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FileHash
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FileHash

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FileHash[file]

gives an integer hash code for the contents of the specified file.

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FileHash[file,"type"]

gives an integer hash of the specified type.

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FileHash[file,"type","format"]

gives a hash code in the specified format.

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FileHash[{file,range},…]

gives the hash code for the specified range of bytes.

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FileHash[{filespec1,filespec2,…},…]

gives the hash codes for a list of files.

Details

  • Values generated by FileHash are based on the raw bytes in a file.
  • Files may be specified as "file", File["file"], CloudObject["url"] or InputStream[…]. Input streams must have been opened with BinaryFormatTrue.
  • FileHash supports the following range specifications:
  • nfirst n bytes
    -nlast n bytes
    {n}byte n only
    {m,n}bytes m through n
    0no bytes
    Allall bytes
  • FileHash[{stream,range},…] effectively extracts data at the specified range of byte positions in an input stream, ignoring any previous stream position.
  • Each filespec can be either file or {file,range}.
  • Possible hash code types include:
  • "Adler32"Adler 32-bit cyclic redundancy check
    "CRC32"32-bit cyclic redundancy check
    "MD2"128-bit MD2 code
    "MD4"128-bit MD4 code
    "MD5"128-bit MD5 code (default)
    "RIPEMD160"160-bit RIPEMD code
    "RIPEMD160SHA256"RIPEMD-160 following SHA-256 (as used in Bitcoin)
    "SHA"160-bit SHA-1 code
    "SHA256"256-bit SHA code
    "SHA256SHA256"double SHA-256 code (as used in Bitcoin)
    "SHA384"384-bit SHA code
    "SHA512"512-bit SHA code
    "SHA3-224"224-bit SHA3 code
    "SHA3-256"256-bit SHA3 code
    "SHA3-384"384-bit SHA3 code
    "SHA3-512"512-bit SHA3 code
    "Keccak224"224-bit Keccak code
    "Keccak256"256-bit Keccak code
    "Keccak384"384-bit Keccak code
    "Keccak512"512-bit Keccak code
  • FileHash by default uses 128-bit MD5 code.
  • Possible formats include:
  • "Integer"integer (default)
    "DecimalString"decimal string
    "HexString"hexadecimal string
    "Base36String"base-36 alphanumeric string
    "Base64Encoding"Base64 encoding
    "ByteArray"hash code as an explicit byte array
  • For compatibility with earlier versions of the Wolfram Language, the syntaxes FileHash[file,"type",range] and FileHash[file,"type",range,"format"] are also supported.

Examples

open allclose all

Basic Examples  (5)Summary of the most common use cases

The fingerprint of a file:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-6pjqah
Out[1]=1

The "SHA512" hash code of a file:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-wp9ooh
Out[1]=1

The "SHA512" hash code of the first 100 bytes of a file:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-dqpzif
Out[1]=1

The "MD5" hash code in hexadecimal form:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-4n4du5
Out[1]=1

Hash of a CloudObject:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-g8xx7
In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-heioc
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0d6fj7yiui-h403je
Out[3]=3

Scope  (11)Survey of the scope of standard use cases

File and Range Specifications  (6)

Compute a hash for the first 100 bytes of a file:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-2lqpay
In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-p99r70
Out[2]=2

Equivalently:

In[3]:=3
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https://wolfram.com/xid/0d6fj7yiui-3zped9
Out[3]=3

Compute a hash for the last 100 bytes:

In[4]:=4
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https://wolfram.com/xid/0d6fj7yiui-q7ofvt
Out[4]=4

Equivalently:

In[5]:=5
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https://wolfram.com/xid/0d6fj7yiui-i91u6p
Out[5]=5

Compute a hash for bytes 100 through 200:

In[6]:=6
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https://wolfram.com/xid/0d6fj7yiui-u7rbqe
Out[6]=6

Compute a hash for all bytes except the first 100 or the last 100:

In[7]:=7
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https://wolfram.com/xid/0d6fj7yiui-6zwoqz
Out[7]=7

Compute the hash for byte 100 only:

In[8]:=8
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https://wolfram.com/xid/0d6fj7yiui-tk55cg

Compute a hash for no bytes:

In[8]:=8
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https://wolfram.com/xid/0d6fj7yiui-5ekrbc
Out[8]=8

Compute the hashes of several files:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-zsrixc
Out[1]=1

Find the hash for a complete file as well as several subsets of it:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-qe929w
In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-vxccr
Out[2]=2

Create a CloudObject:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-c1fp2u

Find the hash of the data contained in the CloudObject:

In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-c01ifz
Out[2]=2

By default, MD5 hash of the full range is calculated:

In[3]:=3
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https://wolfram.com/xid/0d6fj7yiui-hueh1q
Out[3]=3

For hashing, the data from the CloudObject is represented as a string including the newline:

In[4]:=4
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https://wolfram.com/xid/0d6fj7yiui-g7igx0
Out[4]=4

The same hash using the sequence of bytes:

