From af5d23c30f773e275bfbe630d51fbcc7464ded9b Mon Sep 17 00:00:00 2001
From: ferbas <ferbas@7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c>
Date: Tue, 27 Oct 2009 10:47:09 +0000
Subject: added support for dynamic algorithm suites / acos04

git-svn-id: https://joinup.ec.europa.eu/svn/pdf-as/trunk@348 7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c
---
 .../egiz/pdfas/algorithmSuite/AlgorithmMapper.java | 120 +++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 src/main/java/at/gv/egiz/pdfas/algorithmSuite/AlgorithmMapper.java

(limited to 'src/main/java/at/gv/egiz/pdfas/algorithmSuite/AlgorithmMapper.java')

diff --git a/src/main/java/at/gv/egiz/pdfas/algorithmSuite/AlgorithmMapper.java b/src/main/java/at/gv/egiz/pdfas/algorithmSuite/AlgorithmMapper.java
new file mode 100644
index 0000000..8af0db2
--- /dev/null
+++ b/src/main/java/at/gv/egiz/pdfas/algorithmSuite/AlgorithmMapper.java
@@ -0,0 +1,120 @@
+package at.gv.egiz.pdfas.algorithmSuite;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.io.IOUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * Utility for mapping signature and hash algorithms between URI and abbreviation.<br>
+ * Supported algorithms are defined in external resource {@value #SUPPORTED_ALGORITHMS_RESOURCE}<br>
+ * 
+ * e.g. <code>sha1 <-> http://www.w3.org/2000/09/xmldsig#sha1</code>
+ * 
+ * @author dferbas
+ *
+ */
+
+public class AlgorithmMapper {
+	private static final String SUPPORTED_ALGORITHMS_RESOURCE = "supportedAlgorithms.txt";
+	private static Map algorithmMap = new HashMap();
+	private static Log log = LogFactory.getLog(AlgorithmMapper.class);
+
+	/**
+	 * read available algorithms from resource 
+	 */
+	static {
+		try {
+			log.debug("reading supported algorithms from " + SUPPORTED_ALGORITHMS_RESOURCE);
+			List lines = IOUtils.readLines(AlgorithmMapper.class.getResourceAsStream(SUPPORTED_ALGORITHMS_RESOURCE));
+			for (int i = 0; i < lines.size(); i++) {
+				String uri = (String)lines.get(i);
+				if (isValidLine(uri)) {
+					String abbr = parseAbbreviation(uri);
+					algorithmMap.put(abbr, uri);
+					if (log.isDebugEnabled()) {
+						log.debug("added supported algorithm: " + abbr + "=" + uri);
+					}
+				}
+			}
+		} catch (IOException e) {
+			throw new RuntimeException("error loading supportetAlgorithms.properties file", e);
+		}
+	}
+
+	/**
+	 * Get algorithm abbreviation (equals last part after namespace#) from uri<br>
+	 * 
+	 * e.g. <code>sha1 from http://www.w3.org/2000/09/xmldsig#sha1</code>
+	 * 
+	 * @param algorithmUri algorithm URI
+	 * @return algorithm abbreviation
+	 */
+	public static String getAbbreviation(String algorithmUri) {
+		if (!algorithmMap.containsValue(algorithmUri)) {
+			throw new RuntimeException("unsupported Algorithm " + algorithmUri);
+		}
+		return parseAbbreviation(algorithmUri);
+	}
+
+	private static boolean isValidLine(String uri) {
+		if (uri == null || uri.length() == 0) return false;
+		if (uri.trim().startsWith("#")) return false;
+		return true;
+	}
+
+	/**
+	 * Get valid URI from algorithm abbreviation<br>
+	 * 
+	 * e.g. <code>http://www.w3.org/2000/09/xmldsig#sha1 from sha1</code>
+	 * 
+	 * @param algorithmShort
+	 * @return URI
+	 */
+	public static String getUri(String algorithmShort) {
+		if (!algorithmMap.containsKey(algorithmShort)) {
+			throw new RuntimeException("unsupported Algorithm " + algorithmShort);
+		}
+		return (String)algorithmMap.get(algorithmShort);
+	}
+
+	/**
+	 * Get hash (abbreviation) from signature method (eg. sha1 from ecdsa-sha1).
+	 * @param suite abbreviation or full qualified signature method
+	 * @return digest method abbreviation
+	 */
+	public static String getHashAbbrFromSuite(String suite) {
+		try {
+			int pos = suite.lastIndexOf('-');
+			return suite.substring(pos + 1);
+		} catch (Exception e) {
+			throw new RuntimeException("cannot parse algorithm string for hash method: " + suite);
+		}
+	}
+
+	/**
+	 * 
+    * Get hash method (URI) from signature method
+    * @param suite abbreviation or full qualified signature method
+    * @return digest method URI
+    *
+	 */
+	public static String getHashUriFromSuite(String suite) {
+		return getUri(getHashAbbrFromSuite(suite));
+	}
+
+	private static String parseAbbreviation(String algorithmUri) {
+		try {
+			int pos = algorithmUri.lastIndexOf('#');
+			return algorithmUri.substring(pos + 1);
+		} catch (Exception e) {
+			throw new RuntimeException("invalid algorithm entry in " + SUPPORTED_ALGORITHMS_RESOURCE
+					+ ": " + algorithmUri);
+		}
+	}
+
+}
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