524 Zeilen
14 KiB
C
524 Zeilen
14 KiB
C
#include "xmss.h"
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stdint.h>
|
|
#include <math.h>
|
|
|
|
#include "randombytes.h"
|
|
#include "wots.h"
|
|
#include "hash.h"
|
|
#include "prg.h"
|
|
#include "xmss_commons.h"
|
|
|
|
// For testing
|
|
#include "stdio.h"
|
|
|
|
/**
|
|
* Macros used to manipulate the respective fields
|
|
* in the 16byte hash address
|
|
*/
|
|
#define SET_OTS_BIT(a, b) {\
|
|
a[9] = (a[9] & 253) | (b << 1);}
|
|
|
|
#define SET_OTS_ADDRESS(a, v) {\
|
|
a[12] = (a[12] & 1) | ((v << 1) & 255);\
|
|
a[11] = (v >> 7) & 255;\
|
|
a[10] = (v >> 15) & 255;\
|
|
a[9] = (a[9] & 254) | ((v >> 23) & 1);}
|
|
|
|
#define ZEROISE_OTS_ADDR(a) {\
|
|
a[12] = (a[12] & 254);\
|
|
a[13] = 0;\
|
|
a[14] = 0;\
|
|
a[15] = 0;}
|
|
|
|
#define SET_LTREE_BIT(a, b) {\
|
|
a[9] = (a[9] & 254) | b;}
|
|
|
|
#define SET_LTREE_ADDRESS(a, v) {\
|
|
a[12] = v & 255;\
|
|
a[11] = (v >> 8) & 255;\
|
|
a[10] = (v >> 16) & 255;}
|
|
|
|
#define SET_LTREE_TREE_HEIGHT(a, v) {\
|
|
a[13] = (a[13] & 3) | ((v << 2) & 255);}
|
|
|
|
#define SET_LTREE_TREE_INDEX(a, v) {\
|
|
a[15] = (a[15] & 3) | ((v << 2) & 255);\
|
|
a[14] = (v >> 6) & 255;\
|
|
a[13] = (a[13] & 252) | ((v >> 14) & 3);}
|
|
|
|
#define SET_NODE_PADDING(a) {\
|
|
a[10] = 0;\
|
|
a[11] = a[11] & 3;}
|
|
|
|
#define SET_NODE_TREE_HEIGHT(a, v) {\
|
|
a[12] = (a[12] & 3) | ((v << 2) & 255);\
|
|
a[11] = (a[11] & 252) | ((v >> 6) & 3);}
|
|
|
|
#define SET_NODE_TREE_INDEX(a, v) {\
|
|
a[15] = (a[15] & 3) | ((v << 2) & 255);\
|
|
a[14] = (v >> 6) & 255;\
|
|
a[13] = (v >> 14) & 255;\
|
|
a[12] = (a[12] & 252) | ((v >> 22) & 3);}
|
|
|
|
|
|
/**
|
|
* Used for pseudorandom keygeneration,
|
|
* generates the seed for the WOTS keypair at address addr
|
|
*/
|
|
static void get_seed(unsigned char seed[32], const unsigned char *sk_seed, unsigned char addr[16])
|
|
{
|
|
// Make sure that chain addr, hash addr, and key bit are 0!
|
|
ZEROISE_OTS_ADDR(addr);
|
|
// Generate pseudorandom value
|
|
prg_with_counter(seed, 32, sk_seed, 32, addr);
|
|
}
|
|
|
|
/**
|
|
* Initialize xmss params struct
|
|
* parameter names are the same as in the draft
|
|
*/
|
|
void xmss_set_params(xmss_params *params, int m, int n, int h, int w)
|
|
{
|
|
params->h = h;
|
|
params->m = m;
|
|
params->n = n;
|
|
wots_params wots_par;
|
|
wots_set_params(&wots_par, m, n, w);
|
|
params->wots_par = &wots_par;
|
|
}
|
|
|
|
/**
|
|
* Computes a leaf from a WOTS public key using an L-tree.
