DN escaping rules

Understand the distinguished name (DN) characters and how to use them.

A DN can contain special characters. These characters are , (comma), = (equals), + (plus), < (less than), > (greater than), # (number sign), ; (semicolon), \ (backslash), and " " (quotation marks).

To escape these special characters or other characters in an attribute value in a DN string, use any the following methods:

Method 1: If a character to be escaped is one of special characters, precede it by a backslash (\ ASCII 92). This example shows a method of escaping a comma in an organization name:
```
CN=L. Eagle,O=Sue\, Grabbit and Runn,C=GB
```
This is the preferred method.
Method 2: Otherwise replace the character to be escaped by a backslash and two hex digits, which form a single byte in the code of the character. The code of the character must be in UTF-8 code set.
```
CN=L. Eagle,O=Sue\2C Grabbit and Runn,C=GB
```
Method 3: Surround the entire attribute value by " " (quotation marks) (ASCII 34) that are not part of the value. Between the quotation character pair, all characters are taken as is, except for the \ (backslash). The \ (backslash) can be used to escape a backslash (ASCII 92) or quotation marks (ASCII 34), any of the special characters previously mentioned, or hex pairs as in method 2. For example, to escape the quotation marks in cn=xyz"qrs"abc, it becomes cn=xyz\"qrs\"abc or to escape a \:
```
"you need to escape a single backslash this way \\" 
```
Another example, "\Zoo" is illegal, because 'Z' cannot be escaped in this context.

On the server end, when a DN is received in this form, the server reformats the DN using escape mechanisms number 1 and 2 for internal processing.