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Ruby base 64 decoding for Java base 64 encoding

I having a string that is encoded in java using
data = new String(Base64.getEncoder().encode(encVal), StandardCharsets.UTF_8);
I am receiving this encoded data as an API response. I want to base64 decode this in ruby. I am using
Base64.strict_decode64(data)
for this. but this is not working. Can anyone help me with this?

Your Java code is correct:
byte[] encVal = "Hello World".getBytes();
String data = new String(Base64.getEncoder().encode(encVal), StandardCharsets.UTF_8);
System.out.println(data); // SGVsbG8gV29ybGQ=
The SGVsbG8gV29ybGQ= decodes correctly using multiple tools, e.g. https://www.base64decode.org/.
You are observing garbage characters decoding your value most likely due to an error in creating byte[]. Possibly you have to specify the correct encoding when creating byte[].

What is the correct format for the API SurveyQuestionImage.Data field?

I am working with the GCS API, attempting to create a survey with image data.
I am using the NuGet package Google.Apis.ConsumerSurveys.v2 version 1.14.0.564 on the .Net platform. I can create surveys that do not contain image data without problem. However, when I try to create a survey with image data I receive an error from the API.
I have on hand base64 encoded png format image data. My images display properly in an IMG tag on a web page when the src attribute is set to
'data:image/png;base64,<image base64 string>'
I want to send this image data to the API to populate the survey image. My understanding is that I need to set the Data property of the Google.Apis.ConsumerSurveys.v2.Data.SurveyQuestionImage object to a string containing the image data. I have not been successful.
I first decode my base64 string to a byte array:
byte[] bytes = Convert.FromBase64String(<image base64 string>);
I have tried setting the Data property in the SurveyQuestionImage object as:
image.Data = Encoding.Unicode.GetString(bytes);
This results in this error from the API:
Google.Apis.Requests.RequestError Invalid value for ByteString: <the Data string>
I have also tried converting the byte array to a hexadecimal encoded string as:
StringBuilder sb = new StringBuilder(bytes.Length);
foreach (Byte b in bytes)
{
sb.Append(b.ToString("X2"));
}
image.Data = sb.ToString();
This results in the more hopeful error:
Google.Apis.Requests.RequestError Invalid Value supplied to API: image_data was bad. Request Id: 579665c300ff05e6c316a09e600001737e3430322d747269616c320001707573682d30372d32322d72313000010112 [400] Errors [ Message[Invalid Value supplied to API: image_data was bad. Request Id: 579665c300ff05e6c316a09e600001737e3430322d747269616c320001707573682d30372d32322d72313000010112] Location[ - ] Reason[INVALID_VALUE] Domain[global] ]
Does anyone know the correct format for the Data property of the Google.Apis.ConsumerSurveys.v2.Data.SurveyQuestionImage object?

The data needs to be base64 encoded and also "urlsafe" or "websafe" depending on what language you are using. (python and java, respectively)
In other words, you'll need to first base64 encode then:
Web safe encoding uses '-' instead of '+', '_' instead of '/'
Hope this helps!
For c# users, check out this technique for making websafe b64:
How to achieve Base64 URL safe encoding in C#?
For .net users, look at the comments in this question:
Converting string to web-safe Base64 format
And also this link for more info about .net specific options for encoding:
http://www.codeproject.com/Tips/76650/Base-base-url-base-url-and-z-base-encoding
And to specifically answer the original poster, try this for converting your byte array to a string.
public static string ToBase64ForUrlString(byte[] input)
{
StringBuilder result = new StringBuilder(Convert.ToBase64String(input).TrimEnd('='));
result.Replace('+', '-');
result.Replace('/', '_');
return result.ToString();
}

converting String to ASCII--> BASE64

I'm writing a REST client from a C# usage example. Now i need to convert a string in the proper format but can't find the equivalent method on Java.
original:
string Credentials = Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes(string);
At this point I've done this:
String Credentials = new String(DatatypeConverter.parseBase64Binary(String));
but i still need the ASCII conversion and I'm not sure that the things I've fount will work fine, like: Convert character to ASCII numeric value in java
any clues?
Thank you.

