{
    "mode": "man",
    "parameter": "OPENSSL-X509",
    "section": "1SSL",
    "url": "https://www.chedong.com/phpMan.php/man/OPENSSL-X509/1SSL/json",
    "generated": "2026-06-15T14:23:50Z",
    "synopsis": "openssl x509 [-help] [-in filename|uri] [-passin arg] [-new] [-x509toreq] [-req]\n[-copyextensions arg] [-inform DER|PEM] [-vfyopt nm:v] [-key filename|uri] [-keyform\nDER|PEM|P12|ENGINE] [-signkey filename|uri] [-out filename] [-outform DER|PEM] [-nocert]\n[-noout] [-dateopt] [-text] [-certopt option] [-fingerprint] [-alias] [-serial] [-startdate]\n[-enddate] [-dates] [-subject] [-issuer] [-nameopt option] [-email] [-hash] [-subjecthash]\n[-subjecthashold] [-issuerhash] [-issuerhashold] [-ext extensions] [-ocspid] [-ocspuri]\n[-purpose] [-pubkey] [-modulus] [-checkend num] [-checkhost host] [-checkemail host]\n[-checkip ipaddr] [-setserial n] [-nextserial] [-days arg] [-preservedates] [-subj arg]\n[-forcepubkey filename] [-clrext] [-extfile filename] [-extensions section] [-sigopt nm:v]\n[-badsig] [-ddiiggeesstt] [-CA filename|uri] [-CAform DER|PEM|P12] [-CAkey filename|uri]\n[-CAkeyform DER|PEM|P12|ENGINE] [-CAserial filename] [-CAcreateserial] [-trustout] [-setalias\narg] [-clrtrust] [-addtrust arg] [-clrreject] [-addreject arg] [-rand files] [-writerand\nfile] [-engine id] [-provider name] [-provider-path path] [-propquery propq]",
    "sections": {
        "NAME": {
            "content": "openssl-x509 - Certificate display and signing command\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "openssl x509 [-help] [-in filename|uri] [-passin arg] [-new] [-x509toreq] [-req]\n[-copyextensions arg] [-inform DER|PEM] [-vfyopt nm:v] [-key filename|uri] [-keyform\nDER|PEM|P12|ENGINE] [-signkey filename|uri] [-out filename] [-outform DER|PEM] [-nocert]\n[-noout] [-dateopt] [-text] [-certopt option] [-fingerprint] [-alias] [-serial] [-startdate]\n[-enddate] [-dates] [-subject] [-issuer] [-nameopt option] [-email] [-hash] [-subjecthash]\n[-subjecthashold] [-issuerhash] [-issuerhashold] [-ext extensions] [-ocspid] [-ocspuri]\n[-purpose] [-pubkey] [-modulus] [-checkend num] [-checkhost host] [-checkemail host]\n[-checkip ipaddr] [-setserial n] [-nextserial] [-days arg] [-preservedates] [-subj arg]\n[-forcepubkey filename] [-clrext] [-extfile filename] [-extensions section] [-sigopt nm:v]\n[-badsig] [-ddiiggeesstt] [-CA filename|uri] [-CAform DER|PEM|P12] [-CAkey filename|uri]\n[-CAkeyform DER|PEM|P12|ENGINE] [-CAserial filename] [-CAcreateserial] [-trustout] [-setalias\narg] [-clrtrust] [-addtrust arg] [-clrreject] [-addreject arg] [-rand files] [-writerand\nfile] [-engine id] [-provider name] [-provider-path path] [-propquery propq]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "This command is a multi-purposes certificate handling command.  It can be used to print\ncertificate information, convert certificates to various forms, edit certificate trust\nsettings, generate certificates from scratch or from certificating requests and then self-\nsigning them or signing them like a \"micro CA\".\n\nSince there are a large number of options they will split up into various sections.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "Input, Output, and General Purpose Options",
                    "content": ""
                },
                {
                    "name": "-help",
                    "content": "Print out a usage message.\n"
                },
                {
                    "name": "-in",
                    "content": "This specifies the input to read a certificate from or the input file for reading a\ncertificate request if the -req flag is used.  In both cases this defaults to standard\ninput.\n\nThis option cannot be combined with the -new flag.\n"
                },
                {
                    "name": "-passin",
                    "content": "The key and certificate file password source.  For more information about the format of\narg see openssl-passphrase-options(1).\n"
                },
                {
                    "name": "-new",
                    "content": "Generate a certificate from scratch, not using an input certificate or certificate\nrequest. So the -in option must not be used in this case.  Instead, the -subj option\nneeds to be given.  The public key to include can be given with the -forcepubkey option\nand defaults to the key given with the -key (or -signkey) option, which implies self-\nsignature.\n"
                },
                {
                    "name": "-x509toreq",
                    "content": "Output a PKCS#10 certificate request (rather than a certificate).  The -key (or -signkey)\noption must be used to provide the private key for self-signing; the corresponding public\nkey is placed in the subjectPKInfo field.\n\nX.509 extensions included in a certificate input are not copied by default.  X.509\nextensions to be added can be specified using the -extfile option.\n"
                },
                {
                    "name": "-req",
                    "content": "By default a certificate is expected on input.  With this option a PKCS#10 certificate\nrequest is expected instead, which must be correctly self-signed.\n\nX.509 extensions included in the request are not copied by default.  X.509 extensions to\nbe added can be specified using the -extfile option.\n"
                },
                {
                    "name": "-copy",
                    "content": "Determines how to handle X.509 extensions when converting from a certificate to a request\nusing the -x509toreq option or converting from a request to a certificate using the -req\noption.  If arg is none or this option is not present then extensions are ignored.  If\narg is copy or copyall then all extensions are copied, except that subject identifier and\nauthority key identifier extensions are not taken over when producing a certificate\nrequest.\n\nThe -ext option can be used to further restrict which extensions to copy.\n"
                },
                {
                    "name": "-inform",
                    "content": "The input file format; unspecified by default.  See openssl-format-options(1) for\ndetails.\n"
                },
                {
                    "name": "-vfyopt",
                    "content": "Pass options to the signature algorithm during verify operations.  Names and values of\nthese options are algorithm-specific.\n"
