How to Get Md5 Sum of a String Using Python

How to get MD5 sum of a string using python?

For Python 2.x, use python's hashlib

import hashlib
m = hashlib.md5()
m.update("000005fab4534d05api_key9a0554259914a86fb9e7eb014e4e5d52permswrite")
print m.hexdigest()

Output: a02506b31c1cd46c2e0b6380fb94eb3d

How do I calculate the MD5 checksum of a file in Python?

In regards to your error and what's missing in your code. m is a name which is not defined for getmd5() function.

No offence, I know you are a beginner, but your code is all over the place. Let's look at your issues one by one :)

First, you are not using hashlib.md5.hexdigest() method correctly. Please refer explanation on hashlib functions in Python Doc Library. The correct way to return MD5 for provided string is to do something like this:

>>> import hashlib
>>> hashlib.md5("example string").hexdigest()
'2a53375ff139d9837e93a38a279d63e5'

However, you have a bigger problem here. You are calculating MD5 on a file name string, where in reality MD5 is calculated based on file contents. You will need to basically read file contents and pipe it though MD5. My next example is not very efficient, but something like this:

>>> import hashlib
>>> hashlib.md5(open('filename.exe','rb').read()).hexdigest()
'd41d8cd98f00b204e9800998ecf8427e'

As you can clearly see second MD5 hash is totally different from the first one. The reason for that is that we are pushing contents of the file through, not just file name.

A simple solution could be something like that:

# Import hashlib library (md5 method is part of it)
import hashlib

# File to check
file_name = 'filename.exe'

# Correct original md5 goes here
original_md5 = '5d41402abc4b2a76b9719d911017c592'  

# Open,close, read file and calculate MD5 on its contents 
with open(file_name, 'rb') as file_to_check:
    # read contents of the file
    data = file_to_check.read()    
    # pipe contents of the file through
    md5_returned = hashlib.md5(data).hexdigest()

# Finally compare original MD5 with freshly calculated
if original_md5 == md5_returned:
    print "MD5 verified."
else:
    print "MD5 verification failed!."

Please look at the post Python: Generating a MD5 checksum of a file. It explains in detail a couple of ways how it can be achieved efficiently.

Best of luck.

Generating an MD5 checksum of a file

You can use hashlib.md5()

Note that sometimes you won't be able to fit the whole file in memory. In that case, you'll have to read chunks of 4096 bytes sequentially and feed them to the md5 method:

import hashlib
def md5(fname):
    hash_md5 = hashlib.md5()
    with open(fname, "rb") as f:
        for chunk in iter(lambda: f.read(4096), b""):
            hash_md5.update(chunk)
    return hash_md5.hexdigest()

Note: hash_md5.hexdigest() will return the hex string representation for the digest, if you just need the packed bytes use return hash_md5.digest(), so you don't have to convert back.

Comparing the MD5 sum of a string to the contents of a file

Short answer: I think you need to set serialize=FALSE. Supposing that the file doesn't contain the extra newline (see below),

digest(the_string,serialize=FALSE) ==  digest(file=the_file) ## TRUE

(serialize has no effect on the file= version of the command)

dealing with newlines

If you read ?write_lines, it only says

sep: The line separator ... [information about defaults for different OSes]

To me, this seems ambiguous as to whether the separator will be added after the last line or not. (You don't expect a "comma-separated list" to end with a comma ...)

On the other hand, ?base::writeLines is a little more explicit,

sep: character string. A string to be written to the connection
after each line of text.

If you dig down into the source code of readr you can see that it uses

      output << na << sep;

for each line of code, i.e. it's behaving the same way as writeLines.

If you really just want to write the string to the file with no added nonsense, I suggest cat():

identical(the_string, { cat(the_string,file=the_file); readr::read_file(the_file) }) ## TRUE

Python 3 Create md5 hash

You can't get there from here. A hash is a small refactoring of data that destroys virtually all of the information in the data. It is used to identify a revision of the data and can be used later to see if the data has changed. A good hash algorithm changes its output dramatically with even a 1 character change in the data. Consider a Midsummer Night's Dream on gutenberg.org. Its about 100,000 characters and its md5 hash is 16 bytes. You are not going to get the original back from that!

>>> import hashlib
>>> import requests
>>> night = requests.get("http://www.gutenberg.org/ebooks/1514.txt.utf-8")
>>> len(night.text)
112127

>>> print(night.text[20000:20200])
h power to say, Behold!
The jaws of darkness do devour it up:
So quick bright things come to confusion.

HERMIA
If then true lovers have ever cross'd,
It stands as an edict in destiny:
Then let
>>> print(night.text[20000:20300])
h power to say, Behold!
The jaws of darkness do devour it up:
So quick bright things come to confusion.

HERMIA
If then true lovers have ever cross'd,
It stands as an edict in destiny:
Then let us teach our trial patience,
Because it is a customary cross;
As due to love as thoughts, and dre

>>> hash = hashlib.md5(night.text.encode("utf-8")).hexdigest()
>>> print(hash)
cce0d35b8b2c4dafcbde3deb983fec0a

The hash can be very useful to see if the text has changed:

>>> hash2 = hashlib.md5(requests.get("http://www.gutenberg.org/ebooks/1514.txt.utf-8").text.encode("utf-8")).hexdigest()
>>> hash == hash2
True

About one line in an implementation of MD5

The remarks about "bit counters" are likely misleading - ctx->hi and ctx->lo count bytes, just like size does.

You correctly notice that you're just adding size (bytes) to ctx->lo (and then checking for overflow/propagating overflow into ctx->hi). The overflow check is pretty simple - lo is used as a 29-bit integer, and if the result after adding/masking is less than the original value, then overflow occurred.

The checks around used are also evidence for ctx->lo and ctx->hi being byte counters -- body processes data 64 bytes at a time, and the lo counter is ANDed with 0x3F (i.e. 63).

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