PKCS 8 explained

In cryptography, PKCS #8 is a standard syntax for storing private key information. PKCS #8 is one of the family of standards called Public-Key Cryptography Standards (PKCS) created by RSA Laboratories. The latest version, 1.2, is available as RFC 5208.^[1]

The PKCS #8 private key may be encrypted with a passphrase using one of the PKCS #5 standards defined in RFC 2898,^[2] which supports multiple encryption schemes.

A new version 2 was proposed by S. Turner in 2010 as RFC 5958 ^[3] and might obsolete RFC 5208 someday in the future.

PKCS #8 private keys are typically exchanged in the PEM base64-encoded format, for example:-----BEGIN PRIVATE KEY-----MIIBVgIBADANBgkqhkiG9w0BAQEFAASCAUAwggE8AgEAAkEAq7BFUpkGp3+LQmlQYx2eqzDV+xeG8kx/sQFV18S5JhzGeIJNA72wSeukEPojtqUyX2J0CciPBh7eqclQ2zpAswIDAQABAkAgisq4+zRdrzkwH1ITV1vpytnkO/NiHcnePQiOW0VUybPyHoGM/jf75C5xET7ZQpBe5kx5VHsPZj0CBb3b+wSRAiEA2mPWCBytosIU/ODRfq6EiV04lt6waE7I2uSPqIC20LcCIQDJQYIHQII+3YaPqyhGgqMexuuuGx+lDKD6/Fu/JwPb5QIhAKthiYcYKlL9h8bjDsQhZDUACPasjzdsDEdq8inDyLOFAiEAmCr/tZwA3qeAZoBzI10DGPIuoKXBd3nk/eBxPkaxlEECIQCNymjsoI7GldtujVnr1qT+3yedLfHKsrDVjIT3LsvTqw

References

1. Public-Key Cryptography Standards (PKCS) #8: Private-Key Information Syntax Specification Version 1.2. 5208. Kaliski. B.. May 2008. IETF.
2. PKCS #5: Password-Based Cryptography Specification Version 2.0. 2898. Kaliski. B.. September 2000. IETF.
3. - Asymmetric Key Packages