public void Decrypt()
{
var encryptedKeyXml = GetEncryptedKey();
var encryptedKey = new EncryptedKey();
encryptedKey.LoadXml(encryptedKeyXml);
byte[] symmetricKey = RsaOaepSha256.Decrypt(encryptedKey.CipherData.CipherValue, Certificate);
var symmetricAlgorithm = new AesGcm {
Key = symmetricKey
};
foreach (var attachment in Attachments)
{
attachment.Stream.Position = 0;
var nonce = new byte[AesGcm.NonceSize / 8];
attachment.Stream.Read(nonce, 0, nonce.Length);
symmetricAlgorithm.Nonce = nonce;
var decryptedStream = new MemoryStream();
var cryptoStream = new CryptoStream(attachment.Stream, symmetricAlgorithm.CreateDecryptor(), CryptoStreamMode.Read);
cryptoStream.CopyTo(decryptedStream);
if (!cryptoStream.HasFlushedFinalBlock)
{
cryptoStream.FlushFinalBlock();
}
attachment.Stream = decryptedStream;
}
}
public void Encrypt()
{
var encryptionAlgorithm = new AesGcm {
KeySize = 128
};
encryptionAlgorithm.GenerateKey();
byte[] encryptedSymmetricKey = RsaOaepSha256.Encrypt(encryptionAlgorithm.Key, PublicKeyInAsn1Format);
var encryptedKey = new EncryptedKey
{
Id = "ek-" + Guid.NewGuid(),
EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncRSAOAEPUrl),
CipherData = new CipherData
{
CipherValue = encryptedSymmetricKey
}
};
var encryptedDataList = new List <EncryptedData>();
foreach (Attachment attachment in Attachments)
{
attachment.Stream.Position = 0;
Stream encryptedStream = new MemoryStream();
encryptedStream.Write(encryptionAlgorithm.IV, 0, encryptionAlgorithm.IV.Length);
var cryptoStream = new CryptoStream(encryptedStream, encryptionAlgorithm.CreateEncryptor(), CryptoStreamMode.Write);
attachment.Stream.CopyTo(cryptoStream);
cryptoStream.FlushFinalBlock();
attachment.Stream = encryptedStream;
var encryptedData = new EncryptedData
{
Id = "ed-" + Guid.NewGuid(),
Type = "http://docs.oasis-open.org/wss/oasis-wss-SwAProfile-1.1#Attachment-Content-Only",
EncryptionMethod = new EncryptionMethod("http://www.w3.org/2009/xmlenc11#aes128-gcm"),
CipherData = new CipherData
{
CipherReference = new CipherReference("cid:" + attachment.ContentId)
}
};
encryptedData.KeyInfo.AddClause(new SecurityTokenReference(encryptedKey.Id));
encryptedData.CipherData.CipherReference.TransformChain.Add(new AttachmentCiphertextTransform());
encryptedDataList.Add(encryptedData);
encryptedKey.ReferenceList.Add(new DataReference(encryptedData.Id));
}
var securityXml = GetSecurity() ?? CreateSecurity();
foreach (var encryptedData in encryptedDataList)
{
Insert(encryptedData.GetXml(), securityXml);
}
Insert(encryptedKey.GetXml(), securityXml);
}