curve25519.c

00001 /* curve25519.c
00002  *
00003  * Copyright (C) 2006-2017 wolfSSL Inc.
00004  *
00005  * This file is part of wolfSSL.
00006  *
00007  * wolfSSL is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 2 of the License, or
00010  * (at your option) any later version.
00011  *
00012  * wolfSSL is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU General Public License
00018  * along with this program; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
00020  */
00021 
00022 
00023  /* Based On Daniel J Bernstein's curve25519 Public Domain ref10 work. */
00024 
00025 
00026 #ifdef HAVE_CONFIG_H
00027     #include <config.h>
00028 #endif
00029 
00030 #include <wolfcrypt/settings.h>
00031 
00032 #ifdef HAVE_CURVE25519
00033 
00034 #include <wolfcrypt/curve25519.h>
00035 #include <wolfcrypt/error-crypt.h>
00036 #ifdef NO_INLINE
00037     #include <wolfcrypt/misc.h>
00038 #else
00039     #define WOLFSSL_MISC_INCLUDED
00040     #include <wolfcrypt/src/misc.c>
00041 #endif
00042 
00043 #if defined(FREESCALE_LTC_ECC)
00044     #include <wolfcrypt/port/nxp/ksdk_port.h>
00045 #endif
00046 
00047 const curve25519_set_type curve25519_sets[] = {
00048     {
00049         CURVE25519_KEYSIZE,
00050         "CURVE25519",
00051     }
00052 };
00053 
00054 int wc_curve25519_make_key(WC_RNG* rng, int keysize, curve25519_key* key)
00055 {
00056 #ifdef FREESCALE_LTC_ECC
00057     const ECPoint* basepoint = wc_curve25519_GetBasePoint();
00058 #else
00059     unsigned char basepoint[CURVE25519_KEYSIZE] = {9};
00060 #endif
00061     int  ret;
00062 
00063     if (key == NULL || rng == NULL)
00064         return BAD_FUNC_ARG;
00065 
00066     /* currently only a key size of 32 bytes is used */
00067     if (keysize != CURVE25519_KEYSIZE)
00068         return ECC_BAD_ARG_E;
00069 
00070 #ifndef FREESCALE_LTC_ECC
00071     fe_init();
00072 #endif
00073 
00074     /* random number for private key */
00075     ret = wc_RNG_GenerateBlock(rng, key->k.point, keysize);
00076     if (ret != 0)
00077         return ret;
00078 
00079     /* Clamp the private key */
00080     key->k.point[0] &= 248;
00081     key->k.point[CURVE25519_KEYSIZE-1] &= 63; /* same &=127 because |=64 after */
00082     key->k.point[CURVE25519_KEYSIZE-1] |= 64;
00083 
00084     /* compute public key */
00085     #ifdef FREESCALE_LTC_ECC
00086         ret = wc_curve25519(&key->p, key->k.point, basepoint, kLTC_Weierstrass); /* input basepoint on Weierstrass curve */
00087     #else
00088         ret = curve25519(key->p.point, key->k.point, basepoint);
00089     #endif
00090     if (ret != 0) {
00091         ForceZero(key->k.point, keysize);
00092         ForceZero(key->p.point, keysize);
00093         return ret;
00094     }
00095 
00096     return ret;
00097 }
00098 
00099 #ifdef HAVE_CURVE25519_SHARED_SECRET
00100 
00101 int wc_curve25519_shared_secret(curve25519_key* private_key,
00102                                 curve25519_key* public_key,
00103                                 byte* out, word32* outlen)
00104 {
00105     return wc_curve25519_shared_secret_ex(private_key, public_key,
00106                                           out, outlen, EC25519_BIG_ENDIAN);
00107 }
00108 
00109 int wc_curve25519_shared_secret_ex(curve25519_key* private_key,
00110                                    curve25519_key* public_key,
00111                                    byte* out, word32* outlen, int endian)
00112 {
00113     #ifdef FREESCALE_LTC_ECC
00114         ECPoint o = {{0}};
00115     #else
00116         unsigned char o[CURVE25519_KEYSIZE];
00117     #endif
00118     int ret = 0;
00119 
00120     /* sanity check */
00121     if (private_key == NULL || public_key == NULL ||
00122         out == NULL || outlen == NULL || *outlen < CURVE25519_KEYSIZE)
00123         return BAD_FUNC_ARG;
00124 
