Check if string is base64 python

Have you ever received a PDF or an image file from someone via email, only to see strange characters when you open it? This can happen if your email server was only designed to handle text data. Files with binary data, bytes that represent non-text information like images, can be easily corrupted when being transferred and processed to text-only systems.

By encoding our data, we improve the chances of it being processed correctly by various systems.

check if string is base64 python

In this tutorial, we would learn how Base64 encoding and decoding works, and how it can be used. We will then use Python to Base64 encode and decode both text and binary data. In mathematics, the base of a number system refers to how many different characters represent numbers.

The name of this encoding comes directly from the mathematical definition of bases - we have 64 characters that represent numbers. When the computer converts Base64 characters to binary, each Base64 character represents 6 bits of information.

Note: This is not an encryption algorithm, and should not be used for security purposes. Now that we know what Base64 encoding and how it is represented on a computer, let's look deeper into how it works.

We will illustrate how Base64 encoding works by converting text data, as it's more standard than the various binary formats to choose from. If we were to Base64 encode a string we would follow these steps:. Recall that Base64 characters only represent 6 bits of data. We now re-group the 8-bit binary sequences into chunks of 6 bits. The resultant binary will look like this:. Note: Sometimes we are not able to group the data into sequences of 6 bits.

If that occurs, we have to pad the sequence. With our data in groups of 6 bits, we can obtain the decimal value for each group. Using our last result, we get the following decimal values:. Finally, we will convert these decimals into the appropriate Base64 character using the Base64 conversion table:. As you can see, the value 20 corresponds to the letter U.

Then we look at 7 and observe it's mapped to H. Continuing this lookup for all decimal values, we can determine that "Python" is represented as UHl0aG9u when Base64 encoded. You can verify this result with an online converter. To Base64 encode a string, we convert it to binary sequences, then to decimal sequences, and finally, use a lookup table to get a string of ASCII characters.

With that deeper understanding of how it works, let's look at why would we Base64 encode our data. In computers, all data of different types are transmitted as 1s and 0s. However, some communication channels and applications are not able to understand all the bits it receives.The Base64 validator checks whether the submitted text is a valid Base64 encoded string.

It allows you to validate online a variety of Base64 standards. Therefore, try to specify another standard, if one of them failed. If you do not know which standard to choose, check the standard detector.

check if string is base64 python

If you want to decode a string, use the Base64 decoder. If your string contains invalid characters or cannot pass the validation, use the Base64 Repair Tool. If you have any questions, remarks, need help, or just like this page, please feel free to let me know by leaving a comment using the form bellow.

All answers were been digested into 1 function that ensures 100% that its results will be accurate.

I will be happy to read every comment and, if necessary, I will do my best to respond as quickly as possible. Of course, spammers are welcome only as readers. Comments: 4 Rating: 4. Comments 4 I hope you enjoy this discussion. In any case, I ask you to join it. Sarkout4 april at This validator already supports this standard.

Johnc1025 may at Hi there, I found your web site by the use of Google while searching for a similar matter, your site came up, it seems to be good. I've bookmarked it in my google bookmarks. Hello John! I'm glad you found it useful. If you encounter any problems using this site, please let me know. Only direct replies to my comment. Any comments on my conversation.

I love this page, so send me ALL comments. How do you rate this page? Recent blog posts What is "aaaaigzBy using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I realise that this is an old topic, but using the strict parameter isn't necessarily going to help. Just for strings, you could use this function, that checks several base64 properties before returning true:.

This is a really old question, but I found the following approach to be practically bullet proof. It also takes into account those weird strings with invalid characters that would cause an exception when validating.

I got the idea from this page and adapted it to PHP. The above code will may return unexpected results. For e. It seems we must know the range of allowed characters of the original string and then check if the decoded data has those characters. I write this method is working perfectly on my projects.

When you pass the base64 Image to this method, If it valid return true else return false. Let's try and let me know any wrong. I will edit and learn in the feature. You can also use f. I aggregate this check with the function proposed by merlucin.

But a safe way is using Intervention.

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In fact, there is no reliable answer, as many non-baseencoded text will be readable as baseencoded, so there's no default way to know for sure. As jw specifically. I learned this the hard way. That said, your most reliable method is, if you control the input, to add an identifier to the string after you encode it that is unique and not base64, and include it along with other checks.

It's not bullet-proof, but it's a lot more bullet resistant than any other solution I've seen. For example:. Alright guys Use this below function to check if the string is base64 encoded or not. Learn more. Asked 9 years, 10 months ago. Active 5 months ago. Viewed 77k times. I have a string and want to test using PHP if it's a valid base64 encoded or not.

Alias Alias 1 1 gold badge 5 5 silver badges 3 3 bronze badges. This is probably a duplicate. Active Oldest Votes. PottyBert PottyBert 1, 1 1 gold badge 11 11 silver badges 14 14 bronze badges. Why will that not work? Sam That is because "test" is a perfectly fine base64 string.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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check if string is base64 python

This isn't possible. The best you could do would be to verify that a string might be valid Base 64, although many strings consisting of only ASCII text can be decoded as if they were Base I was looking for a solution to the same problem, then a very simple one just struck me in the head.

