have sent |
|||
(calculates HMAC of random server data + possible command, using the shared secret password and compares them) |
|||
and then calls the corresponding function. [ Optional: The response of that function is then calculated |
|||
(HMAC of random server data + response, using the shared secret password) and sent to the Client. ] |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
[ Optional: The Client tries to find what possible response command could the Server have sent |
|||
(calculates HMAC of random server data + response command, using the shared secret password) ] |
|||
</p> |
|||
</li> |
|||
</ol></div> |
|||
</div> |
|||
</div> |
|||
<div class="sect2"> |
|||
<h3 id="_considerations">Considerations</h3> |
|||
<div class="sect3"> |
|||
<h4 id="_pros">Pros</h4> |
|||
<div class="ulist"><ul> |
|||
<li> |
|||
<p> |
|||
Minimalistyc nor verbose |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
minimal memory usage* |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
minimal cpu usage* |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
fast** |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
authentication |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
confidentiality |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
replay protection |
|||
</p> |
|||
</li> |
|||
</ul></div> |
|||
<div class="paragraph"><p>*with the use of appropriate hashing functions</p></div> |
|||
<div class="paragraph"><p>**when a limited ammount of commands is used</p></div> |
|||
</div> |
|||
<div class="sect3"> |
|||
<h4 id="_cons">Cons</h4> |
|||
<div class="ulist"><ul> |
|||
<li> |
|||
<p> |
|||
uses symetric cryptography |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
is not designed to send multiple bytes (1 byte commands recommended) |
|||
</p> |
|||
</li> |
|||
<li> |
|||
<p> |
|||
requires a random seed |
|||
</p> |
|||
</li> |
|||
</ul></div> |
|||
</div> |
|||
</div> |
|||
<div class="sect2"> |
|||
<h3 id="_proof_of_concept">Proof of Concept</h3> |
|||
<div class="paragraph"><p>Tested and fully working demo is attached!</p></div> |
|||
<div class="paragraph"><p>This demo was implemented on a pc (Node.JS Client) and an arduino pro mini with an ethernet shield (Server).</p></div> |
|||
</div> |
|||
</div> |
|||
</div> |
|||
</div> |
|||
<div id="footnotes"><hr /></div> |
|||
<div id="footer"> |
|||
<div id="footer-text"> |
|||
Last updated 2019-11-19 05:33:40 GTB Standard Time |
|||
</div> |
|||
</div> |
|||
</body> |
|||
</html> |
|||
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Reference in new issue