x509Namex509 -- Certificate display and signing utility Synopsisopenssl x509
[-inform DER|PEM|NET]
[-outform DER|PEM|NET]
[-keyform DER|PEM]
[-CAform DER|PEM]
[-CAkeyform DER|PEM]
[-in filename]
[-out filename]
[-serial]
[-hash]
[-subject_hash]
[-issuer_hash]
[-subject]
[-issuer]
[-nameopt option]
[-email]
[-ocsp_uri]
[-startdate]
[-enddate]
[-purpose]
[-dates]
[-modulus]
[-fingerprint]
[-alias]
[-noout]
[-trustout]
[-clrtrust]
[-clrreject]
[-addtrust arg]
[-addreject arg]
[-setalias arg]
[-days arg]
[-set_serial n]
[-signkey filename]
[-x509toreq]
[-req]
[-CA filename]
[-CAkey filename]
[-CAcreateserial]
[-CAserial filename]
[-text]
[-C]
[-md2|-md5|-sha1|-mdc2]
[-clrext]
[-extfile filename]
[-extensions section]
[-engine id] |
DESCRIPTION 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.
OPTIONSINPUT, OUTPUT AND GENERAL PURPOSE OPTIONS - -inform DER|PEM|NET
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 NET option
is an obscure Netscape server format that is now obsolete.
- -outform DER|PEM|NET
This specifies the output format, the options have the same
meaning 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.
- -md2|-md5|-sha1|-mdc2
the digest to use. This affects any signing or display
option that uses a message digest, such as the -fingerprint, -signkey and -CA options. If not specified then
SHA1 is used. If the key being used to sign with is a DSA
key then this option has no effect: SHA1 is always used
with DSA keys.
- -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.
DISPLAY OPTIONS 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.
- -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
request.
- -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.
- -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 versions before
1.0.0.
- -issuer_hash_old
outputs the "hash" of the certificate issuer name using the
older algorithm as used by OpenSSL versions before 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.
- -fingerprint
prints out the digest of the DER encoded version of the
whole certificate (see digest options).
- -C
this outputs the certificate in the form of a C source
file.
TRUST SETTINGS Please note these options are currently experimental and may well
change.
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) and emailProtection
(S/MIME email) are used. 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.
SIGNING OPTIONS The x509 utility can be used to
sign certificates and requests: it can thus behave like a "mini
CA".
- -signkey filename
this option causes the input file to be self signed using
the supplied private key.
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.
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.
- -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
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.
- -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). Negative serial
numbers can also be specified but their use is not
recommended.
- -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 consist 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. Normally if the -CA option is specified and the
serial number file does not exist it is an error.
- -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.
NAME OPTIONS 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. This is equivalent to specifying no
name options at all.
- 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.
- 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_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.
- no_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.
- 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.
TEXT OPTIONS 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, no_version, no_sigdump and no_signame.
EXAMPLES 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 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 MD5 fingerprint:
openssl x509 -in cert.pem -noout -fingerprint |
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 |
NOTES 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 -fingerprint option takes the
digest of the DER encoded certificate. 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.
The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
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.
CERTIFICATE EXTENSIONS 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 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.
BUGS 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.
The code to implement the verify behaviour described in the TRUST SETTINGS is currently being developed.
It thus describes the intended behaviour rather than the current
behaviour. It is hoped that it will represent reality in OpenSSL
0.9.5 and later.
HISTORY Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.
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.
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