"openssl genrsa" Generating Private Key

This section provides a tutorial example on how to generate a RSA private key with the 'openssl genrsa' command. The key file can be then converted to DER or PEM encoding with or without DES encryption.

To understand better about PKCS#8 private key format, I started with "OpenSSL" to generate a RSA private key (it's really a private and public key pair). The "openssl genrsa" command can only store the key in the traditional format. But it offers various encryptions as options.

In the following test, I tried to use:

My command session was recorded as blow:

>rem traditional format, PEM encoding, no encryption
>openssl genrsa -out openssl_key.pem 1024

Loading 'screen' into random state - done
Generating RSA private key, 1024 bit long modulus
.......++++++
........................................++++++
e is 65537 (0x10001)

>rem traditional format, DER encoding, no encryption
>openssl rsa -in openssl_key.pem -inform pem 
-out openssl_key.der -outform der

writing RSA key

>rem traditional format, PEM encoding, DES encryption
>openssl rsa -in openssl_key.pem -inform pem 
-out openssl_key_des.pem -outform pem -des

writing RSA key
Enter PEM pass phrase: keypass
Verifying - Enter PEM pass phrase: keypass

>rem traditional format, DER encoding, DES encryption
>openssl rsa -in openssl_key.pem -inform pem 
-out openssl_key_des.der -outform der -des

writing RSA key

All commands were executed as expected except the last one. The traditional format with DER encoding seems not able to apply the DES encryption.

Anyway, I got my RSA private key stored in OpenSSL traditional format with 3 flavors:

04/01/2007  09:55 AM               608 openssl_key.der
04/01/2007  09:52 AM               887 openssl_key.pem
04/01/2007  10:01 AM               958 openssl_key_des.pem

Now I am ready to my private key to PKCS#8 format as described in the next section.

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"

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

 Certificate X.509 Standard and DER/PEM Formats

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

 What Is PKCS#8?

 What Is PKCS#12?

"openssl genrsa" Generating Private Key

 "openssl pkcs8" Converting Keys to PKCS#8 Format

 "openssl pkcs12" Merging Key with Certificate

 "keytool -list" Verifying PKCS#12 Files

 "keytool -importkeystore" Importing PKCS#12 Files

 Summary - Migrating "OpenSSL" Keys to "keystore"

 Summary - Migrating "keystore" Keys to "OpenSSL"

 Using Certificates in IE (Internet Explorer)

 Using Certificates in Firefox

 Using Certificates in Google Chrome

 Outdated Tutorials

 References

 PDF Printing Version