Code example for CharArrayBuffer

 * <ul> 
 * <li>{@link org.apache.http.auth.params.AuthPNames#CREDENTIAL_CHARSET}</li> 
 * </ul> 
 *  
 * @since 4.0 
 */ 
public class EnhancedDigestScheme extends RFC2617Scheme {
 
	/** 
	 * Hexa values used when creating 32 character long digest in HTTP 
	 * DigestScheme in case of authentication. 
	 *  
	 * @see #encode(byte[]) 
	 */ 
	private static final char[] HEXADECIMAL = { '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; 
 
	/** Whether the digest authentication process is complete */ 
	private boolean complete;
 
	private static final int QOP_UNKNOWN = -1;
	private static final int QOP_MISSING = 0;
	private static final int QOP_AUTH_INT = 1;
	private static final int QOP_AUTH = 2;
 
	private String lastNonce;
	private long nounceCount;
	private String cnonce;