diff options
Diffstat (limited to 'docs/hazmat')
| -rw-r--r-- | docs/hazmat/backends/commoncrypto.rst | 4 | ||||
| -rw-r--r-- | docs/hazmat/backends/interfaces.rst | 18 | ||||
| -rw-r--r-- | docs/hazmat/backends/openssl.rst | 10 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/dsa.rst | 2 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/rsa.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/key-derivation-functions.rst | 107 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/cmac.rst | 7 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/hmac.rst | 3 | ||||
| -rw-r--r-- | docs/hazmat/primitives/mac/index.rst | 3 | ||||
| -rw-r--r-- | docs/hazmat/primitives/padding.rst | 1 | ||||
| -rw-r--r-- | docs/hazmat/primitives/symmetric-encryption.rst | 19 |
13 files changed, 223 insertions, 54 deletions
diff --git a/docs/hazmat/backends/commoncrypto.rst b/docs/hazmat/backends/commoncrypto.rst index 77d6612c..ddaf97e5 100644 --- a/docs/hazmat/backends/commoncrypto.rst +++ b/docs/hazmat/backends/commoncrypto.rst @@ -3,8 +3,8 @@ CommonCrypto backend ==================== -The `CommonCrypto`_ C library provided by Apple on OS X and iOS. The CommonCrypto -backend is only supported on OS X versions 10.8 and above. +The `CommonCrypto`_ C library provided by Apple on OS X and iOS. The +CommonCrypto backend is only supported on OS X versions 10.8 and above. .. currentmodule:: cryptography.hazmat.backends.commoncrypto.backend diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst index f363b541..ff389cb5 100644 --- a/docs/hazmat/backends/interfaces.rst +++ b/docs/hazmat/backends/interfaces.rst @@ -6,8 +6,8 @@ Backend interfaces .. currentmodule:: cryptography.hazmat.backends.interfaces -Backend implementations may provide a number of interfaces to support operations -such as :doc:`/hazmat/primitives/symmetric-encryption`, +Backend implementations may provide a number of interfaces to support +operations such as :doc:`/hazmat/primitives/symmetric-encryption`, :doc:`/hazmat/primitives/cryptographic-hashes`, and :doc:`/hazmat/primitives/mac/hmac`. @@ -275,6 +275,14 @@ A specific ``backend`` may provide one or more of these interfaces. :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding` provider. + :return bytes: The decrypted data. + + :raises cryptography.exceptions.UnsupportedAlgorithm: If an unsupported + MGF, hash function, or padding is chosen. + + :raises ValueError: When decryption fails or key size does not match + ciphertext length. + .. method:: encrypt_rsa(public_key, plaintext, padding) :param public_key: An instance of an @@ -287,6 +295,12 @@ A specific ``backend`` may provide one or more of these interfaces. :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding` provider. + :return bytes: The encrypted data. + + :raises cryptography.exceptions.UnsupportedAlgorithm: If an unsupported + MGF, hash function, or padding is chosen. + + :raises ValueError: When plaintext is too long for the key size. .. class:: TraditionalOpenSSLSerializationBackend diff --git a/docs/hazmat/backends/openssl.rst b/docs/hazmat/backends/openssl.rst index f21116b8..6ad0d045 100644 --- a/docs/hazmat/backends/openssl.rst +++ b/docs/hazmat/backends/openssl.rst @@ -46,9 +46,9 @@ where two different processes can return similar or identical keys and compromise the security of the system. The approach this project has chosen to mitigate this vulnerability is to -include an engine that replaces the OpenSSL default CSPRNG with one that sources -its entropy from ``/dev/urandom`` on UNIX-like operating systems and uses -``CryptGenRandom`` on Windows. This method of pulling from the system pool +include an engine that replaces the OpenSSL default CSPRNG with one that +sources its entropy from ``/dev/urandom`` on UNIX-like operating systems and +uses ``CryptGenRandom`` on Windows. This method of pulling from the system pool allows us to avoid potential issues with `initializing the RNG`_ as well as protecting us from the ``fork()`` weakness. @@ -70,8 +70,8 @@ On Windows the implementation of ``CryptGenRandom`` depends on which version of the operation system you are using. See the `Microsoft documentation`_ for more details. -Linux uses its own PRNG design. ``/dev/urandom`` is a non-blocking source seeded -from the same pool as ``/dev/random``. +Linux uses its own PRNG design. ``/dev/urandom`` is a non-blocking source +seeded from the same pool as ``/dev/random``. .. _`OpenSSL`: https://www.openssl.org/ diff --git a/docs/hazmat/primitives/asymmetric/dsa.rst b/docs/hazmat/primitives/asymmetric/dsa.rst index cc46029c..6848d84c 100644 --- a/docs/hazmat/primitives/asymmetric/dsa.rst +++ b/docs/hazmat/primitives/asymmetric/dsa.rst @@ -120,7 +120,7 @@ DSA ... 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() diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst index 68ad089d..234a5c66 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() + ... ) Handling partial RSA private keys 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/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 1fde1398..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. @@ -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 e20a4034..d56927b9 100644 --- a/docs/hazmat/primitives/mac/hmac.rst +++ b/docs/hazmat/primitives/mac/hmac.rst @@ -69,6 +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() @@ -90,6 +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 4f075417..acfe9bed 100644 --- a/docs/hazmat/primitives/mac/index.rst +++ b/docs/hazmat/primitives/mac/index.rst @@ -6,7 +6,8 @@ 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?`_ +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 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 78bf6637..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) @@ -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:: |