diff options
Diffstat (limited to 'docs/hazmat/primitives')
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/dsa.rst | 101 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/ec.rst | 51 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/index.rst | 2 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/rsa.rst | 100 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/serialization.rst | 100 | ||||
| -rw-r--r-- | docs/hazmat/primitives/constant-time.rst | 2 | ||||
| -rw-r--r-- | docs/hazmat/primitives/cryptographic-hashes.rst | 1 | ||||
| -rw-r--r-- | docs/hazmat/primitives/interfaces.rst | 135 | ||||
| -rw-r--r-- | docs/hazmat/primitives/key-derivation-functions.rst | 107 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/cmac.rst | 13 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/hmac.rst | 7 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/index.rst | 8 | ||||
| -rw-r--r-- | docs/hazmat/primitives/padding.rst | 1 | ||||
| -rw-r--r-- | docs/hazmat/primitives/symmetric-encryption.rst | 23 |
14 files changed, 596 insertions, 55 deletions
diff --git a/docs/hazmat/primitives/asymmetric/dsa.rst b/docs/hazmat/primitives/asymmetric/dsa.rst index 2819bbdb..6848d84c 100644 --- a/docs/hazmat/primitives/asymmetric/dsa.rst +++ b/docs/hazmat/primitives/asymmetric/dsa.rst @@ -38,11 +38,11 @@ DSA Generate a new ``DSAParameters`` instance using ``backend``. :param int key_size: The length of the modulus in bits. It should be - either "1024, 2048 or 3072". For keys generated in 2014 this should - be `at least 2048`_ (See page 41). - Note that some applications (such as SSH) have not yet gained support - for larger key sizes specified in FIPS 186-3 and are still restricted - to only the 1024-bit keys specified in FIPS 186-2. + either 1024, 2048 or 3072. For keys generated in 2014 this should + be `at least 2048`_ (See page 41). Note that some applications + (such as SSH) have not yet gained support for larger key sizes + specified in FIPS 186-3 and are still restricted to only the + 1024-bit keys specified in FIPS 186-2. :return: A new instance of ``DSAParameters`` @@ -97,6 +97,48 @@ DSA or if the OpenSSL version is older than 1.0.0 and the key size is larger than 1024 because older OpenSSL versions don't support a key size larger than 1024. + .. method:: signer(algorithm, backend) + + .. versionadded:: 0.4 + + Sign data which can be verified later by others using the public key. + + .. doctest:: + + >>> from cryptography.hazmat.backends import default_backend + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.asymmetric import dsa + >>> parameters = dsa.DSAParameters.generate( + ... key_size=1024, + ... backend=default_backend() + ... ) + >>> private_key = dsa.DSAPrivateKey.generate( + ... parameters=parameters, + ... backend=default_backend() + ... ) + >>> signer = private_key.signer( + ... hashes.SHA256(), + ... default_backend() + ... ) + >>> data = b"this is some data I'd like to sign" + >>> signer.update(data) + >>> signature = signer.finalize() + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.RSABackend` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext` + + :raises cryptography.exceptions.UnsupportedAlgorithm: This is raised if + the provided ``backend`` does not implement + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + .. class:: DSAPublicKey(modulus, subgroup_order, generator, y) @@ -118,6 +160,55 @@ DSA ``subgroup_order``, ``generator``, or ``y`` do not match the bounds specified in `FIPS 186-4`_. + .. method:: verifier(signature, algorithm, backend) + + .. versionadded:: 0.4 + + Verify data was signed by the private key associated with this public + key. + + .. doctest:: + + >>> from cryptography.hazmat.backends import default_backend + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.asymmetric import dsa + >>> parameters = dsa.DSAParameters.generate( + ... key_size=1024, + ... backend=default_backend() + ... ) + >>> private_key = dsa.DSAPrivateKey.generate( + ... parameters=parameters, + ... backend=default_backend() + ... ) + >>> signer = private_key.signer( + ... hashes.SHA256(), + ... default_backend() + ... ) + >>> data = b"this is some data I'd like to sign" + >>> signer.update(data) + >>> signature = signer.finalize() + >>> public_key = private_key.public_key() + >>> verifier = public_key.verifier( + ... signature, + ... hashes.SHA256(), + ... default_backend() + ... ) + >>> verifier.update(data) + >>> verifier.verify() + + :param bytes signature: The signature to verify. DER encoded as + specified in :rfc:`6979`. