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/**
* @file ristretto.cxx
* @author Mike Hamburg
*
* @copyright
* Copyright (c) 2015 Cryptography Research, Inc. \n
* Released under the MIT License. See LICENSE.txt for license information.
*
* @brief Ristretto implementation widget
*/
#include <decaf.hxx>
#include <stdio.h>
using namespace decaf;
static inline int hexi(char c) {
if (c >= '0' && c <= '9') return c-'0';
if (c >= 'a' && c <= 'f') return c-'a'+0xa;
if (c >= 'A' && c <= 'F') return c-'A'+0xa;
return -1;
}
static int parsehex(uint8_t *out, size_t sizeof_out, const char *hex) {
size_t l = strlen(hex);
if (l%2 != 0) {
fprintf(stderr,"String should be hex, but has odd length\n: %s\n", hex);
return -1;
} else if (l/2 > sizeof_out) {
fprintf(stderr,"Argument is too long: %s\n", hex);
return -1;
}
memset(out,0,sizeof_out);
int ret1,ret2;
for (size_t i=0; i<l/2; i++) {
if ( (ret1 = hexi(hex[2*i ])) < 0
|| (ret2 = hexi(hex[2*i+1])) < 0) {
fprintf(stderr,"Invalid hex %s\n",hex);
return -1;
}
out[i] = ret1*16+ret2;
}
return 0;
}
static void printhex(const uint8_t *in, size_t sizeof_in) {
for (; sizeof_in > 0; in++,sizeof_in--) {
printf("%02x",*in);
}
}
static int g_argc = 0;
static char **g_argv = NULL;
static int error = 0;
static int done = 0;
static void usage() {
const char *me=g_argv[0];
if (!me) me = "ristretto";
for (unsigned i=0; g_argv[0][i]; i++) {
if (g_argv[0][i] == '/' && g_argv[0][i+1] != 0 && g_argv[0][i+1] != '/') {
me = &g_argv[0][i];
}
}
fprintf(stderr,"Usage: %s [points] [operations] ...\n", me);
fprintf(stderr," -b 255|448: Set which group to use (sometimes inferred from lengths)\n");
fprintf(stderr," -E: Display output as Elligator inverses\n");
fprintf(stderr," -D: Display output in EdDSA format (times clearing ratio)\n");
fprintf(stderr," -R: Display raw xyzt\n");
fprintf(stderr," -C: Display output in X[25519|448] format\n");
fprintf(stderr," -H: ... divide by encoding ratio first\n");
fprintf(stderr,"\n");
fprintf(stderr," Ways to create points:\n");
fprintf(stderr," [hex]: Point from point data as hex\n");
fprintf(stderr," -e [hex]: Create point by hashing to curve using elligator\n");
fprintf(stderr," base: Base point of curve\n");
fprintf(stderr," identity: Identity point of curve\n");
fprintf(stderr,"\n");
fprintf(stderr," Operations:\n");
fprintf(stderr," -n [point]: negative of point\n");
fprintf(stderr," -s [scalar] * [point]: Hash to curve using elligator\n");
fprintf(stderr," [point] + [point]: Add two points\n");
fprintf(stderr,"\n");
fprintf(stderr," NB: this is a debugging widget. It doesn't yet have order of operations.\n");
fprintf(stderr," *** DON'T USE THIS UTILITY FOR ACTUAL CRYPTO! ***\n");
fprintf(stderr," It's only for debugging!\n");
fprintf(stderr,"\n");
exit(-2);
}
template<typename Group> class Run {
public:
static void run() {
uint8_t tmp[Group::Point::SER_BYTES];
typename Group::Point a,b;
typename Group::Scalar s;
bool plus=false, empty=true, elligator=false, mul=false, scalar=false, div=false, torque=false,
scalarempty=true, neg=false, einv=false, like_eddsa=false, like_x=false, decoeff=false, raw=false;
