Converting Encoded byte[] to a printable string

Question

I am encoding strings using C#'s Rijndael AES encryption. I generate a key and an IV, and use them to encode strings and values that I can then save to disk (I am using Unity3D's playerprefs).

The problem I am facing is that the PlayerPrefs keys and values need to be valid character sequences, and the encoded bytes are not necessarily valid.

So, after encoding my string with my key and IV, I get a byte array that I can enode in Unicode, but (sometimes) when I try to save it, I get an error message:

byte[] encryptedBytes = Encode("someText", encryptionKey, initVector);
string encodedString = Encoding.Unicode.GetString(encryptedBytes);
PlayerPrefs.SetString("SecretData",encodedString);
PlayerPrefs.Save();

Error:

invalid utf-16 sequence at -1073752512 (missing surrogate tail)

Any way to make sure the string is in a valid format?

Don't forget to save the random IV with the ciphertext or you may not be able to decrypt. Prepend it to the ciphertext before encoding the ciphertext... — Maarten Bodewes, Jun 07 '13 at 19:39
Yeah, I omitted that part from the question because I thought it obvious XD — David Menard, Jun 07 '13 at 19:41

score 2 · Accepted Answer · answered Jun 07 '13 at 19:36

2

The bytes returned by the encrypt function are indistinguishable from random and may not contain valid character encoding. To convert the result into a string (if required) you may use base 64.

answered Jun 07 '13 at 19:36

Maarten Bodewes

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Converting Encoded byte[] to a printable string

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