1 files changed, 114 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/asn1/x509/X509NameEntryConverter.java b/core/src/main/java/org/spongycastle/asn1/x509/X509NameEntryConverter.java
new file mode 100644
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+++ b/core/src/main/java/org/spongycastle/asn1/x509/X509NameEntryConverter.java
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+package org.spongycastle.asn1.x509;
+
+import java.io.IOException;
+
+import org.spongycastle.asn1.ASN1InputStream;
+import org.spongycastle.asn1.ASN1ObjectIdentifier;
+import org.spongycastle.asn1.ASN1Primitive;
+import org.spongycastle.asn1.DERPrintableString;
+import org.spongycastle.util.Strings;
+
+/**
+ * It turns out that the number of standard ways the fields in a DN should be 
+ * encoded into their ASN.1 counterparts is rapidly approaching the
+ * number of machines on the internet. By default the X509Name class 
+ * will produce UTF8Strings in line with the current recommendations (RFC 3280).
+ * <p>
+ * An example of an encoder look like below:
+ * <pre>
+ * public class X509DirEntryConverter
+ *     extends X509NameEntryConverter
+ * {
+ *     public ASN1Primitive getConvertedValue(
+ *         ASN1ObjectIdentifier  oid,
+ *         String               value)
+ *     {
+ *         if (str.length() != 0 &amp;&amp; str.charAt(0) == '#')
+ *         {
+ *             return convertHexEncoded(str, 1);
+ *         }
+ *         if (oid.equals(EmailAddress))
+ *         {
+ *             return new DERIA5String(str);
+ *         }
+ *         else if (canBePrintable(str))
+ *         {
+ *             return new DERPrintableString(str);
+ *         }
+ *         else if (canBeUTF8(str))
+ *         {
+ *             return new DERUTF8String(str);
+ *         }
+ *         else
+ *         {
+ *             return new DERBMPString(str);
+ *         }
+ *     }
+ * }
+ * </pre>
+ */
+public abstract class X509NameEntryConverter
+{
+    /**
+     * Convert an inline encoded hex string rendition of an ASN.1
+     * object back into its corresponding ASN.1 object.
+     * 
+     * @param str the hex encoded object
+     * @param off the index at which the encoding starts
+     * @return the decoded object
+     */
+    protected ASN1Primitive convertHexEncoded(
+        String  str,
+        int     off)
+        throws IOException
+    {
+        str = Strings.toLowerCase(str);
+        byte[] data = new byte[(str.length() - off) / 2];
+        for (int index = 0; index != data.length; index++)
+        {
+            char left = str.charAt((index * 2) + off);
+            char right = str.charAt((index * 2) + off + 1);
+            
+            if (left < 'a')
+            {
+                data[index] = (byte)((left - '0') << 4);
+            }
+            else
+            {
+                data[index] = (byte)((left - 'a' + 10) << 4);
+            }
+            if (right < 'a')
+            {
+                data[index] |= (byte)(right - '0');
+            }
+            else
+            {
+                data[index] |= (byte)(right - 'a' + 10);
+            }
+        }
+
+        ASN1InputStream aIn = new ASN1InputStream(data);
+                                            
+        return aIn.readObject();
+    }
+    
+    /**
+     * return true if the passed in String can be represented without
+     * loss as a PrintableString, false otherwise.
+     */
+    protected boolean canBePrintable(
+        String  str)
+    {
+        return DERPrintableString.isPrintableString(str);
+    }
+    
+    /**
+     * Convert the passed in String value into the appropriate ASN.1
+     * encoded object.
+     * 
+     * @param oid the oid associated with the value in the DN.
+     * @param value the value of the particular DN component.
+     * @return the ASN.1 equivalent for the value.
+     */
+    public abstract ASN1Primitive getConvertedValue(ASN1ObjectIdentifier oid, String value);
+}