Pem To X509

  1. Extensions used for PEM certificates are cer, crt, and pem. They are Base64 encoded ASCII files. The DER format is the binary form of the certificate. DER formatted certificates do not contain the 'BEGIN CERTIFICATE/END CERTIFICATE' statements. DER formatted certificates most often use the '.der' extension. Convert x509 to PEM.
  2. Select the certificate Export select 'DER ENCODED Binary X.509 (.cer)' Choose a file name and save. You now have a DER encoded certificate file for your use. If you have any questions or concerns please contact the Entrust Certificate Services Support department for further assistance.

Use this SSL Converter to convert SSL certificates to and from different formats such as pem, der, p7b, and pfx. Different platforms and devices require SSL certificates to be converted to different formats. For example, a Windows server exports and imports .pfx files while an Apache server uses individual PEM (.crt, .cer) files. To use the SSL Converter, just select your certificate file and its current type (it will try to detect the type from the file extension) and then select what type you want to convert the certificate to and click Convert Certificate. For more information about the different SSL certificate types and how you can convert certificates on your computer using OpenSSL, see below.

Format a X.509 certificate. Sometimes we copy and paste the X.509 certificates from documents and files, and the format is lost. With this tool we can get certificates formated in different ways, which will be ready to be used in the OneLogin SAML Toolkits. Convert a PEM file to DER openssl x509 -outform der -in certificate.pem -out certificate.der Convert a PKCS#12 file (.pfx.p12) containing a private key and certificates to PEM openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes You can add -nocerts to only output the private key or add -nokeys to only output the certificates.

PEM Format

The PEM format is the most common format that Certificate Authorities issue certificates in. PEM certificates usually have extensions such as .pem, .crt, .cer, and .key. They are Base64 encoded ASCII files and contain '-----BEGIN CERTIFICATE-----' and '-----END CERTIFICATE-----' statements. Server certificates, intermediate certificates, and private keys can all be put into the PEM format.

Apache and other similar servers use PEM format certificates. Several PEM certificates, and even the private key, can be included in one file, one below the other, but most platforms, such as Apache, expect the certificates and private key to be in separate files.

DER Format

The DER format is simply a binary form of a certificate instead of the ASCII PEM format. It sometimes has a file extension of .der but it often has a file extension of .cer so the only way to tell the difference between a DER .cer file and a PEM .cer file is to open it in a text editor and look for the BEGIN/END statements. All types of certificates and private keys can be encoded in DER format. DER is typically used with Java platforms. The SSL Converter can only convert certificates to DER format. If you need to convert a private key to DER, please use the OpenSSL commands on this page.

PKCS#7/P7B Format

The PKCS#7 or P7B format is usually stored in Base64 ASCII format and has a file extension of .p7b or .p7c. P7B certificates contain '-----BEGIN PKCS7-----' and '-----END PKCS7-----' statements. A P7B file only contains certificates and chain certificates, not the private key. Several platforms support P7B files including Microsoft Windows and Java Tomcat.

PKCS#12/PFX Format

The PKCS#12 or PFX format is a binary format for storing the server certificate, any intermediate certificates, and the private key in one encryptable file. PFX files usually have extensions such as .pfx and .p12. PFX files are typically used on Windows machines to import and export certificates and private keys.

When converting a PFX file to PEM format, OpenSSL will put all the certificates and the private key into a single file. You will need to open the file in a text editor and copy each certificate and private key (including the BEGIN/END statements) to its own individual text file and save them as certificate.cer, CACert.cer, and privateKey.key respectively.

