NSS and OpenSSL Command Reference

NSS and OpenSSL Command Reference

I am tired of the lack of documentation for how to actually use OpenSSL and NSS to achieve things. Be it missing small important options like "subjectAltNames" in nss commands or OpenSSL's cryptic settings. Here is my complete list of everything you would ever want to do with OpenSSL and NSS.


NSS specific

DB creation and basic listing

NSS does not operate on PEM or DER files like OpenSSL - it interacts with a certificate database.

The older format database contains 3 files: key3.db, cert8.db, and secmod.db

The newer sqlite based format contains 3 files: key4.db, cert9.db, and pkcs11.txt

Create a new certificate database if one doesn't exist. You should see the files listed above. :

certutil -N -d .

List all certificates in a database :

certutil -L -d .

List all private keys in a database :

certutil -K -d . [-f pwdfile.txt]

I have created a password file, which consists of random data on one line in a plain text file. Something like below would suffice. Alternately you can enter a password when prompted by the certutil commands. If you wish to use this for directory server start up, you need to use pin.txt which lists the "token name" and it's corresponding pin. :

echo "Password" > pwdfile.txt
echo "internal:Password" > pin.txt

Importing certificates to NSS

Import a server certificate into the database with no certificate authority trust flags. :

certutil -A -n "Server-cert" -t ",," -i nss.dev.example.com.crt -d .

Import an openSSL generated key and certificate into an NSS database. This needs to be formatted through a pkcs12 bundle.

You can NOT include the CA certificate in these bundles, they must be imported seperately to NSS. :

openssl pkcs12 -export -in server.crt -inkey server.key -out server.p12 -name Test-Server-Cert
pk12util -i server.p12 -d . -k pwdfile.txt

Importing a CA certificate

Import the CA public certificate into the database. Note the [-t "C,,"]{.title-ref} flag which specifies this is trusted as a CA certificate. The nickname has no function other than to help you identify the certificate. :

certutil -A -n "CAcert" -t "C,," -i /etc/pki/CA/nss/ca.crt -d .

Exporting certificates

Export a secret key and certificate from an NSS database for use with OpenSSL. This must pass through a pkcs12 file, in reverse to the import process above. Note that file.pem contains all of the CA cert, cert and private key. :

pk12util -o server-export.p12 -d . -k pwdfile.txt -n Test-Server-Cert
openssl pkcs12 -in server-export.p12 -out file.pem -nodes

You can extract just the private key with:

openssl pkcs12 -in server-export.p12 -out file.pem -nocerts -nodes

Or just the cert and CAcert with

openssl pkcs12 -in server-export.p12 -out file.pem -nokeys -nodes

Both NSS and OpenSSL

Self signed certificates

Create a self signed certificate.

For NSS, note the -n, which creates a "nickname" (should be unique in this DB) and is how applications reference your certificate and key. Also note the -s line, and the CN options. Finally, note the first line has the option -g, which defines the number of bits in the created certificate. Note also the -Z for the hash algorithm. -v is "valid months" which we set to 1. The equivalent openssl command is below.

certutil -S -f pwdfile.txt -d . -t "C,," -x -n "Server-Cert" -k ec -q nistp256 \
-s "CN=nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU" -v 1

openssl req -x509 -newkey ec:<(openssl genpkey -genparam -algorithm ec -pkeyopt ec_paramgen_curve:P-256)
-keyout key.pem -out cert.pem -days 31 -nodes

If you choose to use RSA. 3072 bits is the equivalent in strength to 256 bit ecdsa.

certutil -S -f pwdfile.txt -d . -t "C,," -x -n "Server-Cert" -g 3072 -Z SHA256 \
-s "CN=nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU" -v 1

openssl req -x509 -newkey rsa:3072 -keyout key.pem -out cert.pem -days 31 -nodes


To add subject alternative names, use a comma seperated list with the option -8 IE:

certutil -S -f pwdfile.txt -d . -t "C,," -x -n "Server-Cert" -k ec -q nistp256 \
-s "CN=nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU" \
-8 "nss.dev.example.com,nss-alt.dev.example.com"

openssl req -x509 -newkey ec:<(openssl genpkey -genparam -algorithm ec -pkeyopt ec_paramgen_curve:P-256) \
-keyout key.pem -out cert.pem -days 31 -subj "/C=AU/CN=server.example.com" \
-addext "subjectAltName = DNS:server.example.com" \
-addext "extendedKeyUsage = serverAuth"  -nodes

For OpenSSL there is an alternative method: First, you need to create an altnames.cnf and fill in the details as required.

req_extensions = v3_req
nsComment = "Certificate"
distinguished_name  = req_distinguished_name

[ req_distinguished_name ]

countryName                     = Country Name (2 letter code)
countryName_default             = AU
countryName_min                 = 2
countryName_max                 = 2

stateOrProvinceName             = State or Province Name (full name)
stateOrProvinceName_default     = Queensland

localityName                    = Locality Name (eg, city)
localityName_default            = example/streetAddress=Level

0.organizationName              = Organization Name (eg, company)
0.organizationName_default      = example

organizationalUnitName          = Organizational Unit Name (eg, section)
organizationalUnitName_default = TS

commonName                      = Common Name (eg, your name or your server\'s hostname)
commonName_max                  = 64

[ v3_req ]

# Extensions to add to a certificate request

basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names

DNS.1 = server1.yourdomain.tld
DNS.2 = mail.yourdomain.tld
DNS.3 = www.yourdomain.tld
DNS.4 = www.sub.yourdomain.tld
DNS.5 = mx.yourdomain.tld
DNS.6 = support.yourdomain.tld

Now you run a similar command to before with the altnames configuration added. :

openssl req -x509 -newkey ec:<(openssl genpkey -genparam -algorithm ec -pkeyopt ec_paramgen_curve:P-256)
-keyout key.pem -out cert.pem -days -config altnames.cnf

Check a certificate belongs to a specific key

This checks that a key, signing request and cert belong together.

In NSS when the certificate and key are in the same database, the linkage is shown when you display all keys: :

# certutil -d . -K
< 0> ec       bb4db46fb8a5beb46f57641f8b1bf236bc139666   NSS Certificate DB:Server-Cert

With OpenSSL it's possible to verify this from requests and other parts.

openssl ec -in key.pem -pubout | openssl sha1
openssl x509 -noout -in cert.pem -pubkey | openssl sha1
openssl req -noout -in cert.pem -pubkey | openssl sha1

For an RSA key and certificate. :

openssl rsa -noout -modulus -in client.key | openssl sha1
openssl req -noout -modulus -in client.csr | openssl sha1
openssl x509 -noout -modulus -in client.crt | openssl sha1

View a certificate

View the cert :

certutil -L -d . -n Test-Cert

openssl x509 -noout -text -in client.crt

View the cert in ASCII PEM form (This can be redirected to a file for use with openssl) :

certutil -L -d . -n Test-Cert -a
certutil -L -d . -n Test-Cert -a > cert.pem

Creating a CSR

In a seperate database to your CA.

Create a new certificate request. Again, remember -8 for subjectAltName. This request is for a TLS server with a 24 month certificate lifetime. :

certutil -d . -R -a -o nss.dev.example.com.csr -f pwdfile.txt -k ec -q nistp256 -v 24 \
-s "CN=nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU"

If you want to request for a TLS client that can authenticate to a server with x509. :

certutil -d . -R -a -o user.csr -f pwdfile.txt -k ec -q nistp256 -v 24 \
--keyUsage digitalSignature,nonRepudiation,keyEncipherment,dataEncipherment --nsCertType sslClient --extKeyUsage clientAuth \
-s "CN=username,O=Testing,L=example,ST=Queensland,C=AU"

Using openSSL create a server key, and make a CSR. Note prime256v1 is an alternate name for nistp256 :

openssl ecparam -genkey -name prime256v1 -noout -out key.pem
openssl req -key key.pem -out cert.csr -days 712 -config altnames.cnf -new

For RSA :

openssl genrsa -out key.pem 3072
openssl req -key key.pem -out cert.csr -days 712 -config altnames.cnf -new

Self signed CA

Create a self signed CA (In a different database from the one used by your application) :

certutil -S -n CAissuer -t "C,C,C" -x -f pwdfile.txt -d . -k ec -q nistp256 -v 24 \
--keyUsage certSigning -2 --nsCertType sslCA \
-s "CN=ca.nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU"

Nss will ask you about the constraints on this certificate. Here is a sample output. Note the path length of 0 still allows this CA to issue certificates, but it cannot issue an intermediate CA.

Generating key.  This may take a few moments...

        0 - Digital Signature
        1 - Non-repudiation
        2 - Key encipherment
        3 - Data encipherment
        4 - Key agreement
        5 - Cert signing key
        6 - CRL signing key
        Other to finish
 > 5
        0 - Digital Signature
        1 - Non-repudiation
        2 - Key encipherment
        3 - Data encipherment
        4 - Key agreement
        5 - Cert signing key
        6 - CRL signing key
        Other to finish
 > 9
Is this a critical extension [y/N]?
Is this a CA certificate [y/N]?
Enter the path length constraint, enter to skip [<0 for unlimited path]: > 0
Is this a critical extension [y/N]?
        0 - SSL Client
        1 - SSL Server
        2 - S/MIME
        3 - Object Signing
        4 - Reserved for future use
        5 - SSL CA
        6 - S/MIME CA
        7 - Object Signing CA
        Other to finish
 > 5
        0 - SSL Client
        1 - SSL Server
        2 - S/MIME
        3 - Object Signing
        4 - Reserved for future use
        5 - SSL CA
        6 - S/MIME CA
        7 - Object Signing CA
        Other to finish
 > 9
Is this a critical extension [y/N]?

