openssl-x509, x509 - Certificate display and signing utility
openssl x509 [-help] [-inform DER|PEM] [-outform
  DER|PEM] [-keyform DER|PEM|ENGINE] [-CAform DER|PEM]
  [-CAkeyform DER|PEM] [-in filename] [-out filename]
  [-serial] [-hash] [-subject_hash] [-issuer_hash]
  [-ocspid] [-subject] [-issuer] [-nameopt option]
  [-email] [-ocsp_uri] [-startdate] [-enddate]
  [-purpose] [-dates] [-checkend num] [-modulus]
  [-pubkey] [-fingerprint] [-alias] [-noout]
  [-trustout] [-clrtrust] [-clrreject] [-addtrust
  arg] [-addreject arg] [-setalias arg] [-days arg]
  [-set_serial n] [-signkey arg] [-passin arg]
  [-x509toreq] [-req] [-CA filename] [-CAkey
  filename] [-CAcreateserial] [-CAserial filename]
  [-force_pubkey key] [-text] [-ext extensions]
  [-certopt option] [-C] [-digest]
  [-clrext] [-extfile filename] [-extensions section]
  [-sigopt nm:v] [-rand file...] [-writerand file]
  [-engine id] [-preserve_dates]
The x509 command is a multi purpose certificate utility. It can be used
  to display certificate information, convert certificates to various forms,
  sign certificate requests like a "mini CA" or edit certificate trust
  settings.
Since there are a large number of options they will split up into
    various sections.
  - -help
- Print out a usage message.
- -inform DER|PEM
- This specifies the input format normally the command will expect an X509
      certificate but this can change if other options such as -req are
      present. The DER format is the DER encoding of the certificate and PEM is
      the base64 encoding of the DER encoding with header and footer lines
      added. The default format is PEM.
- -outform DER|PEM
- This specifies the output format, the options have the same meaning and
      default as the -inform option.
- -in filename
- This specifies the input filename to read a certificate from or standard
      input if this option is not specified.
- -out filename
- This specifies the output filename to write to or standard output by
      default.
- -digest
- The digest to use. This affects any signing or display option that uses a
      message digest, such as the -fingerprint, -signkey and
      -CA options. Any digest supported by the OpenSSL dgst
      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.
- -rand file...
- A file or files containing random data used to seed the random number
      generator. Multiple files can be specified separated by an OS-dependent
      character. The separator is ; for MS-Windows, , for OpenVMS,
      and : for all others.
- [-writerand file]
- Writes random data to the specified file upon exit. This can be
      used with a subsequent -rand flag.
- -engine id
- Specifying an engine (by its unique id string) will cause
      x509 to attempt to obtain a functional reference to the specified
      engine, thus initialising it if needed. The engine will then be set as the
      default for all available algorithms.
- -preserve_dates
- When signing a certificate, preserve the "notBefore" and
      "notAfter" dates instead of adjusting them to current time and
      duration. Cannot be used with the -days option.
Note: the -alias and -purpose options are also display options but
  are described in the TRUST SETTINGS section.
  - -text
- Prints out the certificate in text form. Full details are output including
      the public key, signature algorithms, issuer and subject names, serial
      number any extensions present and any trust settings.
- -ext extensions
- Prints out the certificate extensions in text form. Extensions are
      specified with a comma separated string, e.g.,
      "subjectAltName,subjectKeyIdentifier". See the
      x509v3_config(5) manual page for the extension names.
- -certopt option
- Customise the output 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 OPTIONS section for more
      information.
- -noout
- This option prevents output of the encoded version of the
    certificate.
- -pubkey
- Outputs 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.
- -serial
- Outputs the certificate serial number.
- -subject_hash
- Outputs 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.
- -issuer_hash
- Outputs the "hash" of the certificate issuer name.
- -ocspid
- Outputs the OCSP hash values for the subject name and public key.
- -hash
- Synonym for "-subject_hash" for backward compatibility
    reasons.
- -subject_hash_old
- Outputs the "hash" of the certificate subject name using the
      older algorithm as used by OpenSSL before version 1.0.0.
- -issuer_hash_old
- Outputs the "hash" of the certificate issuer name using the
      older algorithm as used by OpenSSL before version 1.0.0.
- -subject
- Outputs the subject name.
- -issuer
- Outputs the issuer name.
- -nameopt option
- Option which determines how the subject or issuer names are displayed. The
      option argument can be a single option or multiple options
      separated by commas. Alternatively the -nameopt switch may be used
      more than once to set multiple options. See the NAME OPTIONS
      section for more information.
