- Generate Aes Key Java
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Java support many secure encryption algorithms but some of them are weak to be used in security-intensive applications. For example, the Data Encryption Standard (DES) encryption algorithm is considered highly insecure; messages encrypted using DES have been decrypted by brute force within a single day by machines such as the Electronic Frontier Foundation’s (EFF) Deep. AES (acronym of Advanced Encryption Standard) is a symmetric encryption algorithm. The algorithm was developed by two Belgian cryptographer Joan Daemen and Vincent Rijmen. AES was designed to be efficient in both hardware and software, and supports a block length of 128 bits and key lengths of 128, 192, and 256 bits. Key generators are constructed using one of the getInstance class methods of this class. KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object can be re-used to generate further keys. There are two ways to generate a key: in an algorithm-independent manner, and in an algorithm-specific manner.
“There’s as many atoms in a single molecule of your DNA as there are stars in the typical galaxy. We are, each of us, a little universe.” ― Neil deGrasse Tyson, Cosmos
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- Jan 06, 2018 AES, also known by its original name Rijndael, was selected by the NIST in 2000 to find a successor for the dated Data Encryption Standard(DES). AES is a block cipher, that means encryption happens on fixed-length groups of bits. In our case the algorithm defines 128 bit blocks. AES supports key lengths of 128, 192 and 256 bit.
- Example Code for Java String Encryption with key generation using AES-GCM. Random key generation using strong secure random number generator. AES-256 authenticated encryption. (String plainText) try // GENERATE key // TODO key should only be generated once and then managed with a key manager/key store. KeyGenerator keyGen.
- Conclusion
1. Introduction
The Advanced Encryption Standard (AES) is a standard for encryption and decryption that has been approved by the U.S. NIST (National Institute of Standards and Technology) in 2001. It is more secure than the previous encryption standard DES(Data Encryption Standard) and 3DES(Triple-DES). You should be using AES for all symmetric encryption needs in preference to DES and 3DES (which are now deprecated).
Symmetric Encryption refers to algorithms that use the same key for encryption as well as decryption. As such, the key should be kept secret and must be exchanged between the encryptor and decryptor using a secure channel.
The core java libraries provide good support for all aspects of encryption and decryption using AES so no external libraries are required. In this article, we show you how to properly perform encryption and decryption using AES with just the core java API.
[Note: Check out how to use AES for file encryption and decryption in python.]
2. The Imports
We need the following import statements for the program.
Generate Aes Key Java
3. Generate an Initialization Vector (IV)
When using AES with a mode known as CBC (Cipher Block Chaining), you need to generate an initialization vector (IV). In the CBC mode, each plaintext block is XORed with the previous ciphertext block before being encrypted. So you need an initialization vector for the first block. To produce different ciphertext with each run of the encryption (even with the same plaintext and key), we use a random initialization vector.
To generate the IV, we use the SecureRandomclass. The block size required depends on the AES encryption block size. For the default block size of 128 bits, we need an initialization vector of 16 bytes.
![Generate aes key from string java code Generate aes key from string java code](/uploads/1/2/6/3/126350978/759044240.png)
From the initialization vector, we create an IvParameterSpecwhich is required when creating the Cipher.
You can save the initialization vector for transmission along with the ciphertext as follows. This file can be transmitted plainly i.e. no encryption is required.
4. Generating or Loading a Secret Key
If you do not already have a key, you should generate one as follows:
If you have a key (maybe one generated previously and stored securely), you can load it from a binary key file using the following code:
If you need to save a generated key for future usage (maybe for loading using the above code), you can do it as follows:
5. Creating the Cipher
The Cipher object is the one that handles the actual encryption and decryption. It needs the secret key and the IvParameterSpec created above.
When encrypting, create the Cipher object as follows:
For decryption, you need to load the initialization vector and create the IvParameterSpec.
Now you can create the Cipher object:
6. Encrypting a String
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Once the Cipher object is created, you can perform the encryption. The encryption process works with byte arrays.
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To encrypt a String, first convert it to a byte array by encoding it in UTF-8. Then write the data to a file as follows:
7. Decrypting Back to a String
Read back encrypted text and convert it to a String as follows:
8. Encrypting a File
The procedure for encrypting a file is a bit more involved. Read the input data in a loop and invoke Cipher.update(). If a byte array is returned, you can write it to the output file. Finally wrap up with a Cipher.doFinal().
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Invoke the encryption as follows:
![Generate Aes Key From String Java Generate Aes Key From String Java](/uploads/1/2/6/3/126350978/145383930.png)
9. Decrypting a File
The outfile obtained from the above procedure can be decrypted quite simply by specifying the decrypt mode as follows:
And that covers the whole story of encryption and decryption using AES.
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Conclusion
The process for encrypting and decrypting using AES is a bit involved. First you generate an IV (initialization vector) and then generate (or load) a secret key. Next you create a cipher object which you can use for encryption and decryption.