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricVerificationContext` .. _`DSA`: https://en.wikipedia.org/wiki/Digital_Signature_Algorithm .. _`public-key`: https://en.wikipedia.org/wiki/Public-key_cryptography diff --git a/docs/hazmat/primitives/asymmetric/ec.rst b/docs/hazmat/primitives/asymmetric/ec.rst new file mode 100644 index 00000000..f88b965a --- /dev/null +++ b/docs/hazmat/primitives/asymmetric/ec.rst @@ -0,0 +1,51 @@ +.. hazmat:: + +Elliptic Curve +============== + +.. currentmodule:: cryptography.hazmat.primitives.asymmetric.ec + + +.. class:: EllipticCurvePrivateNumbers(private_value, public_numbers) + + .. versionadded:: 0.5 + + The collection of integers that make up an EC private key. + + .. attribute:: public_numbers + + :type: :class:`~cryptography.hazmat.primitives.ec.EllipticCurvePublicNumbers` + + The :class:`EllipticCurvePublicNumbers` which makes up the EC public + key associated with this EC private key. + + .. attribute:: private_value + + :type: int + + The private value. + + +.. class:: EllipticCurvePublicNumbers(x, y, curve) + + .. versionadded:: 0.5 + + The collection of integers that make up an EC public key. + + .. attribute:: curve + + :type: :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurve` + + The elliptic curve for this key. + + .. attribute:: x + + :type: int + + The affine x component of the public point used for verifying. + + .. attribute:: y + + :type: int + + The affine y component of the public point used for verifying. diff --git a/docs/hazmat/primitives/asymmetric/index.rst b/docs/hazmat/primitives/asymmetric/index.rst index ca048d11..6a5228ba 100644 --- a/docs/hazmat/primitives/asymmetric/index.rst +++ b/docs/hazmat/primitives/asymmetric/index.rst @@ -7,5 +7,7 @@ Asymmetric algorithms :maxdepth: 1 dsa + ec rsa padding + serialization diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst index 8c34497e..54839119 100644 --- a/docs/hazmat/primitives/asymmetric/rsa.rst +++ b/docs/hazmat/primitives/asymmetric/rsa.rst @@ -85,7 +85,10 @@ RSA :param padding: An instance of a :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding` - provider. + provider. Valid values are + :class:`~cryptography.hazmat.primitives.asymmetric.padding.PSS` and + :class:`~cryptography.hazmat.primitives.asymmetric.padding.PKCS1v15` + (``PSS`` is recommended for all new applications). :param algorithm: An instance of a :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` @@ -154,21 +157,39 @@ RSA :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP` it may also be raised for invalid label values. - .. code-block:: python + .. doctest:: - from cryptography.hazmat.backends import default_backend - from cryptography.hazmat.primitives import hashes - from cryptography.hazmat.primitives.asymmetric import padding + >>> from cryptography.hazmat.backends import default_backend + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.asymmetric import padding - plaintext = private_key.decrypt( - ciphertext, - padding.OAEP( - mgf=padding.MGF1(algorithm=hashes.SHA1()), - algorithm=hashes.SHA1(), - label=None - ), - default_backend() - ) + >>> # Generate a key + >>> private_key = rsa.RSAPrivateKey.generate( + ... public_exponent=65537, + ... key_size=2048, + ... backend=default_backend() + ... ) + >>> public_key = private_key.public_key() + >>> # encrypt some data + >>> ciphertext = public_key.encrypt( + ... b"encrypted data", + ... padding.OAEP( + ... mgf=padding.MGF1(algorithm=hashes.SHA1()), + ... algorithm=hashes.SHA1(), + ... label=None + ... ), + ... default_backend() + ... ) + >>> # Now do the actual decryption + >>> plaintext = private_key.decrypt( + ... ciphertext, + ... padding.OAEP( + ... mgf=padding.MGF1(algorithm=hashes.SHA1()), + ... algorithm=hashes.SHA1(), + ... label=None + ... ), + ... default_backend() + ... ) .. class:: RSAPublicKey(public_exponent, modulus) @@ -216,7 +237,7 @@ RSA ... hashes.SHA256(), ... default_backend() ... ) - >>> data= b"this is some data