All you need to do is decode, then re-encode. If the re-encoded string is equal to the encoded string, then it is base64 encoded. Here is the code:. Edit: Here's a version of the function that works with both the string and bytes objects in Python If the decode fails, then I assume it's raw data. This is required in order for the assert to be generated by the decoder. Without it there will be no complaints about an illegal string. Also not that in my case I wanted to return false if the string is empty to avoid decoding as there's no use in decoding nothing.

Just try to decode doesn't always work. I know I'm almost 8 years late but you can use a regex expression thus you can verify if a given input is BASE Learn more. Check if a string is encoded in base64 using Python Ask Question. Asked 8 years, 1 month ago. Active 1 month ago. Viewed 32k times. Is there a good way to check if a string is encoded in base64 using Python?

Giova 1, 1 1 gold badge 12 12 silver badges 25 25 bronze badges. Active Oldest Votes. Wooble Wooble I want to decode a base64 encoded string, then store it in my database. If the input is not base64 encoded, I need to throw an error. How can I check if the string was base64 enocoded? Check to see IF the string's length is a multiple of 4. Aftwerwards use this regex to make sure all characters in the string are base64 characters.

If the library you use adds a newline as a way of observing the 76 max chars per line rule, replace them with empty strings. If the RegEx does not work and you know the format style of the original string, you can reverse the logic, by regexing for this format. For example I work with base64 encoded xml files and just check if the file contains valid xml markup.

If it does not I can assume, that it's base64 decoded. This is not very dynamic but works fine for my small application. There are many variants of Base64so consider just determining if your string resembles the varient you expect to handle. As such, you may need to adjust the regex below with respect to the index and padding characters i. There is no way to distinct string and base64 encoded, except the string in your system has some specific limitation or identification.

Summary: IsBase64 "string here" returns true if string here is Baseencoded, and it returns false if string here was NOT Baseencoded. Match base64String, 0. This works in Python: import base64 def IsBase64 str : try: base How can you encode a string to Base64 in JavaScript? Something better than Base64 Base64 encoding and decoding in client-side Javascript How to convert an image to base64 encoding?

How to convert image into base64 string using javascript How to do Base64 encoding in node. How do I decode a base64 encoded string? How do I encode and decode a base64 string? NodeJS: How to decode base64 encoded string back to binary?By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Is there a way in C to see if a string is Base 64 encoded other than just trying to convert it and see if there is an error?

How to determine if a string is Base64 decoded or not?

I have code code like this:. I want to avoid the "Invalid character in a Base string" exception that happens if the value is not valid base 64 string. I want to just check and return false instead of handling an exception because I expect that sometimes this value is not going to be a base 64 string. Is there some way to check before using the Convert. FromBase64String function? Update: Thanks for all of your answers. Here is an extension method you can all use so far it seems to make sure your string will pass Convert.

FromBase64String without an exception. NET seems to ignore all trailing and ending spaces when converting to base 64 so "" is valid and so is " ". For those wondering about performance of testing vs catching and exception, in most cases for this base 64 thing it is faster to check than to catch the exception until you reach a certain length.

The smaller the length faster it is. In my very unscientific testing: For iterations for character length- it was 2. For iterations for characters length 1 - 16 characters for total of 16, tests it was I am sure there is a point where it becomes better to test with the exception based method. I just don't know at what point that is. It's pretty easy to recognize a Base64 string, as it will only be composed of characters 'A'.

But instead of comparing these, you'd be better off ignoring the exception, if it occurs. I know you said you didn't want to catch an exception. But, because catching an exception is more reliable, I will go ahead and post this answer.

Update: I've updated the condition thanks to oybek to further improve reliability. Regex is part of the System. RegularExpressions namespace. Just for the sake of completeness I want to provide some implementation.

Generally speaking Regex is an expensive approach, especially if the string is large which happens when transferring large files. The following approach tries the fastest ways of detection first. As suggested by Samyou can also change the source code slightly.Encoding prevents the data from getting corrupted when it is transferred or processed through a text-only system. In this article, we will discuss about Base64 encoding and decoding and its uses to encode and decode binary and text data.

Each Base64 character represents 6 bits of data. To convert a string into a Base64 character the following steps should be followed:. The below image provides us with a Base64 encoding table.

Image Source: Wikipedia. Using Python to decode strings: Decoding Base64 string is exactly opposite to that of encoding. First we convert the Base64 strings into unencoded data bytes followed by conversion into bytes-like object into a string. The below example depicts the decoding of the above example encode string output. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.

See your article appearing on the GeeksforGeeks main page and help other Geeks. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Writing code in comment? Please use ide. To convert a string into a Base64 character the following steps should be followed: Get the ASCII value of each character in the string.

Compute the 8-bit binary equivalent of the ASCII values Convert the 8-bit characters chunk into chunks of 6 bits by re-grouping the digits Convert the 6-bit binary groups to their respective decimal values. Use the Base64 encoding table to align the respective Base64 values for each decimal value. Using python to encode strings: In Python the base64 module is used to encode and decode data.

First, the strings are converted into byte-like objects and then encoded using the base64 module. Recommended Posts: How Base64 encoding and decoding is done in node.

How to convert blob to base64 encoding using JavaScript? Check out this Author's contributed articles. Load Comments. We use cookies to ensure you have the best browsing experience on our website.