where is the file that references accounts in the geth client

Question

There must be a .dat file or something that stores the accounts in the geth client, where is this file located?

As an aside, are Externally Owned Accounts (EOAs) and Contract Accounts actually represented differently?

Update:

In ~/Library/Ethereum/keystore I found a file called UTC--2017-05-26T21-30-22.367673851Z--ca02951f8bcd593e26f54801a4da85c221f89731 which has been reproduced below:

{
    "address":"ca02951f8bcd593e26f54801a4da85c221f89731",
    "crypto":{
                "cipher":"aes-128-ctr",
                "ciphertext":"8e13b86398de9bc1977153c683315d13771d65b38fcb425a99bcc59761071e1f",
                "cipherparams":{
                                "iv":"49227b95cf1fb8c96c749fe1d180b25b"
                                },
                "kdf":"scrypt",
                "kdfparams":{
                                "dklen":32,
                                "n":262144,
                                "p":1,
                                "r":8,
                                "salt":"6233be72e2478cf7ed4aee675e7862c5d55f23a270cd8c46f66cf37460badca0"
                            },
                "mac":"5243792b391ea7171f23b5378cf77bdcf90f4baa03067ba55d988c6ecb9ee8e5"
            },
    "id":"6b3fba5f-d3cb-452e-9d73-2b760085be71",
    "version":3
}

Would someone please explain to me the significance of this file?

I was under the impression that this would be all the accounts on the entire Ethereum blockchain, but it seems to me that this is perhaps only my own account that was automatically generated when I fired up geth, is that right?

Answer 1

something that stores the accounts in the geth client, where is this file located?

The accounts are stored in the keystore folder of the data directory. The default data directory is

Mac: ~/Library/Ethereum
Linux: ~/.ethereum
Windows: %APPDATA%\Ethereum

are Externally Owned Accounts (EOAs) and Contract Accounts actually represented differently?

Externally Owned Accounts and Contract Accounts have differences as Externally owned accounts have only value associated with them, whereas Contract Accounts have value, contract code and data associated with them.

Would someone please explain to me the significance of this file?

The keyfile contains data which combined with your password can decrypt your private key, with which anyone can control your account.

Yes, only the accounts that you have generated will be in that keystore.

Answer 2

I was under the impression that this would be all the accounts on the entire Ethereum blockchain

The Keyfile on your computer (the one in the keystore folder) is where your private keys are stored, for your own account, so it gives you the ability to spend assets sent to you.

All other accounts (public keys) in the Ethereum blockchain belong to someone else, and you don't have the private keys of those. The data about what funds have been sent/received by any account is in the blockchain data, not the keyfile.

Are you asking about some sort of addressbook functionality? You want to enumerate the public account addresses of other people? Any 160-bit number (64 hexadecimal characters) is a valid Ethereum account number. But, there's no guarantee that anyone holds the private key associated with it and would be able to spend them. So, there's no way to enumerate all addresses that are owned by someone. You could do a reasonable guess by looking at the blockchain and looking at all addresses that have both received Ether and spent it. Some of the addresses that have only received Ether but not spent it could be owned by someone who will eventually spend it, or it could be a dead account that someone "burned" their Ether by sending to it (inadvertently or not).