- -email
- Outputs the email address(es) if any.
- -ocsp_uri
- Outputs the OCSP responder address(es) if any.
- -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.
- -checkend arg
- Checks if the certificate expires within the next arg seconds and
      exits nonzero if yes it will expire or zero if not.
- -fingerprint
- Calculates and outputs 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.
- -C
- This outputs the certificate in the form of a C source file.
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 an "alias".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 the description of the verify utility 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
- This causes x509 to output a trusted certificate. 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".
- -alias
- Outputs the certificate alias, if any.
- -clrtrust
- Clears all the permitted or trusted uses of the certificate.
- -clrreject
- Clears all the prohibited or rejected uses of the certificate.
- -addtrust arg
- Adds a trusted certificate use. Any object name can be used here but
      currently only clientAuth (SSL client use), serverAuth (SSL
      server use), emailProtection (S/MIME email) and
      anyExtendedKeyUsage are used. 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.
- -addreject arg
- Adds a prohibited use. It accepts the same values as the -addtrust
      option.
- -purpose
- This option performs tests on the certificate extensions and outputs the
      results. For a more complete description see the CERTIFICATE
      EXTENSIONS section.
The x509 utility can be used to sign certificates and requests: it can
  thus behave like a "mini CA".
  - -signkey arg
- This option causes the input file to be self signed using the supplied
      private key or engine. The private key's format is specified with the
      -keyform option.
    If the input file is a certificate it sets the issuer name to
        the subject name (i.e. makes it self signed) changes the public key to
        the supplied value and changes the start and end dates. The start date
        is set to the current time and the end date is set to a value determined
        by the -days option. Any certificate extensions are retained
        unless the -clrext option is supplied; this includes, for
        example, any existing key identifier extensions. If the input is a certificate request then a self signed
        certificate is created using the supplied private key using the subject
        name in the request. 
- -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 key password source. For more information about the format of
      arg see the PASS PHRASE ARGUMENTS section in
      openssl(1).
- -clrext
- Delete any extensions from a certificate. This option is used when a
      certificate is being created from another certificate (for example with
      the -signkey or the -CA options). Normally all extensions
      are retained.
- -keyform PEM|DER|ENGINE
- Specifies the format (DER or PEM) of the private key file used in the
      -signkey option.
- -days arg
- Specifies the number of days to make a certificate valid for. The default
      is 30 days. Cannot be used with the -preserve_dates option.
- -x509toreq
- Converts a certificate into a certificate request. The -signkey
      option is used to pass the required private key.
- -req
- By default a certificate is expected on input. With this option a
      certificate request is expected instead.
- -set_serial n
- Specifies the serial number to use. This option can be used with either
      the -signkey or -CA options. If used in conjunction with the
      -CA option the serial number file (as specified by the
      -CAserial or -CAcreateserial options) is not used.
    The serial number can be decimal or hex (if preceded by
        0x). 
- -CA filename
- Specifies the CA certificate to be used for signing. When this option is
      present x509 behaves like a "mini CA". The input file is
      signed by this CA using this option: that is its issuer name is set to the
      subject name of the CA and it is digitally signed using the CAs private
      key.
    This option is normally combined with the -req option.
        Without the -req option the input is a certificate which must be
        self signed. 
- -CAkey filename
- Sets the CA private key to sign a certificate with. If this option is not
      specified then it is assumed that the CA private key is present in the CA
      certificate file.
- -CAserial filename
- 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". 
- -CAcreateserial
- 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.
- -extfile filename
- File containing certificate extensions to use. If not specified then no
      extensions are added to the certificate.
- -extensions section
- The section to add certificate 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.
- -force_pubkey key
- When a certificate is created set its public key to key instead of
      the key in the certificate or certificate request. This option is useful
      for creating certificates where the algorithm can't normally sign
      requests, for example DH.
    The format or key can be specified using the
        -keyform option. 
The nameopt command line switch determines how the subject and issuer
  names are displayed. If no nameopt switch is present the default
  "oneline" format is used which is compatible with previous versions
  of OpenSSL. Each option is described in detail below, all options can be
  preceded by a - to turn the option off. Only the first four will
  normally be used.
  - compat
- Use the old format.
- RFC2253
- Displays names compatible with RFC2253 equivalent to esc_2253,
      esc_ctrl, esc_msb, utf8, dump_nostr,
      dump_unknown, dump_der, sep_comma_plus, dn_rev
      and sname.
