예제 #1
0
파일: ec.c 프로젝트: venkatarajasekhar/Qt
/*
** Checks the signature on the given digest using the key provided.
*/
SECStatus 
ECDSA_VerifyDigest(ECPublicKey *key, const SECItem *signature, 
                 const SECItem *digest)
{
    SECStatus rv = SECFailure;
#ifndef NSS_DISABLE_ECC
    mp_int r_, s_;           /* tuple (r', s') is received signature) */
    mp_int c, u1, u2, v;     /* intermediate values used in verification */
    mp_int x1;
    mp_int n;
    mp_err err = MP_OKAY;
    ECParams *ecParams = NULL;
    SECItem pointC = { siBuffer, NULL, 0 };
    int slen;       /* length in bytes of a half signature (r or s) */
    int flen;       /* length in bytes of the field size */
    unsigned olen;  /* length in bytes of the base point order */
    unsigned obits; /* length in bits  of the base point order */

#if EC_DEBUG
    char mpstr[256];
    printf("ECDSA verification called\n");
#endif

    /* Initialize MPI integers. */
    /* must happen before the first potential call to cleanup */
    MP_DIGITS(&r_) = 0;
    MP_DIGITS(&s_) = 0;
    MP_DIGITS(&c) = 0;
    MP_DIGITS(&u1) = 0;
    MP_DIGITS(&u2) = 0;
    MP_DIGITS(&x1) = 0;
    MP_DIGITS(&v)  = 0;
    MP_DIGITS(&n)  = 0;

    /* Check args */
    if (!key || !signature || !digest) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	goto cleanup;
    }

    ecParams = &(key->ecParams);
    flen = (ecParams->fieldID.size + 7) >> 3;  
    olen = ecParams->order.len;  
    if (signature->len == 0 || signature->len%2 != 0 ||
	signature->len > 2*olen) {
	PORT_SetError(SEC_ERROR_INPUT_LEN);
	goto cleanup;
    }
    slen = signature->len/2;

    SECITEM_AllocItem(NULL, &pointC, 2*flen + 1);
    if (pointC.data == NULL)
	goto cleanup;

    CHECK_MPI_OK( mp_init(&r_) );
    CHECK_MPI_OK( mp_init(&s_) );
    CHECK_MPI_OK( mp_init(&c)  );
    CHECK_MPI_OK( mp_init(&u1) );
    CHECK_MPI_OK( mp_init(&u2) );
    CHECK_MPI_OK( mp_init(&x1)  );
    CHECK_MPI_OK( mp_init(&v)  );
    CHECK_MPI_OK( mp_init(&n)  );

    /*
    ** Convert received signature (r', s') into MPI integers.
    */
    CHECK_MPI_OK( mp_read_unsigned_octets(&r_, signature->data, slen) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&s_, signature->data + slen, slen) );
                                          
    /* 
    ** ANSI X9.62, Section 5.4.2, Steps 1 and 2
    **
    ** Verify that 0 < r' < n and 0 < s' < n
    */
    SECITEM_TO_MPINT(ecParams->order, &n);
    if (mp_cmp_z(&r_) <= 0 || mp_cmp_z(&s_) <= 0 ||
        mp_cmp(&r_, &n) >= 0 || mp_cmp(&s_, &n) >= 0) {
	PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
	goto cleanup; /* will return rv == SECFailure */
    }

    /*
    ** ANSI X9.62, Section 5.4.2, Step 3
    **
    ** c = (s')**-1 mod n
    */
    CHECK_MPI_OK( mp_invmod(&s_, &n, &c) );      /* c = (s')**-1 mod n */

    /*
    ** ANSI X9.62, Section 5.4.2, Step 4
    **
    ** u1 = ((HASH(M')) * c) mod n
    */
    SECITEM_TO_MPINT(*digest, &u1);                  /* u1 = HASH(M)     */

    /* In the definition of EC signing, digests are truncated
     * to the length of n in bits. 
     * (see SEC 1 "Elliptic Curve Digit Signature Algorithm" section 4.1.*/
    CHECK_MPI_OK( (obits = mpl_significant_bits(&n)) );
    if (digest->len*8 > obits) {  /* u1 = HASH(M')     */
	mpl_rsh(&u1,&u1,digest->len*8 - obits);
    }

