openssl-dgst¶

NAME¶

openssl-dgst - perform digest operations

SYNOPSIS¶

openssl dgst|digest [-digest] [-list] [-help] [-c] [-d] [-debug] [-hex] [-binary] [-xoflen length] [-r] [-out filename] [-sign filename|uri] [-keyform DER|PEM|P12|ENGINE] [-passin arg] [-verify filename] [-prverify filename] [-signature filename] [-sigopt nm:v] [-hmac key] [-mac alg] [-macopt nm:v] [-fips-fingerprint] [-engine id] [-engine_impl id] [-rand files] [-writerand file] [-provider name] [-provider-path path] [-propquery propq] [file ...]

DESCRIPTION¶

This command output the message digest of a supplied file or files in hexadecimal, and also generates and verifies digital signatures using message digests.

The generic name, openssl dgst, may be used with an option specifying the algorithm to be used. The default digest is sha256. A supported digest name may also be used as the sub-command name. To see the list of supported algorithms, use openssl list -digest-algorithms

OPTIONS¶

-help
Print out a usage message.
-digest
Specifies name of a supported digest to be used. See option -list below :
-list
Prints out a list of supported message digests.
-c
Print out the digest in two digit groups separated by colons, only relevant if the -hex option is given as well.
-d, -debug
Print out BIO debugging information.
-hex
Digest is to be output as a hex dump. This is the default case for a "normal" digest as opposed to a digital signature. See NOTES below for digital signatures using -hex.
-binary
Output the digest or signature in binary form.
-xoflen length
Set the output length for XOF algorithms, such as shake128 and shake256. This option is not supported for signing operations.
For OpenSSL providers it is recommended to set this value for shake algorithms, since the default values are set to only supply half of the maximum security strength.
For backwards compatibility reasons the default xoflen length for shake128 is 16 (bytes) which results in a security strength of only 64 bits. To ensure the maximum security strength of 128 bits, the xoflen should be set to at least 32.
For backwards compatibility reasons the default xoflen length for shake256 is 32 (bytes) which results in a security strength of only 128 bits. To ensure the maximum security strength of 256 bits, the xoflen should be set to at least 64.
-r
Output the digest in the "coreutils" format, including newlines. Used by programs like sha1sum(1).
-out filename
Filename to output to, or standard output by default.
-sign filename|uri
Digitally sign the digest using the given private key. Note this option does not support Ed25519 or Ed448 private keys. Use the openssl-pkeyutl(1) command instead for this.
-keyform DER|PEM|P12|ENGINE
The format of the key to sign with; unspecified by default. See openssl-format-options(1) for details.
-sigopt nm:v
Pass options to the signature algorithm during sign or verify operations. Names and values of these options are algorithm-specific and documented in "Signature parameters" in provider-signature(7).
-passin arg
The private key password source. For more information about the format of arg see openssl-passphrase-options(1).
-verify filename
Verify the signature using the public key in "filename". The output is either "Verified OK" or "Verification Failure".
-prverify filename
Verify the signature using the private key in "filename".
-signature filename
The actual signature to verify.
-hmac key
Create a hashed MAC using "key".
The openssl-mac(1) command should be preferred to using this command line option.
-mac alg
Create MAC (keyed Message Authentication Code). The most popular MAC algorithm is HMAC (hash-based MAC), but there are other MAC algorithms which are not based on hash, for instance gost-mac algorithm, supported by the gost engine. MAC keys and other options should be set via -macopt parameter.
The openssl-mac(1) command should be preferred to using this command line option.
-macopt nm:v
Passes options to MAC algorithm, specified by -mac key. Following options are supported by both by HMAC and gost-mac:
- key:string
  Specifies MAC key as alphanumeric string (use if key contain printable characters only). String length must conform to any restrictions of the MAC algorithm for example exactly 32 chars for gost-mac.
- hexkey:string
  Specifies MAC key in hexadecimal form (two hex digits per byte). Key length must conform to any restrictions of the MAC algorithm for example exactly 32 chars for gost-mac.
The openssl-mac(1) command should be preferred to using this command line option.
-fips-fingerprint
Compute HMAC using a specific key for certain OpenSSL-FIPS operations.
-rand files, -writerand file
See "Random State Options" in openssl(1) for details.
-engine id
See "Engine Options" in openssl(1). This option is deprecated.
The engine is not used for digests unless the -engine_impl option is used or it is configured to do so, see "Engine Configuration Module" in config(5).
-engine_impl id
When used with the -engine option, it specifies to also use engine id for digest operations.
-provider name
-provider-path path
-propquery propq
See "Provider Options" in openssl(1), provider(7), and property(7).
file ...
File or files to digest. If no files are specified then standard input is used.

EXAMPLES¶

To create a hex-encoded message digest of a file:

openssl dgst -md5 -hex file.txt
or
openssl md5 file.txt

To sign a file using SHA-256 with binary file output:

openssl dgst -sha256 -sign privatekey.pem -out signature.sign file.txt
or
openssl sha256 -sign privatekey.pem -out signature.sign file.txt

To verify a signature:

openssl dgst -sha256 -verify publickey.pem \
-signature signature.sign \
file.txt

NOTES¶

The digest mechanisms that are available will depend on the options used when building OpenSSL. The openssl list -digest-algorithms command can be used to list them.

New or agile applications should use probably use SHA-256. Other digests, particularly SHA-1 and MD5, are still widely used for interoperating with existing formats and protocols.

When signing a file, this command will automatically determine the algorithm (RSA, ECC, etc) to use for signing based on the private key's ASN.1 info. When verifying signatures, it only handles the RSA, DSA, or ECDSA signature itself, not the related data to identify the signer and algorithm used in formats such as x.509, CMS, and S/MIME.

A source of random numbers is required for certain signing algorithms, in particular ECDSA and DSA.

The signing and verify options should only be used if a single file is being signed or verified.

Hex signatures cannot be verified using openssl. Instead, use "xxd -r" or similar program to transform the hex signature into a binary signature prior to verification.

The openssl-mac(1) command is preferred over the -hmac, -mac and -macopt command line options.

HISTORY¶

The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0. The FIPS-related options were removed in OpenSSL 1.1.0.

The -engine and -engine_impl options were deprecated in OpenSSL 3.0.

COPYRIGHT¶

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.