                },
                {
                    "name": "-key",
                    "content": "This option provides the private key for signing a new certificate or certificate\nrequest.  Unless -forcepubkey is given, the corresponding public key is placed in the\nnew certificate or certificate request, resulting in a self-signature.\n\nThis option cannot be used in conjunction with the -CA option.\n\nIt sets the issuer name to the subject name (i.e., makes it self-issued) and changes the\npublic key to the supplied value (unless overridden by -forcepubkey).  Unless the\n-preservedates option is supplied, it sets the validity start date to the current time\nand the end date to a value determined by the -days option.\n"
                },
                {
                    "name": "-signkey",
                    "content": "This option is an alias of -key.\n"
                },
                {
                    "name": "-keyform",
                    "content": "The key input format; unspecified by default.  See openssl-format-options(1) for details.\n"
                },
                {
                    "name": "-out",
                    "content": "This specifies the output filename to write to or standard output by default.\n"
                },
                {
                    "name": "-outform",
                    "content": "The output format; the default is PEM.  See openssl-format-options(1) for details.\n"
                },
                {
                    "name": "-nocert",
                    "content": "Do not output a certificate (except for printing as requested by below options).\n"
                },
                {
                    "name": "-noout",
                    "content": "This option prevents output except for printing as requested by below options.\n"
                },
                {
                    "name": "Certificate Printing Options",
                    "content": "Note: the -alias and -purpose options are also printing options but are described in the\n\"Trust Settings\" section.\n"
                },
                {
                    "name": "-dateopt",
                    "content": "Specify the date output format. Values are: rfc822 and iso8601.  Defaults to rfc822.\n"
                },
                {
                    "name": "-text",
                    "content": "Prints out the certificate in text form. Full details are printed including the public\nkey, signature algorithms, issuer and subject names, serial number any extensions present\nand any trust settings.\n"
                },
                {
                    "name": "-certopt",
                    "content": "Customise the print format used with -text. The option argument can be a single option or\nmultiple options separated by commas.  The -certopt switch may be also be used more than\nonce to set multiple options. See the \"Text Printing Flags\" section for more information.\n"
                },
                {
                    "name": "-fingerprint",
                    "content": "Calculates and prints the digest of the DER encoded version of the entire certificate\n(see digest options).  This is commonly called a \"fingerprint\". Because of the nature of\nmessage digests, the fingerprint of a certificate is unique to that certificate and two\ncertificates with the same fingerprint can be considered to be the same.\n"
                },
                {
                    "name": "-alias",
                    "content": "Prints the certificate \"alias\" (nickname), if any.\n"
                },
                {
                    "name": "-serial",
                    "content": "Prints the certificate serial number.\n"
                },
                {
                    "name": "-startdate",
                    "content": "Prints out the start date of the certificate, that is the notBefore date.\n"
                },
                {
                    "name": "-enddate",
                    "content": "Prints out the expiry date of the certificate, that is the notAfter date.\n"
                },
                {
                    "name": "-dates",
                    "content": "Prints out the start and expiry dates of a certificate.\n"
                },
                {
                    "name": "-subject",
                    "content": "Prints the subject name.\n"
                },
                {
                    "name": "-issuer",
                    "content": "Prints the issuer name.\n"
                },
                {
                    "name": "-nameopt",
                    "content": "This specifies how the subject or issuer names are displayed.  See\nopenssl-namedisplay-options(1) for details.\n"
                },
                {
                    "name": "-email",
                    "content": "Prints the email address(es) if any.\n"
                },
                {
                    "name": "-hash",
                    "content": "Synonym for \"-subjecthash\" for backward compatibility reasons.\n"
                },
                {
                    "name": "-subject",
                    "content": "Prints the \"hash\" of the certificate subject name. This is used in OpenSSL to form an\nindex to allow certificates in a directory to be looked up by subject name.\n"
                },
                {
                    "name": "-subject",
                    "content": "Prints the \"hash\" of the certificate subject name using the older algorithm as used by\nOpenSSL before version 1.0.0.\n"
                },
                {
                    "name": "-issuer",
                    "content": "Prints the \"hash\" of the certificate issuer name.\n"
                },
                {
                    "name": "-issuer",
                    "content": "Prints the \"hash\" of the certificate issuer name using the older algorithm as used by\nOpenSSL before version 1.0.0.\n"
                },
                {
                    "name": "-ext",
                    "content": "Prints out the certificate extensions in text form.  Can also be used to restrict which\nextensions to copy.  Extensions are specified with a comma separated string, e.g.,\n\"subjectAltName,subjectKeyIdentifier\".  See the x509v3config(5) manual page for the\nextension names.\n"
