How to convert WKB to WKT?

If you want to use PostGIS to do the conversion, you can choose from the following functions:

bytea WKB = ST_AsBinary(geometry);
text WKT = ST_AsText(geometry);
geometry = ST_GeomFromWKB(bytea WKB, SRID);
geometry = ST_GeometryFromText(text WKT, SRID);

More: http://postgis.net/docs/manual-1.5/ch04.html#OpenGISWKBWKT

If you can work with Java, the JTS Topology Suite can perform such translation by using the classes com.vividsolutions.jts.io.WKBReader and com.vividsolutions.jts.geom.Geometry. A code like this should get the geometry in Well-Known Text format:

import com.vividsolutions.jts.io.WKBReader;
import com.vividsolutions.jts.geom.Geometry;

String wkbString = "0101000000cdcccccc170d2241b81e859bcb405241";
// geometry in WKB format to be translated to WKT
byte[] aux = WKBReader.hexToBytes(wkbString);
Geometry geom = new WKBReader().read(aux);
String wktString = geom.toText();
// geometry in WKT format
System.out.printf("WKB = %s\n", wkbString);
System.out.printf("WKT = %s\n", wktString);