Example 1: To generate a 256-bit random number. The following generate-random example generates a 256-bit (32-byte) random number. When you run this command, you must use the number-of-bytes parameter to specify the length of the random number in bytes. You don't specify a CMK when you run this command. Unless you specify a custom key store, AWS KMS generates the random number.

Encrypt, decrypt and generate a key in C# using AES256.

A A Randomly Generated 256-bit Binary Key Sheet

encryption.cs
#regionEncryption
/// <summary>
/// Generate a private key
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
privatestaticstringGenerateKey(intiKeySize)
{
RijndaelManagedaesEncryption=newRijndaelManaged();
aesEncryption.KeySize=iKeySize;
aesEncryption.BlockSize=128;
aesEncryption.Mode=CipherMode.CBC;
aesEncryption.Padding=PaddingMode.PKCS7;
aesEncryption.GenerateIV();
stringivStr=Convert.ToBase64String(aesEncryption.IV);
aesEncryption.GenerateKey();
stringkeyStr=Convert.ToBase64String(aesEncryption.Key);
stringcompleteKey=ivStr+','+keyStr;
returnConvert.ToBase64String(ASCIIEncoding.UTF8.GetBytes(completeKey));
}
/// <summary>
/// Encrypt
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
privatestaticstringEncrypt(stringiPlainStr, stringiCompleteEncodedKey, intiKeySize)
{
RijndaelManagedaesEncryption=newRijndaelManaged();
aesEncryption.KeySize=iKeySize;
aesEncryption.BlockSize=128;
aesEncryption.Mode=CipherMode.CBC;
aesEncryption.Padding=PaddingMode.PKCS7;
aesEncryption.IV=Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[0]);
aesEncryption.Key=Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[1]);
byte[] plainText=ASCIIEncoding.UTF8.GetBytes(iPlainStr);
ICryptoTransformcrypto=aesEncryption.CreateEncryptor();
byte[] cipherText=crypto.TransformFinalBlock(plainText, 0, plainText.Length);
returnConvert.ToBase64String(cipherText);
}
/// <summary>
/// Decrypt
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
privatestaticstringDecrypt(stringiEncryptedText, stringiCompleteEncodedKey, intiKeySize)
{
RijndaelManagedaesEncryption=newRijndaelManaged();
aesEncryption.KeySize=iKeySize;
aesEncryption.BlockSize=128;
aesEncryption.Mode=CipherMode.CBC;
aesEncryption.Padding=PaddingMode.PKCS7;
aesEncryption.IV=Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[0]);
aesEncryption.Key=Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[1]);
ICryptoTransformdecrypto=aesEncryption.CreateDecryptor();
byte[] encryptedBytes=Convert.FromBase64CharArray(iEncryptedText.ToCharArray(), 0, iEncryptedText.Length);
returnASCIIEncoding.UTF8.GetString(decrypto.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length));
}
#endregion

commented Jun 6, 2014

A a randomly generated 256-bit binary key sheet

hi fairly new to the cryptography...
when im implementing the above code im getting a error while decrypting..
'Padding is invalid and cannot be removed.'

please suggest a resolution
thanks and regards

commented Oct 9, 2017
edited

How-to save -safely- the private key ? Windows registry ? in disk ?

I use ASP.NET applications.

Test your code

Random 256 Bit Key Generator

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