Cryptographic - Private Key

About

This article talks about the secret known as the private key in a asymmetric cryptographic scheme.

A private key is a cryptographic key that is private (that you should be kept secret).

This page is about how to manage/create a What is a Public Key Cryptography (known as Asymmetric Cipher) ? private key.

An What is a Public Key Cryptography (known as Asymmetric Cipher) ? private key is categorized as something you have authentication.

Management

Algorithm Scheme

There is two asymmetric cryptographic scheme that defines how to create a private key.

There is therefore two types of key. The most known being RSA

• RSA Private Key
• DSA

File Format

Different file formats are used to store keys.

• PEM (Open ssh)
• ppk (Putty)
• Distinguished Encoding Rules (DER)

Create

The creation of the private key is format dependent.

Pem

See Management of a RSA Private Key in PEM format (OpenSSH)

Ppk

For a ppk private key (Putty), see ppk create

Decrypt / Suppress passphrase

With a:

• PEM Format: Pem decrypt
• With an openssh private key: OpenSsh keygen

-----BEGIN OPENSSH PRIVATE KEY-----
xxxxxxxxxx
-----END OPENSSH PRIVATE KEY-----

# with prompt of the passphrase
# where N is the new passphrase (ie empty)
# and f is the file
ssh-keygen -p  -N "" -f /path/keyfile.pem

Support

WARNING: UNPROTECTED PRIVATE KEY FILE!

chmod  400 /path/keyfile.pem