Does a private key always generate the same public key and address?

Question

It seems like depending on the method you get different public keys and addresses when using bitcoin-ruby with the same private key. I am probably doing something wrong, but I am not sure where it is...

I can generate a private key, public key, and address using

def generate_address
  private_key, public_key = Bitcoin::generate_key
  address = Bitcoin::pubkey_to_address(public_key)
  [private_key, public_key, address]
end

And, as an example, this could generate:

priv_key= "9d524654045c891327a1dc0c329bcd42311b1767b81d7e997486e841ca5a2a87"
publ_key = "04353457464a32ede1b80fd7299f616320b52cc22796cd27d5b41594f418c2ea26dfeec97273f89b2d908a44fce981ff19f2e2de1408538bb0c0528992ce47f3be"
address = "n1693JDDu5ukbtNh2sHXdZSobKnVEpdtjL"

However, if I then put the private key into another function which generates the key details in a different way, I get a different address! Why is this?

def key_details(prikey)
  #returns prikey, prikey_hash58, pubkey_hash58, pubkey_uncompressed, address as a hash
  my_key = Bitcoin::Key.new(prikey)
  # binding.pry
  { prikey:prikey, 
    prikey_base58:my_key.to_base58, 
    pubkey_58:my_key.pub, 
    pubkey: my_key.pub_uncompressed, 
    address:my_key.addr
  }
end

Answer 1

The difference is that the first function uses uncompressed public keys , and the second function uses compressed public keys. Uncompressed public keys are 65 bytes , and compressed ones are 33 bytes.

For more information on compressed public keys see: What is a compressed Bitcoin key?