Edit File: sha256.1
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" openssl\-dgst, dgst, sha, sha1, mdc2, ripemd160, sha224, sha256, sha384, sha512, md2, md4, md5, dss1 \- message digests .SH "SYNOPSIS" .IX Header "SYNOPSIS" \&\fBopenssl\fR \fBdgst\fR [\fB\-sha|\-sha1|\-mdc2|\-ripemd160|\-sha224|\-sha256|\-sha384|\-sha512|\-md2|\-md4|\-md5|\-dss1\fR] [\fB\-c\fR] [\fB\-d\fR] [\fB\-hex\fR] [\fB\-binary\fR] [\fB\-r\fR] [\fB\-non\-fips\-allow\fR] [\fB\-out filename\fR] [\fB\-sign filename\fR] [\fB\-keyform arg\fR] [\fB\-passin arg\fR] [\fB\-verify filename\fR] [\fB\-prverify filename\fR] [\fB\-signature filename\fR] [\fB\-hmac key\fR] [\fB\-non\-fips\-allow\fR] [\fB\-fips\-fingerprint\fR] [\fBfile...\fR] .PP \&\fBopenssl\fR [\fIdigest\fR] [\fB...\fR] .SH "DESCRIPTION" .IX Header "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. .SH "OPTIONS" .IX Header "OPTIONS" .IP "\fB\-c\fR" 4 .IX Item "-c" print out the digest in two digit groups separated by colons, only relevant if \&\fBhex\fR format output is used. .IP "\fB\-d\fR" 4 .IX Item "-d" print out \s-1BIO\s0 debugging information. .IP "\fB\-hex\fR" 4 .IX Item "-hex" digest is to be output as a hex dump. This is the default case for a \*(L"normal\*(R" digest as opposed to a digital signature. See \s-1NOTES\s0 below for digital signatures using \fB\-hex\fR. .IP "\fB\-binary\fR" 4 .IX Item "-binary" output the digest or signature in binary form. .IP "\fB\-r\fR" 4 .IX Item "-r" output the digest in the \*(L"coreutils\*(R" format used by programs like \fBsha1sum\fR. .IP "\fB\-non\-fips\-allow\fR" 4 .IX Item "-non-fips-allow" Allow use of non \s-1FIPS\s0 digest when in \s-1FIPS\s0 mode. This has no effect when not in \&\s-1FIPS\s0 mode. .IP "\fB\-out filename\fR" 4 .IX Item "-out filename" filename to output to, or standard output by default. .IP "\fB\-sign filename\fR" 4 .IX Item "-sign filename" digitally sign the digest using the private key in \*(L"filename\*(R". .IP "\fB\-keyform arg\fR" 4 .IX Item "-keyform arg" Specifies the key format to sign digest with. The \s-1DER, PEM, P12,\s0 and \s-1ENGINE\s0 formats are supported. .IP "\fB\-engine id\fR" 4 .IX Item "-engine id" Use engine \fBid\fR 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. .IP "\fB\-sigopt nm:v\fR" 4 .IX Item "-sigopt nm:v" Pass options to the signature algorithm during sign or verify operations. Names and values of these options are algorithm-specific. .IP "\fB\-passin arg\fR" 4 .IX Item "-passin arg" the private key password source. For more information about the format of \fBarg\fR see the \fB\s-1PASS PHRASE ARGUMENTS\s0\fR section in \fBopenssl\fR\|(1). .IP "\fB\-verify filename\fR" 4 .IX Item "-verify filename" verify the signature using the the public key in \*(L"filename\*(R". The output is either \*(L"Verification \s-1OK\*(R"\s0 or \*(L"Verification Failure\*(R". .IP "\fB\-prverify filename\fR" 4 .IX Item "-prverify filename" verify the signature using the the private key in \*(L"filename\*(R". .IP "\fB\-signature filename\fR" 4 .IX Item "-signature filename" the actual signature to verify. .IP "\fB\-hmac key\fR" 4 .IX Item "-hmac key" create a hashed \s-1MAC\s0 using \*(L"key\*(R". .IP "\fB\-mac alg\fR" 4 .IX Item "-mac alg" create \s-1MAC\s0 (keyed Message Authentication Code). The most popular \s-1MAC\s0 algorithm is \s-1HMAC\s0 (hash-based \s-1MAC\s0), but there are other \s-1MAC\s0 algorithms which are not based on hash, for instance \fBgost-mac\fR algorithm, supported by \fBccgost\fR engine. \s-1MAC\s0 keys and other options should be set via \fB\-macopt\fR parameter. .IP "\fB\-macopt nm:v\fR" 4 .IX Item "-macopt nm:v" Passes options to \s-1MAC\s0 algorithm, specified by \fB\-mac\fR key. Following options are supported by both by \fB\s-1HMAC\s0\fR and \fBgost-mac\fR: .RS 4 .IP "\fBkey:string\fR" 8 .IX Item "key:string" Specifies \s-1MAC\s0 key as alphnumeric string (use if key contain printable characters only). String length must conform to any restrictions of the \s-1MAC\s0 algorithm for example exactly 32 chars for gost-mac. .IP "\fBhexkey:string\fR" 8 .IX Item "hexkey:string" Specifies \s-1MAC\s0 key in hexadecimal form (two hex digits per byte). Key length must conform to any restrictions of the \s-1MAC\s0 algorithm for example exactly 32 chars for gost-mac. .RE .RS 4 .RE .IP "\fB\-rand file(s)\fR" 4 .IX Item "-rand file(s)" a file or files containing random data used to seed the random number generator, or an \s-1EGD\s0 socket (see \fBRAND_egd\fR\|(3)). Multiple files can be specified separated by a OS-dependent character. The separator is \fB;\fR for MS-Windows, \fB,\fR for OpenVMS, and \fB:\fR for all others. .IP "\fB\-non\-fips\-allow\fR" 4 .IX Item "-non-fips-allow" enable use of non-FIPS algorithms such as \s-1MD5\s0 even in \s-1FIPS\s0 mode. .IP "\fB\-fips\-fingerprint\fR" 4 .IX Item "-fips-fingerprint" compute \s-1HMAC\s0 using a specific key for certain OpenSSL-FIPS operations. .IP "\fBfile...\fR" 4 .IX Item "file..." file or files to digest. If no files are specified then standard input is used. .SH "EXAMPLES" .IX Header "EXAMPLES" To create a hex-encoded message digest of a file: openssl dgst \-md5 \-hex file.txt .PP To sign a file using \s-1SHA\-256\s0 with binary file output: openssl dgst \-sha256 \-sign privatekey.pem \-out signature.sign file.txt .PP To verify a signature: openssl dgst \-sha256 \-verify publickey.pem \e \-signature signature.sign \e file.txt .SH "NOTES" .IX Header "NOTES" The digest of choice for all new applications is \s-1SHA1.\s0 Other digests are however still widely used. .PP When signing a file, \fBdgst\fR will automatically determine the algorithm (\s-1RSA, ECC,\s0 etc) to use for signing based on the private key's \s-1ASN.1\s0 info. When verifying signatures, it only handles the \s-1RSA, DSA,\s0 or \s-1ECDSA\s0 signature itself, not the related data to identify the signer and algorithm used in formats such as x.509, \s-1CMS,\s0 and S/MIME. .PP A source of random numbers is required for certain signing algorithms, in particular \s-1ECDSA\s0 and \s-1DSA.\s0 .PP The signing and verify options should only be used if a single file is being signed or verified. .PP Hex signatures cannot be verified using \fBopenssl\fR. Instead, use \*(L"xxd \-r\*(R" or similar program to transform the hex signature into a binary signature prior to verification.