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#define PY_SSIZE_T_CLEAN
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#include <Python.h>
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#include "lib/sha1.h"
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#if PY_MAJOR_VERSION >= 3
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#define IS_PY3K
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#endif
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/* helper to switch things like string literal depending on Python version */
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#ifdef IS_PY3K
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#define PY23(py2, py3) py3
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#else
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#define PY23(py2, py3) py2
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#endif
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static char sha1dc_doc[] = "Efficient detection of SHA1 collision constructs.";
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/* clang-format off */
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typedef struct {
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PyObject_HEAD
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SHA1_CTX ctx;
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} pysha1ctx;
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/* clang-format on */
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static int pysha1ctx_init(pysha1ctx *self, PyObject *args)
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{
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const char *data = NULL;
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Py_ssize_t len;
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SHA1DCInit(&(self->ctx));
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/* We don't want "safe" sha1s, wherein sha1dc can give you a
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different hash for something that's trying to give you a
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collision. We just want to detect collisions.
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*/
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SHA1DCSetSafeHash(&(self->ctx), 0);
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if (!PyArg_ParseTuple(args, PY23("|s#", "|y#"), &data, &len)) {
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return -1;
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}
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if (data) {
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SHA1DCUpdate(&(self->ctx), data, len);
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}
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return 0;
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}
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static void pysha1ctx_dealloc(pysha1ctx *self)
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{
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PyObject_Del(self);
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}
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static PyObject *pysha1ctx_update(pysha1ctx *self, PyObject *args)
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{
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const char *data;
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Py_ssize_t len;
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if (!PyArg_ParseTuple(args, PY23("s#", "y#"), &data, &len)) {
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return NULL;
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}
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SHA1DCUpdate(&(self->ctx), data, len);
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Py_RETURN_NONE;
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}
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/* it is intentional that this take a ctx by value, as that clones the
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context so we can keep using .update() without poisoning the state
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with padding.
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*/
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static int finalize(SHA1_CTX ctx, unsigned char *hash_out)
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{
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if (SHA1DCFinal(hash_out, &ctx)) {
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PyErr_SetString(PyExc_OverflowError,
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"sha1 collision attack detected");
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return 0;
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}
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return 1;
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}
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static PyObject *pysha1ctx_digest(pysha1ctx *self)
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{
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unsigned char hash[20];
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if (!finalize(self->ctx, hash)) {
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return NULL;
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}
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return PyBytes_FromStringAndSize((char *)hash, 20);
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}
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static PyObject *pysha1ctx_hexdigest(pysha1ctx *self)
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{
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static const char hexdigit[] = "0123456789abcdef";
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unsigned char hash[20];
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char hexhash[40];
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int i;
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if (!finalize(self->ctx, hash)) {
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return NULL;
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}
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for (i = 0; i < 20; ++i) {
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hexhash[i * 2] = hexdigit[hash[i] >> 4];
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hexhash[i * 2 + 1] = hexdigit[hash[i] & 15];
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}
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return PY23(PyString_FromStringAndSize, PyUnicode_FromStringAndSize)(hexhash, 40);
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}
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static PyTypeObject sha1ctxType;
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static PyObject *pysha1ctx_copy(pysha1ctx *self)
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{
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pysha1ctx *clone = (pysha1ctx *)PyObject_New(pysha1ctx, &sha1ctxType);
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if (!clone) {
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return NULL;
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}
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clone->ctx = self->ctx;
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return (PyObject *)clone;
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}
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static PyMethodDef pysha1ctx_methods[] = {
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{"update", (PyCFunction)pysha1ctx_update, METH_VARARGS,
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"Update this hash object's state with the provided bytes."},
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{"digest", (PyCFunction)pysha1ctx_digest, METH_NOARGS,
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"Return the digest value as a string of binary data."},
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{"hexdigest", (PyCFunction)pysha1ctx_hexdigest, METH_NOARGS,
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"Return the digest value as a string of hexadecimal digits."},
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{"copy", (PyCFunction)pysha1ctx_copy, METH_NOARGS,
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"Return a copy of the hash object."},
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{NULL},
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};
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/* clang-format off */
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static PyTypeObject sha1ctxType = {
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PyVarObject_HEAD_INIT(NULL, 0) /* header */
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"sha1dc.sha1", /* tp_name */
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sizeof(pysha1ctx), /* tp_basicsize */
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0, /* tp_itemsize */
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(destructor)pysha1ctx_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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0, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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"sha1 implementation that looks for collisions", /* tp_doc */
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0, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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0, /* tp_iter */
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0, /* tp_iternext */
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pysha1ctx_methods, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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(initproc)pysha1ctx_init, /* tp_init */
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0, /* tp_alloc */
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};
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/* clang-format on */
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static PyMethodDef methods[] = {
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{NULL, NULL},
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};
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static void module_init(PyObject *mod)
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{
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sha1ctxType.tp_new = PyType_GenericNew;
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if (PyType_Ready(&sha1ctxType) < 0) {
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return;
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}
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Py_INCREF(&sha1ctxType);
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PyModule_AddObject(mod, "sha1", (PyObject *)&sha1ctxType);
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}
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#ifdef IS_PY3K
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static struct PyModuleDef sha1dc_module = {PyModuleDef_HEAD_INIT, "sha1dc",
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sha1dc_doc, -1, methods};
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PyMODINIT_FUNC PyInit_sha1dc(void)
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{
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PyObject *mod = PyModule_Create(&sha1dc_module);
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module_init(mod);
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return mod;
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}
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#else
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PyMODINIT_FUNC initsha1dc(void)
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{
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PyObject *mod = Py_InitModule3("sha1dc", methods, sha1dc_doc);
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module_init(mod);
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}
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#endif
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