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ECC ecc_sign+verify_hash_raw > ecc_sign+verify_hash_rfc7518 #235

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Merged
karel-m merged 7 commits into from
Jun 21, 2017
Merged

ECC ecc_sign+verify_hash_raw > ecc_sign+verify_hash_rfc7518 #235

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67200b6
ecc_sign+verify_hash_raw > ecc_sign+verify_hash_rfc7518
karel-m Jun 21, 2017
a937f23
static functions name fix
karel-m Jun 21, 2017
cdf04b6
fix mp_montgomery_setup
karel-m Jun 21, 2017
fff8320
ecc_sign_hash max_iterations
karel-m Jun 21, 2017
0c115a1
whitespace
karel-m Jun 21, 2017
b8f2215
PK_MAX_RETRIES
karel-m Jun 21, 2017
ac02f74
ecc_sign+verify_hash_rfc7518 tests
karel-m Jun 21, 2017
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15 changes: 9 additions & 6 deletions src/headers/tomcrypt_pk.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,9 @@ enum {
/* Indicates standard output formats that can be read e.g. by OpenSSL or GnuTLS */
#define PK_STD 0x1000

/* iterations limit for retry-loops */
#define PK_MAX_RETRIES 20

int rand_prime(void *N, long len, prng_state *prng, int wprng);
int rand_bn_bits(void *N, int bits, prng_state *prng, int wprng);
int rand_bn_range(void *N, void *limit, prng_state *prng, int wprng);
Expand Down Expand Up @@ -314,17 +317,17 @@ int ecc_decrypt_key(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
ecc_key *key);

int ecc_sign_hash_raw(const unsigned char *in, unsigned long inlen,
void *r, void *s,
prng_state *prng, int wprng, ecc_key *key);
int ecc_sign_hash_rfc7518(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int wprng, ecc_key *key);

int ecc_sign_hash(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int wprng, ecc_key *key);

int ecc_verify_hash_raw( void *r, void *s,
const unsigned char *hash, unsigned long hashlen,
int *stat, ecc_key *key);
int ecc_verify_hash_rfc7518(const unsigned char *sig, unsigned long siglen,
const unsigned char *hash, unsigned long hashlen,
int *stat, ecc_key *key);

int ecc_verify_hash(const unsigned char *sig, unsigned long siglen,
const unsigned char *hash, unsigned long hashlen,
Expand Down
159 changes: 88 additions & 71 deletions src/pk/ecc/ecc_sign_hash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,43 +7,29 @@
* guarantee it works.
*/

/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
*
* All curves taken from NIST recommendation paper of July 1999
* Available at http://csrc.nist.gov/cryptval/dss.htm
*/
#include "tomcrypt.h"

#ifdef LTC_MECC

/**
@file ecc_sign_hash.c
ECC Crypto, Tom St Denis
*/

#ifdef LTC_MECC

/**
Sign a hash with ECC
@param in The hash to sign
@param inlen The length of the hash to sign
@param r The "r" integer of the signature (caller must initialize with mp_init() first)
@param s The "s" integer of the signature (caller must initialize with mp_init() first)
@param prng An active PRNG state
@param wprng The index of the PRNG desired
@param key A private ECC key
@return CRYPT_OK if successful
*/
int ecc_sign_hash_raw(const unsigned char *in, unsigned long inlen,
void *r, void *s,
prng_state *prng, int wprng, ecc_key *key)
static int _ecc_sign_hash(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int wprng, ecc_key *key, int sigformat)
{
ecc_key pubkey;
void *e, *p;
int err;
void *r, *s, *e, *p;
int err, max_iterations = PK_MAX_RETRIES;
unsigned long pbits, pbytes, i, shift_right;
unsigned char ch, buf[MAXBLOCKSIZE];

LTC_ARGCHK(in != NULL);
LTC_ARGCHK(r != NULL);
LTC_ARGCHK(s != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_ARGCHK(key != NULL);

/* is this a private key? */
if (key->type != PK_PRIVATE) {
Expand All @@ -59,46 +45,83 @@ int ecc_sign_hash_raw(const unsigned char *in, unsigned long inlen,
return err;
}

/* get the hash and load it as a bignum into 'e' */
/* init the bignums */
if ((err = mp_init_multi(&p, &e, NULL)) != CRYPT_OK) {
if ((err = mp_init_multi(&r, &s, &p, &e, NULL)) != CRYPT_OK) {
return err;
}
if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK) { goto errnokey; }
if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, (int)inlen)) != CRYPT_OK) { goto errnokey; }
if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK) { goto errnokey; }

