--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/demos/demo_dynamic.py	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,309 @@
+
+
+"""
+    demo_dynamic.py                                    v2b
+
+    This program demonstrates Python's use of the dynamic
+    language support additions to LTC, namely access to LTC
+    constants, struct and union sizes, and the binding of a
+    math package to LTC.  Also provided are simple code
+    fragments to illustrate how one might write a Python
+    wrapper for LTC and how an app might call the wrapper.
+    This or a similar model should work for Ruby and other
+    dynamic languages.
+
+    This instance uses Python's ctypes and requires a single
+    .dylib linking together LTC and a math library.  Building
+    a single .dylib is needed because LTC wants a fairly tight
+    relationship between itself and the mathlib.  (ctypes can
+    load multiple .dylibs, but it does not support this level
+    of tight coupling between otherwise independent libraries.)
+
+    My .dylib was created on OSX/macOS with the following:
+        sudo make -j5 -f makefile.shared                        \
+            CFLAGS="-DUSE_TFM -DTFM_DESC -I/usr/local/include"  \
+            EXTRALIBS=/usr/local/lib/libtfm.a  install
+
+    For python 2.7.12 on Ubuntu Xenial the following worked for
+    me (without MPI support):
+        sudo make -f makefile.shared install PREFIX="/usr"
+
+    Reminder: you don't need to bind in a math library unless
+              you are going to use LTC functions that need a
+              mathlib.  For example, public key crypto requires
+              a mathlib; hashing and symmetric encryption do not.
+
+    ------
+
+    This code was originally written for Python 2.7 with the
+    ctypes standard library.  This version is modified to run
+    under both Python 2.7 and 3.6.
+
+    Arguably the biggest change for Python3 has to do with
+    strings.  Under Python2, native strings are ASCII bytes and
+    passing them to LTC is natural and requires no conversion.
+    Under Python3 all native strings are Unicode which requires
+    they be converted to bytes before use by LTC.
+
+    Note the following for Python3.
+        - ASCII keys, IVs and other string arguments must be
+          'bytes'.  Define them with a 'b' prefix or convert
+          via the 'bytes()' function.
+        - "strings" returned from LTC are bytes and conversion
+          to Unicode might be necessary for proper printing.
+          If so, use <string>.decode('utf-8').
+        - The Python2 'print' statement becomes a function in
+          Python3 which requires parenthesis, eg. 'print()'.
+
+    NB: Unicode is achieved under Python2 by either defining
+        a Unicode string with a 'u' prefix or passing ASCII
+        strings thru the 'unicode()' function.
+
+    Larry Bugbee
+    March 2014      v1
+    August 2017     v2b
+
+"""
+
+
+import sys
+from ctypes import *
+from ctypes.util import find_library
+
+# switches to enable/disable selected output
+SHOW_ALL_CONSTANTS      = True
+SHOW_ALL_SIZES          = True
+SHOW_SELECTED_CONSTANTS = True
+SHOW_SELECTED_SIZES     = True
+SHOW_BUILD_OPTIONS_ALGS = True
+SHOW_SHA256_EXAMPLE     = True
+SHOW_CHACHA_EXAMPLE     = True
+
+print(' ')
+print('  demo_dynamic.py')
+
+def inprint(s, indent=0):
+    "prints strings indented, including multline strings"
+    for line in s.split('\n'):
+        print(' '*indent + line)
+
+#-------------------------------------------------------------------------------
+# load the .dylib
+
+libname = 'tomcrypt'
+libpath = find_library(libname)
+print(' ')
+print('  path to library %s: %s' % (libname, libpath))
+
+LTC = cdll.LoadLibrary(libpath)
+print('  loaded: %s' % LTC)
+print(' ')
+
+
+#-------------------------------------------------------------------------------
+# get list of all supported constants followed by a list of all
+# supported sizes.  One alternative: these lists may be parsed
+# and used as needed.
