Last active
September 28, 2016 13:40
-
-
Save eberlitz/d8a3be7467fda5960eab7b69caaa82b9 to your computer and use it in GitHub Desktop.
Simple example to generate A Shared Access Signature that can be used to share URL for file storage
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
var fileName = "sascontainer/sasblob.txt"; | |
var startTime = "2015-04-29T22%3A18%3A26Z"; | |
var expiracyTime = "2015-04-30T02%3A23%3A26Z"; | |
var permissions = "rw"; | |
var message = string.Format("{0},{1},{2},{3}", fileName, startTime, expiracyTime, permissions); | |
var messageBytes = Encoding.UTF8.GetBytes(message); | |
// Chave: Só o servidor conhece | |
byte[] secretkey = new Byte[64]; | |
using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider()) | |
{ | |
rng.GetBytes(secretkey); | |
} | |
// Assinatura | |
string signature; | |
using (HMACSHA256 hmac = new HMACSHA256(secretkey)) | |
{ | |
byte[] hashValue = hmac.ComputeHash(messageBytes); | |
signature = Convert.ToBase64String(hashValue); | |
} | |
// Validação | |
bool err = false; | |
using (HMACSHA256 hmac = new HMACSHA256(secretkey)) | |
{ | |
byte[] storedHash = Convert.FromBase64String(signature); | |
byte[] computedHash = hmac.ComputeHash(messageBytes); | |
for (int i = 0; i < storedHash.Length; i++) | |
{ | |
if (computedHash[i] != storedHash[i]) | |
{ | |
err = true; | |
break; | |
} | |
} | |
if (err) | |
{ | |
Console.WriteLine("Hash values differ! Signed file has been tampered with!"); | |
} | |
else | |
{ | |
Console.WriteLine("Hash values agree -- no tampering occurred."); | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment