10/23/2023 0 Comments Python base64 decode fileThere is an equivalent soundhdr module, and there is also the python-magic project that lets you pass in a number of bytes to determine a file type. I only used the first 33 bytes from the base64 data, to echo what the imghdr.what() function will read from the file you pass it (it reads 32 bytes, but that number doesn't divide by 3). > sample = image_code('base64') # 33 bytes / 3 times 4 is 44 base64 chars > image_data = """iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=""" Your sample is a PNG image you can test for image types using the imghdr module: > import imghdr Decoding just those bytes from the base64 string is trivial. A large number of file formats can be identified from just the first or last series of bytes (a PNG image can be identified by the first 8 bytes, a GIF by the first 6, etc.). So you can decode the first 4 characters to get the 3 bytes, and then use the first two to see if the object is a JPEG image. What you can do is decode just enough of the base64 string to do your filetype fingerprinting. A JPEG image for example, can be identified from the bytes FF D8 or FF D9, but that's two bytes the third byte that follows must also be encoded as part of the 4-character block. Identifying a filetype requires access to those bytes in different block sizes. Each character encodes 6 bits, which means that for every 4 characters, there are 3 bytes encoded. Finally, we create an empty image file pic_decoded_back.jpeg and variable final_decoder that will act as a funnel to transfer decoded data into the image file.You can't, at least not without decoding, because the bytes that help identify the filetype are spread across the base64 characters, which don't directly align with whole bytes.We use variable read_64 to read encoded values stored in the decoder variable.We have Base64 values in the coded_str variable.Let’s recall the steps initiated so far to make everything crystal clear. jpeg file where we will be storing our decoded Base64 values.įinally, we decode and write the contents into a new image file. The variable final_decoder is used to create a new writable. Then the contents of the decoder are read by a variable using the syntax, read_b64 = decoder.read(). The file is loaded as a readable entity because we won’t be writing anything in this file anymore. bin file through the syntax decoder = open('pic_encoding.bin', 'rb'). Variable decoder is created that loads the. Decode Base64 Values and Write Into an Image File It should be made sure that the file is in the same directory where the python.txt file is stored, or the system won’t interact with it. txt file can also be used.Īll it needs is to put the file having Base64 values in the syntax, with open('(filename.extension)', "wb") as file:, and the file will be loaded in the program. The above program can be used to recreate the coded_str variable, but a. Here, the variable coded_str is used in the above program. The file.write(coded_str) syntax simply writes those Base64 values into that. bin file, in which we store the Base64 values. The syntax with open('file_name, "wb") as file: creates a writable ( "wb"). bin file is created to store the Base64 values for this step.
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