- oneline
- A oneline format which is more readable than RFC2253. It is equivalent to
      specifying the esc_2253, esc_ctrl, esc_msb,
      utf8, dump_nostr, dump_der, use_quote,
      sep_comma_plus_space, space_eq and sname options.
      This is the default of no name options are given explicitly.
- multiline
- A multiline format. It is equivalent esc_ctrl, esc_msb,
      sep_multiline, space_eq, lname and align.
- esc_2253
- Escape the "special" characters required by RFC2253 in a field.
      That is ,+"<>;. Additionally # is escaped at the
      beginning of a string and a space character at the beginning or end of a
      string.
- esc_2254
- Escape the "special" characters required by RFC2254 in a field.
      That is the NUL character as well as and ()*.
- esc_ctrl
- Escape control characters. That is those with ASCII values less than 0x20
      (space) and the delete (0x7f) character. They are escaped using the
      RFC2253 \XX notation (where XX are two hex digits representing the
      character value).
- esc_msb
- Escape characters with the MSB set, that is with ASCII values larger than
      127.
- use_quote
- Escapes some characters by surrounding the whole string with "
      characters, without the option all escaping is done with the \
      character.
- utf8
- Convert all strings to UTF8 format first. This is required by RFC2253. If
      you are lucky enough to have a UTF8 compatible terminal then the use of
      this option (and not setting esc_msb) may result in the
      correct display of multibyte (international) characters. Is this option is
      not present then multibyte characters larger than 0xff will be represented
      using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits. Also if
      this option is off any UTF8Strings will be converted to their character
      form first.
- ignore_type
- This option does not attempt to interpret multibyte characters in any way.
      That is their content octets are merely dumped as though one octet
      represents each character. This is useful for diagnostic purposes but will
      result in rather odd looking output.
- show_type
- Show the type of the ASN1 character string. The type precedes the field
      contents. For example "BMPSTRING: Hello World".
- dump_der
- When this option is set any fields that need to be hexdumped will be
      dumped using the DER encoding of the field. Otherwise just the content
      octets will be displayed. Both options use the RFC2253 #XXXX...
      format.
- dump_nostr
- Dump non character string types (for example OCTET STRING) if this option
      is not set then non character string types will be displayed as though
      each content octet represents a single character.
- dump_all
- Dump all fields. This option when used with dump_der allows the DER
      encoding of the structure to be unambiguously determined.
- dump_unknown
- Dump any field whose OID is not recognised by OpenSSL.
- sep_comma_plus, sep_comma_plus_space,
    sep_semi_plus_space, sep_multiline
- These options determine the field separators. The first character is
      between RDNs and the second between multiple AVAs (multiple AVAs are very
      rare and their use is discouraged). The options ending in
      "space" additionally place a space after the separator to make
      it more readable. The sep_multiline uses a linefeed character for
      the RDN separator and a spaced + for the AVA separator. It also
      indents the fields by four characters. If no field separator is specified
      then sep_comma_plus_space is used by default.
- dn_rev
- Reverse the fields of the DN. This is required by RFC2253. As a side
      effect this also reverses the order of multiple AVAs but this is
      permissible.
- nofname, sname, lname, oid
- These options alter how the field name is displayed. nofname does
      not display the field at all. sname uses the "short name"
      form (CN for commonName for example). lname uses the long form.
      oid represents the OID in numerical form and is useful for
      diagnostic purpose.
- align
- Align field values for a more readable output. Only usable with
      sep_multiline.
- space_eq
- Places spaces round the = character which follows the field
    name.
As well as customising the name output format, it is also possible to customise
  the actual fields printed using the certopt options 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 output 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 the ca utility, equivalent to no_issuer,
      no_pubkey, no_header, and no_version.
Note: in these examples the '\' means the example should be all on one line.Display the contents of a certificate:
 openssl x509 -in cert.pem -noout -text
Display the "Subject Alternative Name" extension of a
    certificate:
 openssl x509 -in cert.pem -noout -ext subjectAltName
Display more extensions of a certificate:
 openssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType
Display the certificate serial number:
 openssl x509 -in cert.pem -noout -serial
Display the certificate subject name:
 openssl x509 -in cert.pem -noout -subject
Display the certificate subject name in RFC2253 form:
 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
Display the certificate subject name in oneline form on a terminal
    supporting UTF8:
 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
Display 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 -signkey 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 \
        -signkey 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
The PEM format uses the header and footer lines:
 -----BEGIN CERTIFICATE-----
 -----END CERTIFICATE-----
it will also handle files containing:
 -----BEGIN X509 CERTIFICATE-----
 -----END X509 CERTIFICATE-----
Trusted certificates have the lines
 -----BEGIN TRUSTED CERTIFICATE-----
 -----END TRUSTED CERTIFICATE-----
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 display 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.
