sha256 (1)

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NAME

dgst, sha, sha1, mdc2, ripemd160, sha224, sha256, sha384, sha512, md2, md4, md5, dss1 - message digests

SYNOPSIS

openssl dgst [-sha|-sha1|-mdc2|-ripemd160|-sha224|-sha256|-sha384|-sha512|-md2|-md4|-md5|-dss1] [-c] [-d] [-hex] [-binary] [-r] [-non-fips-allow] [-out filename] [-sign filename] [-keyform arg] [-passin arg] [-verify filename] [-prverify filename] [-signature filename] [-hmac key] [-non-fips-allow] [-fips-fingerprint] [file...]

openssl [digest] [...]

DESCRIPTION

The digest functions output the message digest of a supplied file or files in hexadecimal. The digest functions also generate and verify digital signatures using message digests.

OPTIONS

-c

print out the digest in two digit groups separated by colons, only relevant if hex format output is used.

-d

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.

-r

output the digest in the ``coreutils'' format used by programs like sha1sum.

-non-fips-allow

Allow use of non

FIPS

digest when in

FIPS

mode. This has no effect when not in

FIPS

mode.

-out filename

filename to output to, or standard output by default.

-sign filename

digitally sign the digest using the private key in ``filename''.

-keyform arg

Specifies the key format to sign digest with. The

DER, PEM, P12,

and

ENGINE

formats are supported.

-engine id

Use engine id for operations (including private key storage). This engine is not used as source for digest algorithms, unless it is also specified in the configuration file.

-sigopt nm:v

Pass options to the signature algorithm during sign or verify operations. Names and values of these options are algorithm-specific.

-passin arg

the private key password source. For more information about the format of arg see the

PASS PHRASE ARGUMENTS

section in openssl(1).

-verify filename

verify the signature using the the public key in ``filename''. The output is either ``Verification

OK''

or ``Verification Failure''.

-prverify filename

verify the signature using the the private key in ``filename''.

-signature filename

the actual signature to verify.

-hmac key

create a hashed

MAC

using ``key''.

-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 ccgost engine.

MAC

keys and other options should be set via -macopt parameter.

-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 alphnumeric 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.

-rand file(s)

a file or files containing random data used to seed the random number generator, or an

EGD

socket (see RAND_egd(3)). Multiple files can be specified separated by a OS-dependent character. The separator is ; for MS-Windows, , for OpenVMS, and : for all others.

-non-fips-allow

enable use of non-FIPS algorithms such as

MD5

even in

FIPS

mode.

-fips-fingerprint

compute

HMAC

using a specific key for certain OpenSSL-FIPS operations.

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

To sign a file using

with binary file output:
 openssl dgst -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 of choice for all new applications is Other digests are however still widely used.

When signing a file, dgst will automatically determine the algorithm (

etc) to use for signing based on the private key's info. When verifying signatures, it only handles the or signature itself, not the related data to identify the signer and algorithm used in formats such as x.509, and S/MIME.

A source of random numbers is required for certain signing algorithms, in particular

and

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.