**Cryptography Tutorials - Herong's Tutorial Examples** - v5.40, by Dr. Herong Yang

"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:

- "openssl genrsa" to generate a RSA private key and store it in the traditional format with DER encoding, but no encryption.
- "openssl rsa" to convert the key file format to traditional with PEM encoding, but no encryption.
- "openssl rsa" to convert the key file format to traditional with DER encoding and encryption.
- "openssl rsa" to convert the key file format to traditional with PEM encoding and encryption.

My command session was recorded as blow:

C:\herong>rem traditional format, PEM encoding, no encryption C:\herong>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) C:\herong>rem traditional format, DER encoding, no encryption C:\herong>openssl rsa -in openssl_key.pem -inform pem \ -out openssl_key.der -outform der writing RSA key C:\herong>rem traditional format, PEM encoding, DES encryption C:\herong>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 C:\herong>rem traditional format, DER encoding, DES encryption C:\herong>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:

608 openssl_key.der 887 openssl_key.pem 958 openssl_key_des.pem

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

Table of Contents

Introduction to AES (Advanced Encryption Standard)

DES Algorithm - Illustrated with Java Programs

DES Algorithm Java Implementation

DES Algorithm - Java Implementation in JDK JCE

DES Encryption Operation Modes

PHP Implementation of DES - mcrypt

Blowfish - 8-Byte Block Cipher

Secret Key Generation and Management

Cipher - Secret Key Encryption and Decryption

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

OpenSSL Introduction and Installation

OpenSSL Generating and Managing RSA Keys

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"

►"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"