The -purpose option checks the certificate extensions and determines what
  the certificate can be used for. The actual checks done are rather complex and
  include various hacks and workarounds to handle broken certificates and
  software.
The same code is used when verifying untrusted certificates in
    chains so this section is useful if a chain is rejected by the verify
  code.
The basicConstraints extension CA flag is used to determine
    whether the certificate can be used as a CA. If the CA flag is true then it
    is a CA, if the CA flag is false then it is not a CA. All CAs should
    have the CA flag set to true.
If the basicConstraints extension is absent then the certificate
    is considered to be a "possible CA" other extensions are checked
    according to the intended use of the certificate. A warning is given in this
    case because the certificate should really not be regarded as a CA: however
    it is allowed to be a CA to work around some broken software.
If the certificate is a V1 certificate (and thus has no
    extensions) and it is self signed it is also assumed to be a CA but a
    warning is again given: this is to work around the problem of Verisign roots
    which are V1 self signed certificates.
If the keyUsage extension is present then additional restraints
    are made on the uses of the certificate. A CA certificate must have
    the keyCertSign bit set if the keyUsage extension is present.
The extended key usage extension places additional restrictions on
    the certificate uses. If this extension is present (whether critical or not)
    the key can only be used for the purposes specified.
A complete description of each test is given below. The comments
    about basicConstraints and keyUsage and V1 certificates above apply to
    all CA certificates.
  - SSL Client
- The extended key usage extension must be absent or include the "web
      client authentication" OID. keyUsage must be absent or it must have
      the digitalSignature bit set. Netscape certificate type must be absent or
      it must have the SSL client bit set.
- SSL Client CA
- The extended key usage extension must be absent or include the "web
      client authentication" OID. Netscape certificate type must be absent
      or it must have the SSL CA bit set: this is used as a work around if the
      basicConstraints extension is absent.
- SSL Server
- The extended key usage extension must be absent or include the "web
      server authentication" and/or one of the SGC OIDs. keyUsage must be
      absent or it must have the digitalSignature, the keyEncipherment set or
      both bits set. Netscape certificate type must be absent or have the SSL
      server bit set.
- SSL Server CA
- The extended key usage extension must be absent or include the "web
      server authentication" and/or one of the SGC OIDs. Netscape
      certificate type must be absent or the SSL CA bit must be set: this is
      used as a work around if the basicConstraints extension is absent.
- Netscape SSL Server
- For Netscape SSL clients to connect to an SSL server it must have the
      keyEncipherment bit set if the keyUsage extension is present. This isn't
      always valid because some cipher suites use the key for digital signing.
      Otherwise it is the same as a normal SSL server.
- Common S/MIME Client Tests
- The extended key usage extension must be absent or include the "email
      protection" OID. Netscape certificate type must be absent or should
      have the S/MIME bit set. If the S/MIME bit is not set in Netscape
      certificate type then the SSL client bit is tolerated as an alternative
      but a warning is shown: this is because some Verisign certificates don't
      set the S/MIME bit.
- S/MIME Signing
- In addition to the common S/MIME client tests the digitalSignature bit or
      the nonRepudiation bit must be set if the keyUsage extension is
    present.
- S/MIME Encryption
- In addition to the common S/MIME tests the keyEncipherment bit must be set
      if the keyUsage extension is present.
- S/MIME CA
- The extended key usage extension must be absent or include the "email
      protection" OID. Netscape certificate type must be absent or must
      have the S/MIME CA bit set: this is used as a work around if the
      basicConstraints extension is absent.
- CRL Signing
- The keyUsage extension must be absent or it must have the CRL signing bit
      set.
- CRL Signing CA
- The normal CA tests apply. Except in this case the basicConstraints
      extension must be present.
Extensions in certificates are not transferred to certificate requests and vice
  versa.It is possible to produce invalid certificates or requests by
    specifying the wrong private key 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.
req(1), ca(1), genrsa(1), gendsa(1),
  verify(1), x509v3_config(5)
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 c_rehash or
  similar.
Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (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>.