Is there a human readable easier version to represent PGP Private keys? I'm working on a distributed application, and we need a way to authorize clients. Every client has a PGP keypair associated with them, and we require them to enter their private key (which is not stored) through which their pubkey is derived and used to identify clients and modify their fields on the distributed database. 

Now, considering user experience, entering a private key on a website whenever you need to do something is troublesome. But we also cannot maintain a central database for username/password based authentication as that creates a single failure point (not what the distributed application is meant to do)

I am hoping there is some way to get an easier to remember human readable descriptor of the private key which can be used to authenticate - if something like that exists. Any other ideas are appreciated too.

P.S. - For background, I am not a cryptographer, I am a computer developer, so I don't fully understand how PGP works - excuse me if this is a noob question.
Apparently this answer will be updated as OP develop an understanding of his application. I've never used PGP, but general public-key cryptography concepts are always applicable. 


  entering a private key on a website whenever you need to do something is troublesome


You can let clients derive their keys through memorable string - the user agent first derive a seed using a secure key derivation function (KDF) from 1) the user-supplied string, and 2) a random salt, then the seed is fed to a cryptographic deterministic random bits generator (DRBG), then the key-pair generation is run using the just-seeded DRBG. 

Normally a hard-to guess 16-character string with upper and lower case letters and digits is a minimum. The salt should be a string of at least 16 fully-random bytes. 


  But we also cannot maintain a central database for username/password


If you don't have a database of users, how do you authenticate them (recognize actual users from outsiders)? There is a solution: Use primitives that binds the authenticator to the public key, such as ECQV implicit certificate scheme, or identity-based encryption (IBE). These are not commonly-used public-key cryptography functionalities, and their post-quantum equivalents are far from mature.