import hashlib
from base64 import b64decode

def build_id(pub_key_pem):
    pub_key_der = b64decode(pub_key_pem)
    sha = hashlib.sha256(pub_key_der).hexdigest()
    prefix = sha[:32]

    reencoded = ""
    ord_a = ord('a')
    for old_char in prefix:
        code = int(old_char, 16)
        new_char = chr(ord_a + code)

        reencoded += new_char

    return reencoded

def main():
    pub_key = 'MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCjvF5pjuK8gRaw/2LoRYi37QqRd48B/FeO9yFtT6ueY84z/u0NrJ/xbPFc9OCGBi8RKIblVvcbY0ySGqdmp0QsUr/oXN0b06GL4iB8rMhlO082HhMzrClV8OKRJ+eJNhNBl8viwmtJs3MN0x9ljA4HQLaAPBA9a14IUKLjP0pWuwIDAQAB'

    id_ = build_id(pub_key)
    print(id_)

if __name__ == '__main__':
    main()