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Gong Cheng [end_users]

Generating Self-Signed Test Certificates Using One Single Shell Script

fsmsh.com/2964 [certificate] [openssl]

Looking at the title, you might say: "Not another openssl certificate generation guide!". I know, I know, but I promise that I will try to be different here.

Indeed, there are abundant resources available on how to use openssl to generate digital certificates and I have learned a lot from them. However, I don't think it is easy for all of us to memorize the complicated openssl command line syntax. A lot of times, all I need is to generate a new certificate and for that I just want to have something simple and straightforward that I can simply invoke without digging through old notes or googling for some guides.

To achieve that, I created a single shell script that is able to do three things and only three things:

  • Generating self-signed root CA certificates
  • Generating "client" certificate with XP client extension
  • Generating "server" certificate with XP server extension

The goal here is to make it as self-contained as possible: it only requires a functional openssl (and a /bin/sh of course) installed on the system. You don't even need to know where the openssl.cnf is or modify its content because it is all dynamically generated in the script itself. You don't need to create a separate XP extension file because it is in the script too.

Another goal is to make it as simple as possible: There are only 3 commands for the 3 things it does, each achieved in one step. You just need to type in all the fields of your certs as usual by following the prompt.

Before going to the script, I must disclaim that the certificates generated this way are intended for testing purposes only (for example, testing your wifi security configurations). Use it for any other purposes at your own risk.

The Script

Now the script itself. Due to lack of imagination, I call it certgen.

#!/bin/sh

#

# A script generates self-signed root CA cert/key and client/server certs with

# xp-extensions, using openssl.

# certs generated are for testing purposes only!

#

# Author: Gong Cheng, chengg11@yahoo.com, Aug. 2008

#

# You are free to use this script in anyway but absolutely no warranty!

#



usage ()

{

    echo "Usage:"

    echo "  certgen ca [<ca key> <ca cert>]"

    echo "  certgen client <ca key> <ca cert> [ <client key>  <client cert> ]"

    echo "  certgen server <ca key> <ca cert> [ <server key>  <server cert> ]"

}



gen_config ()

{

    echo "Generating ca_config.cnf"

    cat > ca_config.cnf <<EOT

HOME                    = .

RANDFILE                = $ENV::HOME/.rnd

[ ca ]

default_ca      = CA_default

[ CA_default ]

certs           = .

crl_dir         = .

database        = index.txt

new_certs_dir   = .

certificate     = $2

serial          = serial

private_key     = $1

RANDFILE        = .rand

x509_extensions = usr_cert

name_opt        = ca_default

cert_opt        = ca_default

default_days    = 365

default_crl_days= 30

default_md      = sha1

preserve        = no

policy          = policy_match

[ policy_match ]

countryName             = match

stateOrProvinceName     = match

organizationName        = match

organizationalUnitName  = optional

commonName              = supplied

emailAddress            = optional

[ policy_anything ]

countryName             = optional

stateOrProvinceName     = optional

localityName            = optional

organizationName        = optional

organizationalUnitName  = optional

commonName              = supplied

emailAddress            = optional

[ req ]

default_bits            = 1024

default_md              = sha1

default_keyfile         = privkey.pem

distinguished_name      = req_distinguished_name

attributes              = req_attributes

x509_extensions = v3_ca

string_mask = MASK:0x2002

[ req_distinguished_name ]

countryName                     = Country Name (2 letter code)

countryName_default             = GB

countryName_min                 = 2

countryName_max                 = 2

stateOrProvinceName             = State or Province Name (full name)

stateOrProvinceName_default     = Berkshire

localityName                    = Locality Name (eg, city)

localityName_default            = Newbury

0.organizationName              = Organization Name (eg, company)

0.organizationName_default      = My Company Ltd

organizationalUnitName          = Organizational Unit Name (eg, section)

commonName                      = Common Name (eg, your name or your server's hostname)

commonName_max                  = 64

emailAddress                    = Email Address

emailAddress_max                = 64

[ req_attributes ]

challengePassword               = A challenge password

challengePassword_min           = 4

challengePassword_max           = 20

unstructuredName                = An optional company name

[ usr_cert ]

basicConstraints=CA:FALSE

nsComment                       = "OpenSSL Generated Certificate"