                },
                {
                    "name": "-ocspid",
                    "content": "Prints the OCSP hash values for the subject name and public key.\n"
                },
                {
                    "name": "-ocsp",
                    "content": "Prints the OCSP responder address(es) if any.\n"
                },
                {
                    "name": "-purpose",
                    "content": "This option performs tests on the certificate extensions and outputs the results. For a\nmore complete description see \"Certificate Extensions\" in\nopenssl-verification-options(1).\n"
                },
                {
                    "name": "-pubkey",
                    "content": "Prints the certificate's SubjectPublicKeyInfo block in PEM format.\n"
                },
                {
                    "name": "-modulus",
                    "content": "This option prints out the value of the modulus of the public key contained in the\ncertificate.\n"
                },
                {
                    "name": "Certificate Checking Options",
                    "content": ""
                },
                {
                    "name": "-checkend",
                    "content": "Checks if the certificate expires within the next arg seconds and exits nonzero if yes it\nwill expire or zero if not.\n"
                },
                {
                    "name": "-checkhost",
                    "content": "Check that the certificate matches the specified host.\n"
                },
                {
                    "name": "-checkemail",
                    "content": "Check that the certificate matches the specified email address.\n"
                },
                {
                    "name": "-checkip",
                    "content": "Check that the certificate matches the specified IP address.\n"
                },
                {
                    "name": "Certificate Output Options",
                    "content": ""
                },
                {
                    "name": "-set",
                    "content": "Specifies the serial number to use.  This option can be used with the -key, -signkey, or\n-CA options.  If used in conjunction with the -CA option the serial number file (as\nspecified by the -CAserial option) is not used.\n\nThe serial number can be decimal or hex (if preceded by \"0x\").\n"
                },
                {
                    "name": "-next",
                    "content": "Set the serial to be one more than the number in the certificate.\n"
                },
                {
                    "name": "-days",
                    "content": "Specifies the number of days until a newly generated certificate expires.  The default is\n30.  Cannot be used together with the -preservedates option.\n"
                },
                {
                    "name": "-preserve",
                    "content": "When signing a certificate, preserve \"notBefore\" and \"notAfter\" dates of any input\ncertificate instead of adjusting them to current time and duration.  Cannot be used\ntogether with the -days option.\n"
                },
                {
                    "name": "-subj",
                    "content": "When a certificate is created set its subject name to the given value.  When the\ncertificate is self-signed the issuer name is set to the same value.\n\nThe arg must be formatted as \"/type0=value0/type1=value1/type2=...\".  Special characters\nmay be escaped by \"\\\" (backslash), whitespace is retained.  Empty values are permitted,\nbut the corresponding type will not be included in the certificate.  Giving a single \"/\"\nwill lead to an empty sequence of RDNs (a NULL-DN).  Multi-valued RDNs can be formed by\nplacing a \"+\" character instead of a \"/\" between the AttributeValueAssertions (AVAs) that\nspecify the members of the set.  Example:\n\n\"/DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe\"\n\nThis option can be used in conjunction with the -forcepubkey option to create a\ncertificate even without providing an input certificate or certificate request.\n"
                },
                {
                    "name": "-force",
                    "content": "When a certificate is created set its public key to the key in filename instead of the\nkey contained in the input or given with the -key (or -signkey) option.\n\nThis option is useful for creating self-issued certificates that are not self-signed, for\ninstance when the key cannot be used for signing, such as DH.  It can also be used in\nconjunction with b<-new> and -subj to directly generate a certificate containing any\ndesired public key.\n"
                },
                {
                    "name": "-clrext",
                    "content": "When transforming a certificate to a new certificate by default all certificate\nextensions are retained.\n\nWhen transforming a certificate or certificate request, the -clrext option prevents\ntaking over any extensions from the source.  In any case, when producing a certificate\nrequest, neither subject identifier nor authority key identifier extensions are included.\n"
                },
                {
                    "name": "-extfile",
                    "content": "Configuration file containing certificate and request X.509 extensions to add.\n"
                },
                {
                    "name": "-extensions",
                    "content": "The section in the extfile to add X.509 extensions from.  If this option is not specified\nthen the extensions should either be contained in the unnamed (default) section or the\ndefault section should contain a variable called \"extensions\" which contains the section\nto use.  See the x509v3config(5) manual page for details of the extension section\nformat.\n"
                },
                {
                    "name": "-sigopt",
                    "content": "Pass options to the signature algorithm during sign operations.  This option may be given\nmultiple times.  Names and values provided using this option are algorithm-specific.\n"
                },
                {
                    "name": "-badsig",