In[5]:=5
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https://wolfram.com/xid/0d6fj7yiui-dbbke8
Out[5]=5

Open a binary stream:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-dqmkuz
Out[1]=1

Compute its hash:

In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-hzsf3u
Out[2]=2

The same result is given independently of the current stream position:

In[3]:=3
✖
https://wolfram.com/xid/0d6fj7yiui-xv1b69
Out[3]=3
In[4]:=4
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https://wolfram.com/xid/0d6fj7yiui-kzv2po
Out[4]=4

Close the stream:

In[5]:=5
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https://wolfram.com/xid/0d6fj7yiui-vjy7b1
Out[5]=5

Create an empty file and cloud object:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-fo0a80

Put the same content in the file and cloud object:

In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-v0ifa4

Also open a stream pointing at the file:

In[3]:=3
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https://wolfram.com/xid/0d6fj7yiui-4gm834
Out[3]=3

The hashes of all three objects are the same:

In[4]:=4
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https://wolfram.com/xid/0d6fj7yiui-6o9ak0
Out[4]=4

Close the stream:

In[5]:=5
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https://wolfram.com/xid/0d6fj7yiui-gmaagy

Hash Types and Formats  (5)

Compare different hash codes:

In[1]:=1
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https://wolfram.com/xid/0d6fj7yiui-ftwuo8
Out[1]=1

512-bit SHA code given as an integer:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-ivtv9a
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0d6fj7yiui-wmdxy0
Out[2]=2

512-bit SHA code given as a decimal string, including leading zeros:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-8krt8n
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-9d5c65
Out[2]=2

Compare the different string representations of a hash:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-e7iqlh
Out[1]=1

The double SHA code of the first 50 bytes of a file, given as a ByteArray:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-mevezj
Out[1]=1

The byte array contains the 256 bits of the result:

In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-p04gji
Out[2]=2

View the individual bytes in the array:

In[3]:=3
✖
https://wolfram.com/xid/0d6fj7yiui-tn2iqh
Out[3]=3

Properties & Relations  (10)Properties of the function, and connections to other functions

The default format is "MD5":

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-eeiu57
Out[1]=1

The default range specification is All:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-d5n3v2
Out[1]=1

This is equivalent to {-1,1}:

In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-d14bky
Out[2]=2

Hashing zero bytes is equivalent to finding the hash of an empty file:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-n5b2j0
In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-fwlun3
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0d6fj7yiui-vg71se

"Integer" is the default format:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-9sot34
Out[1]=1

"DecimalString" is the string version of "Integer", padded with zeros if necessary:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-wi2tzj
Out[1]=1

"HexString" is a base-16 representation, padded with zeros if necessary:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-qa6km8
Out[1]=1

"Base36String" is a base-36 representation, padded with zeros if necessary:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-3z7z8g
Out[1]=1

"Base64Encoding" encodes bytes of the result using Base64 encoding:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-v95ick
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0d6fj7yiui-v7v1uk
Out[2]=2

FileHash[file,code] is effectively equivalent to Hash[ReadByteArray[file],code]:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-yla7fn
Out[1]=1

FileHash[file,code] is effectively equivalent to Hash[ByteArray@Import[file,"Byte"]]:

In[1]:=1
✖
https://wolfram.com/xid/0d6fj7yiui-bqzx05
Out[1]=1
Wolfram Research (2007), FileHash, Wolfram Language function, https://reference.wolfram.com/language/ref/FileHash.html (updated 2020).
✖
Wolfram Research (2007), FileHash, Wolfram Language function, https://reference.wolfram.com/language/ref/FileHash.html (updated 2020).

Text

Wolfram Research (2007), FileHash, Wolfram Language function, https://reference.wolfram.com/language/ref/FileHash.html (updated 2020).

✖
Wolfram Research (2007), FileHash, Wolfram Language function, https://reference.wolfram.com/language/ref/FileHash.html (updated 2020).

CMS

Wolfram Language. 2007. "FileHash." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/FileHash.html.

✖
Wolfram Language. 2007. "FileHash." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/FileHash.html.

APA

Wolfram Language. (2007). FileHash. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FileHash.html

✖
Wolfram Language. (2007). FileHash. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FileHash.html

BibTeX

@misc{reference.wolfram_2025_filehash, author="Wolfram Research", title="{FileHash}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/FileHash.html}", note=[Accessed: 25-March-2025 ]}

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@misc{reference.wolfram_2025_filehash, author="Wolfram Research", title="{FileHash}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/FileHash.html}", note=[Accessed: 25-March-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_filehash, organization={Wolfram Research}, title={FileHash}, year={2020}, url={https://reference.wolfram.com/language/ref/FileHash.html}, note=[Accessed: 25-March-2025 ]}

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@online{reference.wolfram_2025_filehash, organization={Wolfram Research}, title={FileHash}, year={2020}, url={https://reference.wolfram.com/language/ref/FileHash.html}, note=[Accessed: 25-March-2025 ]}