summaryrefslogtreecommitdiffhomepage
path: root/src/pk/dh/dh.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/pk/dh/dh.c')
-rw-r--r--src/pk/dh/dh.c524
1 files changed, 524 insertions, 0 deletions
diff --git a/src/pk/dh/dh.c b/src/pk/dh/dh.c
new file mode 100644
index 0000000..a54f29b
--- /dev/null
+++ b/src/pk/dh/dh.c
@@ -0,0 +1,524 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
+ */
+#include "tomcrypt.h"
+
+/**
+ @file dh.c
+ DH crypto, Tom St Denis
+*/
+
+#ifdef MDH
+
+/* max export size we'll encounter (smaller than this but lets round up a bit) */
+#define DH_BUF_SIZE 1200
+
+/* This holds the key settings. ***MUST*** be organized by size from smallest to largest. */
+static const struct {
+ int size;
+ char *name, *base, *prime;
+} sets[] = {
+#ifdef DH768
+{
+ 96,
+ "DH-768",
+ "4",
+ "F///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "//////m3wvV"
+},
+#endif
+#ifdef DH1024
+{
+ 128,
+ "DH-1024",
+ "4",
+ "F///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////m3C47"
+},
+#endif
+#ifdef DH1280
+{
+ 160,
+ "DH-1280",
+ "4",
+ "F///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "//////////////////////////////m4kSN"
+},
+#endif
+#ifdef DH1536
+{
+ 192,
+ "DH-1536",
+ "4",
+ "F///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////m5uqd"
+},
+#endif
+#ifdef DH1792
+{
+ 224,
+ "DH-1792",
+ "4",
+ "F///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "//////////////////////////////////////////////////////mT/sd"
+},
+#endif
+#ifdef DH2048
+{
+ 256,
+ "DH-2048",
+ "4",
+ "3///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "/////////////////////////////////////////m8MPh"
+},
+#endif
+#ifdef DH2560
+{
+ 320,
+ "DH-2560",
+ "4",
+ "3///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "/////mKFpF"
+},
+#endif
+#ifdef DH3072
+{
+ 384,
+ "DH-3072",
+ "4",
+ "3///////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "/////////////////////////////m32nN"
+},
+#endif
+#ifdef DH4096
+{
+ 512,
+ "DH-4096",
+ "4",
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "////////////////////////////////////////////////////////////"
+ "/////////////////////m8pOF"
+},
+#endif
+{
+ 0,
+ NULL,
+ NULL,
+ NULL
+}
+};
+
+static int is_valid_idx(int n)
+{
+ int x;
+
+ for (x = 0; sets[x].size; x++);
+ if ((n < 0) || (n >= x)) {
+ return 0;
+ }
+ return 1;
+}
+
+/**
+ Test the DH sub-system (can take a while)
+ @return CRYPT_OK if successful
+*/
+int dh_test(void)
+{
+ mp_int p, g, tmp;
+ int x, err, primality;
+
+ if ((err = mp_init_multi(&p, &g, &tmp, NULL)) != MP_OKAY) { goto error; }
+
+ for (x = 0; sets[x].size != 0; x++) {
+#if 0
+ printf("dh_test():testing size %d-bits\n", sets[x].size * 8);
+#endif
+ if ((err = mp_read_radix(&g,(char *)sets[x].base, 64)) != MP_OKAY) { goto error; }
+ if ((err = mp_read_radix(&p,(char *)sets[x].prime, 64)) != MP_OKAY) { goto error; }
+
+ /* ensure p is prime */
+ if ((err = is_prime(&p, &primality)) != CRYPT_OK) { goto done; }
+ if (primality == 0) {
+ err = CRYPT_FAIL_TESTVECTOR;
+ goto done;
+ }
+
+ if ((err = mp_sub_d(&p, 1, &tmp)) != MP_OKAY) { goto error; }
+ if ((err = mp_div_2(&tmp, &tmp)) != MP_OKAY) { goto error; }
+
+ /* ensure (p-1)/2 is prime */
+ if ((err = is_prime(&tmp, &primality)) != CRYPT_OK) { goto done; }
+ if (primality == 0) {
+ err = CRYPT_FAIL_TESTVECTOR;
+ goto done;
+ }
+
+ /* now see if g^((p-1)/2) mod p is in fact 1 */
+ if ((err = mp_exptmod(&g, &tmp, &p, &tmp)) != MP_OKAY) { goto error; }
+ if (mp_cmp_d(&tmp, 1)) {
+ err = CRYPT_FAIL_TESTVECTOR;
+ goto done;
+ }
+ }
+ err = CRYPT_OK;
+ goto done;
+error:
+ err = mpi_to_ltc_error(err);
+done:
+ mp_clear_multi(&tmp, &g, &p, NULL);
+ return err;
+}
+
+/**
+ Get the min and max DH key sizes (octets)
+ @param low [out] The smallest key size supported
+ @param high [out] The largest key size supported
+*/
+void dh_sizes(int *low, int *high)
+{
+ int x;
+ LTC_ARGCHK(low != NULL);
+ LTC_ARGCHK(high != NULL);
+ *low = INT_MAX;
+ *high = 0;
+ for (x = 0; sets[x].size != 0; x++) {
+ if (*low > sets[x].size) *low = sets[x].size;
+ if (*high < sets[x].size) *high = sets[x].size;
+ }
+}
+
+/**
+ Returns the key size of a given DH key (octets)
+ @param key The DH key to get the size of
+ @return The size if valid or INT_MAX if not
+*/
+int dh_get_size(dh_key *key)
+{
+ LTC_ARGCHK(key != NULL);
+ if (is_valid_idx(key->idx) == 1) {
+ return sets[key->idx].size;
+ } else {
+ return INT_MAX; /* large value that would cause dh_make_key() to fail */
+ }
+}
+
+/**
+ Make a DH key [private key pair]
+ @param prng An active PRNG state
+ @param wprng The index for the PRNG you desire to use
+ @param keysize The key size (octets) desired
+ @param key [out] Where the newly created DH key will be stored
+ @return CRYPT_OK if successful, note: on error all allocated memory will be freed automatically.