                    "content": "Corrupt the signature before writing it; this can be useful for testing.\n\n-ddiiggeesstt\nThe digest to use.  This affects any signing or printing option that uses a message\ndigest, such as the -fingerprint, -key, and -CA options.  Any digest supported by the\nopenssl-dgst(1) command can be used.  If not specified then SHA1 is used with\n-fingerprint or the default digest for the signing algorithm is used, typically SHA256.\n"
                },
                {
                    "name": "Micro-CA Options",
                    "content": ""
                },
                {
                    "name": "-CA",
                    "content": "Specifies the \"CA\" certificate to be used for signing.  When present, this behaves like a\n\"micro CA\" as follows: The subject name of the \"CA\" certificate is placed as issuer name\nin the new certificate, which is then signed using the \"CA\" key given as detailed below.\n\nThis option cannot be used in conjunction with -key (or -signkey).  This option is\nnormally combined with the -req option referencing a CSR.  Without the -req option the\ninput must be an existing certificate unless the -new option is given, which generates a\ncertificate from scratch.\n"
                },
                {
                    "name": "-CAform",
                    "content": "The format for the CA certificate; unspecifed by default.  See openssl-format-options(1)\nfor details.\n"
                },
                {
                    "name": "-CAkey",
                    "content": "Sets the CA private key to sign a certificate with.  The private key must match the\npublic key of the certificate given with -CA.  If this option is not provided then the\nkey must be present in the -CA input.\n"
                },
                {
                    "name": "-CAkeyform",
                    "content": "The format for the CA key; unspecified by default.  See openssl-format-options(1) for\ndetails.\n"
                },
                {
                    "name": "-CAserial",
                    "content": "Sets the CA serial number file to use.\n\nWhen the -CA option is used to sign a certificate it uses a serial number specified in a\nfile. This file consists of one line containing an even number of hex digits with the\nserial number to use. After each use the serial number is incremented and written out to\nthe file again.\n\nThe default filename consists of the CA certificate file base name with .srl appended.\nFor example if the CA certificate file is called mycacert.pem it expects to find a serial\nnumber file called mycacert.srl.\n"
                },
                {
                    "name": "-CAcreateserial",
                    "content": "With this option the CA serial number file is created if it does not exist: it will\ncontain the serial number \"02\" and the certificate being signed will have the 1 as its\nserial number. If the -CA option is specified and the serial number file does not exist a\nrandom number is generated; this is the recommended practice.\n"
                },
                {
                    "name": "Trust Settings",
                    "content": "A trusted certificate is an ordinary certificate which has several additional pieces of\ninformation attached to it such as the permitted and prohibited uses of the certificate and\npossibly an \"alias\" (nickname).\n\nNormally when a certificate is being verified at least one certificate must be \"trusted\". By\ndefault a trusted certificate must be stored locally and must be a root CA: any certificate\nchain ending in this CA is then usable for any purpose.\n\nTrust settings currently are only used with a root CA.  They allow a finer control over the\npurposes the root CA can be used for.  For example, a CA may be trusted for SSL client but\nnot SSL server use.\n\nSee openssl-verification-options(1) for more information on the meaning of trust settings.\n\nFuture versions of OpenSSL will recognize trust settings on any certificate: not just root\nCAs.\n"
                },
                {
                    "name": "-trustout",
                    "content": "Mark any certificate PEM output as <trusted> certificate rather than ordinary.  An\nordinary or trusted certificate can be input but by default an ordinary certificate is\noutput and any trust settings are discarded.  With the -trustout option a trusted\ncertificate is output. A trusted certificate is automatically output if any trust\nsettings are modified.\n"
                },
                {
                    "name": "-setalias",
                    "content": "Sets the \"alias\" of the certificate. This will allow the certificate to be referred to\nusing a nickname for example \"Steve's Certificate\".\n"
                },
                {
                    "name": "-clrtrust",
                    "content": "Clears all the permitted or trusted uses of the certificate.\n"
                },
                {
                    "name": "-addtrust",
                    "content": "Adds a trusted certificate use.  Any object name can be used here but currently only\nclientAuth, serverAuth, emailProtection, and anyExtendedKeyUsage are defined.  As of\nOpenSSL 1.1.0, the last of these blocks all purposes when rejected or enables all\npurposes when trusted.  Other OpenSSL applications may define additional uses.\n"
                },
                {
                    "name": "-clrreject",
                    "content": "Clears all the prohibited or rejected uses of the certificate.\n"
                },
                {
                    "name": "-addreject",
                    "content": "Adds a prohibited trust anchor purpose.  It accepts the same values as the -addtrust\noption.\n"
                },
                {
                    "name": "Generic options",
                    "content": ""
                },
                {
                    "name": "-rand -writerand",
                    "content": "See \"Random State Options\" in openssl(1) for details.\n"
                },
                {
                    "name": "-engine",
                    "content": "See \"Engine Options\" in openssl(1).  This option is deprecated.\n"
                },
                {
                    "name": "-provider",