OpenSSL Commands to Convert SSL Certificates on Your Machine

It is highly recommended that you convert to and from .pfx files on your own machine using OpenSSL so you can keep the private key there. Use the following OpenSSL commands to convert SSL certificate to different formats on your own machine:

OpenSSL Convert PEM

Convert PEM to DER

openssl x509 -outform der -in certificate.pem -out certificate.der

Convert PEM to P7B

openssl crl2pkcs7 -nocrl -certfile certificate.cer -out certificate.p7b -certfile CACert.cer

Convert PEM to PFX

openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt

OpenSSL Convert DER

Convert DER to PEM

openssl x509 -inform der -in certificate.cer -out certificate.pem

OpenSSL Convert P7B

Convert P7B to PEM

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer

Convert P7B to PFX

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer

openssl pkcs12 -export -in certificate.cer -inkey privateKey.key -out certificate.pfx -certfile CACert.cer

OpenSSL Convert PFX

Convert PFX to PEM

openssl pkcs12 -in certificate.pfx -out certificate.cer -nodes

If you need to convert a Java Keystore file to a different format, it usually easier to create a new private key and certificates but it is possible to convert a Java Keystore to PEM format.


x509 - Certificate display and signing utility


openssl x509 [-inform DER PEM NET] [-outform DER PEM NET] [-keyform DER PEM] [-CAform DER PEM] [-CAkeyformDER 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] [-CAfilename] [-CAkey filename] [-CAcreateserial] [-CAserial filename] [-text] [-C] [-md2 -md5 -sha1 -mdc2][-clrext] [-extfile filename] [-extensions section] [-engine id]


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.



outputs the 'hash' of the certificate issuer name.
synonym for '-subject_hash' for backward compatibility reasons.
outputs the 'hash' of the certificate subject name using the older algorithm as used by OpenSSL versions before 1.0.0.
outputs the 'hash' of the certificate issuer name using the older algorithm as used by OpenSSL versions before 1.0.0.
outputs the subject name.
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 bycommas. Alternatively the -nameopt switch may be used more than once to set multiple options. See the NAME OPTIONS section formore information.
outputs the email address(es) if any.
outputs the OCSP responder address(es) if any.
prints out the start date of the certificate, that is the notBefore date.
prints out the expiry date of the certificate, that is the notAfter date.
prints out the start and expiry dates of a certificate.
prints out the digest of the DER encoded version of the whole certificate (see digest options).

this outputs the certificate in the form of a C source file.


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 andprohibited 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 mustbe 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 usedfor. 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.

this causes x509 to output a trusted certificate. An ordinary or trusted certificate can be input but by default an ordinary certificate isoutput and any trust settings are discarded. With the -trustout option a trusted certificate is output. A trusted certificate is automatically output ifany 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'.
outputs the certificate alias, if any.
clears all the permitted or trusted uses of the certificate.
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.
this option performs tests on the certificate extensions and outputs the results. For a more complete description see the CERTIFICATEEXTENSIONS section.


The x509 utility can be used to sign certificates and requests: it can thus behave like a 'mini CA '.
-signkey filename
Pem To X509this 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 andchanges 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. Anycertificate 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 therequest.

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.
converts a certificate into a certificate request. The -signkey option is used to pass the required private key.
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

Openssl X509 Example

CA '. Theinput 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 isdigitally 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 keyis 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 evennumber 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 certificatefile is called 'mycacert.pem' it expects to find a serial number file called ''.

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 beingsigned 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 fordetails of the extension section format.


- to turn the option off. Only the first four will normally be used.
use the old format. This is equivalent to specifying no name options at all.
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.
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.
a multiline format. It is equivalent esc_ctrl, esc_msb, sep_multiline, space_eq, lname and align.
escape the 'special' characters required by RFC2253 in a field That is ,+'<>;. Additionally # is escaped at the beginningof a string and a space character at the beginning or end of a string.
escape control characters. That is those with ASCII values less than 0x20 (space) and the delete (0x7f) character. They are escaped using theRFC2253 XX notation (where XX are two hex digits representing the character value).
escape characters with the MSB set, that is with ASCII values larger than 127.
escapes some characters by surrounding the whole string with ' characters, without the option all escaping is done with the character.
convert all strings to UTF8 format first. This is required by RFC2253 . If you are lucky enough to have a UTF8compatible 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 for32 bits. Also if this option is off any UTF8Strings will be converted to their character form first.
this option does not attempt to interpret multibyte characters in any way. That is their content octets are merely dumped as though one octet representseach character. This is useful for diagnostic purposes but will result in rather odd looking output.
show the type of the ASN1 character string. The type precedes the field contents. For example ' BMPSTRING: HelloWorld'.
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 contentoctets will be displayed. Both options use the RFC2253#XXXX... format.
dump non character string types (for example OCTET STRING ) if this option is not set then non character string types will be displayed asthough each content octet represents a single character.
dump all fields. This option when used with dump_der allows the DER encoding of the structure to be unambiguously determined.
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 andtheir use is discouraged). The options ending in 'space' additionally place a space after the separator to make it more readable. The sep_multiline usesa linefeed character for the RDN separator and a spaced + for the AVA separator. It also indents the fields by fourcharacters.
reverse the fields of the DN . This is required by RFC2253 . As a side effect this also reverses the order of multiple AVAsbut 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 usefulfor diagnostic purpose.
align field values for a more readable output. Only usable with sep_multiline.
places spaces round the = character which follows the field name.


