c# - Decrypting CryptoStream into MemoryStream -

i have written process file encrypted , uploaded azure, download process has decrypted fails "padding invalid , cannot removed" error, or "length of data decrypt invalid." error.

i've tried numerous solutions online, including c# decrypting mp3 file using rijndaelmanaged , cryptostream, none of them seem work , end bouncing , forth between these 2 errors. encryption process uses same key/iv pair decryption uses, , since decrypt portion of stream feel that's working fine - ends dying above errors.

here code, ideas? please note 3 variants (cryptostream.copyto(decryptedstream), do {} , while) aren't run - here show options i've tried, of fail.

byte[] encryptedbytes = null;  using (var encryptedstream = new memorystream()) {     //download azure     cloudblockblob.downloadtostream(encryptedstream);      //reset positioning reading out     encryptedstream.position = 0;      encryptedbytes = encryptedstream.converttobytearray(); }  //used blob stream azure using (var encryptedstream = new memorystream(encryptedbytes)) {     //stream decrypted contents stored     using (var decryptedstream = new memorystream())     {         using (var aes = new rijndaelmanaged { keysize = 256, key = blobkey.key, iv = blobkey.iv })         {             using (var decryptor = aes.createdecryptor())             {                 //decrypt stream , write parent stream                 using (var cryptostream = new cryptostream(encryptedstream, decryptor, cryptostreammode.read))                 {                     //fails here "length of data decrypt invalid." error                     cryptostream.copyto(decryptedstream);                      int data;                      //fails here "length of data decrypt invalid." error after loops number of times,                     //implying in fact decrypting part of it, not                                         {                         data = cryptostream.readbyte();                         decryptedstream.writebyte((byte)cryptostream.readbyte());                     } while (!cryptostream.hasflushedfinalblock);                      //fails here "length of data decrypt invalid." error after loops number of times,                     //implying in fact decrypting part of it, not                     while ((data = cryptostream.readbyte()) != -1)                     {                         decryptedstream.writebyte((byte)data);                     }                 }             }         }          //reset position in prep reading         decryptedstream.position = 0;         return decryptedstream.converttobytearray();     } } 

one of comments mentioned wanting know converttobytearray is, , it's simple extension method:

/// <summary> /// converts stream byte array. /// </summary> /// <param name="stream">the stream convert.</param> /// <returns>a byte[] array representing current stream.</returns> public static byte[] converttobytearray(this stream stream) {     byte[] buffer = new byte[16 * 1024];     using (memorystream ms = new memorystream())     {         int read;         while ((read = stream.read(buffer, 0, buffer.length)) > 0)         {             ms.write(buffer, 0, read);         }         return ms.toarray();     } } 

the code never reaches though - dies before can ever point.

after lot of , forth various blogs, found had couple of errors in above code nailing me. first, encryption process incorrectly writing array - wrapped cryptostream instance, wasn't utilizing writing unencrypted data azure. here proper route go (filekey part of custom class created generate key/iv pairs, wherever referenced can changed built-in process rijndaelmanaged or else you'd utilize coming key/iv pair):

using (var aes = new rijndaelmanaged { keysize = 256, key = filekey.key, iv = filekey.iv }) {     using (var encryptedstream = new memorystream())     {         using (icryptotransform encryptor = aes.createencryptor())         {             using (cryptostream cryptostream = new cryptostream(encryptedstream, encryptor, cryptostreammode.write))             {                 using (var originalbytestream = new memorystream(file.file.data))                 {                     int data;                     while ((data = originalbytestream.readbyte()) != -1)                         cryptostream.writebyte((byte)data);                 }             }         }          var encryptedbytes = encryptedstream.toarray();         return encryptedbytes;     } } 

second, since encryption process involves multiple steps (three total keys per file - container, filename , file itself), when tried decrypt, using wrong key (which seen above when referenced blobkey decrypt, key used encrypting filename , not file itself. proper decryption method was:

//used blob stream azure using (var encryptedstream = new memorystream(encryptedbytes)) {     //stream decrypted contents stored     using (var decryptedstream = new memorystream())     {         using (var aes = new rijndaelmanaged { keysize = 256, key = blobkey.key, iv = blobkey.iv })         {             using (var decryptor = aes.createdecryptor())             {                 //decrypt stream , write parent stream                 using (var cryptostream = new cryptostream(encryptedstream, decryptor, cryptostreammode.read))                 {                     int data;                      while ((data = cryptostream.readbyte()) != -1)                         decryptedstream.writebyte((byte)data);                 }             }         }          //reset position in prep reading         decryptedstream.position = 0;         return decryptedstream.converttobytearray();     } } 

i had looked azure encryption extensions (http://www.stefangordon.com/introducing-azure-encryption-extensions/), little more local file-centric interested - on end streams/in-memory only, , retrofitting utility going more work worth.

hopefully helps looking encrypt azure blobs 0 reliance on underlying file system!