00125     /* avoid implementation fingerprinting */
00126     if (public_key->p.point[CURVE25519_KEYSIZE-1] > 0x7F)
00127         return ECC_BAD_ARG_E;
00128 
00129     #ifdef FREESCALE_LTC_ECC
00130         ret = wc_curve25519(&o, private_key->k.point, &public_key->p, kLTC_Curve25519 /* input point P on Curve25519 */);
00131     #else
00132         ret = curve25519(o, private_key->k.point, public_key->p.point);
00133     #endif
00134     if (ret != 0) {
00135         #ifdef FREESCALE_LTC_ECC
00136             ForceZero(o.point, CURVE25519_KEYSIZE);
00137             ForceZero(o.pointY, CURVE25519_KEYSIZE);
00138         #else
00139             ForceZero(o, CURVE25519_KEYSIZE);
00140         #endif
00141         return ret;
00142     }
00143 
00144     if (endian == EC25519_BIG_ENDIAN) {
00145         int i;
00146         /* put shared secret key in Big Endian format */
00147         for (i = 0; i < CURVE25519_KEYSIZE; i++)
00148             #ifdef FREESCALE_LTC_ECC
00149                 out[i] = o.point[CURVE25519_KEYSIZE - i -1];
00150             #else
00151                 out[i] = o[CURVE25519_KEYSIZE - i -1];
00152             #endif
00153     }
00154     else /* put shared secret key in Little Endian format */
00155         #ifdef FREESCALE_LTC_ECC
00156             XMEMCPY(out, o.point, CURVE25519_KEYSIZE);
00157         #else
00158             XMEMCPY(out, o, CURVE25519_KEYSIZE);
00159         #endif
00160 
00161     *outlen = CURVE25519_KEYSIZE;
00162 
00163     #ifdef FREESCALE_LTC_ECC
00164         ForceZero(o.point, CURVE25519_KEYSIZE);
00165         ForceZero(o.pointY, CURVE25519_KEYSIZE);
00166     #else
00167         ForceZero(o, CURVE25519_KEYSIZE);
00168     #endif
00169 
00170     return ret;
00171 }
00172 
00173 #endif /* HAVE_CURVE25519_SHARED_SECRET */
00174 
00175 #ifdef HAVE_CURVE25519_KEY_EXPORT
00176 
00177 /* export curve25519 public key (Big endian)
00178  * return 0 on success */
00179 int wc_curve25519_export_public(curve25519_key* key, byte* out, word32* outLen)
00180 {
00181     return wc_curve25519_export_public_ex(key, out, outLen, EC25519_BIG_ENDIAN);
00182 }
00183 
00184 /* export curve25519 public key (Big or Little endian)
00185  * return 0 on success */
00186 int wc_curve25519_export_public_ex(curve25519_key* key, byte* out,
00187                                    word32* outLen, int endian)
00188 {
00189     if (key == NULL || out == NULL || outLen == NULL)
00190         return BAD_FUNC_ARG;
00191 
00192     /* check and set outgoing key size */
00193     if (*outLen < CURVE25519_KEYSIZE) {
00194         *outLen = CURVE25519_KEYSIZE;
00195         return ECC_BAD_ARG_E;
00196     }
00197     *outLen = CURVE25519_KEYSIZE;
00198 
00199     if (endian == EC25519_BIG_ENDIAN) {
00200         int i;
00201 
00202         /* read keys in Big Endian format */
00203         for (i = 0; i < CURVE25519_KEYSIZE; i++)
00204             out[i] = key->p.point[CURVE25519_KEYSIZE - i - 1];
00205     }
00206     else
00207         XMEMCPY(out, key->p.point, CURVE25519_KEYSIZE);
00208 
00209     return 0;
00210 }
00211 
00212 #endif /* HAVE_CURVE25519_KEY_EXPORT */
00213 
00214 #ifdef HAVE_CURVE25519_KEY_IMPORT
00215 
00216 /* import curve25519 public key (Big endian)
00217  *  return 0 on success */
00218 int wc_curve25519_import_public(const byte* in, word32 inLen,
00219                                 curve25519_key* key)
00220 {
00221     return wc_curve25519_import_public_ex(in, inLen, key, EC25519_BIG_ENDIAN);
00222 }
00223 
00224 /* import curve25519 public key (Big or Little endian)
00225  * return 0 on success */
00226 int wc_curve25519_import_public_ex(const byte* in, word32 inLen,
00227                                 curve25519_key* key, int endian)
00228 {
00229     /* sanity check */
00230     if (key == NULL || in == NULL)
