Java implementation of AES encryption algorithm simple example sharing _java

Advanced Encryption Standard (English: Advanced encryption Standard, abbreviation: AES), also known as the Rijndael encryption method in cryptography, is a block encryption standard used by the U.S. federal government. This standard, which replaces the original DES, has been analyzed and widely used worldwide.
Most AES calculations are done in a particular finite field.
The AES encryption process operates on a 4x4 byte matrix, also known as "State", whose initial value is a plaintext block (one element in a matrix is a byte in a plain text block). (Rijndael encryption method to support a larger block, its matrix row number can increase visibility) encryption, the rounds of AES encryption cycle (except the last round) contains 4 steps:

• Each byte in the addroundkey-matrix is XOR with the second wheel secret key (round key), and each subkey is generated by the key generation scheme.
• Subbytes-uses a non-linear substitution function to replace each byte with the corresponding byte in a lookup table.
• shiftrows-shifts each row in the matrix in a cyclic style.
• mixcolumns-to fully blend the operations of each straight line in the matrix. This step uses a linear transformation to mix four bytes of each column.

Omit the Mixcolumns step in the last cryptographic loop and replace it with another addroundkey.

Java Basic implementation:

Package com.stone.security; 
 
Import Java.util.Arrays; 
Import Javax.crypto.Cipher; 
Import Javax.crypto.KeyGenerator; 
Import Javax.crypto.SecretKey; 
 
Import Javax.crypto.spec.IvParameterSpec; 
 /** * AES Algorithm symmetric encryption, cryptography, the Advanced Encryption Standard 2005 become a valid standard * * public class AES {static Cipher Cipher; 
 Static final String key_algorithm = "AES"; 
 Static final String CIPHER_ALGORITHM_ECB = "aes/ecb/pkcs5padding"; 
Static final String CIPHER_ALGORITHM_CBC = "aes/cbc/pkcs5padding"; /** * aes/cbc/nopadding requirement * Key must be 16 bits, initialization vector (IV) must be 16 bits * The length of the content to be encrypted must be a multiple of 16, if not multiples of 16, the following exception will occur: * j 
 Avax.crypto.IllegalBlockSizeException:Input length not multiple of bytes * * * Due to the fixed number of digits, so for the encrypted data has Chinese, add, decrypt incomplete * * Can be seen, in the original data length of 16 integer n times, if the original data length equals 16*n, then use nopadding when the data length is equal to 16*n, * Other cases encrypted data length equal to 16* (n+1). 
 In the case of less than 16 integer times, if the original data length equals 16*n+m[where M is less than 16], the encrypted data length equals 16* (n+1) in any way except for the nopadding padding. 
 
 * * Static final String cipher_algorithm_cbc_nopadding = "aes/cbc/nopadding"; Static SecreTKey Secretkey; 
 public static void Main (string[] args) throws Exception {method1 ("A*jal) k32j8czx 囙 Country is country wide"); 
 METHOD2 ("A*jal) k32j8czx 囙 State"); 
  
 Method3 ("A*jal) k32j8czx 囙 State"); METHOD4 ("123456781234 囙 for Country Wide");/length = METHOD4 ("12345678abcdefgh");/length = 16}/** * uses AES algorithm to encrypt, default mode 
 Type AES/ECB */static void method1 (String str) throws Exception {cipher = Cipher.getinstance (key_algorithm); 
 Keygenerator generates AES algorithm key Secretkey = Keygenerator.getinstance (key_algorithm). GenerateKey (); 
  
 System.out.println ("The length of the key is:" + secretkey.getencoded (). length); Cipher.init (Cipher.encrypt_mode, Secretkey);//Use encryption mode to initialize the key byte[] ENCRYPT = cipher.dofinal (Str.getbytes ()); 
  
 Encrypt or decrypt data in one-part operation, or end a multiple-part operation. 
 SYSTEM.OUT.PRINTLN ("method1-encryption:" + arrays.tostring (encrypt)); 
 Cipher.init (Cipher.decrypt_mode, Secretkey)//Use decryption mode to initialize the key byte[] DECRYPT = cipher.dofinal (encrypt); 
  
 System.out.println ("method1-after decryption:" + new String (decrypt)); /** * uses AES algorithm encryption, default mode aes/ecb/pkcs5padding */static void Method2 (String str) throws Exception {cipher = Cipher.getinstance (cipher_algorithm_e 
 CB); 
 Keygenerator generates AES algorithm key Secretkey = Keygenerator.getinstance (key_algorithm). GenerateKey (); 
  
 System.out.println ("The length of the key is:" + secretkey.getencoded (). length); Cipher.init (Cipher.encrypt_mode, Secretkey);//Use encryption mode to initialize the key byte[] ENCRYPT = cipher.dofinal (Str.getbytes ()); 
  
 Encrypt or decrypt data in one-part operation, or end a multiple-part operation. 
 SYSTEM.OUT.PRINTLN ("method2-encryption:" + arrays.tostring (encrypt)); 
 Cipher.init (Cipher.decrypt_mode, Secretkey)//Use decryption mode to initialize the key byte[] DECRYPT = cipher.dofinal (encrypt); 
  
 System.out.println ("method2-after decryption:" + new String (decrypt));  
 Static byte[] Getiv () {String IV = "1234567812345678";//iv length:must is bytes long return iv.getbytes (); /** * Using AES algorithm encryption, default mode aes/cbc/pkcs5padding/static void method3 (String str) throws Exception {cipher 
 = Cipher.getinstance (CIPHER_ALGORITHM_CBC); Keygenerator generate AES Algorithm key Secretkey = KeYgenerator.getinstance (Key_algorithm). GenerateKey (); 
  
 System.out.println ("The length of the key is:" + secretkey.getencoded (). length); Cipher.init (Cipher.encrypt_mode, Secretkey, New Ivparameterspec (Getiv ());//Use encryption mode to initialize the key byte[] ENCRYPT = Cipher.dofinal (Str.getbytes ()); 
  
 Encrypt or decrypt data in one-part operation, or end a multiple-part operation. 
 SYSTEM.OUT.PRINTLN ("method3-encryption:" + arrays.tostring (encrypt)); Cipher.init (Cipher.decrypt_mode, Secretkey, New Ivparameterspec (Getiv ()))//Use decryption mode to initialize the key byte[] DECRYPT = 
 Cipher.dofinal (encrypt); 
  
 System.out.println ("method3-after decryption:" + new String (decrypt));  /** * uses AES algorithm encryption, default mode aes/cbc/nopadding see above data limits for this mode/static void Method4 (String str) throws Exception 
 {cipher = Cipher.getinstance (cipher_algorithm_cbc_nopadding); 
 Keygenerator generates AES algorithm key Secretkey = Keygenerator.getinstance (key_algorithm). GenerateKey (); 
  
 System.out.println ("The length of the key is:" + secretkey.getencoded (). length); Cipher.init (Cipher.encrypt_mode, Secretkey, New Ivparameterspec (Getiv ()));//Use encryption mode to initialize the secretKey byte[] Encrypt = cipher.dofinal (str.getbytes (), 0, Str.length ()); 
  
 Encrypt or decrypt data in one-part operation, or end a multiple-part operation. 
 SYSTEM.OUT.PRINTLN ("method4-encryption:" + arrays.tostring (encrypt)); Cipher.init (Cipher.decrypt_mode, Secretkey, New Ivparameterspec (Getiv ()))//Use decryption mode to initialize the key byte[] DECRYPT = 
  
 Cipher.dofinal (encrypt); 
  
 System.out.println ("method4-after decryption:" + new String (decrypt));  } 
 
}