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Diffstat (limited to 'doc/lowlevel.txt')
| -rw-r--r-- | doc/lowlevel.txt | 129 |
1 files changed, 36 insertions, 93 deletions
diff --git a/doc/lowlevel.txt b/doc/lowlevel.txt index 8b37345d6..9f1c7bc42 100644 --- a/doc/lowlevel.txt +++ b/doc/lowlevel.txt @@ -16,21 +16,21 @@ Basic Algorithm Abilities There are a small handful of functions implemented by most of Botan's algorithm objects. Among these are: -.. cpp:function:: std::string name() +.. cpp:function:: std::string Algorithm::name() Returns a human-readable string of the name of this algorithm. Examples of names returned are "AES-128" and "HMAC(SHA-512)". You can turn names back into algorithm objects using the functions in ``lookup.h``. -.. cpp:function:: void clear() +.. cpp:function:: void Algorithm::clear() Clear out the algorithm's internal state. A block cipher object will "forget" its key, a hash function will "forget" any data put into it, etc. The object will look and behave as it did when you initially allocated it. -.. cpp:function:: T* clone() +.. cpp:function:: T* Algorithm::clone() This function is central to Botan's name-based interface. The ``clone`` has many different return types, such as ``BlockCipher``\* @@ -84,7 +84,7 @@ those types are derived from the ``SymmetricAlgorithm`` base class. This type provides functions for setting the key, and querying restrictions on the size of the key: -.. cpp:function:: void set_key(const byte* key, size_t length) +.. cpp:function:: void SymmetricAlgorithm::set_key(const byte* key, size_t length) This sets the key to the value specified. Most algorithms only accept keys of certain lengths. If you attempt to call ``set_key`` @@ -97,17 +97,17 @@ restrictions on the size of the key: object. If this is not done, the results are undefined, but probably will not be good. -.. cpp:function:: bool valid_keylength(size_t length) const +.. cpp:function:: bool SymmetricAlgorithm::valid_keylength(size_t length) const This function returns true if and only if ``length`` is a valid keylength for the algorithm. -.. cpp:function:: size_t minimum_keylength() const +.. cpp:function:: size_t SymmetricAlgorithm::minimum_keylength() const Return the smallest key length (in bytes) that is acceptible for the algorithm. -.. cpp:function:: size_t maximum_keylength() const +.. cpp:function:: size_t SymmetricAlgorithm::maximum_keylength() const Return the largest key length (in bytes) that is acceptible for the algorithm @@ -118,37 +118,37 @@ Block Ciphers Block ciphers implement the interface ``BlockCipher``, found in ``block_cipher.h``, as well as the ``SymmetricAlgorithm`` interface. -.. cpp:function:: size_t block_size() const +.. cpp:function:: size_t BlockCipher::block_size() const Returns the block size of the cipher in bytes -.. c:function:: void encrypt_n(const byte in[], byte out[], size_t blocks) const +.. cpp:function:: void BlockCipher::encrypt_n(const byte* in, byte* out, size_t blocks) const Encrypt ``blocks`` blocks of data, taking the input from ``in`` and placing the ciphertext in ``out``. The two pointers may be identical, but should not overlap ranges. -.. c:function:: void encrypt(const byte in[], byte out[]) const +.. cpp:function:: void BlockCipher::encrypt(const byte* in, byte* out) const Encrypt a single block, taking the input from ``in`` and placing it in ``out``. -.. c:function:: void encrypt(byte block[]) const +.. cpp:function:: void BlockCipher::encrypt(byte* block) const Identical to ``encrypt(block, block)``. -.. c:function:: void decrypt_n(const byte in[], byte out[], size_t blocks) const +.. cpp:function:: void BlockCipher::decrypt_n(const byte* in, byte out, size_t blocks) const Decrypt ``blocks`` blocks of data, taking the input from ``in`` and placing the plaintext in ``out``. The two pointers may be identical, but should not overlap ranges. -.. c:function:: void decrypt(const byte in[], byte out[]) const +.. cpp:function:: void BlockCipher::decrypt(const byte* in, byte* out) const Decrypt a single block, taking the input from ``in`` and placing it in ``out``. -.. c:function:: void decrypt(byte block[]) const +.. cpp:function:: void BlockCipher::decrypt(byte* block) const Identical to ``decrypt(block, block)``. @@ -161,35 +161,36 @@ encrypting data results in changing the internal state of the cipher. Also, you may encrypt any length of data in one go (in byte amounts). -.. cpp:function:: void encrypt(const byte* in, byte* out, size_t length) +.. cpp:function:: void StreamCipher::encrypt(const byte* in, byte* out, size_t length) -.. cpp:function:: void encrypt(byte* data, size_t length) +.. cpp:function:: void StreamCipher::encrypt(byte* data, size_t length) Stream ciphers implement the ``SymmetricAlgorithm`` interface. Hash Functions / Message Authentication Codes ---------------------------------------------- -Hash functions take their input without producing any output, only producing -anything when all input has already taken place. MACs are very similar, but are -additionally keyed. Both of these are derived from the base class -``BufferedComputation``, which has the following functions. +Hash functions take their input without producing any output, only +producing anything when all input has already taken place. MACs are +very similar, but are additionally keyed. Both of these are derived +from the base class ``BufferedComputation``, which has the following +functions. -.. cpp:function:: size_t output_length() +.. cpp:function:: size_t BufferedComputation::output_length() Return the size of the output of this function. -.. cpp:function:: void