#if EC_DEBUG
    mp_todecimal(&r_, mpstr);
    printf("r_: %s (dec)\n", mpstr);
    mp_todecimal(&s_, mpstr);
    printf("s_: %s (dec)\n", mpstr);
    mp_todecimal(&c, mpstr);
    printf("c : %s (dec)\n", mpstr);
    mp_todecimal(&u1, mpstr);
    printf("digest: %s (dec)\n", mpstr);
#endif

    CHECK_MPI_OK( mp_mulmod(&u1, &c, &n, &u1) );  /* u1 = u1 * c mod n */

    /*
    ** ANSI X9.62, Section 5.4.2, Step 4
    **
    ** u2 = ((r') * c) mod n
    */
    CHECK_MPI_OK( mp_mulmod(&r_, &c, &n, &u2) );

    /*
    ** ANSI X9.62, Section 5.4.3, Step 1
    **
    ** Compute u1*G + u2*Q
    ** Here, A = u1.G     B = u2.Q    and   C = A + B
    ** If the result, C, is the point at infinity, reject the signature
    */
    if (ec_points_mul(ecParams, &u1, &u2, &key->publicValue, &pointC)
	!= SECSuccess) {
	rv = SECFailure;
	goto cleanup;
    }
    if (ec_point_at_infinity(&pointC)) {
	PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
	rv = SECFailure;
	goto cleanup;
    }

    CHECK_MPI_OK( mp_read_unsigned_octets(&x1, pointC.data + 1, flen) );

    /*
    ** ANSI X9.62, Section 5.4.4, Step 2
    **
    ** v = x1 mod n
    */
    CHECK_MPI_OK( mp_mod(&x1, &n, &v) );

#if EC_DEBUG
    mp_todecimal(&r_, mpstr);
    printf("r_: %s (dec)\n", mpstr);
    mp_todecimal(&v, mpstr);
    printf("v : %s (dec)\n", mpstr);
#endif

    /*
    ** ANSI X9.62, Section 5.4.4, Step 3
    **
    ** Verification:  v == r'
    */
    if (mp_cmp(&v, &r_)) {
	PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
	rv = SECFailure; /* Signature failed to verify. */
    } else {
	rv = SECSuccess; /* Signature verified. */
    }

#if EC_DEBUG
    mp_todecimal(&u1, mpstr);
    printf("u1: %s (dec)\n", mpstr);
    mp_todecimal(&u2, mpstr);
    printf("u2: %s (dec)\n", mpstr);
    mp_tohex(&x1, mpstr);
    printf("x1: %s\n", mpstr);
    mp_todecimal(&v, mpstr);
    printf("v : %s (dec)\n", mpstr);
#endif

cleanup:
    mp_clear(&r_);
    mp_clear(&s_);
    mp_clear(&c);
    mp_clear(&u1);
    mp_clear(&u2);
    mp_clear(&x1);
    mp_clear(&v);
    mp_clear(&n);

    if (pointC.data) SECITEM_FreeItem(&pointC, PR_FALSE);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }

#if EC_DEBUG
    printf("ECDSA verification %s\n",
	(rv == SECSuccess) ? "succeeded" : "failed");
#endif
#else
    PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
#endif /* NSS_DISABLE_ECC */

    return rv;
}
예제 #2
0
파일: ec.c 프로젝트: venkatarajasekhar/Qt
/* Computes the ECDSA signature (a concatenation of two values r and s)
 * on the digest using the given key and the random value kb (used in
 * computing s).
 */
SECStatus 
ECDSA_SignDigestWithSeed(ECPrivateKey *key, SECItem *signature, 
    const SECItem *digest, const unsigned char *kb, const int kblen)
{
    SECStatus rv = SECFailure;
#ifndef NSS_DISABLE_ECC
    mp_int x1;
    mp_int d, k;     /* private key, random integer */
    mp_int r, s;     /* tuple (r, s) is the signature */
    mp_int n;
    mp_err err = MP_OKAY;
    ECParams *ecParams = NULL;
    SECItem kGpoint = { siBuffer, NULL, 0};
    int flen = 0;    /* length in bytes of the field size */
    unsigned olen;   /* length in bytes of the base point order */
    unsigned obits;  /* length in bits  of the base point order */

#if EC_DEBUG
    char mpstr[256];
#endif

    /* Initialize MPI integers. */
    /* must happen before the first potential call to cleanup */
    MP_DIGITS(&x1) = 0;
    MP_DIGITS(&d) = 0;
    MP_DIGITS(&k) = 0;
    MP_DIGITS(&r) = 0;
    MP_DIGITS(&s) = 0;
    MP_DIGITS(&n) = 0;