If you're using java 8 you should take a look at its new Base64 class. It will provide you with a Base64.Encoder whose encodeToString(byte[] src) method accepts a byte array and return a base64 encoded String.
String base64 = Base64.getEncoder().encodeToString("I'm a String".getBytes());
System.out.println(base64); // prints SSdtIGEgU3RyaW5n

Input byte array has incorrect ending byte at 40

I have a string that is base64 encoded. It looks like this:
eyJibGExIjoiYmxhMSIsImJsYTIiOiJibGEyIn0=
Any online tool can decode this to the proper string which is {"bla1":"bla1","bla2":"bla2"}. However, my Java implementation fails:
import java.util.Base64;
System.out.println("payload = " + payload);
String json = new String(Base64.getDecoder().decode(payload));
I'm getting the following error:
payload = eyJibGExIjoiYmxhMSIsImJsYTIiOiJibGEyIn0=
java.lang.IllegalArgumentException: Input byte array has incorrect ending byte at 40
What is wrong with my code?

Okay, I found out. The original String is encoded on an Android device using android.util.Base64 by Base64.encodeToString(json.getBytes("UTF-8"), Base64.DEFAULT);. It uses android.util.Base64.DEFAULT encoding scheme.
Then on the server side when using java.util.Base64 this has to be decoded with Base64.getMimeDecoder().decode(payload) not with Base64.getDecoder().decode(payload)

I was trying to use the strings from the args. I found that if I use arg[0].trim() that it made it work. eg
Base64.getDecoder().decode(arg[0].trim());
I guess there's some sort of whitespace that gets it messed up.

Maybe too late, but I also had this problem.
By default, the Android Base64 util adds a newline character to the end of the encoded string.
The Base64.NO_WRAP flag tells the util to create the encoded string without the newline character.
Your android app should encode src something like this:
String encode = Base64.encodeToString(src.getBytes(), Base64.NO_WRAP);

NSData to Java String

I've been writing a Web Application recently that interacts with iPhones. The iPhone iphone will actually send information to the server in the form of a plist. So it's not uncommon to see something like...
<key>RandomData</key>
<data>UW31vrxbUTl07PaDRDEln3EWTLojFFmsm7YuRAscirI=</data>
Now I know this data is hashed/encrypted in some fashion. When I open up the plist with an editor (Property List Editor), it shows me a more "human readable" format. For example, the data above would be converted into something like...
<346df5da 3c5b5259 74ecf683 4431249f 711630ba 232c54ac 9bf2ee44 0r1c8ab2>
Any idea what the method of converting it is? Mainly I'm looking to get this into a Java String.
Thanks!

According to our friends at wikipedia, the <data> tag contains Base64 encoded data. So, use your favorite Java "Base64" class to decode (see also this question).
ps. technically, this is neither "hashed" nor "encrypted", simply "encoded". "Hashed" implies a one-way transformation where multiple input values can yield the same output value. "Encrypted" implies the need for a (usually secret) "key" to reverse the encryption. Base64 encoding is simply a way of representing arbitrary binary data using only printable characters.

After base64 decoding it you need to hex encode it. This is what PL Editor is showing you.
So...
<key>SomeData</key>
<data>UW31ejxbelle7PaeRAEen3EWMLojbFmsm7LuRAscirI=</data?
Can be represented with...
byte[] bytes = Base64.decode("UW31ejxbelle7PaeRAEen3EWMLojbFmsm7LuRAscirI=");
BigInteger bigInt = new BigInteger(bytes);
String hexString = bigInt.toString(16);
System.out.println(hexString);
To get...
<516df5aa 3c5b5259 74ecf683 4401259f 711630ba 236c59ac 9bb2ee44 0b1c8ab2>