+
+if SHOW_ALL_CONSTANTS:
+    print('-'*60)
+    print('  all supported constants and their values:')
+
+    # get size to allocate for constants output list
+    str_len = c_int(0)
+    ret = LTC.crypt_list_all_constants(None, byref(str_len))
+    print('    need to allocate %d bytes to build list \n' % str_len.value)
+
+    # allocate that size and get (name, size) pairs, each pair
+    # separated by a newline char.
+    names_sizes = c_buffer(str_len.value)
+    ret = LTC.crypt_list_all_constants(names_sizes, byref(str_len))
+    print(names_sizes.value.decode("utf-8"))
+    print(' ')
+
+
+if SHOW_ALL_SIZES:
+    print('-'*60)
+    print('  all supported sizes:')
+
+    # get size to allocate for sizes output list
+    str_len = c_int(0)
+    ret = LTC.crypt_list_all_sizes(None, byref(str_len))
+    print('    need to allocate %d bytes to build list \n' % str_len.value)
+
+    # allocate that size and get (name, size) pairs, each pair
+    # separated by a newline char.
+    names_sizes = c_buffer(str_len.value)
+    ret = LTC.crypt_list_all_sizes(names_sizes, byref(str_len))
+    print(names_sizes.value.decode("utf-8"))
+    print(' ')
+
+
+#-------------------------------------------------------------------------------
+# get individually named constants and sizes
+
+if SHOW_SELECTED_CONSTANTS:
+    print('-'*60)
+    print('\n  selected constants:')
+
+    names = [
+        b'ENDIAN_LITTLE',
+        b'ENDIAN_64BITWORD',
+        b'PK_PUBLIC',
+        b'LTC_MILLER_RABIN_REPS',
+        b'CTR_COUNTER_BIG_ENDIAN',
+    ]
+    for name in names:
+        const_value = c_int(0)
+        rc = LTC.crypt_get_constant(name, byref(const_value))
+        value = const_value.value
+        print('    %-25s  %d' % (name.decode("utf-8"), value))
+    print(' ')
+
+if SHOW_SELECTED_SIZES:
+    print('-'*60)
+    print('\n  selected sizes:')
+
+    names = [
+        b'rijndael_key',
+        b'rsa_key',
+        b'symmetric_CTR',
+        b'twofish_key',
+        b'ecc_point',
+        b'gcm_state',
+        b'sha512_state',
+    ]
+    for name in names:
+        size_value = c_int(0)
+        rc = LTC.crypt_get_size(name, byref(size_value))
+        value = size_value.value
+        print('    %-25s  %d' % (name.decode("utf-8"), value))
+    print(' ')
+
+
+#-------------------------------------------------------------------------------
+#-------------------------------------------------------------------------------
+# LibTomCrypt exposes one interesting string that can be accessed
+# via Python's ctypes module, "crypt_build_settings", which
+# provides a list of this build's compiler switches and supported
+# algorithms.  If someday LTC exposes other interesting strings,
+# they can be found with:
+#   nm /usr/local/lib/libtomcrypt.dylib | grep " D "
+
+def get_named_string(lib, name):
+    return c_char_p.in_dll(lib, name).value.decode("utf-8")
+
+if SHOW_BUILD_OPTIONS_ALGS:
+    print('-'*60)
+    print('This is a string compiled into LTC showing compile')
+    print('options and algorithms supported by this build \n')
+#    print(get_named_string(LTC, 'crypt_build_settings'))
+    inprint(get_named_string(LTC, 'crypt_build_settings'), 4)
+
+
+#-------------------------------------------------------------------------------
+#-------------------------------------------------------------------------------
+# here is an example of how Python code can be written to access
+# LTC's implementation of SHA256 and ChaCha,
+
+# - - - - - - - - - - - - -
+# definitions
+
+from binascii import hexlify, unhexlify