    /* Check args */
    if (!key || !signature || !digest || !kb || (kblen < 0)) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	goto cleanup;
    }

    ecParams = &(key->ecParams);
    flen = (ecParams->fieldID.size + 7) >> 3;
    olen = ecParams->order.len;  
    if (signature->data == NULL) {
	/* a call to get the signature length only */
	goto finish;
    }
    if (signature->len < 2*olen) {
	PORT_SetError(SEC_ERROR_OUTPUT_LEN);
	goto cleanup;
    }


    CHECK_MPI_OK( mp_init(&x1) );
    CHECK_MPI_OK( mp_init(&d) );
    CHECK_MPI_OK( mp_init(&k) );
    CHECK_MPI_OK( mp_init(&r) );
    CHECK_MPI_OK( mp_init(&s) );
    CHECK_MPI_OK( mp_init(&n) );

    SECITEM_TO_MPINT( ecParams->order, &n );
    SECITEM_TO_MPINT( key->privateValue, &d );

    CHECK_MPI_OK( mp_read_unsigned_octets(&k, kb, kblen) );
    /* Make sure k is in the interval [1, n-1] */
    if ((mp_cmp_z(&k) <= 0) || (mp_cmp(&k, &n) >= 0)) {
#if EC_DEBUG
        printf("k is outside [1, n-1]\n");
        mp_tohex(&k, mpstr);
	printf("k : %s \n", mpstr);
        mp_tohex(&n, mpstr);
	printf("n : %s \n", mpstr);
#endif
	PORT_SetError(SEC_ERROR_NEED_RANDOM);
	goto cleanup;
    }

    /*
    ** We do not want timing information to leak the length of k,
    ** so we compute k*G using an equivalent scalar of fixed
    ** bit-length.
    ** Fix based on patch for ECDSA timing attack in the paper
    ** by Billy Bob Brumley and Nicola Tuveri at
    **   http://eprint.iacr.org/2011/232
    **
    ** How do we convert k to a value of a fixed bit-length?
    ** k starts off as an integer satisfying 0 <= k < n.  Hence,
    ** n <= k+n < 2n, which means k+n has either the same number
    ** of bits as n or one more bit than n.  If k+n has the same
    ** number of bits as n, the second addition ensures that the
    ** final value has exactly one more bit than n.  Thus, we
    ** always end up with a value that exactly one more bit than n.
    */
    CHECK_MPI_OK( mp_add(&k, &n, &k) );
    if (mpl_significant_bits(&k) <= mpl_significant_bits(&n)) {
	CHECK_MPI_OK( mp_add(&k, &n, &k) );
    }

    /* 
    ** ANSI X9.62, Section 5.3.2, Step 2
    **
    ** Compute kG
    */
    kGpoint.len = 2*flen + 1;
    kGpoint.data = PORT_Alloc(2*flen + 1);
    if ((kGpoint.data == NULL) ||
	(ec_points_mul(ecParams, &k, NULL, NULL, &kGpoint)
	    != SECSuccess))
	goto cleanup;

    /* 
    ** ANSI X9.62, Section 5.3.3, Step 1
    **
    ** Extract the x co-ordinate of kG into x1
    */
    CHECK_MPI_OK( mp_read_unsigned_octets(&x1, kGpoint.data + 1, 
	                                  (mp_size) flen) );

    /* 
    ** ANSI X9.62, Section 5.3.3, Step 2
    **
    ** r = x1 mod n  NOTE: n is the order of the curve
    */
    CHECK_MPI_OK( mp_mod(&x1, &n, &r) );

    /*
    ** ANSI X9.62, Section 5.3.3, Step 3
    **
    ** verify r != 0 
    */
    if (mp_cmp_z(&r) == 0) {
	PORT_SetError(SEC_ERROR_NEED_RANDOM);
	goto cleanup;
    }

    /*                                  
    ** ANSI X9.62, Section 5.3.3, Step 4
    **
    ** s = (k**-1 * (HASH(M) + d*r)) mod n 
    */
    SECITEM_TO_MPINT(*digest, &s);        /* s = HASH(M)     */

