"certtool" Command for Certificates on macOS

PKI Tutorials - Herong's Tutorial Examples

∟macOS Certificate Stores and Keychain Access

∟"certtool" Command for Certificates on macOS

This section provides a tutorial example on how to use the 'certtool' command to manage certificates on macOS computers.

macOS also offers another command line interface called "certtool" for you to manage certificate files. Here are some examples on how to use the "certtool" command.

Create a self-signed certificate - It will be stored in a given keychain.

herong$ certtool c k=MyChain
  Enter key and certificate label: MyRoot
  
  Select key algorithm by letter: e
  Enter key size in bits or CR for default: 256
  You have selected algorithm ECDSA, key size 256 bits.
    OK (y/anything)? y

  Enter cert/key usage (s=signing, b=signing AND encrypting, ...: b
  ...Generating key pair...

  Select signature algorithm by letter: 2
  You have selected algorithm ECDSA with SHA256.
    OK (y/anything)? y

  ...creating certificate...
  ..cert stored in Keychain.

List all certificates in a given keychain

herong$ certtool y k=MyChain 

Serial Number      : 41 9F 61 
Issuer Name        :
   Common Name     : MyRoot
   Country         : US
   Org             : Apple
   OrgUnit         : Engineering
   State           : California
   Email addrs     : joe@apple.com
Subject Name       :
   Common Name     : MyRoot
   Country         : US
   Org             : Apple
...
...1 certificates found
...0 CRLs found

Dump a certificate from a given keychain

herong$ security find-certificate -c MyRoot -p MyChain > MyRoot.pem

herong$ ls -l *.pem 
-rw-r--r--  1 herong  staff  733 May  4 08:37 MyRoot.pem

Display info from a given certificate file

herong$ certtool d MyRoot.pem

Serial Number      : 41 9F 61 
Issuer Name        :
   Common Name     : MyRoot
   Country         : US
   Org             : Apple
   OrgUnit         : Engineering
   State           : California
   Email addrs     : joe@apple.com
Subject Name       :
   Common Name     : MyRoot
   Country         : US
   Org             : Apple
...