Key handling — Paramiko documentation

# Key handling

## Parent key class

Common API for all public keys.

class `paramiko.pkey.` `PKey`(msg=None, data=None)

  Base class for public keys.

  `__cmp__`(other)

    Compare this key to another. Returns 0 if this key is equivalent to the given key, or non-0 if they are different. Only the public parts of the key are compared, so a public key will compare equal to its corresponding private key.

    Parameters: | other (PKey) – key to compare to.

  `__init__`(msg=None, data=None)

    Create a new instance of this public key type. If `msg` is given, the key’s public part(s) will be filled in from the message. If `data` is given, the key’s public part(s) will be filled in from the string.

    Parameters: | msg (Message) – an optional SSH `Message` containing a public key of this type. data (str) – an optional string containing a public key of this type
    Raises: | `SSHException` – if a key cannot be created from the `data` or `msg` given, or no key was passed in.

  `__weakref__`

    list of weak references to the object (if defined)

  `asbytes`()

    Return a string of an SSH `Message` made up of the public part(s) of this key. This string is suitable for passing to `__init__` to re-create the key object later.

  `can_sign`()

    Return `True` if this key has the private part necessary for signing data.

  classmethod `from_private_key`(file_obj, password=None)

    Create a key object by reading a private key from a file (or file-like) object. If the private key is encrypted and `password` is not `None`, the given password will be used to decrypt the key (otherwise `PasswordRequiredException` is thrown).

    Parameters: | file_obj – the file-like object to read from password (str) – an optional password to use to decrypt the key, if it’s encrypted
    Returns: | a new `PKey` based on the given private key
    Raises: | `IOError` – if there was an error reading the key
    Raises: | `PasswordRequiredException` – if the private key file is encrypted, and `password` is `None`
    Raises: | `SSHException` – if the key file is invalid

  classmethod `from_private_key_file`(filename, password=None)

    Create a key object by reading a private key file. If the private key is encrypted and `password` is not `None`, the given password will be used to decrypt the key (otherwise `PasswordRequiredException` is thrown). Through the magic of Python, this factory method will exist in all subclasses of PKey (such as `RSAKey` or `DSSKey`), but is useless on the abstract PKey class.

    Parameters: | filename (str) – name of the file to read password (str) – an optional password to use to decrypt the key file, if it’s encrypted
    Returns: | a new `PKey` based on the given private key
    Raises: | `IOError` – if there was an error reading the file
    Raises: | `PasswordRequiredException` – if the private key file is encrypted, and `password` is `None`
    Raises: | `SSHException` – if the key file is invalid

  `get_base64`()

    Return a base64 string containing the public part of this key. Nothing secret is revealed. This format is compatible with that used to store public key files or recognized host keys.

    Returns: | a base64 `string` containing the public part of the key.

  `get_bits`()

    Return the number of significant bits in this key. This is useful for judging the relative security of a key.

    Returns: | bits in the key (as an `int`)

  `get_fingerprint`()

    Return an MD5 fingerprint of the public part of this key. Nothing secret is revealed.

    Returns: | a 16-byte `string` (binary) of the MD5 fingerprint, in SSH format.

  `get_name`()

    Return the name of this private key implementation.

    Returns: | name of this private key type, in SSH terminology, as a `str` (for example, `"ssh-rsa"`).

  `load_certificate`(value)

    Supplement the private key contents with data loaded from an OpenSSH public key (`.pub`) or certificate (`-cert.pub`) file, a string containing such a file, or a `Message` object.

    The .pub contents adds no real value, since the private key file includes sufficient information to derive the public key info. For certificates, however, this can be used on the client side to offer authentication requests to the server based on certificate instead of raw public key.

    See: https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.certkeys

    Note: very little effort is made to validate the certificate contents, that is for the server to decide if it is good enough to authenticate successfully.

  `sign_ssh_data`(data)

    Sign a blob of data with this private key, and return a `Message` representing an SSH signature message.

    Parameters: | data (str) – the data to sign.
    Returns: | an SSH signature `message`.