    /* In the definition of EC signing, digests are truncated
     * to the length of n in bits. 
     * (see SEC 1 "Elliptic Curve Digit Signature Algorithm" section 4.1.*/
    CHECK_MPI_OK( (obits = mpl_significant_bits(&n)) );
    if (digest->len*8 > obits) {
	mpl_rsh(&s,&s,digest->len*8 - obits);
    }

#if EC_DEBUG
    mp_todecimal(&n, mpstr);
    printf("n : %s (dec)\n", mpstr);
    mp_todecimal(&d, mpstr);
    printf("d : %s (dec)\n", mpstr);
    mp_tohex(&x1, mpstr);
    printf("x1: %s\n", mpstr);
    mp_todecimal(&s, mpstr);
    printf("digest: %s (decimal)\n", mpstr);
    mp_todecimal(&r, mpstr);
    printf("r : %s (dec)\n", mpstr);
    mp_tohex(&r, mpstr);
    printf("r : %s\n", mpstr);
#endif

    CHECK_MPI_OK( mp_invmod(&k, &n, &k) );      /* k = k**-1 mod n */
    CHECK_MPI_OK( mp_mulmod(&d, &r, &n, &d) );  /* d = d * r mod n */
    CHECK_MPI_OK( mp_addmod(&s, &d, &n, &s) );  /* s = s + d mod n */
    CHECK_MPI_OK( mp_mulmod(&s, &k, &n, &s) );  /* s = s * k mod n */

#if EC_DEBUG
    mp_todecimal(&s, mpstr);
    printf("s : %s (dec)\n", mpstr);
    mp_tohex(&s, mpstr);
    printf("s : %s\n", mpstr);
#endif

    /*
    ** ANSI X9.62, Section 5.3.3, Step 5
    **
    ** verify s != 0
    */
    if (mp_cmp_z(&s) == 0) {
	PORT_SetError(SEC_ERROR_NEED_RANDOM);
	goto cleanup;
    }

   /*
    **
    ** Signature is tuple (r, s)
    */
    CHECK_MPI_OK( mp_to_fixlen_octets(&r, signature->data, olen) );
    CHECK_MPI_OK( mp_to_fixlen_octets(&s, signature->data + olen, olen) );
finish:
    signature->len = 2*olen;

    rv = SECSuccess;
    err = MP_OKAY;
cleanup:
    mp_clear(&x1);
    mp_clear(&d);
    mp_clear(&k);
    mp_clear(&r);
    mp_clear(&s);
    mp_clear(&n);

    if (kGpoint.data) {
	PORT_ZFree(kGpoint.data, 2*flen + 1);
    }

    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }

#if EC_DEBUG
    printf("ECDSA signing with seed %s\n",
	(rv == SECSuccess) ? "succeeded" : "failed");
#endif
#else
    PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
#endif /* NSS_DISABLE_ECC */

   return rv;
}
예제 #3
0
파일: ec.c 프로젝트: venkatarajasekhar/Qt
/* 
** Performs an ECDH key derivation by computing the scalar point
** multiplication of privateValue and publicValue (with or without the
** cofactor) and returns the x-coordinate of the resulting elliptic
** curve point in derived secret.  If successful, derivedSecret->data
** is set to the address of the newly allocated buffer containing the
** derived secret, and derivedSecret->len is the size of the secret
** produced. It is the caller's responsibility to free the allocated
** buffer containing the derived secret.
*/
SECStatus 
ECDH_Derive(SECItem  *publicValue, 
            ECParams *ecParams,
            SECItem  *privateValue,
            PRBool    withCofactor,
            SECItem  *derivedSecret)
{
    SECStatus rv = SECFailure;
#ifndef NSS_DISABLE_ECC
    unsigned int len = 0;
    SECItem pointQ = {siBuffer, NULL, 0};
    mp_int k; /* to hold the private value */
    mp_int cofactor;
    mp_err err = MP_OKAY;
#if EC_DEBUG
    int i;
#endif

    if (!publicValue || !ecParams || !privateValue || 
	!derivedSecret) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }

    MP_DIGITS(&k) = 0;
    memset(derivedSecret, 0, sizeof *derivedSecret);
    len = (ecParams->fieldID.size + 7) >> 3;  
    pointQ.len = 2*len + 1;
    if ((pointQ.data = PORT_Alloc(2*len + 1)) == NULL) goto cleanup;