                    "content": ""
                },
                {
                    "name": "-provider-path",
                    "content": ""
                },
                {
                    "name": "-propquery",
                    "content": "See \"Provider Options\" in openssl(1), provider(7), and property(7).\n"
                },
                {
                    "name": "Text Printing Flags",
                    "content": "As well as customising the name printing format, it is also possible to customise the actual\nfields printed using the certopt option when the text option is present. The default\nbehaviour is to print all fields.\n"
                },
                {
                    "name": "compatible",
                    "content": "Use the old format. This is equivalent to specifying no printing options at all.\n\nnoheader\nDon't print header information: that is the lines saying \"Certificate\" and \"Data\".\n\nnoversion\nDon't print out the version number.\n\nnoserial\nDon't print out the serial number.\n\nnosigname\nDon't print out the signature algorithm used.\n\nnovalidity\nDon't print the validity, that is the notBefore and notAfter fields.\n\nnosubject\nDon't print out the subject name.\n\nnoissuer\nDon't print out the issuer name.\n\nnopubkey\nDon't print out the public key.\n\nnosigdump\nDon't give a hexadecimal dump of the certificate signature.\n\nnoaux\nDon't print out certificate trust information.\n\nnoextensions\nDon't print out any X509V3 extensions.\n\nextdefault\nRetain default extension behaviour: attempt to print out unsupported certificate\nextensions.\n\nexterror\nPrint an error message for unsupported certificate extensions.\n\nextparse\nASN1 parse unsupported extensions.\n\nextdump\nHex dump unsupported extensions.\n\ncadefault\nThe value used by openssl-ca(1), equivalent to noissuer, nopubkey, noheader, and\nnoversion.\n"
                }
            ]
        },
        "EXAMPLES": {
            "content": "Note: in these examples the '\\' means the example should be all on one line.\n\nPrint the contents of a certificate:\n\nopenssl x509 -in cert.pem -noout -text\n\nPrint the \"Subject Alternative Name\" extension of a certificate:\n\nopenssl x509 -in cert.pem -noout -ext subjectAltName\n\nPrint more extensions of a certificate:\n\nopenssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType\n\nPrint the certificate serial number:\n\nopenssl x509 -in cert.pem -noout -serial\n\nPrint the certificate subject name:\n\nopenssl x509 -in cert.pem -noout -subject\n\nPrint the certificate subject name in RFC2253 form:\n\nopenssl x509 -in cert.pem -noout -subject -nameopt RFC2253\n\nPrint the certificate subject name in oneline form on a terminal supporting UTF8:\n\nopenssl x509 -in cert.pem -noout -subject -nameopt oneline,-escmsb\n\nPrint the certificate SHA1 fingerprint:\n\nopenssl x509 -sha1 -in cert.pem -noout -fingerprint\n\nConvert a certificate from PEM to DER format:\n\nopenssl x509 -in cert.pem -inform PEM -out cert.der -outform DER\n\nConvert a certificate to a certificate request:\n\nopenssl x509 -x509toreq -in cert.pem -out req.pem -key key.pem\n\nConvert a certificate request into a self-signed certificate using extensions for a CA:\n\nopenssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3ca \\\n-key key.pem -out cacert.pem\n\nSign a certificate request using the CA certificate above and add user certificate\nextensions:\n\nopenssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3usr \\\n-CA cacert.pem -CAkey key.pem -CAcreateserial\n\nSet a certificate to be trusted for SSL client use and change set its alias to \"Steve's Class\n1 CA\"\n\nopenssl x509 -in cert.pem -addtrust clientAuth \\\n-setalias \"Steve's Class 1 CA\" -out trust.pem\n",
            "subsections": []
        },
        "NOTES": {
            "content": "The conversion to UTF8 format used with the name options assumes that T61Strings use the\nISO8859-1 character set. This is wrong but Netscape and MSIE do this as do many certificates.\nSo although this is incorrect it is more likely to print the majority of certificates\ncorrectly.\n\nThe -email option searches the subject name and the subject alternative name extension. Only\nunique email addresses will be printed out: it will not print the same address more than\nonce.\n",
            "subsections": []
        },
        "BUGS": {
            "content": "It is possible to produce invalid certificates or requests by specifying the wrong private\nkey, using unsuitable X.509 extensions, or using inconsistent options in some cases: these\nshould be checked.\n\nThere should be options to explicitly set such things as start and end dates rather than an\noffset from the current time.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "openssl(1), openssl-req(1), openssl-ca(1), openssl-genrsa(1), openssl-gendsa(1),\nopenssl-verify(1), x509v3config(5)\n",
            "subsections": []
        },
        "HISTORY": {
            "content": "The hash algorithm used in the -subjecthash and -issuerhash options before OpenSSL 1.0.0\nwas based on the deprecated MD5 algorithm and the encoding of the distinguished name. In\nOpenSSL 1.0.0 and later it is based on a canonical version of the DN using SHA1. This means\nthat any directories using the old form must have their links rebuilt using openssl-rehash(1)\nor similar.\n\nThe -signkey option has been renamed to -key in OpenSSL 3.0, keeping the old name as an\nalias.\n\nThe -engine option was deprecated in OpenSSL 3.0.\n\nThe -C option was removed in OpenSSL 3.0.\n",
            "subsections": []
        },
        "COPYRIGHT": {
            "content": "Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.\n\nLicensed under the Apache License 2.0 (the \"License\").  You may not use this file except in\ncompliance with the License.  You can obtain a copy in the file LICENSE in the source\ndistribution or at <https://www.openssl.org/source/license.html>.\n\n\n\n3.0.2                                        2026-06-02                           OPENSSL-X509(1SSL)",
            "subsections": []
        }
    },
    "summary": "openssl-x509 - Certificate display and signing command",
    "flags": [