+
+def _err2str(err):
+    # define return type
+    errstr = LTC.error_to_string
+    errstr.restype = c_char_p
+    # get and return err string
+    return errstr(err)
+
+def _get_size(name):
+    size = c_int(0)
+    rc = LTC.crypt_get_size(bytes(name), byref(size))
+    if rc != 0:
+        raise Exception('LTC.crypt_get_size(%s) rc = %d' % (name, rc))
+    return size.value
+
+def _get_constant(name):
+    constant = c_int(0)
+    rc = LTC.crypt_get_constant(bytes(name), byref(constant))
+    if rc != 0:
+        raise Exception('LTC.crypt_get_constant(%s) rc = %d' % (name, rc))
+    return constant.value
+
+CRYPT_OK = _get_constant(b'CRYPT_OK')
+
+class SHA256(object):
+    def __init__(self):
+        self.state = c_buffer(_get_size(b'sha256_state'))
+        LTC.sha256_init(byref(self.state))
+    def update(self, data):
+        LTC.sha256_process(byref(self.state), data, len(data))
+    def digest(self):
+        md = c_buffer(32)
+        LTC.sha256_done(byref(self.state), byref(md))
+        return md.raw
+
+class ChaCha(object):
+    def __init__(self, key, rounds):
+        self.state   = c_buffer(_get_size(b'chacha_state'))
+        self.counter = c_int(1)
+        err = LTC.chacha_setup(byref(self.state), key, len(key), rounds)
+        if err != CRYPT_OK:
+            raise Exception('LTC.chacha_setup(), err = %d, "%s"' % (err, _err2str(err)))
+    def set_iv32(self, iv):
+        err = LTC.chacha_ivctr32(byref(self.state), iv, len(iv), byref(self.counter))
+        if err != CRYPT_OK:
+            raise Exception('LTC.chacha_ivctr32(), err = %d, "%s"' % (err, _err2str(err)))
+    def crypt(self, datain):
+        dataout = c_buffer(len(datain))
+        err = LTC.chacha_crypt(byref(self.state), datain, len(datain), byref(dataout))
+        if err != CRYPT_OK:
+            raise Exception('LTC.chacha_crypt(), err = %d, "%s"' % (err, _err2str(err)))
+        return dataout.raw
+
+# - - - - - - - - - - - - -
+# a SHA256 app fragment
+
+if SHOW_SHA256_EXAMPLE:
+    print('-'*60)
+    data = b'hello world'               # we want bytes, not Unicode
+
+    sha256 = SHA256()
+    sha256.update(data)
+    md = sha256.digest()
+
+    template = '\n  the SHA256 digest for "%s" is %s \n'
+    print(template % (data, hexlify(md)))
+
+# - - - - - - - - - - - - -
+# a ChaCha app fragment
+
+if SHOW_CHACHA_EXAMPLE:
+    print('-'*60)
+    key     = b'hownowbrowncow\x00\x00' # exactly 16 or 32 bytes
+    rounds  = 12                        # common values: 8, 12, 20
+    iv      = b'123456789012'           # exactly 12 bytes
+    plain   = b'Kilroy was here, there, and everywhere!'
+
+    cha = ChaCha(key, rounds)
+    cha.set_iv32(iv)
+    cipher = cha.crypt(plain)
+
+    template = '\n  ChaCha%d ciphertext   for "%s" is "%s"'
+    print(template % (rounds, plain, hexlify(cipher)))
+
+    cha.set_iv32(iv)                    # reset to decrypt
+    decrypted = cha.crypt(cipher)
+
+    template = '  ChaCha%d decoded text for "%s" is "%s" \n'
+    print(template % (rounds, plain, decrypted.decode("utf-8")))
+
+# Footnote: Keys should be erased fm memory as soon as possible after use,
+# and that includes Python.  For a tip on how to do that in Python, see
+# http://buggywhip.blogspot.com/2010/12/erase-keys-and-credit-card-numbers-in.html
+
+#-------------------------------------------------------------------------------
+#-------------------------------------------------------------------------------
+#-------------------------------------------------------------------------------