When testing with a `private_key = '0000000000000000000000000000000000000000000000000000000000000001'` instead of `private_key = bitcoin.random_key()`,
the generated Private Key (WIF-Compressed) is wrong `5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsrefhvB5QZ`, it should be `KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn`. As it turns out, the proper way to get the correct compressed WIF is to pass `'wif_compressed'` and not `'wif'` to the `bitcoin.encode_privkey` function, as pointed out in the Main.py from the bitcoin python package.
```
def encode_privkey(priv, formt, vbyte=0):
if not isinstance(priv, int_types):
return encode_privkey(decode_privkey(priv), formt, vbyte)
if formt == 'decimal': return priv
elif formt == 'bin': return encode(priv, 256, 32)
elif formt == 'bin_compressed': return encode(priv, 256, 32)+b'\x01'
elif formt == 'hex': return encode(priv, 16, 64)
elif formt == 'hex_compressed': return encode(priv, 16, 64)+'01'
elif formt == 'wif':
return bin_to_b58check(encode(priv, 256, 32), 128+int(vbyte))
elif formt == 'wif_compressed':
return bin_to_b58check(encode(priv, 256, 32)+b'\x01', 128+int(vbyte))
else: raise Exception("Invalid format!")
```
The fix can be done in a couple ways:
`bitcoin.encode_privkey(bitcoin.decode_privkey(compressed_private_key, 'hex'), 'wif')` -> 5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsrefhvB5QZ (WRONG)
`bitcoin.encode_privkey(bitcoin.decode_privkey(compressed_private_key, 'hex'), 'wif_compressed')` -> KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU9FMLM39zT (WRONG)
`bitcoin.encode_privkey(bitcoin.decode_privkey(compressed_private_key, 'hex_compressed'), 'wif_compressed')` -> KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn (CORRECT)
`bitcoin.encode_privkey(bitcoin.decode_privkey(private_key, 'hex'), 'wif_compressed')` -> KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn (CORRECT)
On the elliptic curve, a line that goes through two different points
with the same `x` coordinates, but different `y` coordinates (they must
be `y` and `-y`) is not "tangent".