/* get the hash and load it as a bignum into 'e' */
pbits = mp_count_bits(p);
pbytes = (pbits+7) >> 3;
if (pbits > inlen*8) {
if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, inlen)) != CRYPT_OK) { goto errnokey; }
}
else if (pbits % 8 == 0) {
if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, pbytes)) != CRYPT_OK) { goto errnokey; }
}
else {
shift_right = 8 - pbits % 8;
for (i=0, ch=0; i<pbytes; i++) {
buf[i] = ch;
ch = (in[i] << (8-shift_right));
buf[i] = buf[i] ^ (in[i] >> shift_right);
}
if ((err = mp_read_unsigned_bin(e, (unsigned char *)buf, pbytes)) != CRYPT_OK) { goto errnokey; }
}

/* make up a key and export the public copy */
for (;;) {
do {
if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) {
goto errnokey;
}

/* find r = x1 mod n */
if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK) { goto error; }
if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK) { goto error; }

if (mp_iszero(r) == LTC_MP_YES) {
ecc_free(&pubkey);
} else {
/* find s = (e + xr)/k */
if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK) { goto error; } /* k = 1/k */
if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK) { goto error; } /* s = xr */
if ((err = mp_add(e, s, s)) != CRYPT_OK) { goto error; } /* s = e + xr */
if ((err = mp_mod(s, p, s)) != CRYPT_OK) { goto error; } /* s = e + xr */
if ((err = mp_mulmod(s, pubkey.k, p, s)) != CRYPT_OK) { goto error; } /* s = (e + xr)/k */
ecc_free(&pubkey);
if (mp_iszero(s) == LTC_MP_NO) {
break;
}
/* find s = (e + xr)/k */
if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK) { goto error; } /* k = 1/k */
if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK) { goto error; } /* s = xr */
if ((err = mp_add(e, s, s)) != CRYPT_OK) { goto error; } /* s = e + xr */
if ((err = mp_mod(s, p, s)) != CRYPT_OK) { goto error; } /* s = e + xr */
if ((err = mp_mulmod(s, pubkey.k, p, s)) != CRYPT_OK) { goto error; } /* s = (e + xr)/k */
ecc_free(&pubkey);
if (mp_iszero(s) == LTC_MP_NO) {
break;
}
}
} while (--max_iterations > 0);

if (max_iterations == 0) {
goto errnokey;
}

err = CRYPT_OK;
if (sigformat == 1) {
/* RFC7518 format */
if (*outlen < 2*pbytes) { err = CRYPT_MEM; goto errnokey; }
zeromem(out, 2*pbytes);
i = mp_unsigned_bin_size(r);
if ((err = mp_to_unsigned_bin(r, out + (pbytes - i))) != CRYPT_OK) { goto errnokey; }
i = mp_unsigned_bin_size(s);
if ((err = mp_to_unsigned_bin(s, out + (2*pbytes - i))) != CRYPT_OK) { goto errnokey; }
*outlen = 2*pbytes;
err = CRYPT_OK;
}
else {
/* store as ASN.1 SEQUENCE { r, s -- integer } */
err = der_encode_sequence_multi(out, outlen,
LTC_ASN1_INTEGER, 1UL, r,
LTC_ASN1_INTEGER, 1UL, s,
LTC_ASN1_EOL, 0UL, NULL);
}
goto errnokey;

error:
ecc_free(&pubkey);
errnokey:
mp_clear_multi(p, e, NULL);
mp_clear_multi(r, s, p, e, NULL);
return err;
}

Expand All @@ -117,35 +140,29 @@ int ecc_sign_hash(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int wprng, ecc_key *key)
{
void *r, *s;
int err;

LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_ARGCHK(key != NULL);

if (mp_init_multi(&r, &s, NULL) != CRYPT_OK) {
return CRYPT_MEM;
}

if ((err = ecc_sign_hash_raw(in, inlen, r, s, prng, wprng, key)) != CRYPT_OK) {
goto error;
}

/* store as SEQUENCE { r, s -- integer } */
err = der_encode_sequence_multi(out, outlen,
LTC_ASN1_INTEGER, 1UL, r,
LTC_ASN1_INTEGER, 1UL, s,
LTC_ASN1_EOL, 0UL, NULL);
return _ecc_sign_hash(in, inlen, out, outlen, prng, wprng, key, 0);
}

error:
mp_clear_multi(r, s, NULL);
return err;
/**
Sign a message digest in RFC7518 format
@param in The message digest to sign
@param inlen The length of the digest
@param out [out] The destination for the signature
@param outlen [in/out] The max size and resulting size of the signature
@param prng An active PRNG state
@param wprng The index of the PRNG you wish to use
@param key A private ECC key
@return CRYPT_OK if successful
*/
int ecc_sign_hash_rfc7518(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int wprng, ecc_key *key)
{
return _ecc_sign_hash(in, inlen, out, outlen, prng, wprng, key, 1);
}

#endif

/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */

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