if (done || error) return;
for (int i=1; i<g_argc && !error; i++) {
bool point = false;
if (!strcmp(g_argv[i],"-b") && ++i<g_argc) {
if (atoi(g_argv[i]) == Group::bits()) continue;
else return;
} else if (!strcmp(g_argv[i],"+")) {
if (elligator || scalar || empty) usage();
plus = true;
} else if (!strcmp(g_argv[i],"-n")) {
neg = !neg;
} else if (!strcmp(g_argv[i],"-E")) {
einv = true;
} else if (!strcmp(g_argv[i],"-R")) {
raw = true;
} else if (!strcmp(g_argv[i],"-D")) {
like_eddsa = true;
} else if (!strcmp(g_argv[i],"-C")) {
like_x = true;
} else if (!strcmp(g_argv[i],"-H")) {
decoeff = true;
} else if (!strcmp(g_argv[i],"-T")) {
torque = true;
} else if (!strcmp(g_argv[i],"*")) {
if (elligator || scalar || scalarempty || div) usage();
mul = true;
} else if (!strcmp(g_argv[i],"/")) {
if (elligator || scalar || scalarempty || mul) usage();
div = true;
} else if (!strcmp(g_argv[i],"-s")) {
if (elligator || scalar || !scalarempty) usage();
scalar = true;
} else if (!strcmp(g_argv[i],"-e")) {
if (elligator || scalar) usage();
elligator = true;
} else if (!strcmp(g_argv[i],"base")) {
if (elligator || scalar) usage();
b = b.base();
point = true;
} else if (!strcmp(g_argv[i],"identity")) {
if (elligator || scalar) usage();
b = b.identity();
point = true;
} else if ((strlen(g_argv[i]) == 2*sizeof(tmp)
|| ((scalar || elligator) && strlen(g_argv[i]) <= 2*sizeof(tmp)))
&& !(error=parsehex(tmp,sizeof(tmp),g_argv[i]))) {
if (scalar) {
s = Block(tmp,sizeof(tmp)); scalar=false; scalarempty=false;
} else if (elligator) {
point = true;
b.set_to_hash(Block(tmp,sizeof(tmp))); elligator=false;
} else if (DECAF_SUCCESS != b.decode(Block(tmp,sizeof(tmp)))) {
fprintf(stderr,"Error: %s isn't in the group\n",g_argv[i]);
error = -1;
} else {
point = true;
}
} else if (error || !empty) usage();
if (point) {
if (neg) { b = -b; neg = false; }
if (div) { b /= s; div=false; }
if (torque) { b = b.debugging_torque(); torque=false; }
if (mul) { b *= s; mul=false; }
if (empty) { a = b; empty=false; }
else if (plus) { a += b; plus=false; }
else usage();
}
}
if (!error && !empty) {
if (einv) {
uint8_t buffer[Group::Point::HASH_BYTES];
for (int h=0; h<1<<Group::Point::INVERT_ELLIGATOR_WHICH_BITS; h++) {
if (DECAF_SUCCESS == a.invert_elligator(
Buffer(buffer,sizeof(buffer)), h
)) {
printhex(buffer,sizeof(buffer));
printf("\n");
}
}
} else if (raw) {
printhex((const uint8_t *)&a, sizeof(a));
printf("\n");
} else if (like_eddsa) {
if (decoeff) a /= (Group::Point::EDDSA_ENCODE_RATIO);
SecureBuffer b = a.mul_by_ratio_and_encode_like_eddsa();
printhex(b.data(),b.size());
printf("\n");
} else if (like_x) {
if (decoeff) a /= (Group::Point::LADDER_ENCODE_RATIO);
SecureBuffer b = a.mul_by_ratio_and_encode_like_ladder();
printhex(b.data(),b.size());
printf("\n");
} else {
a.serialize_into(tmp);
printhex(tmp,sizeof(tmp));
printf("\n");
}
done = true;
}
}
};
int main(int argc, char **argv) {
g_argc = argc;
g_argv = argv;
run_for_all_curves<Run>();
if (!done) usage();
return (error<0) ? -error : error;
}
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