I'd like to sign" + >>> data = b"this is some data I'd like to sign" >>> signer.update(data) >>> signature = signer.finalize() >>> public_key = private_key.public_key() @@ -236,7 +257,10 @@ RSA :param padding: An instance of a :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding` - provider. + provider. Valid values are + :class:`~cryptography.hazmat.primitives.asymmetric.padding.PSS` and + :class:`~cryptography.hazmat.primitives.asymmetric.padding.PKCS1v15` + (``PSS`` is recommended for all new applications). :param algorithm: An instance of a :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` @@ -306,27 +330,29 @@ RSA :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP` it may also be raised for invalid label values. - .. code-block:: python - - from cryptography.hazmat.backends import default_backend - from cryptography.hazmat.primitives import hashes - from cryptography.hazmat.primitives.asymmetric import padding, rsa - - private_key = rsa.RSAPrivateKey.generate( - public_exponent=65537, - key_size=2048, - backend=default_backend() - ) - public_key = private_key.public_key() - ciphertext = public_key.encrypt( - plaintext, - padding.OAEP( - mgf=padding.MGF1(algorithm=hashes.SHA1()), - algorithm=hashes.SHA1(), - label=None - ), - default_backend() - ) + .. doctest:: + + >>> from cryptography.hazmat.backends import default_backend + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.asymmetric import padding + + >>> # Generate a key + >>> private_key = rsa.RSAPrivateKey.generate( + ... public_exponent=65537, + ... key_size=2048, + ... backend=default_backend() + ... ) + >>> public_key = private_key.public_key() + >>> # encrypt some data + >>> ciphertext = public_key.encrypt( + ... b"encrypted data", + ... padding.OAEP( + ... mgf=padding.MGF1(algorithm=hashes.SHA1()), + ... algorithm=hashes.SHA1(), + ... label=None + ... ), + ... default_backend() + ... ) .. class:: RSAPublicNumbers(e, n) diff --git a/docs/hazmat/primitives/asymmetric/serialization.rst b/docs/hazmat/primitives/asymmetric/serialization.rst new file mode 100644 index 00000000..2b3eb511 --- /dev/null +++ b/docs/hazmat/primitives/asymmetric/serialization.rst @@ -0,0 +1,100 @@ +.. hazmat:: + +Key Serialization +================= + +.. currentmodule:: cryptography.hazmat.primitives.serialization + +There are several common schemes for serializing asymmetric private and public +keys to bytes. They generally support encryption of private keys and additional +key metadata. + +Many serialization formats support multiple different types of asymmetric keys +and will return an an instance of the appropriate type. You should check that +the returned key matches the type your application expects when using these +methods. + + .. code-block:: pycon + + >>> key = load_pkcs8_private_key(pem_data, None, backend) + >>> if isinstance(key, rsa.RSAPrivateKey): + >>> signature = sign_with_rsa_key(key, message) + >>> elif isinstance(key, dsa.DSAPrivateKey): + >>> signature = sign_with_dsa_key(key, message) + >>> else: + >>> raise TypeError + + +PKCS #8 Format +~~~~~~~~~~~~~~ + +PKCS #8 is a serialization format originally standardized by RSA and +currently maintained by the IETF in :rfc:`5208`. It supports password based +encryption and additional key metadata attributes. + + +.. function:: load_pkcs8_private_key(data, password, backend) + + .. versionadded:: 0.5 + + Deserialize a private key from PEM encoded data to one of the supported + asymmetric private key types. + + :param bytes data: The PEM encoded key data. + + :param bytes password: The password to use to decrypt the data. Should + be ``None`` if the private key is not encrypted. + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.PKCS8SerializationBackend` + provider. + + :returns: A new instance of a private key. + + :raises ValueError: If the PEM data could not be decrypted or if its + structure could not be decoded successfully. + + :raises TypeError: If a ``password`` was given and the private key was + not encrypted. Or if the key was encrypted but no + password was supplied. + + :raises UnsupportedAlgorithm: If the serialized key is of a type that + is not supported by the backend or if the key is encrypted with a + symmetric cipher that is not supported by the