Several commonly used cryptographic functions of PHP "reprint"

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In the development process of the website, we often need to encrypt some data (such as user password), this article mainly introduces several common cryptographic functions of PHP.

MD5 Encryption:

String MD5 (string $str [, bool $raw _output = false])

1.MD5 () returns the hash value by default as a 32-character hexadecimal number, which accepts two parameters, the first is the string to encrypt, the second is a Boolean value of Raw_output, the default is False, and if set to TRUE,MD5 () returns the original 16 BITS binary Format Message summary

2.MD5 () is a one-way encryption, there is no reverse decryption algorithm, but still can be some common string through collection, enumeration, collision and other methods to crack

<?php $username = ' Jellybool ';  $password = ' jellybool.com '; echo MD5 ( $username);  " echo MD5 ( $password);  " /* It is more recommended to encrypt important sensitive data multiple times to prevent it from being easily cracked */echo MD5 (MD5 ( $password) ); /* above output: username:4f5436e5d72608fb647b691e8edcf42e password:7bf02cf0f4af6da4accbc73d2a175476 Password (two-time encryption): 864704bb35754f8cd0232cba6b91521b*/   

Crypt Encryption:

String crypt (String $str [, String $salt])

1.crypt () accepts two parameters, the first is a string that needs to be encrypted, the second is a salt value (that is, the encryption interference value, if not provided, it is automatically generated by PHP, the salt parameters are optional. However, if not salt ,crypt () will create a weak password. PHP 5.6 and later will throw an E_notice level error without it. For better security, be sure to specify a salt value that is sufficiently strong ), return a hashed string, or a string that is less than 13 characters in order to distinguish the salt value.

2.crypt () is one-way encryption, just like MD5.

<?php$password =' Jellybool.com ';Echo Crypt ($password);Output: $1$fe0.qr5. $WOhkI 4/5vpo7n7tnxhh5k/* The eight characters between the second $ and the third $ are generated by PHP and change once per refresh */echo " Echo Crypt ($password,"Jellybool");  Output: Je7fniu1knaes/* When we want to add a custom salt value, such as the example of Jellybool as the second parameter is added directly, more than two characters will intercept the first two */echo " Echo Crypt ($password,' $1$jellybool$ ');  Output: $1$jellyboo$dxh7wf7sygrpwb6xbbgfh//* Crypt cryptographic functions have a variety of salt-valued encryption support, the above example shows that the MD5 hash as the salt value, in this way the salt value is added in the form of $1$$, If the Jellybool in the example is added between the last two $ characters, the top eight bits will be truncated, the total length is 12 bits, and the default is this form, which exceeds the eight-bit character. */echo " Crypt also has a variety of salt-valued encryption support, see the manual                

SHA1 Encryption:

String SHA1 (String $str [, bool $raw _output = false]

1. Unlike MD5, the difference is that SHA1 () returns a hash value of 40 characters by default, passing in a parameter, the first is an encrypted string, the second is a Boolean value of Raw_output, the default is False, and if set to TRUE,SHA1 () returns the original 20 Bit RAW Format Message summary

2.SHA1 () is also a single-line encryption, no reverse decryption algorithm

<?php$my_intro="jellybool";echo sha1($my_intro);//输出：c98885c04c1208fd4d0b1dadd3bd2a9ff4d042caecho "//当然，可以将多种加密算法混合使用echo md5(sha1($my_intro));//输出：94f25bf9214f88b1ef065a3f9b5d9874//这种方式的双重加密也可以提高数据的安全性

UrlEncode Encryption:

String UrlEncode (String $str)

1. A parameter, passing in the string to be encrypted (usually applied to the encryption of the URL),

2.urlencode is two-way encryption, can be encrypted with urldecode (strictly speaking, not true encryption)

3. Returns the string, in addition to-_, in this string. All non-alphanumeric characters are replaced with a percent sign (%) followed by a two-digit hexadecimal number, and a space is encoded as a plus (+).

<?php//urlencode () is typically used to hide plaintext data in a URL$my _urlencode="Jellybool.com?jellybool=true + 4-3%5= \&@!"; Echo UrlEncode ($my _urlencode);Output: jellybool.com%3fjellybool%3dtrue+%2b+4-3%255%3d+%5c%26+%40%21echo"$my _urldecode="Jellybool.com%3fjellybool%3dtrue+%2b+4-3%255%3d+%5c%26+%40%21 "; Echo UrlDecode ($my _urldecode);Output: Jellybool.com?jellybool=true +4-3%5= \&@! Restore theOutput echo of the $my _urlencode"$my _urldecode="Http://www.baidu.com/s?word=jellybool+%e8%a7%89%e7%b4%af%e4%b8%8d%e7%88%b1&tn=98236947_hao_pg&ie=utf-8 "; Echo UrlDecode ($my _urldecode);/* Output: http://www.baidu.com/s?word=jellybool feel tired not love &tn=98236947_hao_pg&ie=utf-8 Yes, this is in Baidu search Jellybool feel tired not love **========================================================================= solves the second classic problem ========================== ===============================================*/$pre _url_encode= "jellybool.com?username=jellybool&password=jelly";//In actual development, we often have to construct this URL, which is no problem $url _decode = "jellybool.com?username=jelly&bool&password=jelly";/* Note the difference between the two variables above: the first Username=jellybool, The second is username=jelly&bool in this case with $_get () to accept the problem, which can be solved in the following way */$username = "Jelly&bool"; $url _decode = "Jellybool.com?username=". UrlEncode ($username). " &password=jelly ";//This is a good solution to the problem */* Summarize the Common urlencode () conversion characters? = =%3f = = = %3d% = %25 & = %26 \ = %5c + = %2b space = +*/ 

Base64 encoded encryption:

String Base64_decode (String $encoded _data)

1.base64_encode () accepts a parameter, which is the data to be encoded (no strings are said here, Because many times base64 is used to encode pictures)

2.base64_encode () is bidirectional encryption and can be decrypted with Base64_decode ()

 <?php $my _intro=< Span class= "hljs-string" > "Jellybool is a stature has height, shoulder width, chest muscle has thickness, thought has the depth of the national exemption five a class high quality pseudo front end it male cock silk"; echo base64_encode ( $my _intro);  " /* Output: SMVSBHLCB29S5PIV5LIA5LIQ6LQR5P2Q5PYJ6AUY5BQMLOICQEIGGOACIEWUVEW6PIZOG7JOGOZMNINLJPRLUQYS5OCD5OOZ5PYJ5REX5BQM55QE5ZU9 5a625ywn5qoa5lquqee6p+s8moi0qos8quwjjeerr0lu55s35bgm5lid*/echo Base64_decode (/* output: Jellybool is a stature has height, shoulder width, chest muscle has thickness, thought has the depth of the national inspection-exempt five A-level high-quality pseudo front-end it male cock silk */    

An example of a picture:

<?php/*一个图片的应用例子*/$filename="https://worktile.com/img/index/index_video.png";$data=file_get_contents($filename);echo base64_encode($data);/*然后你查看网页源码就会得到一大串base64的字符串，再用base64_decode()还原就可以得到图片*/

Several commonly used cryptographic functions of PHP "reprint"