+*/
+int dh_make_key(prng_state *prng, int wprng, int keysize, dh_key *key)
+{
+ unsigned char *buf;
+ unsigned long x;
+ mp_int p, g;
+ int err;
+
+ LTC_ARGCHK(key != NULL);
+
+ /* good prng? */
+ if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
+ return err;
+ }
+
+ /* find key size */
+ for (x = 0; (keysize > sets[x].size) && (sets[x].size != 0); x++);
+#ifdef FAST_PK
+ keysize = MIN(sets[x].size, 32);
+#else
+ keysize = sets[x].size;
+#endif
+
+ if (sets[x].size == 0) {
+ return CRYPT_INVALID_KEYSIZE;
+ }
+ key->idx = x;
+
+ /* allocate buffer */
+ buf = XMALLOC(keysize);
+ if (buf == NULL) {
+ return CRYPT_MEM;
+ }
+
+ /* make up random string */
+ if (prng_descriptor[wprng].read(buf, keysize, prng) != (unsigned long)keysize) {
+ err = CRYPT_ERROR_READPRNG;
+ goto error2;
+ }
+
+ /* init parameters */
+ if ((err = mp_init_multi(&g, &p, &key->x, &key->y, NULL)) != MP_OKAY) {
+ goto error;
+ }
+ if ((err = mp_read_radix(&g, sets[key->idx].base, 64)) != MP_OKAY) { goto error; }
+ if ((err = mp_read_radix(&p, sets[key->idx].prime, 64)) != MP_OKAY) { goto error; }
+
+ /* load the x value */
+ if ((err = mp_read_unsigned_bin(&key->x, buf, keysize)) != MP_OKAY) { goto error; }
+ if ((err = mp_exptmod(&g, &key->x, &p, &key->y)) != MP_OKAY) { goto error; }
+ key->type = PK_PRIVATE;
+
+ if ((err = mp_shrink(&key->x)) != MP_OKAY) { goto error; }
+ if ((err = mp_shrink(&key->y)) != MP_OKAY) { goto error; }
+
+ /* free up ram */
+ err = CRYPT_OK;
+ goto done;
+error:
+ err = mpi_to_ltc_error(err);
+error2:
+ mp_clear_multi(&key->x, &key->y, NULL);
+done:
+#ifdef LTC_CLEAN_STACK
+ zeromem(buf, keysize);
+#endif
+ mp_clear_multi(&p, &g, NULL);
+ XFREE(buf);
+ return err;
+}
+
+/**
+ Free the allocated ram for a DH key
+ @param key The key which you wish to free
+*/
+void dh_free(dh_key *key)
+{
+ LTC_ARGCHK(key != NULL);
+ mp_clear_multi(&key->x, &key->y, NULL);
+}
+
+/**
+ Export a DH key to a binary packet
+ @param out [out] The destination for the key
+ @param outlen [in/out] The max size and resulting size of the DH key
+ @param type Which type of key (PK_PRIVATE or PK_PUBLIC)
+ @param key The key you wish to export
+ @return CRYPT_OK if successful
+*/
+int dh_export(unsigned char *out, unsigned long *outlen, int type, dh_key *key)
+{
+ unsigned long y, z;
+ int err;
+
+ LTC_ARGCHK(out != NULL);
+ LTC_ARGCHK(outlen != NULL);
+ LTC_ARGCHK(key != NULL);
+
+ /* can we store the static header? */
+ if (*outlen < (PACKET_SIZE + 2)) {
+ return CRYPT_BUFFER_OVERFLOW;
+ }
+
+ if (type == PK_PRIVATE && key->type != PK_PRIVATE) {
+ return CRYPT_PK_NOT_PRIVATE;
+ }
+
+ /* header */
+ y = PACKET_SIZE;
+
+ /* header */
+ out[y++] = type;
+ out[y++] = (unsigned char)(sets[key->idx].size / 8);
+
+ /* export y */
+ OUTPUT_BIGNUM(&key->y, out, y, z);
+
+ if (type == PK_PRIVATE) {
+ /* export x */
+ OUTPUT_BIGNUM(&key->x, out, y, z);
+ }
+
+ /* store header */
+ packet_store_header(out, PACKET_SECT_DH, PACKET_SUB_KEY);
+
+ /* store len */
+ *outlen = y;
+ return CRYPT_OK;
+}
+
+/**
+ Import a DH key from a binary packet
+ @param in The packet to read
+ @param inlen The length of the input packet
+ @param key [out] Where to import the key to
+ @return CRYPT_OK if successful, on error all allocated memory is freed automatically