don't print out the version number.
don't print out the serial number.
don't print out the signature algorithm used.
don't print the validity, that is the notBefore and notAfter fields.
don't print out the subject name.
don't print out the issuer name.
don't print out the public key.
don't give a hexadecimal dump of the certificate signature.
don't print out certificate trust information.
don't print out any X509V3 extensions.
retain default extension behaviour: attempt to print out unsupported certificate extensions.
print an error message for unsupported certificate extensions.
ASN1 parse unsupported extensions.
hex dump unsupported extensions.
the value used by the ca utility, equivalent to no_issuer, no_pubkey, no_header, no_version, no_sigdump andno_signame.


Note: in these examples the ' means the example should be all on one line.

Display the contents of a certificate:Display the certificate serial number:Display the certificate subject name:Display the certificate subject name in RFC2253 form:Display the certificate subject name in oneline form on a terminal supporting UTF8:Display the certificate MD5 fingerprint:Display the certificate SHA1 fingerprint:Convert a certificate from PEM to DER format:Convert a certificate to a certificate request:Convert a certificate request into a self signed certificate using extensions for a CA:Sign a certificate request using the CA certificate above and add user certificate extensions:Set a certificate to be trusted for SSL client use and change set its alias to 'Steve's Class 1 CA '


The PEM format uses the header and footer lines:it will also handle files containing:Trusted certificates have the linesThe conversion to UTF8 format used with the name options assumes that T61Strings use the ISO8859-1 character set. This iswrong but Netscape and MSIE do this as do many certificates. So although this is incorrect it is more likely to display the majority ofcertificates correctly.

The -fingerprint option takes the digest of the DER encoded certificate. This is commonly called a 'fingerprint'. Because of thenature of message digests the fingerprint of a certificate is unique to that certificate and two certificates with the same fingerprint can be considered to bethe 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 notprint 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 complexand 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 theCA flag is true then it is a CA , if the CA flag is false then it is not a CA . All CAsshould 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 accordingto the intended use of the certificate. A warning is given in this case because the certificate should really not be regarded as a CA: howeverit 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 isagain 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 havethe 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 canonly be used for the purposes specified.

Convert Pem To X509

A complete description of each test is given below. The comments about basicConstraints and keyUsage and V1 certificates above apply to allCA certificates.

OID . keyUsage must be absent or it must have thedigitalSignature 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 orit 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 beabsent or it must have the digitalSignature, the keyEncipherment set or both bits set. Netscape certificate type must be absent or have the SSLserver 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 certificatetype 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 ispresent. This isn't always valid because some cipher suites use the key for digital signing. Otherwise it is the same as a normal SSLserver.
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 shouldhave 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 awarning 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.
The extended key usage extension must be absent or include the 'email protection' OID . Netscape certificate type must be absent or must havethe 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 bechecked.

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 theintended behaviour rather than the current behaviour. It is hoped that it will represent reality in OpenSSL 0.9.5 and later.

See Also

req(1), ca(1), genrsa(1), gendsa(1), verify(1), x509v3_config(5)


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 MD5algorithm and the encoding of the distinguished name. In OpenSSL 1.0.0 and later it is based on a canonical version of the DN usingSHA1 . This means that any directories using the old form must have their links rebuilt using c_rehash or similar.

Referenced By,config(5),crl(1),openssl

Pem To X509 Base64