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Print out a usage message."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This specifies the input to read a certificate from or the input file for reading a certificate request if the -req flag is used. In both cases this defaults to standard input. This option cannot be combined with the -new flag."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The key and certificate file password source. For more information about the format of arg see openssl-passphrase-options(1)."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Generate a certificate from scratch, not using an input certificate or certificate request. So the -in option must not be used in this case. Instead, the -subj option needs to be given. The public key to include can be given with the -forcepubkey option and defaults to the key given with the -key (or -signkey) option, which implies self- signature."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Output a PKCS#10 certificate request (rather than a certificate). The -key (or -signkey) option must be used to provide the private key for self-signing; the corresponding public key is placed in the subjectPKInfo field. X.509 extensions included in a certificate input are not copied by default. X.509 extensions to be added can be specified using the -extfile option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "By default a certificate is expected on input. With this option a PKCS#10 certificate request is expected instead, which must be correctly self-signed. X.509 extensions included in the request are not copied by default. X.509 extensions to be added can be specified using the -extfile option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Determines how to handle X.509 extensions when converting from a certificate to a request using the -x509toreq option or converting from a request to a certificate using the -req option. If arg is none or this option is not present then extensions are ignored. If arg is copy or copyall then all extensions are copied, except that subject identifier and authority key identifier extensions are not taken over when producing a certificate request. The -ext option can be used to further restrict which extensions to copy."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The input file format; unspecified by default. See openssl-format-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Pass options to the signature algorithm during verify operations. Names and values of these options are algorithm-specific."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This option provides the private key for signing a new certificate or certificate request. Unless -forcepubkey is given, the corresponding public key is placed in the new certificate or certificate request, resulting in a self-signature. This option cannot be used in conjunction with the -CA option. It sets the issuer name to the subject name (i.e., makes it self-issued) and changes the public key to the supplied value (unless overridden by -forcepubkey). Unless the -preservedates option is supplied, it sets the validity start date to the current time and the end date to a value determined by the -days option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This option is an alias of -key."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The key input format; unspecified by default. See openssl-format-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This specifies the output filename to write to or standard output by default."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The output format; the default is PEM. See openssl-format-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Do not output a certificate (except for printing as requested by below options)."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This option prevents output except for printing as requested by below options."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Specify the date output format. Values are: rfc822 and iso8601. Defaults to rfc822."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints out the certificate in text form. Full details are printed including the public key, signature algorithms, issuer and subject names, serial number any extensions present and any trust settings."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Customise the print format used with -text. The option argument can be a single option or multiple options separated by commas. The -certopt switch may be also be used more than once to set multiple options. See the \"Text Printing Flags\" section for more information."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Calculates and prints the digest of the DER encoded version of the entire certificate (see digest options). This is commonly called a \"fingerprint\". Because of the nature of message digests, the fingerprint of a certificate is unique to that certificate and two certificates with the same fingerprint can be considered to be the same."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the certificate \"alias\" (nickname), if any."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the certificate serial number."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints out the start date of the certificate, that is the notBefore date."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints out the expiry date of the certificate, that is the notAfter date."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints out the start and expiry dates of a certificate."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the subject name."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the issuer name."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This specifies how the subject or issuer names are displayed. See openssl-namedisplay-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the email address(es) if any."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Synonym for \"-subjecthash\" for backward compatibility reasons."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the \"hash\" of the certificate subject name. This is used in OpenSSL to form an index to allow certificates in a directory to be looked up by subject name."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the \"hash\" of the certificate subject name using the older algorithm as used by OpenSSL before version 1.0.0."