git clone https://github.com/royaltm/certool.git
cd certool
[sudo] make install

make prefix=/usr install

make destdir=$HOME/scripts/ install

certool - displays help
certool new - creates new key/csr named ssl.key.secure and ssl.csr
certool self - creates self-signed key/crt named ssl.key.secure and ssl.crt

certool: <command> [ssl_name|host]

ssl_name: name of a file without extension (default: ssl)
host: remote hostname to check ("connect" only)

commands:

  Generate:
  - new:     a new private key and Certificate Signing Request (CSR)
  - self:    a self-signed certificate
  - req:     a CSR for an existing private key
  - reqcrt:  a CSR based on an existing certificate
  - rmpass:  Remove a passphrase from a private key

  Check:
  - readcsr: a Certificate Signing Request (CSR)
  - readkey: a private key
  - readcrt: a certificate
  - readpfx: a PKCS#12 file (.pfx)
  - readp12: a PKCS#12 file (.p12)
  - md5:     if MD5 of the public key matches with CSR and private key
  - connect: Show all the certificates (including Intermediates) from the host

  Convert:
  - derpem:  DER (binary) file (.der) to PEM (ascii) file (.crt)
  - pemder:  PEM (ascii) file (.crt) to DER (binary) file (.der)
  - pfxpem:  PKCS#12 (.pfx) containing a key and certificates to PEM (.pem)
  - p12pem:  PKCS#12 (.p12) containing a key and certificates to PEM (.pem)
  - pfx:     certificate file and a private key to PKCS#12 (.pfx)