MySQL | AES_DECRYPT ( ) Function

The MySQL AES_DECRYPT function returns the original string after decrypting an encrypted string. It uses AES(Advanced Encryption Standard) algorithm to perform the decryption. The AES_DECRYPT function returns the decrypted string or NULL if it detects invalid data. 

The value returned by the AES_DECRYPT function is the original plaintext string encrypted using AES_ENCRYPT function. The AES_DECRYPT function accepts two parameters which are the encrypted string and a string used to decrypt the encrypted string. 

Syntax:

AES_DECRYPT(encrypted_string, key_string)

Parameters Used:

• encrypted_string – It is used to specify the encrypted string.
• key_string – It is used to specify the String which is used to decrypt encrypted_string.

Return Value:
The AES_DECRYPT function in MySQL returns the original plaintext string encrypted using AES_ENCRYPT function. 

Supported Versions of MySQL:

• MySQL 5.7
• MySQL 5.6
• MySQL 5.5
• MySQL 5.1
• MySQL 5.0
• MySQL 4.1

Example-1: Implementing AES_DECRYPT function on a string. 

SELECT  
AES_DECRYPT(AES_ENCRYPT('ABC', 'key_string'), 'key_string'); 

Output:

ABC 

Example-2: Implementing AES_DECRYPT function on a string with a combination of characters and integer values. 

SELECT  
AES_DECRYPT(AES_ENCRYPT('ABC123', 'key_string'), 'key_string'); 

Output:

ABC123 

Example-3: Implementing AES_DECRYPT function on a bigger string. 

SELECT  
AES_DECRYPT(AES_ENCRYPT('geeksforgeeks', 'key_string'), 'key_string'); 

Output:

geeksforgeeks 

Example-4: Implementing AES_DECRYPT function on a NULL string. 

SELECT  
AES_DECRYPT(AES_ENCRYPT(NULL, 'key_string'), 'key_string'); 

Output:

NULL