"OpenSSL" Generating CA's Private Key

This section provides a tutorial example on how to use OpenSSL to generate a RSA private key of 2048 bit long with OpenSSL. This key will be used as the CA's private key and must stored securely in a file with password protection.

As a CA, I must have a good private key (2048 bit long) and I must store it securely in a file. This can be done with a single OpenSSL command "openssl genrsa" as shown in the following command window session:

>openssl genrsa -out herong.key -des 2048

Loading 'screen' into random state - done
Generating RSA private key, 2048 bit long modulus
..........................................................+++
.......................+++
e is 65537 (0x10001)
Enter pass phrase for herong.key: keypass
Verifying - Enter pass phrase for herong.key: keypass

>type herong.key

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-CBC,65D5EB070215060E

l5d+v8KbkPwCgFlrsMD+5FpVsldoCZPeCjMrrWzyym5wIKHKqVltfAjO...
Z2JBXMGxAV4kGky0Jca6/Kxb/tWAmJci0YaDXO0EjwTxeulj9MVL5t3m...
...
bHbZhRs6lUxB4PNosjkhZrgPzYRD7A3EmVqo6ZLXeYO2I2lVIe7k+Lec...
-----END RSA PRIVATE KEY-----

Notes about what I did here:

Error message received when "-passout keypass" is used:

>openssl genrsa -out test.key -des -passout keypass 2048
Invalid password argument "keypass"
Error getting password

Recently, someone emailed me the correct syntax of the "-passout" option: "-passout pass:<password>". Here is an example of how to use the "-passout" option correctly:

>openssl genrsa -out test.key -des -passout pass:keypass 2048
Loading 'screen' into random state - done
Generating RSA private key, 2048 bit long modulus
.....................................................................
...........+++
............................+++
e is 65537 (0x10001)

Want to see some details about my private key? Run the "openssl rsa" command as shown below:

>openssl rsa -in herong.key -text
Enter pass phrase for herong.key: keypass
Private-Key: (2048 bit)
modulus:
    00:ba:a3:a2:d1:ab:9b:9f:26:e6:b5:79:b4:52:11:
    ...
publicExponent: 65537 (0x10001)
privateExponent:
    00:9d:62:da:2d:57:3a:2f:36:5d:bc:d0:f9:97:6f:
    ...
exponent1:
    27:6c:ec:a2:b8:78:5f:55:67:b9:47:eb:3e:25:5d:
    ...
exponent2:
    00:a9:17:88:e5:d7:63:c3:7b:f8:6f:57:78:de:53:
    ...
coefficient:
    30:f5:86:b6:81:ad:1d:35:2c:1a:c1:ba:b9:d9:ab:
    ...
writing RSA key
-----BEGIN RSA PRIVATE KEY-----
MIIEpAIBAAKCAQEAuqOi0aubnybmtXm0UhE47JSDcCrc/NGtfbtJdk+9...
    ...
-----END RSA PRIVATE KEY-----

Now I am ready to generate a self-signed public key certificate based on my private key file as described in the section below.

Last update: 2013.

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

 Introduction to AES (Advanced Encryption Standard)

 Introduction to DES Algorithm

 DES Algorithm - Illustrated with Java Programs

 DES Algorithm Java Implementation

 DES Algorithm - Java Implementation in JDK JCE

 DES Encryption Operation Modes

 DES in Stream Cipher Modes

 PHP Implementation of DES - mcrypt

 Blowfish - 8-Byte Block Cipher

 Secret Key Generation and Management

 Cipher - Secret Key Encryption and Decryption

 Introduction of RSA Algorithm

 RSA Implementation using java.math.BigInteger Class

 Introduction of DSA (Digital Signature Algorithm)

 Java Default Implementation of DSA

 Private key and Public Key Pair Generation

 PKCS#8/X.509 Private/Public Encoding Standards

 Cipher - Public Key Encryption and Decryption

 MD5 Mesasge Digest Algorithm

 SHA1 Mesasge Digest Algorithm

 OpenSSL Introduction and Installation

 OpenSSL Generating and Managing RSA Keys

 OpenSSL Managing Certificates

 OpenSSL Generating and Signing CSR

 OpenSSL Validating Certificate Path

 "keytool" and "keystore" from JDK

"OpenSSL" Signing CSR Generated by "keytool"

 "OpenSSL" Acting as a CA (Certificate Authority)

"OpenSSL" Generating CA's Private Key

 "OpenSSL" Self-Signing CA's Public Key

 "keytool" Generating Maria's Private Key

 "keytool" Generating Maria's CSR

 "OpenSSL" Signing Maria's CSR

 "OpenSSL" Managing Serial Numbers when Signing CSR

 "keytool" Importing CA's Own Certificate

 ""keytool" Importing Maria's Certificate Signed by CA

 Migrating Keys from "keystore" to "OpenSSL" Key Files

 Certificate X.509 Standard and DER/PEM Formats

 Migrating Keys from "OpenSSL" Key Files to "keystore"

 Using Certificates in IE (Internet Explorer)

 Using Certificates in Firefox

 Using Certificates in Google Chrome

 Outdated Tutorials

 References

 PDF Printing Version