.NET provides high-level level classes for various encryption algorithms, both symmetric and asymmetric. Advanced Encryption Standard (AES) is one of the symmetric encryption algorithms that allows both parties, sender, and receiver, to use the same key to encrypt and decrypt data.
AES was developed by two Belgian cryptographers, Vincent Rijmen and Jan Daemen. In 2001, AES was selected as a standard for encryption by the U. S. National Institute of Standards and Technology (NIST). AES supports 128, 192, and 256 bits key sizes and 128 bits sizes.
AesManaged class is a managed implementation of the AES algorithm. This article demonstrates the use AesManaged class to apply an AES algorithm to encrypt and decrypt data in .NET and C#.
The following steps are required to encrypt data using AesManaged.
Step 1
Create AesManaged,
AesManagedaes=newAesManaged();
Step 2
Create Encryptor,
ICryptoTransformencryptor=aes.CreateEncryptor(Key,IV);
Step 3
Create MemoryStream,
MemoryStreamms=newMemoryStream();
Step 4
Create CryptoStream from MemoryStream and Encrypter and write it.
using(CryptoStreamcs=newCryptoStream(ms,encryptor,CryptoStreamMode.Write)){//CreateStreamWriterandwritedatatoastreamusing(StreamWritersw=newStreamWriter(cs))sw.Write(plainText);encrypted=ms.ToArray();}
The complete code is listed in Listing 1. To test the code, create a .NET Core project in Visual Studio and copy and paste the code.
usingSystem;usingSystem.IO;usingSystem.Security.Cryptography;classManagedAesSample{publicstaticvoidMain(){Console.WriteLine("Entertextthatneedstobeencrypted..");stringdata=Console.ReadLine();EncryptAesManaged(data);Console.ReadLine();}staticvoidEncryptAesManaged(stringraw){try{//CreateAesthatgeneratesanewkeyandinitializationvector(IV).//Samekeymustbeusedinencryptionanddecryptionusing(AesManagedaes=newAesManaged()){//Encryptstringbyte[]encrypted=Encrypt(raw,aes.Key,aes.IV);//PrintencryptedstringConsole.WriteLine($"Encrypteddata:{System.Text.Encoding.UTF8.GetString(encrypted)}");//decryptthebytestoastring.stringdecrypted=Decrypt(encrypted,aes.Key,aes.IV);//Printdecryptedstring.ItshouldbesameasrawdataConsole.WriteLine($"Decrypteddata:{decrypted}");}}catch(Exceptionexp){Console.WriteLine(exp.Message);}Console.ReadKey();}staticbyte[]Encrypt(stringplainText,byte[]Key,byte[]IV){byte[]encrypted;//CreateanewAesManaged.using(AesManagedaes=newAesManaged()){//CreateencryptorICryptoTransformencryptor=aes.CreateEncryptor(Key,IV);//CreateMemoryStreamusing(MemoryStreamms=newMemoryStream()){//CreatecryptostreamusingtheCryptoStreamclass.Thisclassisthekeytoencryption//andencryptsanddecryptsdatafromanygivenstream.Inthiscase,wewillpassamemorystream//toencryptusing(CryptoStreamcs=newCryptoStream(ms,encryptor,CryptoStreamMode.Write)){//CreateStreamWriterandwritedatatoastreamusing(StreamWritersw=newStreamWriter(cs))sw.Write(plainText);encrypted=ms.ToArray();}}}//Returnencrypteddatareturnencrypted;}staticstringDecrypt(byte[]cipherText,byte[]Key,byte[]IV){stringplaintext=null;//CreateAesManagedusing(AesManagedaes=newAesManaged()){//CreateadecryptorICryptoTransformdecryptor=aes.CreateDecryptor(Key,IV);//Createthestreamsusedfordecryption.using(MemoryStreamms=newMemoryStream(cipherText)){//Createcryptostreamusing(CryptoStreamcs=newCryptoStream(ms,decryptor,CryptoStreamMode.Read)){//Readcryptostreamusing(StreamReaderreader=newStreamReader(cs))plaintext=reader.ReadToEnd();}}}returnplaintext;}}
Listing 1.
The output looks like the following, where you can type any text that will be encrypted and decrypted.
References
- https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
- https://docs.microsoft.com
FAQs
Implementing AES Encryption in C#:
- Step 1: Create an Instance of the AES Class. ADVERTIsem*nT. ...
