From 3d982813b34f6f230baf4a467cdc37ec92a77595 Mon Sep 17 00:00:00 2001
From: netconomy <netconomy@7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c>
Date: Fri, 17 Aug 2007 06:10:56 +0000
Subject: Performance

git-svn-id: https://joinup.ec.europa.eu/svn/pdf-as/trunk@167 7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c
---
 .../java/at/gv/egiz/pdfas/utils/DataHashUtils.java | 136 +++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 src/main/java/at/gv/egiz/pdfas/utils/DataHashUtils.java

(limited to 'src/main/java/at/gv/egiz/pdfas/utils/DataHashUtils.java')

diff --git a/src/main/java/at/gv/egiz/pdfas/utils/DataHashUtils.java b/src/main/java/at/gv/egiz/pdfas/utils/DataHashUtils.java
new file mode 100644
index 0000000..19d7b33
--- /dev/null
+++ b/src/main/java/at/gv/egiz/pdfas/utils/DataHashUtils.java
@@ -0,0 +1,136 @@
+/**
+ * 
+ */
+package at.gv.egiz.pdfas.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+import java.security.DigestInputStream;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+import org.apache.commons.codec.binary.Base64;
+
+import at.knowcenter.wag.egov.egiz.pdf.BinarySignatureHolder;
+import at.knowcenter.wag.egov.egiz.pdf.SignatureHolder;
+import at.knowcenter.wag.egov.egiz.pdf.TextualSignatureHolder;
+
+/**
+ * Contains helpful methods for building data hashed.
+ * 
+ * <p>
+ * Data hashes are useful for summarizing the signed data of signatures for
+ * debugging and testing purposes. Do not use these hashes for signatures.
+ * </p>
+ * <p>
+ * A data hash is always a Base64 encoded String.
+ * </p>
+ * 
+ * @author wprinz
+ * 
+ */
+public final class DataHashUtils
+{
+
+  /**
+   * 
+   * @param text
+   * @return
+   */
+  public static String buildDataHash(String text)
+  {
+    try
+    {
+      MessageDigest md = getMessageDigest();
+      // probable performance leak for very large texts
+      md.update(text.getBytes("UTF-8"));
+      byte[] rawDigest = md.digest();
+
+      return encodeDigest(rawDigest);
+    }
+    catch (UnsupportedEncodingException e)
+    {
+      throw new RuntimeException(e);
+    }
+  }
+
+  public static String buildDataHash(byte[] data)
+  {
+    MessageDigest md = getMessageDigest();
+    md.update(data);
+    byte[] rawDigest = md.digest();
+
+    return encodeDigest(rawDigest);
+  }
+
+  public static String buildDataHash(InputStream is)
+  {
+    try
+    {
+      MessageDigest md = getMessageDigest();
+
+      DigestInputStream dis = new DigestInputStream(is, md);
+
+      byte[] temp = new byte[1024];
+      int i = 0;
+      while (dis.read(temp) >= 0)
+      {
+        // this just keeps the compiler from optimizing this loop away
+        i++;
+      }
+      dis.close();
+
+      byte[] rawDigest = md.digest();
+
+      return encodeDigest(rawDigest);
+    }
+    catch (IOException e)
+    {
+      throw new RuntimeException(e);
+    }
+  }
+  
+  public static String buildDataHash(SignatureHolder sh)
+  {
+    if (sh instanceof TextualSignatureHolder)
+    {
+      TextualSignatureHolder tsh = (TextualSignatureHolder) sh;
+      String signedText = tsh.getSignedText();
+      return buildDataHash(signedText);
+    }
+    
+    {
+      BinarySignatureHolder bsh = (BinarySignatureHolder) sh;
+      InputStream is = bsh.getSignedPdf().createInputStream();
+      return buildDataHash(is);
+    }
+  }
+
+  protected static MessageDigest getMessageDigest()
+  {
+    try
+    {
+      MessageDigest sha1 = MessageDigest.getInstance("SHA-1");
+      return sha1;
+    }
+    catch (NoSuchAlgorithmException e)
+    {
+      throw new RuntimeException(e);
+    }
+  }
+
+  protected static String encodeDigest(byte[] rawDigest)
+  {
+    try
+    {
+      byte[] encoded = Base64.encodeBase64(rawDigest);
+      String str = new String(encoded, "US-ASCII");
+      return str;
+    }
+    catch (UnsupportedEncodingException e)
+    {
+      throw new RuntimeException(e);
+    }
+  }
+}
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