00231         return BAD_FUNC_ARG;
00232 
00233     /* check size of incoming keys */
00234     if (inLen != CURVE25519_KEYSIZE)
00235        return ECC_BAD_ARG_E;
00236 
00237     if (endian == EC25519_BIG_ENDIAN) {
00238         int i;
00239 
00240         /* read keys in Big Endian format */
00241         for (i = 0; i < CURVE25519_KEYSIZE; i++)
00242             key->p.point[i] = in[CURVE25519_KEYSIZE - i - 1];
00243     }
00244     else
00245         XMEMCPY(key->p.point, in, inLen);
00246 
00247     key->dp = &curve25519_sets[0];
00248 
00249     /* LTC needs also Y coordinate - let's compute it */
00250     #ifdef FREESCALE_LTC_ECC
00251         ltc_pkha_ecc_point_t ltcPoint;
00252         ltcPoint.X = &key->p.point[0];
00253         ltcPoint.Y = &key->p.pointY[0];
00254         LTC_PKHA_Curve25519ComputeY(&ltcPoint);
00255     #endif
00256 
00257     return 0;
00258 }
00259 
00260 #endif /* HAVE_CURVE25519_KEY_IMPORT */
00261 
00262 
00263 #ifdef HAVE_CURVE25519_KEY_EXPORT
00264 
00265 /* export curve25519 private key only raw (Big endian)
00266  * outLen is in/out size
00267  * return 0 on success */
00268 int wc_curve25519_export_private_raw(curve25519_key* key, byte* out,
00269                                      word32* outLen)
00270 {
00271     return wc_curve25519_export_private_raw_ex(key, out, outLen,
00272                                                EC25519_BIG_ENDIAN);
00273 }
00274 
00275 /* export curve25519 private key only raw (Big or Little endian)
00276  * outLen is in/out size
00277  * return 0 on success */
00278 int wc_curve25519_export_private_raw_ex(curve25519_key* key, byte* out,
00279                                         word32* outLen, int endian)
00280 {
00281     /* sanity check */
00282     if (key == NULL || out == NULL || outLen == NULL)
00283         return BAD_FUNC_ARG;
00284 
00285     /* check size of outgoing buffer */
00286     if (*outLen < CURVE25519_KEYSIZE) {
00287         *outLen = CURVE25519_KEYSIZE;
00288         return ECC_BAD_ARG_E;
00289     }
00290     *outLen = CURVE25519_KEYSIZE;
00291 
00292     if (endian == EC25519_BIG_ENDIAN) {
00293         int i;
00294 
00295         /* put the key in Big Endian format */
00296         for (i = 0; i < CURVE25519_KEYSIZE; i++)
00297             out[i] = key->k.point[CURVE25519_KEYSIZE - i - 1];
00298     }
00299     else
00300         XMEMCPY(out, key->k.point, CURVE25519_KEYSIZE);
00301 
00302     return 0;
00303 }
00304 
00305 /* curve25519 key pair export (Big or Little endian)
00306  * return 0 on success */
00307 int wc_curve25519_export_key_raw(curve25519_key* key,
00308                                  byte* priv, word32 *privSz,
00309                                  byte* pub, word32 *pubSz)
00310 {
00311     return wc_curve25519_export_key_raw_ex(key, priv, privSz,
00312                                            pub, pubSz, EC25519_BIG_ENDIAN);
00313 }
00314 
00315 /* curve25519 key pair export (Big or Little endian)
00316  * return 0 on success */
00317 int wc_curve25519_export_key_raw_ex(curve25519_key* key,
00318                                     byte* priv, word32 *privSz,
00319                                     byte* pub, word32 *pubSz,
00320                                     int endian)
00321 {
00322     int ret;
00323 
00324     /* export private part */
00325     ret = wc_curve25519_export_private_raw_ex(key, priv, privSz, endian);
00326     if (ret != 0)
00327         return ret;
00328 
00329     /* export public part */
00330     return wc_curve25519_export_public_ex(key, pub, pubSz, endian);
00331 }
00332 
00333 #endif /* HAVE_CURVE25519_KEY_EXPORT */
00334 
00335 #ifdef HAVE_CURVE25519_KEY_IMPORT
00336 
00337 /* curve25519 private key import (Big endian)
00338  * Public key to match private key needs to be imported too
