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OpenSSL is a giant command-line binary capable of a lot of various securityrelated utilities. Each utility is easily broken down via the first argument ofopenssl. For instance, to generate an RSA key, the command to use will beopenssl genpkey.

Generate 2048-bit AES-256 Encrypted RSA Private Key .pem

1. To encrypt the raw data we pass the file as input to openssl using the encode option and tell it to cipher using the aes-256-cbc algorithm. Any other cipher method supported by openssl can be substitued for aes-256-cbc. The previoulsy generated random key will serve as the code needed to unlock the file.
2. Generate an AES key plus Initialization vector (iv) with openssl and; how to encode/decode a file with the generated key/iv pair; Note: AES is a symmetric-key algorithm which means it uses the same key during encryption/decryption. Generating key/iv pair. We want to generate a 256-bit key and use Cipher Block Chaining (CBC).
3. A restriction in OpenSSL 1.0.1c and earlier requires the tag before any AAD or ciphertext if (status && tag) EVPCIPHERCTXctrl (ctx, EVPCTRLGCMSETTAG, AES256GCMTAGLENGTH, tag); // add optional AAD (Additional Auth Data).

As I showed, the command, OK, sorry then I misunderstood you. The madpwd3 utility is used to create the password. Note: tested on Ubuntu 14.04.2, Debian 7.8 and CentOS 7. # openssl genrsa -aes128 -out key.pem This command uses AES 128 only to protect the RSA key pair with a passphrase, just in case an unauthorized person can get the key file.

The following command will result in an output file of private.pem in whichwill be a private RSA key in the PEM format.

Let’s break this command down:

• openssl: The binary that contains the code to generate an RSA key (and manyother utilities).
• genpkey: Specifies the utility to use.
• -algorithm RSA: Specifies to use the RSA algorithm.
• -aes256: Specifies to use the AES-256 cipher, which is newer and moresecure than DES. Default is no cipher.
• -out private.pem: Specifies that a file named “private.pem” should becreated with the contents of the private key. Default is STDOUT.

When executing this command, it will ask for a password to encrypt the keywith. After selecting a password, a file will be created in the currentdirector named private.pem.

Private RSA keys generated with this utility start with the text -----BEGIN PRIVATE KEY-----.

You can inspect this file with the command cat private.pem.

Export Public RSA Key From Private Key

In order to export the public key from the freshly generated private RSA Key,the openssl rsautility, which is used for processing RSA keys.

The command to export a public key is as follows:

Openssl Generate Aes Gcm Keys

This will result in a public key, due to the flag -pubout.

Inspect this file with cat public.pem:

The public key can be uploaded to other servers and services to encrypt datafor the private key to decrypt.

Openssl Generate Aes Gcm Key Code

This file will start with -----BEGIN PUBLIC KEY-----. If this file doesn’tstart with “BEGIN PUBLIC KEY”, do not upload it as a public key to any source!