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Manual: openssl-x509

OPENSSL-X509(1SSL) OpenSSL OPENSSL-X509(1SSL)

NAME
openssl-x509 - Certificate display and signing command

SYNOPSIS
openssl x509 [-help] [-in filename|uri] [-passin arg] [-new] [-x509toreq] [-req] [-copy_extensions arg] [-inform
DER|PEM] [-vfyopt nm:v] [-key filename|uri] [-keyform DER|PEM|P12|ENGINE] [-signkey filename|uri] [-out filename]
[-outform DER|PEM] [-nocert] [-noout] [-dateopt] [-text] [-certopt option] [-fingerprint] [-alias] [-serial]
[-startdate] [-enddate] [-dates] [-subject] [-issuer] [-nameopt option] [-email] [-hash] [-subject_hash]
[-subject_hash_old] [-issuer_hash] [-issuer_hash_old] [-ext extensions] [-ocspid] [-ocsp_uri] [-purpose] [-pubkey]
[-modulus] [-checkend num] [-checkhost host] [-checkemail host] [-checkip ipaddr] [-set_serial n] [-next_serial]
[-not_before date] [-not_after date] [-days arg] [-preserve_dates] [-set_issuer arg] [-set_subject arg] [-subj arg]
[-force_pubkey filename] [-clrext] [-extfile filename] [-extensions section] [-sigopt nm:v] [-badsig] [-digest] [-CA
filename|uri] [-CAform DER|PEM|P12] [-CAkey filename|uri] [-CAkeyform DER|PEM|P12|ENGINE] [-CAserial filename]
[-CAcreateserial] [-trustout] [-setalias arg] [-clrtrust] [-addtrust arg] [-clrreject] [-addreject arg] [-rand files]
[-writerand file] [-engine id] [-provider name] [-provider-path path] [-provparam [name:]key=value] [-propquery
propq]

DESCRIPTION
This command is a multi-purposes certificate handling command. It can be used to print certificate information,
convert certificates to various forms, edit certificate trust settings, generate certificates from scratch or from
certification requests and then self-signing them or signing them like a "micro CA".

Generated certificates bear X.509 version 3. Unless specified otherwise, key identifier extensions are included as
described in x509v3_config(5).

Since there are a large number of options they will split up into various sections.

OPTIONS
Input, Output, and General Purpose Options
-help
Print out a usage message.

-in filename|uri
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.

-passin arg
The key and certificate file password source. For more information about the format of arg see
openssl-passphrase-options(1).

-new
Generate a certificate from scratch, not using an input certificate or certificate request. So this excludes the
-in and -req options. Instead, the -set_subject option needs to be given. The public key to include can be
given with the -force_pubkey option and defaults to the key given with the -key (or -signkey) option, which
implies self-signature.

-x509toreq
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.

-req
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.

-copy_extensions arg
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.

-inform DER|PEM
The input file format to use; by default PEM is tried first. See openssl-format-options(1) for details.

-vfyopt nm:v
Pass options to the signature algorithm during verify operations. Names and values of these options are
algorithm-specific.

-key filename|uri
This option provides the private key for signing a new certificate or certificate request. Unless -force_pubkey
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). Unless the -preserve_dates 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. Start date and end date can also be explicitly supplied with options -not_before and -not_after.

-signkey filename|uri
This option is an alias of -key.

-keyform DER|PEM|P12|ENGINE
The key input format; unspecified by default. See openssl-format-options(1) for details.

-out filename
This specifies the output filename to write to or standard output by default.

-outform DER|PEM
The output format; the default is PEM. See openssl-format-options(1) for details.

-nocert
Do not output a certificate (except for printing as requested by below options).

-noout
This option prevents output except for printing as requested by below options.

Certificate Printing Options
Note: the -alias and -purpose options are also printing options but are described in the "Trust Settings" section.

-dateopt
Specify the date output format. Values are: rfc_822 and iso_8601. Defaults to rfc_822.

-text
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.

-certopt option
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.

-fingerprint
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.

-alias
Prints the certificate "alias" (nickname), if any.

-serial
Prints the certificate serial number.

-startdate
Prints out the start date of the certificate, that is the notBefore date.

-enddate
Prints out the expiry date of the certificate, that is the notAfter date.

-dates
Prints out the start and expiry dates of a certificate.

-subject
Prints the subject name.

-issuer
Prints the issuer name.

-nameopt option
This specifies how the subject or issuer names are displayed. See openssl-namedisplay-options(1) for details.

-email
Prints the email address(es) if any.

-hash
Synonym for "-subject_hash" for backward compatibility reasons.

-subject_hash
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.

-subject_hash_old
Prints the "hash" of the certificate subject name using the older algorithm as used by OpenSSL before version
1.0.0.

-issuer_hash
Prints the "hash" of the certificate issuer name.

-issuer_hash_old
Prints the "hash" of the certificate issuer name using the older algorithm as used by OpenSSL before version
1.0.0.

-ext extensions
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
x509v3_config(5) manual page for the extension names.

-ocspid
Prints the OCSP hash values for the subject name and public key.

-ocsp_uri
Prints the OCSP responder address(es) if any.

-purpose
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).

-pubkey
Prints the certificate's SubjectPublicKeyInfo block in PEM format.

-modulus
This option prints out the value of the modulus of the public key contained in the certificate.

Certificate Checking Options
-checkend arg
Checks if the certificate expires within the next arg seconds and exits nonzero if yes it will expire or zero if
not.

-checkhost host
Check that the certificate matches the specified host.

-checkemail email
Check that the certificate matches the specified email address.

-checkip ipaddr
Check that the certificate matches the specified IP address.

Certificate Output Options
-set_serial n
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").

-next_serial
Set the serial to be one more than the number in the certificate.

-not_before date
This allows the start date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an ASN1
UTCTime structure), or YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In both formats, seconds
SS and timezone Z must be present. Alternatively, you can also use "today".

Cannot be used together with the -preserve_dates option.

-not_after date
This allows the expiry date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an ASN1
UTCTime structure), or YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In both formats, seconds
SS and timezone Z must be present. Alternatively, you can also use "today".

Cannot be used together with the -preserve_dates option. This overrides the option -days.

-days arg
Specifies the number of days from today until a newly generated certificate expires. The default is 30.

Cannot be used together with the option -preserve_dates. If option -not_after is set, the explicit expiry date
takes precedence.

-preserve_dates
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 options -days, -not_before and
-not_after.

-set_issuer arg
When a certificate is created set its issuer name to the given value.

See -set_subject on how the arg must be formatted.

-set_subject arg
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, unless the -set_issuer option is given.

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 with the -new and -force_pubkey options to create a new certificate without providing an
input certificate or certificate request.

-subj arg
This option is an alias of -set_subject.

-force_pubkey filename
When a new certificate or certificate request is created set its public key to the given key instead of the key
contained in the input or given with the -key (or -signkey) option. If the input contains no public key but a
private key, its public part is used.

This option can be used in conjunction with b<-new> and -set_subject to directly generate a certificate
containing any desired public key.

This option is also useful for creating self-issued certificates that are not self-signed, for instance when the
key cannot be used for signing, such as DH.

-clrext
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.

-extfile filename
Configuration file containing certificate and request X.509 extensions to add.

-extensions section
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 x509v3_config(5) manual page for details of the extension section format.

Unless specified otherwise, key identifier extensions are included as described in x509v3_config(5).

-sigopt nm:v
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.

-badsig
Corrupt the signature before writing it; this can be useful for testing.

-digest
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.

Micro-CA Options
-CA filename|uri
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.

-CAform DER|PEM|P12,
The format for the CA certificate; unspecified by default. See openssl-format-options(1) for details.

-CAkey filename|uri
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.

-CAkeyform DER|PEM|P12|ENGINE
The format for the CA key; unspecified by default. See openssl-format-options(1) for details.

-CAserial filename
Sets the CA serial number file to use.

When creating a certificate with this option and with the -CA option, the certificate serial number is stored in
the given file. This file consists of one line containing an even number of hex digits with the serial number
used last time. After reading this number, it is incremented and used, and the file is updated.

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.

If the -CA option is specified and neither <-CAserial> or <-CAcreateserial> is given and the default serial
number file does not exist, a random number is generated; this is the recommended practice.