backend. + + +Traditional OpenSSL Format +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The "traditional" PKCS #1 based serialization format used by OpenSSL. +It supports password based symmetric key encryption. Commonly found in +OpenSSL based TLS applications. It is usually found in PEM format with a +header that mentions the type of the serialized key. e.g. +``-----BEGIN RSA PRIVATE KEY-----``. + +.. function:: load_pem_traditional_openssl_private_key(data, password, backend) + + .. versionadded:: 0.5 + + Deserialize a private key from PEM encoded data to one of the supported + asymmetric private key types. + + :param bytes data: The PEM encoded key data. + + :param bytes password: The password to use to decrypt the data. Should + be ``None`` if the private key is not encrypted. + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.TraditionalOpenSSLSerializationBackend` + provider. + + :returns: A new instance of a private key. + + :raises ValueError: If the PEM data could not be decrypted or if its + structure could not be decoded successfully. + + :raises TypeError: If a ``password`` was given and the private key was + not encrypted. Or if the key was encrypted but no + password was supplied. + + :raises UnsupportedAlgorithm: If the serialized key is of a type that + is not supported by the backend or if the key is encrypted with a + symmetric cipher that is not supported by the backend. diff --git a/docs/hazmat/primitives/constant-time.rst b/docs/hazmat/primitives/constant-time.rst index c6fcb3a3..1394b6b3 100644 --- a/docs/hazmat/primitives/constant-time.rst +++ b/docs/hazmat/primitives/constant-time.rst @@ -36,6 +36,8 @@ about the timing attacks on KeyCzar and Java's ``MessageDigest.isEqual()``. :param bytes b: The right-hand side. :returns bool: ``True`` if ``a`` has the same bytes as ``b``, otherwise ``False``. + :raises TypeError: This exception is raised if ``a`` or ``b`` is not + ``bytes``. .. _`Coda Hale's blog post`: http://codahale.com/a-lesson-in-timing-attacks/ diff --git a/docs/hazmat/primitives/cryptographic-hashes.rst b/docs/hazmat/primitives/cryptographic-hashes.rst index 773d97f6..7e5295c4 100644 --- a/docs/hazmat/primitives/cryptographic-hashes.rst +++ b/docs/hazmat/primitives/cryptographic-hashes.rst @@ -54,6 +54,7 @@ Message digests :param bytes data: The bytes to be hashed. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize`. + :raises TypeError: This exception is raised if ``data`` is not ``bytes``. .. method:: copy() diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst index c76582c0..b2857f58 100644 --- a/docs/hazmat/primitives/interfaces.rst +++ b/docs/hazmat/primitives/interfaces.rst @@ -381,6 +381,23 @@ Asymmetric interfaces The DSAParameters object associated with this private key. + .. method:: signer(algorithm, backend) + + .. versionadded:: 0.4 + + Sign data which can be verified later by others using the public key. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext` + .. attribute:: key_size :type: int @@ -412,17 +429,129 @@ Asymmetric interfaces The bit length of the modulus. + .. attribute:: y + + :type: int + + The public key. + .. method:: parameters() :return: :class:`~cryptography.hazmat.primitives.interfaces.DSAParameters` The DSAParameters object associated with this public key. - .. attribute:: y + .. method:: verifier(signature, algorithm, backend) + + .. versionadded:: 0.4 + + Verify data was signed by the private key associated with this public + key. + + :param bytes signature: The signature to verify. DER encoded as + specified in :rfc:`6979`. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricVerificationContext` + + +.. class:: EllipticCurve + + .. versionadded:: 0.5 + + A named elliptic curve. + + .. attribute:: name + + :type: string + + The name of the curve. Usually the name used for the ASN.1 OID such as + ``secp256k1``. + + .. attribute:: key_size :type: int - The public key. + The bit length of the curve's base point. + + +.. class:: EllipticCurveSignatureAlgorithm + + .. versionadded:: 0.5 + + A signature algorithm for use with elliptic curve keys. + + .. attribute:: algorithm + + :type: :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + + The digest algorithm to be used with the signature