aws_encryption_sdk.internal.formatting.deserialize

Components for handling AWS Encryption SDK message deserialization.

Functions

deserialize_encrypted_data_keys(stream[, ...])	Deserialize some encrypted data keys from a stream.
deserialize_footer(stream[, verifier])	Deserializes a footer.
deserialize_frame(stream, header[, verifier])	Deserializes a frame from a body.
deserialize_header(stream[, ...])	Deserializes the header from a source stream
deserialize_header_auth(version, stream, ...)	Deserializes a MessageHeaderAuthentication object from a source stream.
deserialize_non_framed_values(stream, header)	Deserializes the IV and body length from a non-framed stream.
deserialize_tag(stream, header[, verifier])	Deserialize the Tag value from a non-framed stream.
deserialize_wrapped_key(wrapping_algorithm, ...)	Extracts and deserializes EncryptedData from a Wrapped EncryptedDataKey.
unpack_values(format_string, stream[, verifier])	Helper function to unpack struct data from a stream and update the signature verifier.
validate_header(header, header_auth, ...)	Validates the header using the header authentication data.

aws_encryption_sdk.internal.formatting.deserialize.validate_header(header, header_auth, raw_header, data_key)

Validates the header using the header authentication data.

Parameters

• header (aws_encryption_sdk.structures.MessageHeader) – Deserialized header

• header_auth (aws_encryption_sdk.internal.structures.MessageHeaderAuthentication) – Deserialized header auth

• raw_header (bytes) – Raw header bytes

• data_key (bytes) – Data key with which to perform validation

Raises

SerializationError – if header authorization fails

aws_encryption_sdk.internal.formatting.deserialize.deserialize_encrypted_data_keys(stream: IO, max_encrypted_data_keys: Optional[int] = None) → Set[aws_encryption_sdk.structures.EncryptedDataKey]

Deserialize some encrypted data keys from a stream.

Parameters

• stream – Stream from which to read encrypted data keys

• max_encrypted_data_keys – Maximum number of encrypted data keys to deserialize

Returns

Loaded encrypted data keys

Return type

set of EncryptedDataKey

aws_encryption_sdk.internal.formatting.deserialize.deserialize_header(stream: IO, max_encrypted_data_keys: Optional[int] = None) → aws_encryption_sdk.structures.MessageHeader

Deserializes the header from a source stream

Parameters

• stream (io.BytesIO) – Source data stream

• max_encrypted_data_keys (None or positive int) – Maximum number of encrypted keys to deserialize

Returns

Deserialized MessageHeader object

Return type

aws_encryption_sdk.structures.MessageHeader and bytes

Raises

• NotSupportedError – if unsupported data types are found

• UnknownIdentityError – if unknown data types are found

• SerializationError – if IV length does not match algorithm

aws_encryption_sdk.internal.formatting.deserialize.deserialize_header_auth(version, stream, algorithm, verifier=None)

Deserializes a MessageHeaderAuthentication object from a source stream.

Parameters

• version (int) – The serialization version of the message

• stream (io.BytesIO) – Source data stream

• algorithm – The AlgorithmSuite object type contained in the header

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object (optional)

Returns

Deserialized MessageHeaderAuthentication object

Return type

aws_encryption_sdk.internal.structures.MessageHeaderAuthentication

aws_encryption_sdk.internal.formatting.deserialize.deserialize_non_framed_values(stream, header, verifier=None)

Deserializes the IV and body length from a non-framed stream.

Parameters

• stream (io.BytesIO) – Source data stream

• header (aws_encryption_sdk.structures.MessageHeader) – Deserialized header

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object (optional)

Returns

IV and Data Length values for body

Return type

tuple of bytes and int

aws_encryption_sdk.internal.formatting.deserialize.deserialize_tag(stream, header, verifier=None)

Deserialize the Tag value from a non-framed stream.

Parameters

• stream (io.BytesIO) – Source data stream

• header (aws_encryption_sdk.structures.MessageHeader) – Deserialized header

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object (optional)

Returns

Tag value for body

Return type

bytes

aws_encryption_sdk.internal.formatting.deserialize.deserialize_frame(stream, header, verifier=None)

Deserializes a frame from a body.

Parameters

• stream (io.BytesIO) – Source data stream

• header (aws_encryption_sdk.structures.MessageHeader) – Deserialized header

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object (optional)

Returns

Deserialized frame and a boolean stating if this is the final frame

Return type

aws_encryption_sdk.internal.structures.MessageFrameBody and bool

aws_encryption_sdk.internal.formatting.deserialize.deserialize_footer(stream, verifier=None)

Deserializes a footer.

Parameters

• stream (io.BytesIO) – Source data stream

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object (optional)

Returns

Deserialized footer

Return type

aws_encryption_sdk.internal.structures.MessageFooter

Raises

SerializationError – if verifier supplied and no footer found

aws_encryption_sdk.internal.formatting.deserialize.unpack_values(format_string, stream, verifier=None)

Helper function to unpack struct data from a stream and update the signature verifier.

Parameters

• format_string (str) – Struct format string

• stream (io.BytesIO) – Source data stream

• verifier (aws_encryption_sdk.internal.crypto.Verifier) – Signature verifier object

Returns

Unpacked values

Return type

tuple

aws_encryption_sdk.internal.formatting.deserialize.deserialize_wrapped_key(wrapping_algorithm, wrapping_key_id, wrapped_encrypted_key)

Extracts and deserializes EncryptedData from a Wrapped EncryptedDataKey.

Parameters

• wrapping_algorithm (aws_encryption_sdk.identifiers.WrappingAlgorithm) – Wrapping Algorithm with which to wrap plaintext_data_key

• wrapping_key_id (bytes) – Key ID of wrapping MasterKey

• wrapped_encrypted_key (aws_encryption_sdk.structures.EncryptedDataKey) – Raw Wrapped EncryptedKey

Returns

EncryptedData of deserialized Wrapped EncryptedKey

Return type

aws_encryption_sdk.internal.structures.EncryptedData

Raises

• SerializationError – if wrapping_key_id does not match deserialized wrapping key id

• SerializationError – if wrapping_algorithm IV length does not match deserialized IV length