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid,issuer

[ v3_req ]

basicConstraints = CA:FALSE

keyUsage = nonRepudiation, digitalSignature, keyEncipherment

[ v3_ca ]

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer:always

basicConstraints = CA:true

[xpclient_ext]

extendedKeyUsage = 1.3.6.1.5.5.7.3.2

[xpserver_ext]

extendedKeyUsage = 1.3.6.1.5.5.7.3.1

EOT

}



gen_ca ()

{

    echo "generating CA cert:$1, $2";

    openssl req -config ca_config.cnf -new -x509 -extensions v3_ca -days 3650 -passin pass:whatever -passout pass:whatever -keyout $1 -out $2

}



gen_client_cert ()

{

    echo "generating client cert:$1, $2";

    openssl req -config ca_config.cnf -new -nodes -keyout $1 -out temp.csr -days 3650



    openssl ca -config ca_config.cnf -policy policy_anything -out $2 -days 3650 -key whatever -extensions xpclient_ext -infiles temp.csr



    rm temp.csr

}



gen_server_cert ()

{

    echo "generating server cert:$1, $2";

    openssl req -config ca_config.cnf -new -nodes -keyout $1 -out temp.csr -days 3650



    openssl ca -config ca_config.cnf -policy policy_anything -out $2 -days 3650 -key whatever -extensions xpserver_ext -infiles temp.csr



    rm temp.csr

}



#at least one argument

if [ $# -lt 1 ]

then

    usage

    exit 1

fi





#default file names if not specified in command line

ca_key_file=cakey.pem

ca_cert_file=cacert.pem

client_key_file=client_key.pem

client_cert_file=client_cert.pem

server_key_file=server_key.pem

server_cert_file=server_cert.pem



case $1 in

ca)

    if [ x$2 != x ]

    then

        ca_key_file=$2

        ca_cert_file=$3

    fi

    gen_config $ca_key_file $ca_cert_file

    gen_ca $ca_key_file $ca_cert_file

    if [ -f $ca_key_file -a -f $ca_cert_file ]

    then

        echo "Generated files: key: $ca_key_file , cert: $ca_cert_file"

    else

        echo "Failed to generated all files"

    fi

    ;;

client)

    if [ $# -ne 3 -a $# -ne 5 ]

    then

        usage

        exit 1

    fi

    ca_key_file=$2

    ca_cert_file=$3

    gen_config $ca_key_file $ca_cert_file

    if [ x$4 != x ]

    then

        client_key_file=$4

        client_cert_file=$5

    fi

    if [ ! -f index.txt ]

    then

        touch index.txt

    fi



    if [ ! -f serial ]

    then

        echo 01 > serial

    fi

    gen_client_cert $client_key_file $client_cert_file

    if [ -f $client_key_file -a -f $client_cert_file ]

    then

        echo "Generated files: key: $client_key_file , cert: $client_cert_file"

    else

        echo "Failed to generated all files"

    fi

    if [ $client_cert_file != `cat serial.old`.pem ]

    then

        rm `cat serial.old`.pem

    fi

    ;;

server)

    if [ $# -ne 3 -a $# -ne 5 ]

    then

        usage

        exit 1

    fi

    ca_key_file=$2

    ca_cert_file=$3

    gen_config $ca_key_file $ca_cert_file

    if [ x$4 != x ]

    then

        server_key_file=$4

        server_cert_file=$5

    fi

    if [ ! -f index.txt ]

    then

        touch index.txt

    fi



    if [ ! -f serial ]

    then

        echo 01 > serial

    fi

    gen_server_cert $server_key_file $server_cert_file

    if [ -f $server_key_file -a -f $server_cert_file ]

    then

        echo "Generated files: key: $server_key_file , cert: $server_cert_file"

    else

        echo "Failed to generated all files"

    fi

    if [ $server_cert_file != `cat serial.old`.pem ]

    then

        rm `cat serial.old`.pem

    fi

    ;;

*) usage; exit 1;;

esac







#cleanups

rm ca_config.cnf

How To Use It?

Easy. Invoke certgen without any parameter, it gives you the usage:

$ ./certgen

Usage:

  certgen ca [<ca key> <ca cert>]

  certgen client <ca key> <ca cert> [ <client key>  <client cert> ]

  certgen server <ca key> <ca cert> [ <server key>  <server cert> ]

The generated file names are optional. If you don't specify them, the default file names generated are:

  • cacert.pem, the root CA certificate
  • cakey.pem, the root CA private key file, pass phrase "whatever"
  • client_cert.pem, the client certificate
  • client_key.pem, the client private key, pass phrase your choice
  • server_cert.pem, the server certificate
  • server_key.pem, the server private key, pass phrase your choice

Here is a sample run that should explain everything:

cheng@gong-ubuntu:~/tmp/certs$ ls

gcheng@gong-ubuntu:~/tmp/certs$ /home/gcheng/src/mine/cert/certgen ca mycakey.pem mycacert.pem

Generating ca_config.cnf

generating CA cert:mycakey.pem, mycacert.pem

Generating a 1024 bit RSA private key

.........++++++

.................++++++

unable to write 'random state'

writing new private key to 'mycakey.pem'

-----

You are about to be asked to enter information that will be incorporated

into your certificate request.

What you are about to enter is what is called a Distinguished Name or a DN.

There are quite a few fields but you can leave some blank

For some fields there will be a default value,

If you enter '.', the field will be left blank.

-----

Country Name (2 letter code) [GB]:US

State or Province Name (full name) [Berkshire]:California

Locality Name (eg, city) [Newbury]:San Jose

Organization Name (eg, company) [My Company Ltd]:test.com

Organizational Unit Name (eg, section) []:eng

Common Name (eg, your name or your servers hostname) []:eng root CA

Email Address []:eng_ca@test.com

Generated files: key: mycakey.pem , cert: mycacert.pem

gcheng@gong-ubuntu:~/tmp/certs$ ls

mycacert.pem  mycakey.pem

gcheng@gong-ubuntu:~/tmp/certs$ /home/gcheng/src/mine/cert/certgen client mycakey.pem mycacert.pem myclientkey.pem myclientcert.pem

Generating ca_config.cnf

generating client cert:myclientkey.pem, myclientcert.pem

Generating a 1024 bit RSA private key

.........................++++++

....................................................................++++++

unable to write 'random state'

writing new private key to 'myclientkey.pem'

-----

You are about to be asked to enter information that will be incorporated

into your certificate request.

What you are about to enter is what is called a Distinguished Name or a DN.

There are quite a few fields but you can leave some blank

For some fields there will be a default value,

If you enter '.', the field will be left blank.

-----

Country Name (2 letter code) [GB]:US

State or Province Name (full name) [Berkshire]:California

Locality Name (eg, city) [Newbury]:San Jose

Organization Name (eg, company) [My Company Ltd]:test.com

Organizational Unit Name (eg, section) []:eng

Common Name (eg, your name or your servers hostname) []:eng test client

Email Address []:eng_client@test.com



Please enter the following 'extra' attributes

to be sent with your certificate request

A challenge password []:whatever

An optional company name []:test.com

Using configuration from ca_config.cnf

Check that the request matches the signature

Signature ok

Certificate Details:

        Serial Number: 1 (0x1)

        Validity

            Not Before: Aug  7 19:51:58 2008 GMT

            Not After : Aug  5 19:51:58 2018 GMT

        Subject:

            countryName               = US

            stateOrProvinceName       = California

            localityName              = San Jose

            organizationName          = test.com

            organizationalUnitName    = eng

            commonName                = eng test client

            emailAddress              = eng_client@test.com

        X509v3 extensions:

            X509v3 Extended Key Usage:

                TLS Web Client Authentication

Certificate is to be certified until Aug  5 19:51:58 2018 GMT (3650 days)

Sign the certificate? [y/n]:y





1 out of 1 certificate requests certified, commit? [y/n]y

Write out database with 1 new entries

Data Base Updated

unable to write 'random state'

Generated files: key: myclientkey.pem , cert: myclientcert.pem

gcheng@gong-ubuntu:~/tmp/certs$ ls

index.txt       index.txt.old  mycakey.pem       myclientkey.pem  serial.old

index.txt.attr  mycacert.pem   myclientcert.pem  serial

gcheng@gong-ubuntu:~/tmp/certs$ /home/gcheng/src/mine/cert/certgen server mycakey.pem mycacert.pem myserverkey.pem myservercert.pem

Generating ca_config.cnf

generating server cert:myserverkey.pem, myservercert.pem

Generating a 1024 bit RSA private key

...........................++++++

........................................++++++

unable to write 'random state'

writing new private key to 'myserverkey.pem'

-----

You are about to be asked to enter information that will be incorporated

into your certificate request.

What you are about to enter is what is called a Distinguished Name or a DN.

There are quite a few fields but you can leave some blank

For some fields there will be a default value,

If you enter '.', the field will be left blank.

-----

Country Name (2 letter code) [GB]:US

State or Province Name (full name) [Berkshire]:California

Locality Name (eg, city) [Newbury]:San Jose

Organization Name (eg, company) [My Company Ltd]:test.com

Organizational Unit Name (eg, section) []:eng

Common Name (eg, your name or your servers hostname) []:eng test server

Email Address []:eng_server@test.com



Please enter the following 'extra' attributes

to be sent with your certificate request

A challenge password []:whatever

An optional company name []:test.com

Using configuration from ca_config.cnf

Check that the request matches the signature

Signature ok

Certificate Details:

        Serial Number: 2 (0x2)

        Validity

            Not Before: Aug  7 19:53:17 2008 GMT

            Not After : Aug  5 19:53:17 2018 GMT

        Subject:

            countryName               = US

            stateOrProvinceName       = California

            localityName              = San Jose

            organizationName          = test.com

            organizationalUnitName    = eng

            commonName                = eng test server

            emailAddress              = eng_server@test.com

        X509v3 extensions:

            X509v3 Extended Key Usage:

                TLS Web Server Authentication

Certificate is to be certified until Aug  5 19:53:17 2018 GMT (3650 days)

Sign the certificate? [y/n]:y





1 out of 1 certificate requests certified, commit? [y/n]y

Write out database with 1 new entries

Data Base Updated

unable to write 'random state'

Generated files: key: myserverkey.pem , cert: myservercert.pem

gcheng@gong-ubuntu:~/tmp/certs$ ls

index.txt           index.txt.old  myclientcert.pem  myserverkey.pem

index.txt.attr      mycacert.pem   myclientkey.pem   serial

index.txt.attr.old  mycakey.pem    myservercert.pem  serial.old

Verification of the Certificates

You can use openssl to verify the validity of the certs and print the contents of the fields too. See below:

gcheng@gong-ubuntu:~/tmp/certs$ openssl verify -CAfile mycacert.pem myclientcert.pem myservercert.pem

myclientcert.pem: OK

myservercert.pem: OK

gcheng@gong-ubuntu:~/tmp/certs$ openssl x509 -text -in mycacert.pem

Certificate:

    Data:

        Version: 3 (0x2)

        Serial Number:

            f2:ed:cf:36:05:b2:91:31

        Signature Algorithm: sha1WithRSAEncryption

        Issuer: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng root CA/emailAddress=eng_ca@test.com

        Validity

            Not Before: Aug  7 19:50:15 2008 GMT

            Not After : Aug  5 19:50:15 2018 GMT

        Subject: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng root CA/emailAddress=eng_ca@test.com

        Subject Public Key Info:

            Public Key Algorithm: rsaEncryption

            RSA Public Key: (1024 bit)

                Modulus (1024 bit):

                    00:c5:f3:d7:ad:18:ca:07:0e:1d:4a:19:52:e3:ab:

                    93:6f:dd:dd:74:1a:4b:c4:9d:57:8c:60:ec:db:bc:

                    53:b8:94:27:41:78:2b:07:56:9b:66:0b:25:a7:37:

                    13:90:ee:63:2f:8f:5a:6d:a6:f2:a1:fd:ce:28:b3:

                    d1:cb:35:1a:00:cb:7e:5a:f8:a3:44:4b:bc:75:63:

                    f4:04:2e:95:4e:6a:2a:16:27:ca:1d:b1:85:ce:79:

                    53:dd:32:a1:fb:02:25:fe:d1:79:68:51:9c:d1:b6:

                    bc:c2:dc:21:33:32:88:97:07:10:d6:52:65:84:1a:



                    d3:e5:fb:a5:de:2a:05:14:d9

                Exponent: 65537 (0x10001)

        X509v3 extensions:

            X509v3 Subject Key Identifier:

                7C:00:6A:A9:AB:52:C8:CE:39:65:1B:AF:7C:CF:13:E4:6E:2E:D4:72

            X509v3 Authority Key Identifier:

                keyid:7C:00:6A:A9:AB:52:C8:CE:39:65:1B:AF:7C:CF:13:E4:6E:2E:D4:72

                DirName:/C=US/ST=California/L=San Jose/O=test.com/OU=eng/CN=eng root CA/emailAddress=eng_ca@test.com

                serial:F2:ED:CF:36:05:B2:91:31



            X509v3 Basic Constraints:

                CA:TRUE

    Signature Algorithm: sha1WithRSAEncryption

        9b:30:4f:61:bd:b1:d9:0b:a0:56:b8:77:5a:08:e6:d2:a6:80:

        13:0b:aa:2d:f5:1e:d1:5f:4e:b2:59:9a:ad:d3:b3:a2:11:8e:

        a1:51:e5:6b:f3:d4:b1:94:d3:9a:ba:43:04:d9:48:dc:d1:c2:

        e9:25:27:81:44:54:1f:bc:7f:2e:44:26:2f:f2:7e:46:ad:26:

        f3:21:47:1b:20:9b:50:61:f7:ae:41:54:8d:e6:41:72:77:4d:

        d0:29:2a:16:56:2a:df:f0:f9:19:2c:19:e6:1d:67:a7:ed:d7:

        6a:49:66:9a:d4:25:1d:36:0f:0a:89:f1:b5:e5:5c:63:e1:c3:

        d5:b3

-----BEGIN CERTIFICATE-----

MIIDjTCCAvagAwIBAgIJAPLtzzYFspExMA0GCSqGSIb3DQEBBQUAMIGMMQswCQYD

VQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTERMA8GA1UEBxMIU2FuIEpvc2Ux

