# generate new RSA private key
openssl genrsa -out private.pem 1024
# CSR and signed certificate are needed to export as PKCS12 store
openssl req -new -key private.pem -out certificate.csr
openssl x509 -req -days 365 -in certificate.csr -signkey private.pem -out certificate.crt
# export as PKCS12 keystore
openssl pkcs12 -export -out keystore.pfx -inkey private.pem -in certificate.crt -passout pass:password

Để đảm bảo chứng chỉ và private key khớp nhau, dùng lệnh sau, tránh bị lỗi “Error: curl: (58) unable to set private key file: 'server.key' type PEM”:

% openssl rsa -noout -modulus -in private.pem | openssl md5
MD5(stdin)= 5850122413002ab1fdc5d703638f55a8
% openssl x509 -noout -modulus -in certificate.crt | openssl md5
MD5(stdin)= 5850122413002ab1fdc5d703638f55a8

https://michaelheap.com/curl-58-unable-to-set-private-key-file-server-key-type-pem

Example:

tungnt@TungNTs-MacBook-Pro transfer % openssl genrsa -des3 -out vpb_private_key.key 2048
Generating RSA private key, 2048 bit long modulus (2 primes)
..........................................................................................+++++
..+++++
e is 65537 (0x010001)
Enter pass phrase for vpb_private_key.key:
Verifying - Enter pass phrase for vpb_private_key.key:
 
tungnt@TungNTs-MacBook-Pro vpb % openssl req -new -key vpb_private_key.key -out vpb_private_key.csr
Enter pass phrase for vpb_private_key.key:
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) [AU]:VI
State or Province Name (full name) [Some-State]:Ha Noi
Locality Name (eg, city) []:Ha Noi
Organization Name (eg, company) [Internet Widgits Pty Ltd]:NPay
Organizational Unit Name (eg, section) []:NKT
Common Name (e.g. server FQDN or YOUR name) []:
Email Address []:
 
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:        
An optional company name []:
 
tungnt@TungNTs-MacBook-Pro vpb % openssl req -new -x509 -days 1001 -key vpb_private_key.key -sha256  -out vpb_public_key.cer
Enter pass phrase for vpb_private_key.key:
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) [AU]:VI
State or Province Name (full name) [Some-State]:Ha Noi
Locality Name (eg, city) []:Ha Noi
Organization Name (eg, company) [Internet Widgits Pty Ltd]:NPay
Organizational Unit Name (eg, section) []:NKT
Common Name (e.g. server FQDN or YOUR name) []:
Email Address []:
 
tungnt@TungNTs-MacBook-Pro vpb % openssl req -new -x509 -nodes -sha256 -days 365 -key vpb_private_key.key -out vpb.cert
Enter pass phrase for vpb_private_key.key:
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) [AU]:VI
State or Province Name (full name) [Some-State]:Ha Noi
Locality Name (eg, city) []:Ha Noi
Organization Name (eg, company) [Internet Widgits Pty Ltd]:NPay
Organizational Unit Name (eg, section) []:NKT
Common Name (e.g. server FQDN or YOUR name) []:
Email Address []: