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Standard Library

PHP openssl Functions

Encryption with OpenSSL

PHP openssl functions encrypt data with openssl_encrypt().

Introduction to PHP openssl Functions

PHP's openssl extension provides a set of functions for data encryption and decryption. These functions enable secure data handling through the OpenSSL library, supporting various encryption algorithms. The primary function for encryption is openssl_encrypt(), which allows developers to encrypt data using a symmetric cipher.

How openssl_encrypt() Works

The openssl_encrypt() function encrypts plain text into cipher text using a specified encryption method and key. It requires several parameters:

  • data: The plaintext to be encrypted.
  • method: The encryption algorithm (e.g., AES-128-CBC).
  • key: The secret key used for encryption.
  • options: A bitwise disjunction of flags (optional).
  • iv: The initialization vector for the encryption method.

Additional parameters include tag, aad, and tag_length for authenticated encryption modes like GCM.

Example: Encrypting Data with openssl_encrypt()

Let's look at a simple example of using openssl_encrypt() to encrypt a string using the AES-128-CBC algorithm:

Decrypting Data with openssl_decrypt()

The openssl_decrypt() function is used to convert the cipher text back to the original plain text. It uses similar parameters as openssl_encrypt(). Below is an example of how to decrypt the data encrypted in the previous example:

Choosing the Right Encryption Method

Choosing the right encryption method is crucial for application security. Common methods include:

  • AES-128-CBC and AES-256-CBC: Widely used with a balance of performance and security.
  • AES-256-GCM: Offers authenticated encryption with additional data (AEAD), providing integrity and authenticity.

Always ensure that the key and IV are of appropriate length for the chosen method.

Common Pitfalls and Best Practices

Here are some best practices to avoid common pitfalls when using openssl functions:

  • Always use a secure and random initialization vector (IV).
  • Do not use the same key and IV combination for multiple encryptions.
  • Consider authenticated encryption methods like GCM for added security.
  • Securely store and manage encryption keys.

Following these practices ensures that your encryption is robust and secure.

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