Dec 01, 2015 A public key is the one that is released to the public. It allows anyone to use it for encrypting messages to be sent to the user, as well as for decrypting messages received from the user. F you use OpenSSL to generate certificates, the private key will contain public key information, therefore the public key does not have to be generated. $ openssl pkey -in private-key.pem -out public-key.pem -pubout You may once again view the key details, using a slightly different command this time. $ openssl pkey -in public-key.pem -pubin -text The output for the public key will be shorter, as it carries much less information, and it will look something like this. May 15, 2009 RSA public key cryptography in Java Date May 15, 2009 Tags Java, JCE, OpenSSL, public key cryptography, RSA Public key cryptography is a well-known concept, but for some reason the JCE (Java Cryptography Extensions documentation doesn’t at all make it clear how to interoperate with common public key formats such as those produced. How to Generate & Use Private Keys using OpenSSL's Command Line Tool. These commands generate and use private keys in unencrypted binary (not Base64 “PEM”) PKCS#8 format. The PKCS#8 format is used here because it is the most interoperable format when dealing with software that isn't based on OpenSSL.
- A PEM file is simply a DER file that's been Base64 encoded. To convert from one to the other you can use openssl with the -inform and -outform arguments. Each one takes one of PEM, DER or NET (a dated Netscape format, which you can ignore).
- A PEM file is simply a DER file that's been Base64 encoded. To convert from one to the other you can use openssl with the -inform and -outform arguments. Each one takes one of PEM, DER or NET (a dated Netscape format, which you can ignore). You can change a key from one format to the other with the openssl rsa command (assuming it's an RSA key.
Common OpenSSL Commands with Keys and Certificates
Generate RSA private key with certificate in a single command
Generate Certificate Signing Request (CSR) from private key with passphrase
Generate RSA private key (2048 bit)
Generate a Certificate Signing Request (CSR)
Generate RSA private key (2048 bit) and a Certificate Signing Request (CSR) with a single command
Convert private key to PEM format
Generate a self-signed certificate that is valid for a year with sha256 hash
View details of a RSA private key
View details of a CSR
View details of a Certificate
Openssl Read Key
View details of a Certificate in DER format
Convert a DER file (.crt .cer .der) to PEM
Convert a PEM file to DER
To perform the following actions for Windows or Linux, you must have OpenSSL installed on your system.
Generating the Private Key -- Windows
In Windows:
1. Open the Command Prompt (Start > Programs > Accessories > Command Prompt).
2. Navigate to the following folder:
C:Program FilesListManagertclwebbincerts
3. Type the following:
openssl genrsa -out rsa.private 1024
4. Press ENTER. The private key is generated and saved in a file named 'rsa.private' located in the same folder.
NOTE The number '1024' in the above command indicates the size of the private key. You can choose one of five sizes: 512, 758, 1024, 1536 or 2048 (these numbers represent bits). The larger sizes offer greater security, but this is offset by a penalty in CPU performance. We recommend the best practice size of 1024.
Generating the Public Key -- Windows
1. At the command prompt, type the following:
openssl rsa -in rsa.private -out rsa.public -pubout -outform PEM
2. Press ENTER. The public key is saved in a file named rsa.public located in the same folder.
Generating the Private Key -- Linux
1. Open the Terminal.
2. Navigate to the folder with the ListManager directory.
3. Type the following:
openssl genrsa -out rsa.private 1024
4. Press ENTER. The private key is generated and saved in a file named 'rsa.private' located in the same folder.
Generating the Public Key -- Linux
1. Open the Terminal.
2. Type the following:
openssl rsa -in rsa.private -out rsa.public -pubout -outform PEM
2. Press ENTER. The public key is saved in a file named rsa.public located in the same folder.