    CHECK_MPI_OK( mp_init(&k) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&k, privateValue->data, 
	                                  (mp_size) privateValue->len) );

    if (withCofactor && (ecParams->cofactor != 1)) {
	    /* multiply k with the cofactor */
	    MP_DIGITS(&cofactor) = 0;
	    CHECK_MPI_OK( mp_init(&cofactor) );
	    mp_set(&cofactor, ecParams->cofactor);
	    CHECK_MPI_OK( mp_mul(&k, &cofactor, &k) );
    }

    /* Multiply our private key and peer's public point */
    if (ec_points_mul(ecParams, NULL, &k, publicValue, &pointQ) != SECSuccess)
	goto cleanup;
    if (ec_point_at_infinity(&pointQ)) {
	PORT_SetError(SEC_ERROR_BAD_KEY);  /* XXX better error code? */
	goto cleanup;
    }

    /* Allocate memory for the derived secret and copy
     * the x co-ordinate of pointQ into it.
     */
    SECITEM_AllocItem(NULL, derivedSecret, len);
    memcpy(derivedSecret->data, pointQ.data + 1, len);

    rv = SECSuccess;

#if EC_DEBUG
    printf("derived_secret:\n");
    for (i = 0; i < derivedSecret->len; i++) 
	printf("%02x:", derivedSecret->data[i]);
    printf("\n");
#endif

cleanup:
    mp_clear(&k);

    if (err) {
	MP_TO_SEC_ERROR(err);
    }

    if (pointQ.data) {
	PORT_ZFree(pointQ.data, 2*len + 1);
    }
#else
    PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
#endif /* NSS_DISABLE_ECC */

    return rv;
}
예제 #4
0
파일: ec.c 프로젝트: venkatarajasekhar/Qt
/* Generates a new EC key pair. The private key is a supplied
 * value and the public key is the result of performing a scalar 
 * point multiplication of that value with the curve's base point.
 */
SECStatus 
ec_NewKey(ECParams *ecParams, ECPrivateKey **privKey, 
    const unsigned char *privKeyBytes, int privKeyLen)
{
    SECStatus rv = SECFailure;
#ifndef NSS_DISABLE_ECC
    PLArenaPool *arena;
    ECPrivateKey *key;
    mp_int k;
    mp_err err = MP_OKAY;
    int len;

#if EC_DEBUG
    printf("ec_NewKey called\n");
#endif
    MP_DIGITS(&k) = 0;

    if (!ecParams || !privKey || !privKeyBytes || (privKeyLen < 0)) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }

    /* Initialize an arena for the EC key. */
    if (!(arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE)))
	return SECFailure;

    key = (ECPrivateKey *)PORT_ArenaZAlloc(arena, sizeof(ECPrivateKey));
    if (!key) {
	PORT_FreeArena(arena, PR_TRUE);
	return SECFailure;
    }

    /* Set the version number (SEC 1 section C.4 says it should be 1) */
    SECITEM_AllocItem(arena, &key->version, 1);
    key->version.data[0] = 1;

    /* Copy all of the fields from the ECParams argument to the
     * ECParams structure within the private key.
     */
    key->ecParams.arena = arena;
    key->ecParams.type = ecParams->type;
    key->ecParams.fieldID.size = ecParams->fieldID.size;
    key->ecParams.fieldID.type = ecParams->fieldID.type;
    if (ecParams->fieldID.type == ec_field_GFp) {
	CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.fieldID.u.prime,
	    &ecParams->fieldID.u.prime));
    } else {
	CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.fieldID.u.poly,
	    &ecParams->fieldID.u.poly));
    }
    key->ecParams.fieldID.k1 = ecParams->fieldID.k1;
    key->ecParams.fieldID.k2 = ecParams->fieldID.k2;
    key->ecParams.fieldID.k3 = ecParams->fieldID.k3;
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.a,
	&ecParams->curve.a));
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.b,
	&ecParams->curve.b));
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.seed,
	&ecParams->curve.seed));
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.base,
	&ecParams->base));
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.order,
	&ecParams->order));
    key->ecParams.cofactor = ecParams->cofactor;
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.DEREncoding,
	&ecParams->DEREncoding));
    key->ecParams.name = ecParams->name;
    CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curveOID,
	&ecParams->curveOID));

    len = (ecParams->fieldID.size + 7) >> 3;
    SECITEM_AllocItem(arena, &key->publicValue, 2*len + 1);
    len = ecParams->order.len;
    SECITEM_AllocItem(arena, &key->privateValue, len);

