First commit, Vystem v0.1

Blastproof/initfsgen/utils.c

@@ -0,0 +1,154 @@
+#include <string.h>
+
+#include "utils.h"
+#include "params.h"
+#include "hash.h"
+#include "thash.h"
+#include "address.h"
+
+/**
+ * Converts the value of 'in' to 'outlen' bytes in big-endian byte order.
+ */
+void ull_to_bytes(unsigned char *out, unsigned int outlen,
+                  unsigned long long in)
+{
+    int i;
+
+    /* Iterate over out in decreasing order, for big-endianness. */
+    for (i = (signed int)outlen - 1; i >= 0; i--) {
+        out[i] = in & 0xff;
+        in = in >> 8;
+    }
+}
+
+void u32_to_bytes(unsigned char *out, uint32_t in)
+{
+    out[0] = (unsigned char)(in >> 24);
+    out[1] = (unsigned char)(in >> 16);
+    out[2] = (unsigned char)(in >> 8);
+    out[3] = (unsigned char)in;
+}
+
+/**
+ * Converts the inlen bytes in 'in' from big-endian byte order to an integer.
+ */
+unsigned long long bytes_to_ull(const unsigned char *in, unsigned int inlen)
+{
+    unsigned long long retval = 0;
+    unsigned int i;
+
+    for (i = 0; i < inlen; i++) {
+        retval |= ((unsigned long long)in[i]) << (8*(inlen - 1 - i));
+    }
+    return retval;
+}
+
+/**
+ * Computes a root node given a leaf and an auth path.
+ * Expects address to be complete other than the tree_height and tree_index.
+ */
+void compute_root(unsigned char *root, const unsigned char *leaf,
+                  uint32_t leaf_idx, uint32_t idx_offset,
+                  const unsigned char *auth_path, uint32_t tree_height,
+                  const spx_ctx *ctx, uint32_t addr[8])
+{
+    uint32_t i;
+    unsigned char buffer[2 * SPX_N];
+
+    /* If leaf_idx is odd (last bit = 1), current path element is a right child
+       and auth_path has to go left. Otherwise it is the other way around. */
+    if (leaf_idx & 1) {
+        memcpy(buffer + SPX_N, leaf, SPX_N);
+        memcpy(buffer, auth_path, SPX_N);
+    }
+    else {
+        memcpy(buffer, leaf, SPX_N);
+        memcpy(buffer + SPX_N, auth_path, SPX_N);
+    }
+    auth_path += SPX_N;
+
+    for (i = 0; i < tree_height - 1; i++) {
+        leaf_idx >>= 1;
+        idx_offset >>= 1;
+        /* Set the address of the node we're creating. */
+        set_tree_height(addr, i + 1);
+        set_tree_index(addr, leaf_idx + idx_offset);
+
+        /* Pick the right or left neighbor, depending on parity of the node. */
+        if (leaf_idx & 1) {
+            thash(buffer + SPX_N, buffer, 2, ctx, addr);
+            memcpy(buffer, auth_path, SPX_N);
+        }
+        else {
+            thash(buffer, buffer, 2, ctx, addr);
+            memcpy(buffer + SPX_N, auth_path, SPX_N);
+        }
+        auth_path += SPX_N;
+    }
+
+    /* The last iteration is exceptional; we do not copy an auth_path node. */
+    leaf_idx >>= 1;
+    idx_offset >>= 1;
+    set_tree_height(addr, tree_height);
+    set_tree_index(addr, leaf_idx + idx_offset);
+    thash(root, buffer, 2, ctx, addr);
+}
+
+/**
+ * For a given leaf index, computes the authentication path and the resulting
+ * root node using Merkle's TreeHash algorithm.
+ * Expects the layer and tree parts of the tree_addr to be set, as well as the
+ * tree type (i.e. SPX_ADDR_TYPE_HASHTREE or SPX_ADDR_TYPE_FORSTREE).
+ * Applies the offset idx_offset to indices before building addresses, so that
+ * it is possible to continue counting indices across trees.
+ */
+void treehash(unsigned char *root, unsigned char *auth_path, const spx_ctx* ctx,
+              uint32_t leaf_idx, uint32_t idx_offset, uint32_t tree_height,
+              void (*gen_leaf)(
+                 unsigned char* /* leaf */,
+                 const spx_ctx* /* ctx */,
+                 uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+              uint32_t tree_addr[8])
+{
+    SPX_VLA(uint8_t, stack, (tree_height+1)*SPX_N);
+    SPX_VLA(unsigned int, heights, tree_height+1);
+    unsigned int offset = 0;
+    uint32_t idx;
+    uint32_t tree_idx;
+
+    for (idx = 0; idx < (uint32_t)(1 << tree_height); idx++) {
+        /* Add the next leaf node to the stack. */
+        gen_leaf(stack + offset*SPX_N, ctx, idx + idx_offset, tree_addr);
+        offset++;
+        heights[offset - 1] = 0;
+
+        /* If this is a node we need for the auth path.. */
+        if ((leaf_idx ^ 0x1) == idx) {
+            memcpy(auth_path, stack + (offset - 1)*SPX_N, SPX_N);
+        }
+
+        /* While the top-most nodes are of equal height.. */
+        while (offset >= 2 && heights[offset - 1] == heights[offset - 2]) {
+            /* Compute index of the new node, in the next layer. */
+            tree_idx = (idx >> (heights[offset - 1] + 1));
+
+            /* Set the address of the node we're creating. */
+            set_tree_height(tree_addr, heights[offset - 1] + 1);
+            set_tree_index(tree_addr,
+                           tree_idx + (idx_offset >> (heights[offset-1] + 1)));
+            /* Hash the top-most nodes from the stack together. */
+            thash(stack + (offset - 2)*SPX_N,
+                  stack + (offset - 2)*SPX_N, 2, ctx, tree_addr);
+            offset--;
+            /* Note that the top-most node is now one layer higher. */
+            heights[offset - 1]++;
+
+            /* If this is a node we need for the auth path.. */
+            if (((leaf_idx >> heights[offset - 1]) ^ 0x1) == tree_idx) {
+                memcpy(auth_path + heights[offset - 1]*SPX_N,
+                       stack + (offset - 1)*SPX_N, SPX_N);
+            }
+        }
+    }
+    memcpy(root, stack, SPX_N);
+}