  `verify_ssh_sig`(data, msg)

    Given a blob of data, and an SSH message representing a signature of that data, verify that it was signed with this key.

    Parameters: | data (str) – the data that was signed. msg (Message) – an SSH signature message
    Returns: | `True` if the signature verifies correctly; `False` otherwise.

  `write_private_key`(file_obj, password=None)

    Write private key contents into a file (or file-like) object. If the password is not `None`, the key is encrypted before writing.

    Parameters: | file_obj – the file-like object to write into password (str) – an optional password to use to encrypt the key
    Raises: | `IOError` – if there was an error writing to the file
    Raises: | `SSHException` – if the key is invalid

  `write_private_key_file`(filename, password=None)

    Write private key contents into a file. If the password is not `None`, the key is encrypted before writing.

    Parameters: | filename (str) – name of the file to write password (str) – an optional password to use to encrypt the key file
    Raises: | `IOError` – if there was an error writing the file
    Raises: | `SSHException` – if the key is invalid

class `paramiko.pkey.` `PublicBlob`(type_, blob, comment=None)

  OpenSSH plain public key or OpenSSH signed public key (certificate).

  Tries to be as dumb as possible and barely cares about specific per-key-type data.

  ..note::
    Most of the time you’ll want to call `from_file`, `from_string` or `from_message` for useful instantiation, the main constructor is basically “I should be using `attrs` for this.”
  `__init__`(type_, blob, comment=None)

    Create a new public blob of given type and contents.

    Parameters: | type (str) – Type indicator, eg `ssh-rsa`. blob – The blob bytes themselves. comment (str) – A comment, if one was given (e.g. file-based.)

  `__weakref__`

    list of weak references to the object (if defined)

  classmethod `from_file`(filename)

    Create a public blob from a `-cert.pub`-style file on disk.

  classmethod `from_message`(message)

    Create a public blob from a network `Message`.

    Specifically, a cert-bearing pubkey auth packet, because by definition OpenSSH-style certificates ‘are’ their own network representation.”

  classmethod `from_string`(string)

    Create a public blob from a `-cert.pub`-style string.

## DSA (DSS)

DSS keys.

class `paramiko.dsskey.` `DSSKey`(msg=None, data=None, filename=None, password=None, vals=None, file_obj=None)

  Representation of a DSS key which can be used to sign an verify SSH2 data.

  static `generate`(bits=1024, progress_func=None)

    Generate a new private DSS key. This factory function can be used to generate a new host key or authentication key.

    Parameters: | bits (int) – number of bits the generated key should be. progress_func – Unused
    Returns: | new `DSSKey` private key

## RSA

RSA keys.

class `paramiko.rsakey.` `RSAKey`(msg=None, data=None, filename=None, password=None, key=None, file_obj=None)

  Representation of an RSA key which can be used to sign and verify SSH2 data.

  static `generate`(bits, progress_func=None)

    Generate a new private RSA key. This factory function can be used to generate a new host key or authentication key.

    Parameters: | bits (int) – number of bits the generated key should be. progress_func – Unused
    Returns: | new `RSAKey` private key

## ECDSA

ECDSA keys

class `paramiko.ecdsakey.` `ECDSAKey`(msg=None, data=None, filename=None, password=None, vals=None, file_obj=None, validate_point=True)

  Representation of an ECDSA key which can be used to sign and verify SSH2 data.

  classmethod `generate`(curve=<cryptography.hazmat.primitives.asymmetric.ec.SECP256R1 object>, progress_func=None, bits=None)

    Generate a new private ECDSA key. This factory function can be used to generate a new host key or authentication key.

    Parameters: | progress_func – Not used for this type of key.
    Returns: | A new private key (`ECDSAKey`) object

## Ed25519

class `paramiko.ed25519key.` `Ed25519Key`(msg=None, data=None, filename=None, password=None, file_obj=None)

  Representation of an Ed25519 key.

  Note

  Ed25519 key support was added to OpenSSH in version 6.5.

  New in version 2.2.

  Changed in version 2.3: Added a `file_obj` parameter to match other key classes.