-CAcreateserial
With this option and the -CA option the CA serial number file is created if it does not exist. A random number
is generated, used for the certificate, and saved into the serial number file determined as described above.

Trust Settings
A trusted certificate is an ordinary certificate which has several additional pieces of information attached to it
such as the permitted and prohibited uses of the certificate and possibly an "alias" (nickname).

Normally when a certificate is being verified at least one certificate must be "trusted". By default a trusted
certificate must be stored locally and must be a root CA: any certificate chain ending in this CA is then usable for
any purpose.

Trust settings currently are only used with a root CA. They allow a finer control over the purposes the root CA can
be used for. For example, a CA may be trusted for SSL client but not SSL server use.

See openssl-verification-options(1) for more information on the meaning of trust settings.

Future versions of OpenSSL will recognize trust settings on any certificate: not just root CAs.

-trustout
Mark any certificate PEM output as 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.

-setalias arg
Sets the "alias" of the certificate. This will allow the certificate to be referred to using a nickname for
example "Steve's Certificate".

-clrtrust
Clears all the permitted or trusted uses of the certificate.

-addtrust arg
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.

-clrreject
Clears all the prohibited or rejected uses of the certificate.

-addreject arg
Adds a prohibited trust anchor purpose. It accepts the same values as the -addtrust option.

Generic options
-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.

-provider name
-provider-path path
-provparam [name:]key=value
-propquery propq
See "Provider Options" in openssl(1), provider(7), and property(7).

Text Printing Flags
As well as customising the name printing format, it is also possible to customise the actual fields printed using the
certopt option when the text option is present. The default behaviour is to print all fields.

compatible
Use the old format. This is equivalent to specifying no printing options at all.

no_header
Don't print header information: that is the lines saying "Certificate" and "Data".

no_version
Don't print out the version number.

no_serial
Don't print out the serial number.

no_signame
Don't print out the signature algorithm used.

no_validity
Don't print the validity, that is the notBefore and notAfter fields.

no_subject
Don't print out the subject name.

no_issuer
Don't print out the issuer name.

no_pubkey
Don't print out the public key.

no_sigdump
Don't give a hexadecimal dump of the certificate signature.

no_aux
Don't print out certificate trust information.

no_extensions
Don't print out any X509V3 extensions.

ext_default
Retain default extension behaviour: attempt to print out unsupported certificate extensions.

ext_error
Print an error message for unsupported certificate extensions.

ext_parse
ASN1 parse unsupported extensions.

ext_dump
Hex dump unsupported extensions.

ca_default
The value used by openssl-ca(1), equivalent to no_issuer, no_pubkey, no_header, and no_version.

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,-esc_msb

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 v3_ca \
-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 v3_usr \
-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

NOTES
The conversion to UTF8 format used with the name options assumes that T61Strings use the ISO8859-1 character set.
This is wrong but Netscape and MSIE do this as do many certificates. So although this is incorrect it is more likely
to print the majority of certificates correctly.

The -email option searches the subject name and the subject alternative name extension. Only unique email addresses
will be printed out: it will not print the same address more than once.

BUGS
It is possible to produce invalid certificates or requests by specifying the wrong private key, using unsuitable
X.509 extensions, or using inconsistent options in some cases: these should be checked.

There should be options to explicitly set such things as start and end dates rather than an offset from the current
time.

SEE ALSO
openssl(1), openssl-req(1), openssl-ca(1), openssl-genrsa(1), openssl-gendsa(1), openssl-verify(1), x509v3_config(5)

HISTORY
The hash algorithm used in the -subject_hash and -issuer_hash options before OpenSSL 1.0.0 was based on the
deprecated MD5 algorithm and the encoding of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
canonical version of the DN using SHA1. This means that any directories using the old form must have their links
rebuilt using openssl-rehash(1) or similar.

The -signkey option has been renamed to -key in OpenSSL 3.0, keeping the old name as an alias.

The -engine option was deprecated in OpenSSL 3.0.

The -C option was removed in OpenSSL 3.0.

Since OpenSSL 3.2, generated certificates bear X.509 version 3, and key identifier extensions are included by
default.

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
.

3.5.5 2026-01-27 OPENSSL-X509(1SSL)

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Manual: openssl-x509

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