In PHP, Encryption and Decryption of a string is possible using one of the Cryptography Extensions called OpenSSL function for encrypt and decrypt.
openssl_encrypt() Function: The openssl_encrypt() function is used to encrypt the data.
Syntax is as follows :
string openssl_encrypt( string $data, string $method, string $key,
$options = 0, string $iv, string $tag= NULL,
string $aad, int $tag_length = 16 )
Parameters are as follows :
$data: It holds the string or data which need to be encrypted.
$method: The cipher method is adopted using openssl_get_cipher_methods() function.
$key: It holds the encryption key.
$options: It holds the bitwise disjunction of the flags OPENSSL_RAW_DATA and
OPENSSL_ZERO_PADDING.
$iv: It holds the initialization vector which is not NULL.
$tag: It holds the authentication tag which is passed by reference when using AEAD cipher mode (GCM or CCM).
$aad: It holds the additional authentication data.
$tag_length: It holds the length of the authentication tag. The length of authentication tag lies between 4 to 16 for GCM mode.
Return Value: It returns the encrypted string on success or FALSE on failure.
openssl_decrypt() Function The openssl_decrypt() function is used to decrypt the data.
Syntax is as follows :
string openssl_decrypt( string $data, string $method, string $key,
int $options = 0, string $iv, string $tag, string $aad)
Parameters are as follows :
$data: It holds the string or data which need to be encrypted.
$method: The cipher method is adopted using openssl_get_cipher_methods() function.
$key: It holds the encryption key.
$options: It holds the bitwise disjunction of the flags OPENSSL_RAW_DATA and OPENSSL_ZERO_PADDING.
$iv: It holds the initialization vector which is not NULL.
$tag: It holds the authentication tag using AEAD cipher mode (GCM or CCM). When authentication fails openssl_decrypt() returns FALSE.
$aad: It holds the additional authentication data.
Return Value: It returns the decrypted string on success or FALSE on failure.
Approach: First declare a string and store it into variable and use openssl_encrypt() function to encrypt the given string and use openssl_decrypt() function to descrypt the given string.
You can find the examples at : https://www.geeksforgeeks.org/how-to-encrypt-and-decrypt-a-php-string/