ETAPBgNVBAoTCHRlc3QuY29tMQwwCgYDVQQLEwNlbmcxFDASBgNVBAMTC2VuZyBy

b290IENBMR4wHAYJKoZIhvcNAQkBFg9lbmdfY2FAdGVzdC5jb20wHhcNMDgwODA3

MTk1MDE1WhcNMTgwODA1MTk1MDE1WjCBjDELMAkGA1UEBhMCVVMxEzARBgNVBAgT

CkNhbGlmb3JuaWExETAPBgNVBAcTCFNhbiBKb3NlMREwDwYDVQQKEwh0ZXN0LmNv

bTEMMAoGA1UECxMDZW5nMRQwEgYDVQQDEwtlbmcgcm9vdCBDQTEeMBwGCSqGSIb3

DQEJARYPZW5nX2NhQHRlc3QuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB

gQDF89etGMoHDh1KGVLjq5Nv3d10GkvEnVeMYOzbvFO4lCdBeCsHVptmCyWnNxOQ

7mMvj1ptpvKh/c4os9HLNRoAy35a+KNES7x1Y/QELpVOaioWJ8odsYXOeVPdMqH7

AiX+0XloUZzRtrzC3CEzMoiXBxDWUmWEGtPl+6XeKgUU2QIDAQABo4H0MIHxMB0G

A1UdDgQWBBR8AGqpq1LIzjllG698zxPkbi7UcjCBwQYDVR0jBIG5MIG2gBR8AGqp

q1LIzjllG698zxPkbi7UcqGBkqSBjzCBjDELMAkGA1UEBhMCVVMxEzARBgNVBAgT

CkNhbGlmb3JuaWExETAPBgNVBAcTCFNhbiBKb3NlMREwDwYDVQQKEwh0ZXN0LmNv

bTEMMAoGA1UECxMDZW5nMRQwEgYDVQQDEwtlbmcgcm9vdCBDQTEeMBwGCSqGSIb3

DQEJARYPZW5nX2NhQHRlc3QuY29tggkA8u3PNgWykTEwDAYDVR0TBAUwAwEB/zAN

BgkqhkiG9w0BAQUFAAOBgQCbME9hvbHZC6BWuHdaCObSpoATC6ot9R7RX06yWZqt

07OiEY6hUeVr89SxlNOaukME2Ujc0cLpJSeBRFQfvH8uRCYv8n5GrSbzIUcbIJtQ

YfeuQVSN5kFyd03QKSoWVirf8PkZLBnmHWen7ddqSWaa1CUdNg8KifG15Vxj4cPV

sw==

-----END CERTIFICATE-----

gcheng@gong-ubuntu:~/tmp/certs$ openssl x509 -text -in myclientcert.pem

Certificate:

    Data:

        Version: 3 (0x2)

        Serial Number: 1 (0x1)

        Signature Algorithm: sha1WithRSAEncryption

        Issuer: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng root CA/emailAddress=eng_ca@test.com

        Validity

            Not Before: Aug  7 19:51:58 2008 GMT

            Not After : Aug  5 19:51:58 2018 GMT

        Subject: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng test client/emailAddress=eng_client@test.com

        Subject Public Key Info:

            Public Key Algorithm: rsaEncryption

            RSA Public Key: (1024 bit)

                Modulus (1024 bit):

                    00:91:96:8d:69:88:6d:a3:80:b4:6b:d0:07:3c:1b:

                    2e:5a:dc:9f:fe:ec:9b:3b:ed:83:b6:95:98:f4:26:

                    45:ab:63:1b:76:a3:9b:bb:f0:a3:aa:1f:7d:53:72:

                    05:bb:ac:ff:c0:58:f6:47:8b:ef:fe:4f:e5:01:cb:

                    3c:10:51:52:78:ec:ec:8f:5b:df:c8:f0:d3:96:f0:

                    84:d9:5a:88:81:9c:fb:c9:09:b2:18:1d:d8:55:97:

                    ab:77:8a:b9:26:07:c6:f7:13:47:37:20:6b:78:f8:

                    f5:40:3b:0d:5f:b8:1d:b3:7b:a1:3e:19:bd:31:01:

                    0d:09:69:d7:16:dc:3e:7c:37

                Exponent: 65537 (0x10001)

        X509v3 extensions:

            X509v3 Extended Key Usage:

                TLS Web Client Authentication

    Signature Algorithm: sha1WithRSAEncryption

        5d:36:31:22:5a:4b:ca:cf:de:26:72:8b:e9:5c:b7:01:97:53:

        02:c7:02:70:cc:39:a5:f0:2e:96:8a:0c:53:99:bf:f8:2d:c9:

        d2:f3:4f:31:fa:0d:87:b0:85:4b:03:fa:1e:09:34:7e:80:60:

        59:f5:24:4b:75:ba:c2:ed:df:d6:b2:85:c3:e3:69:df:b9:66:

        de:09:83:3c:36:82:ad:96:47:0c:26:d6:af:ad:74:c6:95:2b:

        48:76:2f:6b:49:4f:50:f5:28:ac:50:00:e5:cf:01:74:a8:01:

        71:ba:c8:69:41:11:62:5a:b3:e4:ac:45:cf:aa:9e:9a:0c:e3:

        aa:8f

-----BEGIN CERTIFICATE-----

MIICrzCCAhigAwIBAgIBATANBgkqhkiG9w0BAQUFADCBjDELMAkGA1UEBhMCVVMx

EzARBgNVBAgTCkNhbGlmb3JuaWExETAPBgNVBAcTCFNhbiBKb3NlMREwDwYDVQQK

Ewh0ZXN0LmNvbTEMMAoGA1UECxMDZW5nMRQwEgYDVQQDEwtlbmcgcm9vdCBDQTEe

MBwGCSqGSIb3DQEJARYPZW5nX2NhQHRlc3QuY29tMB4XDTA4MDgwNzE5NTE1OFoX

DTE4MDgwNTE5NTE1OFowgZQxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9y

bmlhMREwDwYDVQQHEwhTYW4gSm9zZTERMA8GA1UEChMIdGVzdC5jb20xDDAKBgNV

BAsTA2VuZzEYMBYGA1UEAxMPZW5nIHRlc3QgY2xpZW50MSIwIAYJKoZIhvcNAQkB

FhNlbmdfY2xpZW50QHRlc3QuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB

gQCRlo1piG2jgLRr0Ac8Gy5a3J/+7Js77YO2lZj0JkWrYxt2o5u78KOqH31TcgW7

rP/AWPZHi+/+T+UByzwQUVJ47OyPW9/I8NOW8ITZWoiBnPvJCbIYHdhVl6t3irkm

B8b3E0c3IGt4+PVAOw1fuB2ze6E+Gb0xAQ0JadcW3D58NwIDAQABoxcwFTATBgNV

HSUEDDAKBggrBgEFBQcDAjANBgkqhkiG9w0BAQUFAAOBgQBdNjEiWkvKz94mcovp

XLcBl1MCxwJwzDml8C6WigxTmb/4LcnS808x+g2HsIVLA/oeCTR+gGBZ9SRLdbrC

7d/WsoXD42nfuWbeCYM8NoKtlkcMJtavrXTGlStIdi9rSU9Q9SisUADlzwF0qAFx

ushpQRFiWrPkrEXPqp6aDOOqjw==

-----END CERTIFICATE-----

gcheng@gong-ubuntu:~/tmp/certs$ openssl x509 -text -in myservercert.pem

Certificate:

    Data:

        Version: 3 (0x2)

        Serial Number: 2 (0x2)

        Signature Algorithm: sha1WithRSAEncryption

        Issuer: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng root CA/emailAddress=eng_ca@test.com

        Validity

            Not Before: Aug  7 19:53:17 2008 GMT

            Not After : Aug  5 19:53:17 2018 GMT

        Subject: C=US, ST=California, L=San Jose, O=test.com, OU=eng, CN=eng test server/emailAddress=eng_server@test.com

        Subject Public Key Info:

            Public Key Algorithm: rsaEncryption

            RSA Public Key: (1024 bit)

                Modulus (1024 bit):

                    00:9e:fa:d9:76:96:ee:19:cf:e3:95:b5:3a:2c:bf:

                    eb:af:77:0b:f9:29:7a:87:d2:e6:8d:66:44:49:b7:

                    fd:de:2f:f1:21:75:9f:82:7b:01:70:c7:33:48:ec:

                    4b:fb:12:6c:01:b2:39:4d:7d:10:d4:0d:d2:a6:76:

                    b3:51:0b:e9:1e:d3:c6:2e:c3:0d:a8:f7:69:38:96:

                    79:72:ec:93:17:bc:25:f8:61:64:d7:26:3d:84:36:

                    b5:78:a9:9d:25:c9:73:3c:0e:22:21:90:d7:2f:21:

                    b0:ee:cf:c9:55:fb:d8:d7:87:9e:18:0d:ee:97:22:

                    ae:82:0c:d4:d3:e1:bd:53:4f

                Exponent: 65537 (0x10001)

        X509v3 extensions:

            X509v3 Extended Key Usage:

                TLS Web Server Authentication

    Signature Algorithm: sha1WithRSAEncryption

        0b:0c:e7:71:3d:66:4a:d1:43:1f:a4:3f:84:a5:af:0d:7e:74:

        7e:24:d9:13:64:28:27:31:f1:bf:ff:ed:a7:f6:9a:65:01:88:

        f8:1f:58:cc:b1:ba:26:8a:6e:0a:12:8c:a8:b8:09:0a:37:c8:

        41:e0:38:a4:fa:13:2b:9c:61:03:c3:3e:6e:e9:38:8b:f4:43:

        5a:8c:2c:54:87:ab:cc:96:71:b0:25:cd:75:fd:65:bc:7c:da:

        1b:df:db:60:6d:f6:73:5c:54:2e:46:85:bc:ed:d8:7d:cc:ed:

        6b:af:82:fc:45:01:4c:e1:c1:25:15:c2:c3:52:b5:0f:dd:df:

        5e:f0

-----BEGIN CERTIFICATE-----

MIICrzCCAhigAwIBAgIBAjANBgkqhkiG9w0BAQUFADCBjDELMAkGA1UEBhMCVVMx

EzARBgNVBAgTCkNhbGlmb3JuaWExETAPBgNVBAcTCFNhbiBKb3NlMREwDwYDVQQK

Ewh0ZXN0LmNvbTEMMAoGA1UECxMDZW5nMRQwEgYDVQQDEwtlbmcgcm9vdCBDQTEe

MBwGCSqGSIb3DQEJARYPZW5nX2NhQHRlc3QuY29tMB4XDTA4MDgwNzE5NTMxN1oX

DTE4MDgwNTE5NTMxN1owgZQxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9y

bmlhMREwDwYDVQQHEwhTYW4gSm9zZTERMA8GA1UEChMIdGVzdC5jb20xDDAKBgNV

BAsTA2VuZzEYMBYGA1UEAxMPZW5nIHRlc3Qgc2VydmVyMSIwIAYJKoZIhvcNAQkB

FhNlbmdfc2VydmVyQHRlc3QuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB

gQCe+tl2lu4Zz+OVtTosv+uvdwv5KXqH0uaNZkRJt/3eL/EhdZ+CewFwxzNI7Ev7

EmwBsjlNfRDUDdKmdrNRC+ke08Yuww2o92k4lnly7JMXvCX4YWTXJj2ENrV4qZ0l

yXM8DiIhkNcvIbDuz8lV+9jXh54YDe6XIq6CDNTT4b1TTwIDAQABoxcwFTATBgNV

HSUEDDAKBggrBgEFBQcDATANBgkqhkiG9w0BAQUFAAOBgQALDOdxPWZK0UMfpD+E

pa8NfnR+JNkTZCgnMfG//+2n9pplAYj4H1jMsbomim4KEoyouAkKN8hB4Dik+hMr

nGEDwz5u6TiL9ENajCxUh6vMlnGwJc11/WW8fNob39tgbfZzXFQuRoW87dh9zO1r

r4L8RQFM4cElFcLDUrUP3d9e8A==

-----END CERTIFICATE-----

Explanation about client/server certificate

In theory, a certificate is a certificate, then why the difference between client and server certificate? Apparently, windows clients need that distinction. There is a extension called XP extension that does different things for "client" and "sever". Your windows laptop's EAP supplicant must use the "client" version of it (if it needs a certificate like in EAP-TLS) and its EAP peer/RADIUS server should use the server version of it. Otherwise, things might break. I know it will before but I haven't tried any lately.

Some Restrictions

To avoid bloating the command line syntax, I made a few restrictions:

  • The key-guard passphrase for root CA is hardcoded to "whatever" in the script
  • Due to the above hardcoded pass phrase, you can only use certgen to create client
  • Instead of asking the user how long should the certificates be valid, I hardcoded the expiration time to be 3650 days. Search for that number and you can change it.

Testing

I must admit that the script is still fresh. I haven't done extensive testing, but I have tried it on a few ubuntu and fc8 systems of mine and it worked fine. I also tried it using the eapol_test/freeradius interaction (see my post about this ) with EAP-TLS and the certs passed.

License

Verbatim copying and distribution of this entire article are permitted worldwide, without royalty, in any medium, provided this notice is preserved.