scheme. + + +.. class:: EllipticCurvePrivateKey + + .. versionadded:: 0.5 + + An elliptic curve private key for use with an algorithm such as `ECDSA`_ or + `EdDSA`_. + + .. classmethod:: signer(signature_algorithm) + + Sign data which can be verified later by others using the public key. + + :param signature_algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurveSignatureAlgorithm` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext` + + .. attribute:: curve + + :type: :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurve` + + The elliptic curve for this key. + + .. method:: public_key() + + :return: :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurvePublicKey` + + The EllipticCurvePublicKey object for this private key. + + +.. class:: EllipticCurvePublicKey + + .. versionadded:: 0.5 + + An elliptic curve public key. + + .. classmethod:: verifier(signer, signature_algorithm) + + Verify data was signed by the private key associated with this public + key. + + :param bytes signature: The signature to verify. + + :param signature_algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurveSignatureAlgorithm` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext` + + .. attribute:: curve + + :type: :class:`~cryptography.hazmat.primitives.interfaces.EllipticCurve` + + The elliptic curve for this key. .. class:: AsymmetricSignatureContext @@ -574,3 +703,5 @@ Key derivation functions .. _`Chinese remainder theorem`: https://en.wikipedia.org/wiki/Chinese_remainder_theorem .. _`DSA`: https://en.wikipedia.org/wiki/Digital_Signature_Algorithm .. _`CMAC`: https://en.wikipedia.org/wiki/CMAC +.. _`ECDSA`: http://en.wikipedia.org/wiki/ECDSA +.. _`EdDSA`: http://en.wikipedia.org/wiki/EdDSA diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst index 269f949d..f68b12c1 100644 --- a/docs/hazmat/primitives/key-derivation-functions.rst +++ b/docs/hazmat/primitives/key-derivation-functions.rst @@ -88,6 +88,8 @@ Different KDFs are suitable for different tasks such as: provided ``backend`` does not implement :class:`~cryptography.hazmat.backends.interfaces.PBKDF2HMACBackend` + :raises TypeError: This exception is raised if ``salt`` is not ``bytes``. + .. method:: derive(key_material) :param bytes key_material: The input key material. For PBKDF2 this @@ -99,6 +101,9 @@ Different KDFs are suitable for different tasks such as: called more than once. + :raises TypeError: This exception is raised if ``key_material`` is not + ``bytes``. + This generates and returns a new key from the supplied password. .. method:: verify(key_material, expected_key) @@ -191,10 +196,108 @@ Different KDFs are suitable for different tasks such as: provided ``backend`` does not implement :class:`~cryptography.hazmat.backends.interfaces.HMACBackend` + :raises TypeError: This exception is raised if ``salt`` or ``info`` is not + ``bytes``. + + .. method:: derive(key_material) + + :param bytes key_material: The input key material. + :return bytes: The derived key. + :raises TypeError: This exception is raised if ``key_material`` is not + ``bytes``. + + Derives a new key from the input key material by performing both the + extract and expand operations. + + .. method:: verify(key_material, expected_key) + + :param key_material bytes: The input key material. This is the same as + ``key_material`` in :meth:`derive`. + :param expected_key bytes: The expected result of deriving a new key, + this is the same as the return value of + :meth:`derive`. + :raises cryptography.exceptions.InvalidKey: This is raised when the + derived key does not match + the expected key. + :raises cryptography.exceptions.AlreadyFinalized: This is raised when + :meth:`derive` or + :meth:`verify` is + called more than + once. + + This checks whether deriving a new key from the supplied + ``key_material`` generates the same key as the ``expected_key``, and + raises an exception if they do not match. + + +.. class:: HKDFExpand(algorithm, length, info, backend) + + .. versionadded:: 0.5 + + HKDF consists of two stages, extract and expand. This class exposes an + expand only version of HKDF that is suitable when the key material is + already cryptographically strong. + + .. warning:: + + HKDFExpand should only be used if the key material is + cryptographically