    /* Copy private key */
    if (privKeyLen >= len) {
	memcpy(key->privateValue.data, privKeyBytes, len);
    } else {
	memset(key->privateValue.data, 0, (len - privKeyLen));
	memcpy(key->privateValue.data + (len - privKeyLen), privKeyBytes, privKeyLen);
    }

    /* Compute corresponding public key */
    CHECK_MPI_OK( mp_init(&k) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&k, key->privateValue.data, 
	(mp_size) len) );

    rv = ec_points_mul(ecParams, &k, NULL, NULL, &(key->publicValue));
    if (rv != SECSuccess) goto cleanup;
    *privKey = key;

cleanup:
    mp_clear(&k);
    if (rv)
	PORT_FreeArena(arena, PR_TRUE);

#if EC_DEBUG
    printf("ec_NewKey returning %s\n", 
	(rv == SECSuccess) ? "success" : "failure");
#endif
#else
    PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
#endif /* NSS_DISABLE_ECC */

    return rv;

}
예제 #5
0
파일: ec.c 프로젝트: txazo/hotspot
/* Computes the ECDSA signature (a concatenation of two values r and s)
 * on the digest using the given key and the random value kb (used in
 * computing s).
 */
SECStatus
ECDSA_SignDigestWithSeed(ECPrivateKey *key, SECItem *signature,
    const SECItem *digest, const unsigned char *kb, const int kblen, int kmflag)
{
    SECStatus rv = SECFailure;
    mp_int x1;
    mp_int d, k;     /* private key, random integer */
    mp_int r, s;     /* tuple (r, s) is the signature */
    mp_int n;
    mp_err err = MP_OKAY;
    ECParams *ecParams = NULL;
    SECItem kGpoint = { siBuffer, NULL, 0};
    int flen = 0;    /* length in bytes of the field size */
    unsigned olen;   /* length in bytes of the base point order */

#if EC_DEBUG
    char mpstr[256];
#endif

    /* Initialize MPI integers. */
    /* must happen before the first potential call to cleanup */
    MP_DIGITS(&x1) = 0;
    MP_DIGITS(&d) = 0;
    MP_DIGITS(&k) = 0;
    MP_DIGITS(&r) = 0;
    MP_DIGITS(&s) = 0;
    MP_DIGITS(&n) = 0;

    /* Check args */
    if (!key || !signature || !digest || !kb || (kblen < 0)) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        goto cleanup;
    }

    ecParams = &(key->ecParams);
    flen = (ecParams->fieldID.size + 7) >> 3;
    olen = ecParams->order.len;
    if (signature->data == NULL) {
        /* a call to get the signature length only */
        goto finish;
    }
    if (signature->len < 2*olen) {
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        rv = SECBufferTooSmall;
        goto cleanup;
    }


    CHECK_MPI_OK( mp_init(&x1, kmflag) );
    CHECK_MPI_OK( mp_init(&d, kmflag) );
    CHECK_MPI_OK( mp_init(&k, kmflag) );
    CHECK_MPI_OK( mp_init(&r, kmflag) );
    CHECK_MPI_OK( mp_init(&s, kmflag) );
    CHECK_MPI_OK( mp_init(&n, kmflag) );

    SECITEM_TO_MPINT( ecParams->order, &n );
    SECITEM_TO_MPINT( key->privateValue, &d );
    CHECK_MPI_OK( mp_read_unsigned_octets(&k, kb, kblen) );
    /* Make sure k is in the interval [1, n-1] */
    if ((mp_cmp_z(&k) <= 0) || (mp_cmp(&k, &n) >= 0)) {
#if EC_DEBUG
        printf("k is outside [1, n-1]\n");
        mp_tohex(&k, mpstr);
        printf("k : %s \n", mpstr);
        mp_tohex(&n, mpstr);
        printf("n : %s \n", mpstr);
#endif
        PORT_SetError(SEC_ERROR_NEED_RANDOM);
        goto cleanup;
    }

    /*
     * Using an equivalent exponent of fixed length (same as n or 1 bit less
     * than n) to keep the kG timing relatively constant.
     *
     * Note that this is an extra step on top of the approach defined in
     * ANSI X9.62 so as to make a fixed length K.
     */
    CHECK_MPI_OK( mp_add(&k, &n, &k) );
    CHECK_MPI_OK( mp_div_2(&k, &k) );