|
|
*/
|
|
static void l_tree(unsigned char *leaf, unsigned char *wots_pk, const xmss_params *params, const unsigned char *pub_seed, unsigned char addr[16])
|
|
{
|
|
uint l = params->wots_par->len;
|
|
uint n = params->n;
|
|
unsigned long i = 0;
|
|
uint height = 0;
|
|
|
|
//ADRS.setTreeHeight(0);
|
|
SET_LTREE_TREE_HEIGHT(addr,height);
|
|
unsigned long bound;
|
|
while ( l > 1 )
|
|
{
|
|
bound = l >> 1; //floor(l / 2);
|
|
for ( i = 0; i < bound; i = i + 1 ) {
|
|
//ADRS.setTreeIndex(i);
|
|
SET_LTREE_TREE_INDEX(addr,i);
|
|
//wots_pk[i] = RAND_HASH(pk[2i], pk[2i + 1], SEED, ADRS);
|
|
hash_2n_n(wots_pk+i*n,wots_pk+i*2*n, pub_seed, addr, n);
|
|
}
|
|
//if ( l % 2 == 1 ) {
|
|
if(l&1)
|
|
{
|
|
//pk[floor(l / 2) + 1] = pk[l];
|
|
memcpy(wots_pk+(l>>1)*n,wots_pk+(l-1)*n, n);
|
|
//l = ceil(l / 2);
|
|
l=(l>>1)+1;
|
|
}
|
|
else
|
|
{
|
|
//l = ceil(l / 2);
|
|
l=(l>>1);
|
|
}
|
|
//ADRS.setTreeHeight(ADRS.getTreeHeight() + 1);
|
|
height++;
|
|
SET_LTREE_TREE_HEIGHT(addr,height);
|
|
}
|
|
//return pk[0];
|
|
memcpy(leaf,wots_pk,n);
|
|
}
|
|
|
|
/**
|
|
* Computes the leaf at a given address. First generates the WOTS key pair, then computes leaf using l_tree. As this happens position independent, we only require that addr encodes the right ltree-address.
|
|
*/
|
|
static void gen_leaf_wots(unsigned char *leaf, const unsigned char *sk_seed, const xmss_params *params, const unsigned char *pub_seed, unsigned char ltree_addr[16], unsigned char ots_addr[16])
|
|
{
|
|
unsigned char seed[32];
|
|
unsigned char pk[params->wots_par->keysize];
|
|
|
|
get_seed(seed, sk_seed, ots_addr);
|
|
wots_pkgen(pk, seed, params->wots_par, pub_seed, ots_addr);
|
|
|
|
l_tree(leaf, pk, params, pub_seed, ltree_addr);
|
|
}
|
|
|
|
/**
|
|
* Merkle's TreeHash algorithm. The address only needs to initialize the first 78 bits of addr. Everything else will be set by treehash.
|
|
* Currently only used for key generation.
|
|
*
|
|
*/
|
|
static void treehash(unsigned char *node, int height, int index, const unsigned char *sk_seed, const xmss_params *params, const unsigned char *pub_seed, const unsigned char addr[16])
|
|
{
|
|
|
|
uint idx = index;
|
|
uint n = params->n;
|
|
// use three different addresses because at this point we use all three formats in parallel
|
|
unsigned char ots_addr[16];
|
|
unsigned char ltree_addr[16];
|
|
unsigned char node_addr[16];
|
|
memcpy(ots_addr, addr, 10);
|
|
SET_OTS_BIT(ots_addr, 1);
|
|
memcpy(ltree_addr, addr, 10);
|
|
SET_OTS_BIT(ltree_addr, 0);
|
|
SET_LTREE_BIT(ltree_addr, 1);
|
|
memcpy(node_addr, ltree_addr, 10);
|
|
SET_LTREE_BIT(node_addr, 0);
|
|
SET_NODE_PADDING(node_addr);
|
|
|
|
int lastnode,i;
|
|
unsigned char stack[(height+1)*n];
|
|
unsigned int stacklevels[height+1];
|
|
unsigned int stackoffset=0;
|
|
|
|
lastnode = idx+(1<<height);
|
|
|
|
for(;idx<lastnode;idx++)
|
|
{
|
|
SET_LTREE_ADDRESS(ltree_addr,idx);
|
|
SET_OTS_ADDRESS(ots_addr,idx);
|
|
gen_leaf_wots(stack+stackoffset*n,sk_seed,params, pub_seed, ltree_addr, ots_addr);
|
|
stacklevels[stackoffset] = 0;
|
|
stackoffset++;
|
|
while(stackoffset>1 && stacklevels[stackoffset-1] == stacklevels[stackoffset-2])
|
|
{
|
|
SET_NODE_TREE_HEIGHT(node_addr,stacklevels[stackoffset-1]);
|
|
SET_NODE_TREE_INDEX(node_addr, (idx >> (stacklevels[stackoffset-1]+1)));
|
|
hash_2n_n(stack+(stackoffset-2)*n,stack+(stackoffset-2)*n, pub_seed,
|
|
node_addr, n);
|
|
stacklevels[stackoffset-2]++;
|
|
stackoffset--;
|
|
}
|
|
}
|
|
for(i=0;i<n;i++)
|
|
node[i] = stack[i];
|
|
}
|
|
|
|
/**
|
|
* Computes a root node given a leaf and an authapth
|
|
*/
|
|
static void validate_authpath(unsigned char *root, const unsigned char *leaf, unsigned long leafidx, const unsigned char *authpath, const xmss_params *params, const unsigned char *pub_seed, unsigned char addr[16])
|
|
{
|
|
uint n = params->n;
|
|
|
|
int i,j;
|
|
unsigned char buffer[2*n];
|
|
|
|
// If leafidx is odd (last bit = 1), current path element is a right child and authpath has to go to the left.
