I am trying to upload file to Amazon S3 directly from browser. I read the documentation and followed the example provided by amazon
the example methods works except post method. the error message is The request signature we calculated does not match the signature you provided. Check your key and signing method.
I also checked this code sample. and applied the answer to the code and still getting the same error.
public class PolicyBuilder
{
public static string Key = "Key";
public static string Secret = "Secret";
public static string GetS3PolicySignatureV4()
{
var policyBuilder = new StringBuilder();
policyBuilder.AppendFormat("{{ \"expiration\": \"{0}\",\r\n", "2018-12-30T12:00:00.000Z");
policyBuilder.Append(" \"conditions\": [\r\n");
policyBuilder.Append(" [\"starts-with\", \"$key\", \"\"],\r\n");
policyBuilder.AppendFormat(" {{\"x-amz-credential\": \"{0}\"}},\r\n", Key + "/20180308/us-east-1/s3/aws4_request");
policyBuilder.Append(" {\"x-amz-algorithm\": \"AWS4-HMAC-SHA256\"},\r\n");
policyBuilder.Append(" {\"x-amz-date\": \"20180308T000000Z\" }\r\n");
policyBuilder.Append(" ]\r\n}");
var policyString = policyBuilder.ToString();
var policyStringBytes = Encoding.UTF8.GetBytes(policyString);
var policy = Convert.ToBase64String(policyStringBytes);
byte[] signingKey = GetSignatureKey(Key, "20180308", "us-east-1", "s3");
byte[] signature = HmacSHA256(policy, signingKey);
var sig = ToHexString(signature, true);
return sig;
}
static byte[] HmacSHA256(String data, byte[] key)
{
String algorithm = "HmacSHA256";
KeyedHashAlgorithm kha = KeyedHashAlgorithm.Create(algorithm);
kha.Key = key;
return kha.ComputeHash(Encoding.UTF8.GetBytes(data));
}
static byte[] GetSignatureKey(String key, String dateStamp, String regionName, String serviceName)
{
byte[] kSecret = Encoding.UTF8.GetBytes(("AWS4" + key).ToCharArray());
byte[] kDate = HmacSHA256(dateStamp, kSecret);
byte[] kRegion = HmacSHA256(regionName, kDate);
byte[] kService = HmacSHA256(serviceName, kRegion);
byte[] kSigning = HmacSHA256("aws4_request", kService);
return kSigning;
}
public static string ToHexString(byte[] data, bool lowercase)
{
var sb = new StringBuilder();
for (var i = 0; i < data.Length; i++)
{
sb.Append(data[i].ToString(lowercase ? "x2" : "X2"));
}
return sb.ToString();
}
}
and here is the form:
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<form action="http://MyBucket.s3.amazonaws.com/" method="post" enctype="multipart/form-data">
<input type="hidden" name="key" value="/images/a5827206-ea2c-4fc6-a66b-aebde27d0ea3.jpg" />
<input type="hidden" name="x-amz-credential" value="Key/20180308/us-east-1/s3/aws4_request" />
<input type="hidden" name="x-amz-algorithm" value="AWS4-HMAC-SHA256" />
<input type="hidden" name="x-amz-date" value="20180308T000000Z" />
<input type="hidden" name="policy" value='<Base64PolicyResult>' />
<input type="hidden" name="x-amz-signature" value="<GenerateSignature>" />
File:
<input type="file" name="file" /> <br />
<input type="submit" name="submit" value="Upload to Amazon S3" />
</form>
</body>
</html>I am still getting the same error. Should I set any specific policy for my bucket on amazon s3? is there anything wrong in my code? :(