+*/
+int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key)
+{
+ unsigned long x, y, s;
+ int err;
+
+ LTC_ARGCHK(in != NULL);
+ LTC_ARGCHK(key != NULL);
+
+ /* make sure valid length */
+ if ((2+PACKET_SIZE) > inlen) {
+ return CRYPT_INVALID_PACKET;
+ }
+
+ /* check type byte */
+ if ((err = packet_valid_header((unsigned char *)in, PACKET_SECT_DH, PACKET_SUB_KEY)) != CRYPT_OK) {
+ return err;
+ }
+
+ /* init */
+ if ((err = mp_init_multi(&key->x, &key->y, NULL)) != MP_OKAY) {
+ return mpi_to_ltc_error(err);
+ }
+
+ /* advance past packet header */
+ y = PACKET_SIZE;
+
+ /* key type, e.g. private, public */
+ key->type = (int)in[y++];
+
+ /* key size in bytes */
+ s = (unsigned long)in[y++] * 8;
+
+ for (x = 0; (s > (unsigned long)sets[x].size) && (sets[x].size != 0); x++);
+ if (sets[x].size == 0) {
+ err = CRYPT_INVALID_KEYSIZE;
+ goto error;
+ }
+ key->idx = (int)x;
+
+ /* type check both values */
+ if ((key->type != PK_PUBLIC) && (key->type != PK_PRIVATE)) {
+ err = CRYPT_PK_TYPE_MISMATCH;
+ goto error;
+ }
+
+ /* is the key idx valid? */
+ if (is_valid_idx(key->idx) != 1) {
+ err = CRYPT_PK_TYPE_MISMATCH;
+ goto error;
+ }
+
+ /* load public value g^x mod p*/
+ INPUT_BIGNUM(&key->y, in, x, y, inlen);
+
+ if (key->type == PK_PRIVATE) {
+ INPUT_BIGNUM(&key->x, in, x, y, inlen);
+ }
+
+ /* eliminate private key if public */
+ if (key->type == PK_PUBLIC) {
+ mp_clear(&key->x);
+ }
+
+ return CRYPT_OK;
+error:
+ mp_clear_multi(&key->y, &key->x, NULL);
+ return err;
+}
+
+/**
+ Create a DH shared secret.
+ @param private_key The private DH key in the pair
+ @param public_key The public DH key in the pair
+ @param out [out] The destination of the shared data
+ @param outlen [in/out] The max size and resulting size of the shared data.
+ @return CRYPT_OK if successful
+*/
+int dh_shared_secret(dh_key *private_key, dh_key *public_key,
+ unsigned char *out, unsigned long *outlen)
+{
+ mp_int tmp, p;
+ unsigned long x;
+ int err;
+
+ LTC_ARGCHK(private_key != NULL);
+ LTC_ARGCHK(public_key != NULL);
+ LTC_ARGCHK(out != NULL);
+ LTC_ARGCHK(outlen != NULL);
+
+ /* types valid? */
+ if (private_key->type != PK_PRIVATE) {
+ return CRYPT_PK_NOT_PRIVATE;
+ }
+
+ /* same idx? */
+ if (private_key->idx != public_key->idx) {
+ return CRYPT_PK_TYPE_MISMATCH;
+ }
+
+ /* compute y^x mod p */
+ if ((err = mp_init_multi(&tmp, &p, NULL)) != MP_OKAY) {
+ return mpi_to_ltc_error(err);
+ }
+
+ if ((err = mp_read_radix(&p, (char *)sets[private_key->idx].prime, 64)) != MP_OKAY) { goto error; }
+ if ((err = mp_exptmod(&public_key->y, &private_key->x, &p, &tmp)) != MP_OKAY) { goto error; }
+
+ /* enough space for output? */
+ x = (unsigned long)mp_unsigned_bin_size(&tmp);
+ if (*outlen < x) {
+ err = CRYPT_BUFFER_OVERFLOW;
+ goto done;
+ }
+ if ((err = mp_to_unsigned_bin(&tmp, out)) != MP_OKAY) { goto error; }
+ *outlen = x;
+ err = CRYPT_OK;
+ goto done;
+error:
+ err = mpi_to_ltc_error(err);
+done:
+ mp_clear_multi(&p, &tmp, NULL);
+ return err;
+}
+
+#include "dh_sys.c"
+
+#endif
+
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/dh/dh.c,v $ */
+/* $Revision: 1.3 $ */
+/* $Date: 2005/05/05 14:35:59 $ */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 07:39:42 +0000