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the \"hash\" of the certificate issuer name."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the \"hash\" of the certificate issuer name using the older algorithm as used by OpenSSL before version 1.0.0."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints out the certificate extensions in text form. Can also be used to restrict which extensions to copy. Extensions are specified with a comma separated string, e.g., \"subjectAltName,subjectKeyIdentifier\". See the x509v3config(5) manual page for the extension names."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the OCSP hash values for the subject name and public key."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the OCSP responder address(es) if any."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This option performs tests on the certificate extensions and outputs the results. For a more complete description see \"Certificate Extensions\" in openssl-verification-options(1)."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Prints the certificate's SubjectPublicKeyInfo block in PEM format."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "This option prints out the value of the modulus of the public key contained in the certificate."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Checks if the certificate expires within the next arg seconds and exits nonzero if yes it will expire or zero if not."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Check that the certificate matches the specified host."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Check that the certificate matches the specified email address."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Check that the certificate matches the specified IP address."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Specifies the serial number to use. This option can be used with the -key, -signkey, or -CA options. If used in conjunction with the -CA option the serial number file (as specified by the -CAserial option) is not used. The serial number can be decimal or hex (if preceded by \"0x\")."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Set the serial to be one more than the number in the certificate."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Specifies the number of days until a newly generated certificate expires. The default is 30. Cannot be used together with the -preservedates option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "When signing a certificate, preserve \"notBefore\" and \"notAfter\" dates of any input certificate instead of adjusting them to current time and duration. Cannot be used together with the -days option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "When a certificate is created set its subject name to the given value. When the certificate is self-signed the issuer name is set to the same value. The arg must be formatted as \"/type0=value0/type1=value1/type2=...\". Special characters may be escaped by \"\\\" (backslash), whitespace is retained. Empty values are permitted, but the corresponding type will not be included in the certificate. Giving a single \"/\" will lead to an empty sequence of RDNs (a NULL-DN). Multi-valued RDNs can be formed by placing a \"+\" character instead of a \"/\" between the AttributeValueAssertions (AVAs) that specify the members of the set. Example: \"/DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe\" This option can be used in conjunction with the -forcepubkey option to create a certificate even without providing an input certificate or certificate request."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "When a certificate is created set its public key to the key in filename instead of the key contained in the input or given with the -key (or -signkey) option. This option is useful for creating self-issued certificates that are not self-signed, for instance when the key cannot be used for signing, such as DH. It can also be used in conjunction with b<-new> and -subj to directly generate a certificate containing any desired public key."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "When transforming a certificate to a new certificate by default all certificate extensions are retained. When transforming a certificate or certificate request, the -clrext option prevents taking over any extensions from the source. In any case, when producing a certificate request, neither subject identifier nor authority key identifier extensions are included."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Configuration file containing certificate and request X.509 extensions to add."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The section in the extfile to add X.509 extensions from. If this option is not specified then the extensions should either be contained in the unnamed (default) section or the default section should contain a variable called \"extensions\" which contains the section to use. See the x509v3config(5) manual page for details of the extension section format."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Pass options to the signature algorithm during sign operations. This option may be given multiple times. Names and values provided using this option are algorithm-specific."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Corrupt the signature before writing it; this can be useful for testing. -ddiiggeesstt The digest to use. This affects any signing or printing option that uses a message digest, such as the -fingerprint, -key, and -CA options. Any digest supported by the openssl-dgst(1) command can be used. If not specified then SHA1 is used with -fingerprint or the default digest for the signing algorithm is used, typically SHA256."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Specifies the \"CA\" certificate to be used for signing. When present, this behaves like a \"micro CA\" as follows: The subject name of the \"CA\" certificate is placed as issuer name in the new certificate, which is then signed using the \"CA\" key given as detailed below. This option cannot be used in conjunction with -key (or -signkey). This option is normally combined with the -req option referencing a CSR. Without the -req option the input must be an existing certificate unless the -new option is given, which generates a certificate from scratch."