|
|
// Otherwise, it is the other way around
|
|
if(leafidx&1)
|
|
{
|
|
for(j=0;j<n;j++)
|
|
buffer[n+j] = leaf[j];
|
|
for(j=0;j<n;j++)
|
|
buffer[j] = authpath[j];
|
|
}
|
|
else
|
|
{
|
|
for(j=0;j<n;j++)
|
|
buffer[j] = leaf[j];
|
|
for(j=0;j<n;j++)
|
|
buffer[n+j] = authpath[j];
|
|
}
|
|
authpath += n;
|
|
|
|
for(i=0;i<params->h-1;i++)
|
|
{
|
|
SET_NODE_TREE_HEIGHT(addr,i);
|
|
leafidx >>= 1;
|
|
SET_NODE_TREE_INDEX(addr, leafidx);
|
|
if(leafidx&1)
|
|
{
|
|
hash_2n_n(buffer+n,buffer,pub_seed, addr, n);
|
|
for(j=0;j<n;j++)
|
|
buffer[j] = authpath[j];
|
|
}
|
|
else
|
|
{
|
|
hash_2n_n(buffer,buffer,pub_seed, addr, n);
|
|
for(j=0;j<n;j++)
|
|
buffer[j+n] = authpath[j];
|
|
}
|
|
authpath += n;
|
|
}
|
|
SET_NODE_TREE_HEIGHT(addr, (params->h-1));
|
|
leafidx >>= 1;
|
|
SET_NODE_TREE_INDEX(addr, leafidx);
|
|
hash_2n_n(root,buffer,pub_seed,addr,n);
|
|
}
|
|
|
|
/**
|
|
* Computes the authpath and the root. This method is using a lot of space as we build the whole tree and then select the authpath nodes.
|
|
* For more efficient algorithms see e.g. the chapter on hash-based signatures in Bernstein, Buchmann, Dahmen. "Post-quantum Cryptography", Springer 2009.
|
|
* It returns the authpath in "authpath" with the node on level 0 at index 0.
|
|
*/
|
|
static void compute_authpath_wots(unsigned char *root, unsigned char *authpath, unsigned long leaf_idx, const unsigned char *sk_seed, const xmss_params *params, unsigned char *pub_seed, unsigned char addr[16])
|
|
{
|
|
uint i, j, level;
|
|
int n = params->n;
|
|
int h = params->h;
|
|
|
|
unsigned char tree[2*(1<<h)*n];
|
|
|
|
unsigned char ots_addr[16];
|
|
unsigned char ltree_addr[16];
|
|
unsigned char node_addr[16];
|
|
|
|
memcpy(ots_addr, addr, 10);
|
|
SET_OTS_BIT(ots_addr, 1);
|
|
memcpy(ltree_addr, addr, 10);
|
|
SET_OTS_BIT(ltree_addr, 0);
|
|
SET_LTREE_BIT(ltree_addr, 1);
|
|
memcpy(node_addr, ltree_addr, 10);
|
|
SET_LTREE_BIT(node_addr, 0);
|
|
SET_NODE_PADDING(node_addr);
|
|
|
|
|
|
// Compute all leaves
|
|
for(i = 0; i < (1<<h); i++)
|
|
{
|
|
SET_LTREE_ADDRESS(ltree_addr,i);
|
|
SET_OTS_ADDRESS(ots_addr,i);
|
|
gen_leaf_wots(tree+((1<<h)*n + i*n), sk_seed, params, pub_seed, ltree_addr, ots_addr);
|
|
}
|
|
|
|
|
|
level = 0;
|
|
// Compute tree:
|
|
// Outer loop: For each inner layer
|
|
for (i = (1<<h); i > 0; i>>=1)
|
|
{
|
|
SET_NODE_TREE_HEIGHT(node_addr, level);
|
|
// Inner loop: for each pair of sibling nodes
|
|
for (j = 0; j < i; j+=2)
|
|
{
|
|
SET_NODE_TREE_INDEX(node_addr, j>>1);
|
|
hash_2n_n(tree + (i>>1)*n + (j>>1) * n, tree + i*n + j*n, pub_seed, node_addr, n);
|
|
}
|
|
level++;
|
|
}
|
|
|
|
// copy authpath
|
|
for(i=0;i<h;i++)
|
|
memcpy(authpath + i*n, tree + ((1<<h)>>i)*n + ((leaf_idx >> i) ^ 1) * n, n);
|
|
|
|
// copy root
|
|
memcpy(root, tree+n, n);
|
|
}
|
|
|
|
|
|
/*
|
|
* Generates a XMSS key pair for a given parameter set.