strong. You should use + :class:`~cryptography.hazmat.primitives.kdf.hkdf.HKDF` if + you are unsure. + + .. doctest:: + + >>> import os + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.kdf.hkdf import HKDFExpand + >>> from cryptography.hazmat.backends import default_backend + >>> backend = default_backend() + >>> info = b"hkdf-example" + >>> key_material = os.urandom(16) + >>> hkdf = HKDFExpand( + ... algorithm=hashes.SHA256(), + ... length=32, + ... info=info, + ... backend=backend + ... ) + >>> key = hkdf.derive(key_material) + >>> hkdf = HKDFExpand( + ... algorithm=hashes.SHA256(), + ... length=32, + ... info=info, + ... backend=backend + ... ) + >>> hkdf.verify(key_material, key) + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param int length: The desired length of the derived key. Maximum is + ``255 * (algorithm.digest_size // 8)``. + + :param bytes info: Application specific context information. If ``None`` + is explicitly passed an empty byte string will be used. + + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.HMACBackend` + provider. + + :raises cryptography.exceptions.UnsupportedAlgorithm: This is raised if the + provided ``backend`` does not implement + :class:`~cryptography.hazmat.backends.interfaces.HMACBackend` + :raises TypeError: This is raised if the provided ``info`` is a unicode object + :raises TypeError: This exception is raised if ``info`` is not ``bytes``. + .. method:: derive(key_material) :param bytes key_material: The input key material. - :retunr bytes: The derived key. + :return bytes: The derived key. + + :raises TypeError: This is raised if the provided ``key_material`` is + a unicode object + :raises TypeError: This exception is raised if ``key_material`` is not + ``bytes``. Derives a new key from the input key material by performing both the extract and expand operations. @@ -214,6 +317,8 @@ Different KDFs are suitable for different tasks such as: :meth:`verify` is called more than once. + :raises TypeError: This is raised if the provided ``key_material`` is + a unicode object This checks whether deriving a new key from the supplied ``key_material`` generates the same key as the ``expected_key``, and diff --git a/docs/hazmat/primitives/mac/cmac.rst b/docs/hazmat/primitives/mac/cmac.rst index a6b048b5..498b8b1e 100644 --- a/docs/hazmat/primitives/mac/cmac.rst +++ b/docs/hazmat/primitives/mac/cmac.rst @@ -10,8 +10,8 @@ Cipher-based message authentication code import binascii key = binascii.unhexlify(b"0" * 32) -`Cipher-based message authentication codes`_ (or CMACs) are a tool for calculating -message authentication codes using a block cipher coupled with a +`Cipher-based message authentication codes`_ (or CMACs) are a tool for +calculating message authentication codes using a block cipher coupled with a secret key. You can use an CMAC to verify both the integrity and authenticity of a message. @@ -38,9 +38,9 @@ A subset of CMAC with the AES-128 algorithm is described in :rfc:`4493`. :class:`~cryptography.exceptions.UnsupportedAlgorithm` exception will be raised. - If the `algorithm`` isn't a - :class:`~cryptography.primitives.interfaces.BlockCipherAlgorithm` provider, - ``TypeError`` will be raised. + If ``algorithm`` isn't a + :class:`~cryptography.hazmat.primitives.interfaces.BlockCipherAlgorithm` + provider then ``TypeError`` will be raised. To check that a given signature is correct use the :meth:`verify` method. You will receive an exception if the signature is wrong: @@ -68,6 +68,7 @@ A subset of CMAC with the AES-128 algorithm is described in :rfc:`4493`. :param bytes data: The bytes to hash and authenticate. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize` + :raises TypeError: This exception is raised if ``data`` is not ``bytes``. .. method:: copy() @@ -89,6 +90,8 @@ A subset of CMAC with the AES-128 algorithm is described in :rfc:`4493`. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize` :raises cryptography.exceptions.InvalidSignature: If signature does not match digest + :raises TypeError: This exception is raised if ``signature`` is not + ``bytes``. .. method:: finalize() diff --git a/docs/hazmat/primitives/mac/hmac.rst b/docs/hazmat/primitives/mac/hmac.rst index 11b10735..d56927b9 100644 --- a/docs/hazmat/primitives/mac/hmac.rst +++ b/docs/hazmat/primitives/mac/hmac.rst @@ -38,6 +38,10 @@ of a message. :class:`~cryptography.exceptions.UnsupportedAlgorithm` exception will be raised. + If ``algorithm`` isn't a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` provider + then ``TypeError`` will be raised. + To check that a given signature is correct use the :meth:`verify` method. You will receive an exception if the signature is wrong: @@ -65,6 +69,7 @@ of a message. :param bytes msg: The bytes to hash and authenticate. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize` + :raises TypeError: This exception is raised if ``msg`` is not ``bytes``. .. method:: copy() @@ -86,6 +91,8 @@ of a message. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize` :raises cryptography.exceptions.InvalidSignature: If signature does not match digest + :raises TypeError: This exception is raised if ``signature`` is not + ``bytes``. .. method:: finalize() diff --git a/docs/hazmat/primitives/mac/index.rst b/docs/hazmat/primitives/mac/index.rst index 59fb8da2..acfe9bed 100644 --- a/docs/hazmat/primitives/mac/index.rst +++ b/docs/hazmat/primitives/mac/index.rst @@ -3,6 +3,14 @@ Message Authentication Codes ============================ +While cryptography supports both the CMAC and HMAC algorithms, we strongly +recommend that HMAC should be used unless you have a good reason otherwise. + +For more information on why HMAC is preferred, see `Use cases for CMAC vs. +HMAC?`_ + +.. _`Use cases for CMAC vs. HMAC?`: http://crypto.stackexchange.com/questions/15721/use-cases-for-cmac-vs-hmac + .. toctree:: :maxdepth: 1 diff --git a/docs/hazmat/primitives/padding.rst b/docs/hazmat/primitives/padding.rst index 4092ac00..0322f9d2 100644 --- a/docs/hazmat/primitives/padding.rst +++ b/docs/hazmat/primitives/padding.rst @@ -70,6 +70,7 @@ multiple of the block size. :return bytes: Returns the data that was padded or unpadded. :raises TypeError: Raised if data is not bytes. :raises cryptography.exceptions.AlreadyFinalized: See :meth:`finalize`. + :raises TypeError: This exception is raised if ``data`` is not ``bytes``. .. method:: finalize() diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst index c98b3814..bca78354 100644 --- a/docs/hazmat/primitives/symmetric-encryption.rst +++ b/docs/hazmat/primitives/symmetric-encryption.rst @@ -20,9 +20,9 @@ provides secrecy but not authenticity. That means an attacker can't see the message but an attacker can create bogus messages and force the application to decrypt them. -For this reason it is *strongly* recommended to combine encryption with a -message authentication code, such as :doc:`HMAC </hazmat/primitives/mac/hmac>`, in -an "encrypt-then-MAC" formulation as `described by Colin Percival`_. +For this reason it is **strongly** recommended to combine encryption with a +message authentication code, such as :doc:`HMAC </hazmat/primitives/mac/hmac>`, +in an "encrypt-then-MAC" formulation as `described by Colin Percival`_. .. class:: Cipher(algorithm, mode, backend) @@ -134,8 +134,8 @@ Algorithms .. versionadded:: 0.4 - SEED is a block cipher developed by the Korea Information Security Agency ( - KISA). It is defined in :rfc:`4269` and is used broadly throughout South + SEED is a block cipher developed by the Korea Information Security Agency + (KISA). It is defined in :rfc:`4269` and is used broadly throughout South Korean industry, but rarely found elsewhere. :param bytes key: The secret key. This must be kept secret. ``128`` bits in @@ -275,6 +275,19 @@ Modes Must be the same number of bytes as the ``block_size`` of the cipher. Do not reuse an ``initialization_vector`` with a given ``key``. +.. class:: CFB8(initialization_vector) + + CFB (Cipher Feedback) is a mode of operation for block ciphers. It + transforms a block cipher into a stream cipher. The CFB8 variant uses an + 8-bit shift register. + + **This mode does not require padding.** + + :param bytes initialization_vector: Must be random bytes. They do not need + to be kept secret and they can be included in a transmitted message. + Must be the same number of bytes as the ``block_size`` of the cipher. + Do not reuse an ``initialization_vector`` with a given ``key``. + .. class:: GCM(initialization_vector, tag=None) .. danger:: |