Using the PHP Function openssl_pkcs7_decrypt()

PHP Functions are a very powerful tool that allow you to separate your programming logic into smaller chunks of code. This helps to make your code more modular and reusable across multiple applications. The PHP language comes with many built-in functions, including array functions, math functions, internationalization functions and other miscellaneous functions. In addition, you can also write your own custom functions in PHP.

openssl_pkcs7_decrypt(infilename, cipherdata, encryption_method, encryption_key, padding) – decrypts the given cipher data, returning the original plain text result. cipherdata is the base64 encoded cipher data, encryption_method is the chosen cipher algorithm, and encryption_key is the key used to encrypt the cipher data. if padding is included, it is an initialization vector (IV) which is mixed in with the cipher data to mitigate any patterns that may develop in the cipher data, making it harder for attackers to crack your encryption key.

Aside from the cipher algorithm and encryption key, openssl_pkcs7_decrypt() can take several other input variables such as headers (for prepending the MIME content type headers to the output) and flags that control how the cipher is implemented. For example, the MIME type of a message can be set to opaque signing in order to resist translation by mail relays or cleartext signing in order to allow for easier reading of messages.

In addition, the php function can take an argument called cainfo, which is an array of file and directory names that specify the locations of trusted CA files. You can also specify options such as OPENSSL_PKCS1_PADDING or OPENSSL_NO_PADDING to modify how the cipher is processed.