update(const byte* input, size_t length) +.. cpp:function:: void BufferedComputation::update(const byte* input, size_t length) -.. cpp:function:: void update(byte input) +.. cpp:function:: void BufferedComputation::update(byte input) -.. cpp:function:: void update(const std::string& input) +.. cpp:function:: void BufferedComputation::update(const std::string& input) Updates the hash/mac calculation with ``input``. -.. cpp:function:: void final(byte* out) +.. cpp:function:: void BufferedComputation::final(byte* out) -.. cpp:function:: SecureVector<byte> final() +.. cpp:function:: SecureVector<byte> BufferedComputation::final() Complete the hash/MAC calculation and place the result into ``out``. For the argument taking an array, exactly ``output_length`` bytes will @@ -216,74 +217,16 @@ away; the key is kept around). A MAC has the ``SymmetricAlgorithm`` interface in addition to the ``BufferedComputation`` interface. -User Interfaces ---------------------------------- - -Botan has recently changed some infrastructure to better accommodate -more complex user interfaces, in particular ones that are based on -event loops. Primary among these was the fact that when doing -something like loading a PKCS #8 encoded private key, a passphrase -might be needed, but then again it might not (a PKCS #8 key doesn't -have to be encrypted). Asking for a passphrase to decrypt an -unencrypted key is rather pointless. Not only that, but the way to -handle the user typing the wrong passphrase was complicated, -undocumented, and inefficient. - -So now Botan has an object called ``User_Interface``, which provides a -simple interface for the aspects of user interaction the library has -to be concerned with. Currently, this means getting a passphrase from -the user, and that's it (``User_Interface`` will probably be extended -in the future to support other operations as they are needed). The -base ``User_Interface`` class is very stupid, because the library -can't directly assume anything about the environment that it's running -under (for example, if there will be someone sitting at the terminal, -if the application is even *attached* to a terminal, and so on). But -since you can subclass ``User_Interface`` to use whatever method -happens to be appropriate for your application, this isn't a big deal: - -.. cpp:function:: std::string User_Interface::get_passphrase(const std::string& what, const std::string& source, UI_Result& result) const - - The ``what`` argument specifies what the passphrase is needed for - (for example, PKCS #8 key loading passes ``what`` as "PKCS #8 - private key"). This lets you provide the user with some indication - of *why* your application is asking for a passphrase; feel free to - pass the string through ``gettext(3)`` or moral equivalent for i18n - purposes. Similarly, ``source`` specifies where the data in question - came from, if available (for example, a file name). If the source is - not available for whatever reason, then ``source`` will be an empty - string; be sure to account for this possibility when writing a - ``User_Interface`` subclass. - - The function returns the passphrase as the return value, and a - status code in ``result`` (either ``OK`` or ``CANCEL_ACTION``). If - ``CANCEL_ACTION`` is returned in ``result``, then the return value - will be ignored, and the caller will take whatever action is - necessary (typically, throwing an exception stating that the - passphrase couldn't be determined). In the specific case of PKCS #8 - key decryption, a ``Decoding_Error`` exception will be thrown; your - UI should assume this can happen, and provide appropriate error - handling (such as putting up a dialog box informing the user of the - situation, and canceling the operation in progress). - -There is an example ``User_Interface`` that uses GTK+ available on the -web site. The ``GTK_UI`` code is cleanly separated from the rest of -the example, so if you happen to be using GTK+, you can copy (and/or -adapt) that code for your application. If you write a -``User_Interface`` object for another windowing system (Win32, Qt, -wxWidgets, FOX, etc), and would like to make it available to users in -general (ideally under a permissive license such as public domain or -MIT/BSD), feel free to send in a copy. - - Checksums ---------------------------------- +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Checksums are very similar to hash functions, and in fact share the same -interface. But there are some significant differences, the major ones being -that the output size is very small (usually in the range of 2 to 4 bytes), and -is not cryptographically secure. But for their intended purpose (error -checking), they perform very well. Some examples of checksums included in Botan -are the Adler32 and CRC32 checksums. +Checksums are very similar to hash functions, and in fact share the +same interface. But there are some significant differences, the major +ones being that the output size is very small (usually in the range of +2 to 4 bytes), and is not cryptographically secure. But for their +intended purpose (error checking), they perform very well. Some +examples of checksums included in Botan are the Adler32 and CRC32 +checksums. Threads and Mutexes --------------------------------- @@ -349,7 +292,7 @@ data into its buffer. Like ``SecureBuffer``, it implements ``clear`` and ``size``. Allocators ---------------------------------- +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The containers described above get their memory from allocators. As a user of the library, you can add new allocator methods at run time for |