- Step 2: Set the Key Size and Mode. The Aes class provides properties for setting the key size and mode. ...
- Step 3: Generate a Random Key and Initialization Vector. ...
- Step 4: Encrypt the Data. ...
- Step 5: Decrypt the Data.
If you ask how long will it take to crack 128-bit encryption using a brute force attack, the answer would be 1 billion years. A machine that can crack a DES key in a second would take 149 trillion years to crack a 128-bit AES key.
Why is 256 AES so hard to crack? ›
AES is a substitution-permutation network that uses a key expansion process where the initial key is used to come up with new keys called round keys. The round keys are generated over multiple rounds of modification. Each round makes it harder to break the encryption. The AES-256 encryption uses 14 such rounds.
How much data can AES encrypt? ›
Each cipher encrypts and decrypts data in blocks of 128 bits using cryptographic keys of 128, 192 and 256 bits, respectively. The 128-, 192- and 256-bit keys undergo 10, 12 and 14 rounds of encryption, respectively.
What is the key size for AES encryption C#? ›
For AES, the legal key sizes are 128, 192, and 256 bits.
What is the secret key for AES algorithm? ›
AES has three variants that are selected based on the secret key length, all of which use a fixed-sized block of 16 bytes (or 128 bits). Because the block size of AES is set to 16 bytes, the plaintext must be at least 16 bytes long.
Can I decrypt AES without a key? ›
If its encrypted, the only way to get the contents without the encryption key is to brute-force it, but I wouldn't get your hopes up. All these malware variants as of late rely on encryption being nearly unbreakable without government-funded super computing power, and even then its time consuming.
Should I use AES 128 or 256? ›
Our best guidance is that AES-128 provides more than adequate security while being faster and more resource-efficient but readers who want that extra security provided by greater key sizes and more rounds in the algorithm should choose AES-256.
What is the strongest AES encryption? ›
AES 256-bit encryption is the strongest and most robust encryption standard that is commercially available today. While it is theoretically true that AES 256-bit encryption is harder to crack than AES 128-bit encryption, AES 128-bit encryption has never been cracked.
Is AES still unbreakable? ›
The primary reason AES 256 is considered unbreakable is the sheer number of possible encryption key combinations. With a 256-bit key size, there are 2^256 possible key combinations, making it practically impossible for an attacker to guess the correct key and decrypt the ciphertext.
AES-192 and AES-128 are not considered quantum resistant due to their smaller key sizes. AES-192 has a strength of 96 bits against quantum attacks and AES-128 has 64 bits of strength against quantum attacks, making them both insecure.
How to decrypt an AES password? ›
Decrypting a File
- Locate the file that needs to be decrypted. The encrypted file will have an “. ...
- Double click on the file, or right click on the file and select AES Decrypt.
- You will be prompted to enter a password. This is the password that was set when the file was encrypted. ...
- Enter the password and click OK.
AES-256 is unbreakable by brute force
It is the strongest encryption and is almost impossible to break. A brute force attack is when a hacker checks different key combinations until he/she arrives at the correct combination. The larger the key size, the more difficult it becomes to break the encryption.
Can AES be breached? ›
Hackers may not be able to brute force your AES 256 algorithm, but they don't give up that fast. They can (and will) still be able to try and: Gain access to your AES 256 cryptographic keys. Leverage side-channel attacks such as mining leaked information.
Does https use AES-256? ›
For HTTPS File Transfers
Navigate to Server > Settings > Web > SSL/TLS Ciphers and then select the cipher suites you're comfortable with that use AES 256.
How to generate 256-bit AES key in C#? ›
Create an AES 256-bit key in C#
The easiest way to create an AES 256-bit key is to use the Aes. Create method. That method initializes a cryptographic object implementing the AES algorithm. With that instance, you will be able to call the GenerateKey method to create a new AES key.
How to encrypt a file in C#? ›
How to Encrypt a File in C#:
- Generate a cryptographic key: Use a cryptographic algorithm like AES or RSA to generate a secure encryption key.
- Open the file for encryption: Open the file you want to encrypt using the FileStream class in C#.
- 10 Common Encryption Algorithms and Libraries in C# codezone. ...
- AES (Advanced Encryption Standard) NuGet Package: System.Security.Cryptography.AesManaged. ...
- RSA (Rivest–Shamir–Adleman) ...
- DES (Data Encryption Standard) ...
- Triple DES (3DES) ...
- Blowfish. ...
- Twofish. ...
- Serpent.