    /*
    ** ANSI X9.62, Section 5.3.2, Step 2
    **
    ** Compute kG
    */
    kGpoint.len = 2*flen + 1;
    kGpoint.data = PORT_Alloc(2*flen + 1, kmflag);
    if ((kGpoint.data == NULL) ||
        (ec_points_mul(ecParams, &k, NULL, NULL, &kGpoint, kmflag)
            != SECSuccess))
        goto cleanup;

    /*
    ** ANSI X9.62, Section 5.3.3, Step 1
    **
    ** Extract the x co-ordinate of kG into x1
    */
    CHECK_MPI_OK( mp_read_unsigned_octets(&x1, kGpoint.data + 1,
                                          (mp_size) flen) );

    /*
    ** ANSI X9.62, Section 5.3.3, Step 2
    **
    ** r = x1 mod n  NOTE: n is the order of the curve
    */
    CHECK_MPI_OK( mp_mod(&x1, &n, &r) );

    /*
    ** ANSI X9.62, Section 5.3.3, Step 3
    **
    ** verify r != 0
    */
    if (mp_cmp_z(&r) == 0) {
        PORT_SetError(SEC_ERROR_NEED_RANDOM);
        goto cleanup;
    }

    /*
    ** ANSI X9.62, Section 5.3.3, Step 4
    **
    ** s = (k**-1 * (HASH(M) + d*r)) mod n
    */
    SECITEM_TO_MPINT(*digest, &s);        /* s = HASH(M)     */

    /* In the definition of EC signing, digests are truncated
     * to the length of n in bits.
     * (see SEC 1 "Elliptic Curve Digit Signature Algorithm" section 4.1.*/
    if (digest->len*8 > (unsigned int)ecParams->fieldID.size) {
        mpl_rsh(&s,&s,digest->len*8 - ecParams->fieldID.size);
    }

#if EC_DEBUG
    mp_todecimal(&n, mpstr);
    printf("n : %s (dec)\n", mpstr);
    mp_todecimal(&d, mpstr);
    printf("d : %s (dec)\n", mpstr);
    mp_tohex(&x1, mpstr);
    printf("x1: %s\n", mpstr);
    mp_todecimal(&s, mpstr);
    printf("digest: %s (decimal)\n", mpstr);
    mp_todecimal(&r, mpstr);
    printf("r : %s (dec)\n", mpstr);
    mp_tohex(&r, mpstr);
    printf("r : %s\n", mpstr);
#endif

    CHECK_MPI_OK( mp_invmod(&k, &n, &k) );      /* k = k**-1 mod n */
    CHECK_MPI_OK( mp_mulmod(&d, &r, &n, &d) );  /* d = d * r mod n */
    CHECK_MPI_OK( mp_addmod(&s, &d, &n, &s) );  /* s = s + d mod n */
    CHECK_MPI_OK( mp_mulmod(&s, &k, &n, &s) );  /* s = s * k mod n */

#if EC_DEBUG
    mp_todecimal(&s, mpstr);
    printf("s : %s (dec)\n", mpstr);
    mp_tohex(&s, mpstr);
    printf("s : %s\n", mpstr);
#endif

    /*
    ** ANSI X9.62, Section 5.3.3, Step 5
    **
    ** verify s != 0
    */
    if (mp_cmp_z(&s) == 0) {
        PORT_SetError(SEC_ERROR_NEED_RANDOM);
        goto cleanup;
    }

   /*
    **
    ** Signature is tuple (r, s)
    */
    CHECK_MPI_OK( mp_to_fixlen_octets(&r, signature->data, olen) );
    CHECK_MPI_OK( mp_to_fixlen_octets(&s, signature->data + olen, olen) );
finish:
    signature->len = 2*olen;

    rv = SECSuccess;
    err = MP_OKAY;
cleanup:
    mp_clear(&x1);
    mp_clear(&d);
    mp_clear(&k);
    mp_clear(&r);
    mp_clear(&s);
    mp_clear(&n);

    if (kGpoint.data) {
        PORT_ZFree(kGpoint.data, 2*flen + 1);
    }

    if (err) {
        MP_TO_SEC_ERROR(err);
        rv = SECFailure;
    }

#if EC_DEBUG
    printf("ECDSA signing with seed %s\n",
        (rv == SECSuccess) ? "succeeded" : "failed");
#endif

