Generate Random Strings in Apex

GenRandomString.cls

//Option 1
String myRandomString = EncodingUtil.convertToHex(Crypto.generateAesKey(128)).substring(0, 32)

//Option 2
Integer len = 32; 
Blob blobKey = crypto.generateAesKey(192);
String key = EncodingUtil.base64encode(blobKey);
String myRandomString = key.substring(0,len);

//Option 2.1
Integer len = 32; 
String myRandomString = EncodingUtil.base64encode(Crypto.generateAesKey(192)).substring(0,len);