|
|
* Format sk: [(32bit) idx || SK_SEED || SK_PRF || PUB_SEED]
|
|
* Format pk: [root || PUB_SEED] omitting algo oid.
|
|
*/
|
|
int xmss_keypair(unsigned char *pk, unsigned char *sk, xmss_params *params)
|
|
{
|
|
uint n = params->n;
|
|
uint m = params->m;
|
|
// Set idx = 0
|
|
sk[0] = 0;
|
|
sk[1] = 0;
|
|
sk[2] = 0;
|
|
sk[3] = 0;
|
|
// Init SK_SEED (n byte), SK_PRF (m byte), and PUB_SEED (n byte)
|
|
randombytes(sk+4,2*n+m);
|
|
// Copy PUB_SEED to public key
|
|
memcpy(pk+n, sk+4+n+m,n);
|
|
|
|
unsigned char addr[16] = {0,0,0,0};
|
|
// Compute root
|
|
treehash(pk, params->h, 0, sk+4, params, sk+4+n+m, addr);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Signs a message.
|
|
* Returns
|
|
* 1. an array containing the signature followed by the message AND
|
|
* 2. an updated secret key!
|
|
*
|
|
*/
|
|
int xmss_sign(unsigned char *sk, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen, const xmss_params *params, unsigned char* pk)
|
|
{
|
|
uint n = params->n;
|
|
uint m = params->m;
|
|
|
|
// Extract SK
|
|
unsigned long idx = (sk[0] << 24) | (sk[1] << 16) | (sk[2] << 8) || sk[3];
|
|
unsigned char sk_seed[n];
|
|
memcpy(sk_seed,sk+4,n);
|
|
unsigned char sk_prf[m];
|
|
memcpy(sk_prf,sk+4+n,m);
|
|
unsigned char pub_seed[n];
|
|
memcpy(pub_seed,sk+4+n+m,n);
|
|
|
|
// Update SK
|
|
sk[0] = ((idx + 1) >> 24) & 255;
|
|
sk[1] = ((idx + 1) >> 16) & 255;
|
|
sk[2] = ((idx + 1) >> 8) & 255;
|
|
sk[3] = (idx + 1) & 255;
|
|
// -- Secret key for this non-forward-secure version is now updated.
|
|
// -- A productive implementation should use a file handle instead and write the updated secret key at this point!
|
|
|
|
// Init working params
|
|
unsigned long long i;
|
|
unsigned char R[m];
|
|
unsigned char msg_h[m];
|
|
unsigned char root[n];
|
|
unsigned char ots_seed[n];
|
|
unsigned char ots_addr[16] = {0,0,0,0};
|
|
|
|
// ---------------------------------
|
|
// Message Hashing
|
|
// ---------------------------------
|
|
|
|
// Message Hash:
|
|
// First compute pseudorandom key
|
|
prf_m(R, msg, msglen, sk_prf, m);
|
|
// Then use it for message digest
|
|
hash_m(msg_h, msg, msglen, R, m, m);
|
|
|
|
// Start collecting signature
|
|
*sig_msg_len = 0;
|
|
|
|
// Copy index to signature
|
|
sig_msg[0] = (idx >> 24) & 255;
|
|
sig_msg[1] = (idx >> 16) & 255;
|
|
sig_msg[2] = (idx >> 8) & 255;
|
|
sig_msg[3] = idx & 255;
|
|
|
|
sig_msg += 4;
|
|
*sig_msg_len += 4;
|
|
|
|
// Copy R to signature
|
|
for(i=0; i<m; i++)
|
|
sig_msg[i] = R[i];
|
|
|
|
sig_msg += m;
|
|
*sig_msg_len += m;
|
|
|
|
// ----------------------------------
|
|
// Now we start to "really sign"
|
|
// ----------------------------------
|
|
|
|
// Prepare Address
|
|
SET_OTS_BIT(ots_addr,1);
|
|
SET_OTS_ADDRESS(ots_addr,idx);
|
|
|
|
// Compute seed for OTS key pair
|
|
get_seed(ots_seed, sk_seed, ots_addr);
|
|
|
|
// Compute WOTS signature
|
|
wots_sign(sig_msg, msg_h, ots_seed, params->wots_par, pub_seed, ots_addr);
|
|
|
|
sig_msg += params->wots_par->keysize;
|
|
*sig_msg_len += params->wots_par->keysize;
|
|
|
|
compute_authpath_wots(root, sig_msg, idx, sk_seed, params, pub_seed, ots_addr);
|
|
sig_msg += params->h*n;
|
|
*sig_msg_len += params->h*n;
|
|
|
|
//DEBUG
|
|
for(i=0;i<n;i++)
|
|
if(root[i] != pk[i])
|
|
printf("Different PK's %llu",i);
|
|
|
|
//Whipe secret elements?
