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Common PHP String Encryption and Decryption Functions Explained with Code Examples

gitbox 2025-07-28

Overview of String Encryption and Decryption in PHP

In web development, encrypting sensitive data is essential for protecting user information. PHP offers several encryption and decryption functions to help developers achieve this goal.

This article will provide a detailed overview of the most common encryption and decryption functions in PHP, along with practical code examples to help developers understand and apply these functions.

Encryption Functions in PHP

PHP provides several encryption functions, and here are two commonly used methods.

md5 Encryption Function

The md5 function is one of the most commonly used encryption functions in PHP. It can convert a string of any length into a fixed 32-character encrypted string.

The syntax of the md5 function is as follows:

<span class="fun">string md5(string $str, bool $raw_output = false)</span>

Parameter explanation:

  • $str: The string to be encrypted.
  • $raw_output: Optional. Defaults to false. If set to true, the function will output the raw binary data.

Here’s an example of using md5 encryption:

$originalString = "Hello, World!";
$encryptedString = md5($originalString);

echo "Original string: " . $originalString . "\n";
echo "Encrypted string: " . $encryptedString . "\n";

Output:

Original string: Hello, World!
Encrypted string: b10a8db164e0754105b7a99be72e3fe5

sha1 Encryption Function

The sha1 function performs an SHA-1 hash calculation on the input string and returns a 40-character hexadecimal encrypted string.

The syntax of the sha1 function is as follows:

<span class="fun">string sha1(string $str, bool $raw_output = false)</span>

Parameter explanation:

  • $str: The string to be encrypted.
  • $raw_output: Optional. Defaults to false. If set to true, the function will output 20 bytes of binary data.

Here’s an example of using sha1 encryption:

$originalString = "Hello, World!";
$encryptedString = sha1($originalString);

echo "Original string: " . $originalString . "\n";
echo "Encrypted string: " . $encryptedString . "\n";

Output:

Original string: Hello, World!
Encrypted string: 0a4d55a8d778e5022fab701977c5d840bbc486d0

Decryption Functions in PHP

In addition to encryption functions, PHP also offers decryption functions. Here’s one commonly used decryption method.

base64_decode Decryption Function

The base64_decode function decodes a base64-encoded string, returning the original data.

The syntax of the base64_decode function is as follows:

<span class="fun">string base64_decode(string $data, bool $strict = false)</span>

Parameter explanation:

  • $data: The base64-encoded string.
  • $strict: Optional. If set to true, the input base64 string must be valid.

Here’s an example of using base64_decode:

$encodedString = "SGVsbG8sIFdvcmxkIQ==";
$decodedString = base64_decode($encodedString);

echo "Encoded string: " . $encodedString . "\n";
echo "Decoded string: " . $decodedString . "\n";

Output:

Encoded string: SGVsbG8sIFdvcmxkIQ==
Decoded string: Hello, World!

Conclusion

This article introduced the common encryption and decryption functions in PHP, along with practical code examples. The md5 and sha1 functions are used to encrypt strings, while the base64_decode function is used to decode base64-encoded strings.

When working with sensitive data, choosing the appropriate encryption and decryption methods is crucial. Developers can select the most suitable functions based on their specific needs to ensure data security.

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