00339  * return 0 on success */
00340 int wc_curve25519_import_private_raw(const byte* priv, word32 privSz,
00341                                      const byte* pub, word32 pubSz,
00342                                      curve25519_key* key)
00343 {
00344     return wc_curve25519_import_private_raw_ex(priv, privSz, pub, pubSz,
00345                                                key, EC25519_BIG_ENDIAN);
00346 }
00347 
00348 /* curve25519 private key import (Big or Little endian)
00349  * Public key to match private key needs to be imported too
00350  * return 0 on success */
00351 int wc_curve25519_import_private_raw_ex(const byte* priv, word32 privSz,
00352                                         const byte* pub, word32 pubSz,
00353                                         curve25519_key* key, int endian)
00354 {
00355     int ret;
00356 
00357     /* import private part */
00358     ret = wc_curve25519_import_private_ex(priv, privSz, key, endian);
00359     if (ret != 0)
00360         return ret;
00361 
00362     /* import public part */
00363     return wc_curve25519_import_public_ex(pub, pubSz, key, endian);
00364 }
00365 
00366 /* curve25519 private key import only. (Big endian)
00367  * return 0 on success */
00368 int wc_curve25519_import_private(const byte* priv, word32 privSz,
00369                                  curve25519_key* key)
00370 {
00371     return wc_curve25519_import_private_ex(priv, privSz,
00372                                            key, EC25519_BIG_ENDIAN);
00373 }
00374 
00375 /* curve25519 private key import only. (Big or Little endian)
00376  * return 0 on success */
00377 int wc_curve25519_import_private_ex(const byte* priv, word32 privSz,
00378                                     curve25519_key* key, int endian)
00379 {
00380     /* sanity check */
00381     if (key == NULL || priv == NULL)
00382         return BAD_FUNC_ARG;
00383 
00384     /* check size of incoming keys */
00385     if ((int)privSz != CURVE25519_KEYSIZE)
00386         return ECC_BAD_ARG_E;
00387 
00388     if (endian == EC25519_BIG_ENDIAN) {
00389         int i;
00390 
00391         /* read the key in Big Endian format */
00392         for (i = 0; i < CURVE25519_KEYSIZE; i++)
00393             key->k.point[i] = priv[CURVE25519_KEYSIZE - i - 1];
00394     }
00395     else
00396         XMEMCPY(key->k.point, priv, CURVE25519_KEYSIZE);
00397 
00398     key->dp = &curve25519_sets[0];
00399 
00400     /* Clamp the key */
00401     key->k.point[0] &= 248;
00402     key->k.point[privSz-1] &= 63; /* same &=127 because |=64 after */
00403     key->k.point[privSz-1] |= 64;
00404 
00405     return 0;
00406 }
00407 
00408 #endif /* HAVE_CURVE25519_KEY_IMPORT */
00409 
00410 
00411 int wc_curve25519_init(curve25519_key* key)
00412 {
00413     if (key == NULL)
00414        return BAD_FUNC_ARG;
00415 
00416     XMEMSET(key, 0, sizeof(*key));
00417 
00418     /* currently the format for curve25519 */
00419     key->dp = &curve25519_sets[0];
00420 
00421 #ifndef FREESCALE_LTC_ECC
00422     fe_init();
00423 #endif
00424 
00425     return 0;
00426 }
00427 
00428 
00429 /* Clean the memory of a key */
00430 void wc_curve25519_free(curve25519_key* key)
00431 {
00432    if (key == NULL)
00433        return;
00434 
00435    key->dp = NULL;
00436    ForceZero(key->p.point, sizeof(key->p.point));
00437    ForceZero(key->k.point, sizeof(key->k.point));
00438    #ifdef FREESCALE_LTC_ECC
00439        ForceZero(key->p.point, sizeof(key->p.pointY));
00440        ForceZero(key->k.point, sizeof(key->k.pointY));
00441    #endif
00442 }
00443 
00444 
00445 /* get key size */
00446 int wc_curve25519_size(curve25519_key* key)
00447 {
00448     if (key == NULL)
00449         return 0;
00450 
00451     return key->dp->size;
00452 }
00453 
00454 #endif /*HAVE_CURVE25519*/
00455 
00456