Question:What is the most convenient hashing method to be used to hash passwords? 

It is preferable to use crypt() which natively supports several hashing algorithms or the function hash() which supports more variants than crypt() rather than using the common hashing algorithms such as md5, sha1 or sha256 because they are conceived to be fast. hence, hashing passwords with these algorithms can vulnerability.

Question:Which cryptographic extension provide generation and verification of digital signatures? 

The PHP-openssl extension provides several cryptographic operations including generation and verification of digital signatures.

Question:What is htaccess? Why do we use this and Where? 

.htaccess files are configuration files of Apache Server which provide a way to make configuration changes on a per-directory basis. A file, containing one or more configuration directives, is placed in a particular document directory, and the directives apply to that directory, and all sub directories thereof.

Question:34.What are the benefits of using PEAR? 

PHP users have a particularly useful trove of code at their disposal, made available through the PHP Extension and Application Repository, better known as PEAR. 

1.PEAR taking advantage of this community-driven service will save you countless hours of programming time. 
2.PEAR packages are available for accomplishing everything from creating barcode images,
 compressing files, abstracting database access, documenting code, and much more.

Question:What is data encryption? 

Data Encryption: Data encryption can be defined as the translation of data into a format that is intended to be unreadable by anyone except the intended party. The intended party can then decode, or decrypt, the encrypted data through the use of some secret, typically a secret key or password.

Question:What are the three methodology of authentication? 

coming soon...

Question:What are the PHP authentication variables? 

coming soon...

Question:
Breifly explain the following functions:
explode()
list()
fwrite()
fputs()
fclose()
md5()
rand()
uniqid()
substr()
filter_var()
 

coming soon...

Question:How to send http authentication header with php header() function? 

coming soon...

Question:What are the four lines we need to write to .htaccess file to restrict any folder in the webserver? 

coming soon...