   return rv;
}
예제 #6
0
/*
** Performs an ECDH key derivation by computing the scalar point
** multiplication of privateValue and publicValue (with or without the
** cofactor) and returns the x-coordinate of the resulting elliptic
** curve point in derived secret.  If successful, derivedSecret->data
** is set to the address of the newly allocated buffer containing the
** derived secret, and derivedSecret->len is the size of the secret
** produced. It is the caller's responsibility to free the allocated
** buffer containing the derived secret.
*/
SECStatus
ECDH_Derive(SECItem *publicValue,
            ECParams *ecParams,
            SECItem *privateValue,
            PRBool withCofactor,
            SECItem *derivedSecret)
{
    SECStatus rv = SECFailure;
#ifndef NSS_DISABLE_ECC
    unsigned int len = 0;
    SECItem pointQ = { siBuffer, NULL, 0 };
    mp_int k; /* to hold the private value */
    mp_int cofactor;
    mp_err err = MP_OKAY;
#if EC_DEBUG
    int i;
#endif

    if (!publicValue || !ecParams || !privateValue || !derivedSecret ||
        !ecParams->name) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return SECFailure;
    }

    /* Perform curve specific multiplication using ECMethod */
    if (ecParams->fieldID.type == ec_field_plain) {
        const ECMethod *method;
        memset(derivedSecret, 0, sizeof(*derivedSecret));
        derivedSecret = SECITEM_AllocItem(NULL, derivedSecret, ecParams->pointSize);
        if (derivedSecret == NULL) {
            PORT_SetError(SEC_ERROR_NO_MEMORY);
            return SECFailure;
        }
        method = ec_get_method_from_name(ecParams->name);
        if (method == NULL || method->validate == NULL ||
            method->mul == NULL) {
            PORT_SetError(SEC_ERROR_UNSUPPORTED_ELLIPTIC_CURVE);
            return SECFailure;
        }
        if (method->validate(publicValue) != SECSuccess) {
            PORT_SetError(SEC_ERROR_BAD_KEY);
            return SECFailure;
        }
        return method->mul(derivedSecret, privateValue, publicValue);
    }

    /*
     * We fail if the public value is the point at infinity, since
     * this produces predictable results.
     */
    if (ec_point_at_infinity(publicValue)) {
        PORT_SetError(SEC_ERROR_BAD_KEY);
        return SECFailure;
    }

    MP_DIGITS(&k) = 0;
    memset(derivedSecret, 0, sizeof *derivedSecret);
    len = (ecParams->fieldID.size + 7) >> 3;
    pointQ.len = ecParams->pointSize;
    if ((pointQ.data = PORT_Alloc(ecParams->pointSize)) == NULL)
        goto cleanup;

    CHECK_MPI_OK(mp_init(&k));
    CHECK_MPI_OK(mp_read_unsigned_octets(&k, privateValue->data,
                                         (mp_size)privateValue->len));

    if (withCofactor && (ecParams->cofactor != 1)) {
        /* multiply k with the cofactor */
        MP_DIGITS(&cofactor) = 0;
        CHECK_MPI_OK(mp_init(&cofactor));
        mp_set(&cofactor, ecParams->cofactor);
        CHECK_MPI_OK(mp_mul(&k, &cofactor, &k));
    }

    /* Multiply our private key and peer's public point */
    if (ec_points_mul(ecParams, NULL, &k, publicValue, &pointQ) != SECSuccess) {
        goto cleanup;
    }
    if (ec_point_at_infinity(&pointQ)) {
        PORT_SetError(SEC_ERROR_BAD_KEY); /* XXX better error code? */
        goto cleanup;
    }

    /* Allocate memory for the derived secret and copy
     * the x co-ordinate of pointQ into it.
     */
    SECITEM_AllocItem(NULL, derivedSecret, len);
    memcpy(derivedSecret->data, pointQ.data + 1, len);

    rv = SECSuccess;

#if EC_DEBUG
    printf("derived_secret:\n");
    for (i = 0; i < derivedSecret->len; i++)
        printf("%02x:", derivedSecret->data[i]);
    printf("\n");
#endif

cleanup:
    mp_clear(&k);

    if (err) {
        MP_TO_SEC_ERROR(err);
    }

    if (pointQ.data) {
        PORT_ZFree(pointQ.data, ecParams->pointSize);
    }
#else
    PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
#endif /* NSS_DISABLE_ECC */

    return rv;
}