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The format for the CA certificate; unspecifed by default. See openssl-format-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Sets the CA private key to sign a certificate with. The private key must match the public key of the certificate given with -CA. If this option is not provided then the key must be present in the -CA input."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "The format for the CA key; unspecified by default. See openssl-format-options(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Sets the CA serial number file to use. When the -CA option is used to sign a certificate it uses a serial number specified in a file. This file consists of one line containing an even number of hex digits with the serial number to use. After each use the serial number is incremented and written out to the file again. The default filename consists of the CA certificate file base name with .srl appended. For example if the CA certificate file is called mycacert.pem it expects to find a serial number file called mycacert.srl."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "With this option the CA serial number file is created if it does not exist: it will contain the serial number \"02\" and the certificate being signed will have the 1 as its serial number. If the -CA option is specified and the serial number file does not exist a random number is generated; this is the recommended practice."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Mark any certificate PEM output as <trusted> certificate rather than ordinary. An ordinary or trusted certificate can be input but by default an ordinary certificate is output and any trust settings are discarded. With the -trustout option a trusted certificate is output. A trusted certificate is automatically output if any trust settings are modified."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Sets the \"alias\" of the certificate. This will allow the certificate to be referred to using a nickname for example \"Steve's Certificate\"."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Clears all the permitted or trusted uses of the certificate."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Adds a trusted certificate use. Any object name can be used here but currently only clientAuth, serverAuth, emailProtection, and anyExtendedKeyUsage are defined. As of OpenSSL 1.1.0, the last of these blocks all purposes when rejected or enables all purposes when trusted. Other OpenSSL applications may define additional uses."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Clears all the prohibited or rejected uses of the certificate."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "Adds a prohibited trust anchor purpose. It accepts the same values as the -addtrust option."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "See \"Random State Options\" in openssl(1) for details."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "See \"Engine Options\" in openssl(1). This option is deprecated."
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": ""
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": ""
        },
        {
            "flag": "",
            "long": null,
            "arg": null,
            "description": "See \"Provider Options\" in openssl(1), provider(7), and property(7)."
        }
    ],
    "examples": [
        "Note: in these examples the '\\' means the example should be all on one line.",
        "Print the contents of a certificate:",
        "openssl x509 -in cert.pem -noout -text",
        "Print the \"Subject Alternative Name\" extension of a certificate:",
        "openssl x509 -in cert.pem -noout -ext subjectAltName",
        "Print more extensions of a certificate:",
        "openssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType",
        "Print the certificate serial number:",
        "openssl x509 -in cert.pem -noout -serial",
        "Print the certificate subject name:",
        "openssl x509 -in cert.pem -noout -subject",
        "Print the certificate subject name in RFC2253 form:",
        "openssl x509 -in cert.pem -noout -subject -nameopt RFC2253",
        "Print the certificate subject name in oneline form on a terminal supporting UTF8:",
        "openssl x509 -in cert.pem -noout -subject -nameopt oneline,-escmsb",
        "Print the certificate SHA1 fingerprint:",
        "openssl x509 -sha1 -in cert.pem -noout -fingerprint",
        "Convert a certificate from PEM to DER format:",
        "openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER",
        "Convert a certificate to a certificate request:",
        "openssl x509 -x509toreq -in cert.pem -out req.pem -key key.pem",
        "Convert a certificate request into a self-signed certificate using extensions for a CA:",
        "openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3ca \\",
        "-key key.pem -out cacert.pem",
        "Sign a certificate request using the CA certificate above and add user certificate",
        "extensions:",
        "openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3usr \\",
        "-CA cacert.pem -CAkey key.pem -CAcreateserial",
        "Set a certificate to be trusted for SSL client use and change set its alias to \"Steve's Class",
        "1 CA\"",
        "openssl x509 -in cert.pem -addtrust clientAuth \\",
        "-setalias \"Steve's Class 1 CA\" -out trust.pem"
    ],
    "see_also": [
        {
            "name": "openssl",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl/1/json"
        },
        {
            "name": "openssl-req",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl-req/1/json"
        },
        {
            "name": "openssl-ca",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl-ca/1/json"
        },
        {
            "name": "openssl-genrsa",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl-genrsa/1/json"
        },
        {
            "name": "openssl-gendsa",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl-gendsa/1/json"
        },
        {
            "name": "openssl-verify",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/openssl-verify/1/json"
        },
        {
            "name": "x509v3config",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/x509v3config/5/json"
        }
    ]
}