OpenSSL is the same as a self signed cert. It's probably wise to add path length and other policies here, which are specified via -config :

openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days X -config ca.cnf

Renewing the self signed CA

This happens if your CA is about to or has expired. You need to reissue all your certs after this is done! Be sure to substitute your domain and certificate nicknames.

certutil -d . -R -k "NSS Certificate DB:ca" -s "CN=ca.net.blackhats.net.au,O=Blackhats,L=Brisbane,ST=Queensland,C=AU" -a -o renew.req -1 -2 -5

certutil -C -d . -c "ca" -a -i renew.req -t "C,C,C" -o cacert.crt -v 12

certutil -A -d . -n "ca" -a -i cacert.crt -t "C,C,C"

Signing with the CA

Create a certificate in the same database, and sign it with the CAissuer certificate.

certutil -S -n Test-Cert -t ",," -c CAissuer -f pwdfile.txt -d . \
-s "CN=test.nss.dev.example.com,O=Testing,L=example,ST=Queensland,C=AU"

If from a CSR, review the CSR you have recieved.

/usr/lib[64]/nss/unsupported-tools/derdump -i /etc/httpd/alias/nss.dev.example.com.csr
openssl req -inform DER -text -in /etc/httpd/alias/nss.dev.example.com.csr  ## if from nss
openssl req -inform PEM -text -in server.csr  ## if from openssl

On the CA, sign the CSR.

certutil -C -d . -f pwdfile.txt -a -i /etc/httpd/alias/nss.dev.example.com.csr \
-o /etc/httpd/alias/nss.dev.example.com.crt -c CAissuer

For openssl CSR, note the use of -a that allows an ASCII formatted PEM input, and will create and ASCII PEM certificate output.

certutil -C -d . -f pwdfile.txt -i server.csr -o server.crt -a -c CAissuer

### Note, you may need a caserial file ...
openssl x509 -req -days 1024 -in client.csr -CA root.crt -CAkey root.key -out client.crt

Check validity of a certificate

Test the new cert for validity as an SSL server. This assumes the CA cert is in the DB. (Else you need openssl or to import it). The second example is validating a user certificate.

certutil -V -d . -n Test-Cert -u V

certutil -V -d . -n usercert -u C

openssl verify -verbose -CAfile ca.crt client.crt

Export the CA certificate

Export the CA public certificate :

certutil -L -d . -n CAissuer -r > ca.crt

NSS sqlite db

Finally, these commands all use the old DBM formatted NSS databases. To use the new "shareable" sqlite formatting, follow the steps found from this blog post.

How to upgrade from cert8.db to cert9.db

You can either use environment variables or use sql: prefix in database directory parameter of certutil:

$certutil -K -d /tmp/nss -X


$certutil -K -d sql:/tmp/nss -X

When you upgrade these are the files you get

key3.db -> key4.db
cert8.db -> cert9.db
secmod.db -> pkcs11.txt

The contents of the pkcs11.txt files are basically identical to the contents of the old secmod.db, just not in the old Berkeley DB format. If you run the command "$modutil -dbdir DBDIR -rawlist" on an older secmod.db file, you should get output similar to what you see in pkcs11.txt.

What needs to be done in programs / C code

Either add environment variable NSS_DEFAULT_DB_TYPE "sql"

NSS_Initialize call in https://developer.mozilla.org/en/NSS_Initialize takes this "configDir" parameter as shown below.

NSS_Initialize(configDir, "", "", "secmod.db", NSS_INIT_READONLY);

For cert9.db, change this first parameter to "sql:" + configDir (like "sql:/tmp/nss/") i.e. prefix "sql:" in the directory name where these NSS Databases exist. This code will work with cert8.db as well if cert9.db is not present.


Display a human readable certificate from an SSL socket

Note: port 636 is LDAPS, but all SSL sockets are supported. For TLS only a limited set of protocols are supported. Add -starttls to the command. See man 1 s_client.

openssl s_client -connect ldap.example.com:636

[ant@ant-its-example-edu-au ~]$ echo -n | openssl s_client -connect ldap.example.com:636 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | openssl x509 -noout -text

depth=3 C = SE, O = AddTrust AB, OU = AddTrust External TTP Network, CN = AddTrust External CA Root
verify return:1
depth=2 C = US, ST = UT, L = Salt Lake City, O = The USERTRUST Network, OU = http://www.usertrust.com, CN = UTN-USERFirst-Hardware
verify return:1
depth=1 C = AU, O = AusCERT, OU = Certificate Services, CN = AusCERT Server CA
verify return:1
depth=0 C = AU, postalCode = 5000, ST = Queensland, L = example, street = Level, street = Place, O =Example, OU = Technology Services, CN = ldap.example.com
verify return:1
        Version: 3 (0x2)
        Serial Number:
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: C=AU, O=AusCERT, OU=Certificate Services, CN=AusCERT Server CA
            Not Before: XX
            Not After : XX
        Subject: C=AU/postalCode=4000, ST=Queensland, L=example/street=Level /street=Place, O=Example, OU=Technology Services, CN=ldap.example.com
        Subject Public Key Info:
            X509v3 Subject Alternative Name: 

You can use this to display a CA chain if you can't get it from other locations.

openssl s_client -connect ldap.example.com:636 -showcerts