|
|
//zerobytes(tsk, CRYPTO_SECRETKEYBYTES);
|
|
|
|
memcpy(sig_msg,msg,msglen);
|
|
*sig_msg_len += msglen;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Verifies a given message signature pair under a given public key.
|
|
*/
|
|
int xmss_sign_open(unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk, const xmss_params *params)
|
|
{
|
|
uint n = params->n;
|
|
uint m = params->m;
|
|
|
|
unsigned long long i, m_len;
|
|
unsigned long idx=0;
|
|
unsigned char wots_pk[params->wots_par->keysize];
|
|
unsigned char pkhash[n];
|
|
unsigned char root[n];
|
|
unsigned char msg_h[m];
|
|
|
|
unsigned char pub_seed[n];
|
|
memcpy(pub_seed,pk+n,n);
|
|
|
|
// Init addresses
|
|
unsigned char ots_addr[16] = {0,0,0,0};
|
|
unsigned char ltree_addr[16];
|
|
unsigned char node_addr[16];
|
|
|
|
SET_OTS_BIT(ots_addr, 1);
|
|
|
|
memcpy(ltree_addr, ots_addr, 10);
|
|
SET_OTS_BIT(ltree_addr, 0);
|
|
SET_LTREE_BIT(ltree_addr, 1);
|
|
|
|
memcpy(node_addr, ltree_addr, 10);
|
|
SET_LTREE_BIT(node_addr, 0);
|
|
SET_NODE_PADDING(node_addr);
|
|
|
|
// Extract index
|
|
idx = (sig_msg[0] << 24) | (sig_msg[1] << 16) | (sig_msg[2] << 8) || sig_msg[3];
|
|
sig_msg += 4;
|
|
sig_msg_len -= 4;
|
|
|
|
// hash message (recall, R is now on pole position at sig_msg
|
|
unsigned long long tmp_sig_len = m+params->wots_par->keysize+params->h*n;
|
|
m_len = sig_msg_len - tmp_sig_len;
|
|
hash_m(msg_h, sig_msg + tmp_sig_len, m_len, sig_msg, m, m);
|
|
|
|
sig_msg += m;
|
|
sig_msg_len -= m;
|
|
|
|
//-----------------------
|
|
// Verify signature
|
|
//-----------------------
|
|
|
|
// Prepare Address
|
|
SET_OTS_ADDRESS(ots_addr,idx);
|
|
// Check WOTS signature
|
|
wots_pkFromSig(wots_pk, sig_msg, msg_h, params->wots_par, pub_seed, ots_addr);
|
|
|
|
sig_msg += params->wots_par->keysize;
|
|
sig_msg_len -= params->wots_par->keysize;
|
|
|
|
// Compute Ltree
|
|
SET_LTREE_ADDRESS(ltree_addr, idx);
|
|
l_tree(pkhash, wots_pk, params, pub_seed, ltree_addr);
|
|
|
|
// Compute root
|
|
validate_authpath(root, pkhash, idx, sig_msg, params, pub_seed, node_addr);
|
|
|
|
sig_msg += params->h*n;
|
|
sig_msg_len -= params->h*n;
|
|
|
|
for(i=0;i<n;i++)
|
|
if(root[i] != pk[i])
|
|
goto fail;
|
|
|
|
*msglen = sig_msg_len;
|
|
for(i=0;i<*msglen;i++)
|
|
msg[i] = sig_msg[i];
|
|
|
|
return 0;
|
|
|
|
|
|
fail:
|
|
*msglen = sig_msg_len;
|
|
for(i=0;i<*msglen;i++)
|
|
msg[i] = 0;
|
|
*msglen = -1;
|
|
return -1;
|
|
} |