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Merge #701: Make ec_ arithmetic more consistent and add documentation 

7e3952ae82 Clarify documentation of tweak functions. (Jonas Nick)
89853a0f2e Make tweak function documentation more consistent. (Jonas Nick)
41fc785602 Make ec_privkey functions aliases for ec_seckey_negate, ec_seckey_tweak_add and ec_seckey_mul (Jonas Nick)
22911ee6da Rename private key to secret key in public API (with the exception of function names) (Jonas Nick)
5a73f14d6c Mention that value is unspecified for In/Out parameters if the function returns 0 (Jonas Nick)
f03df0e6d7 Define valid ECDSA keys in the documentation of seckey_verify (Jonas Nick)
5894e1f1df Return 0 if the given seckey is invalid in privkey_negate, privkey_tweak_add and privkey_tweak_mul (Jonas Nick)
8f814cddb9 Add test for boundary conditions of scalar_set_b32 with respect to overflows (Jonas Nick)
3fec982608 Use scalar_set_b32_seckey in ecdsa_sign, pubkey_create and seckey_verify (Jonas Nick)
9ab2cbe0eb Add scalar_set_b32_seckey which does the same as scalar_set_b32 and also returns whether it's a valid secret key (Jonas Nick)

Pull request description:

  Fixes #671. Supersedes #668.

  This PR unifies handling of invalid secret keys by introducing a new function `scalar_set_b32_secret` which returns false if the b32 overflows or is 0. By using this in `privkey_{negate, tweak_add, tweak_mul}` these function will now return 0 if the secret key is invalid which matches the behavior of `ecdsa_sign` and `pubkey_create`.

  Instead of deciding whether to zeroize the secret key on failure, I only added documentation for now that the value is undefined on failure.

ACKs for top commit:
  real-or-random:
    ACK 7e3952ae82 I read the diff carefully and tested the changes
  apoelstra:
    ACK 7e3952ae82

Tree-SHA512: 8e9a66799cd3b6ec1c3acb731d6778035417e3dca9300d840e2437346ff0ac94f0c9be4de20aa2fac9bb4ae2f8a36d4e6a34795a640b9cfbfee8311decb102f0
This commit is contained in:
Tim Ruffing 2020-04-30 18:11:53 +02:00
parent 39198a03ea 7e3952ae82
commit f39f99be0e
No known key found for this signature in database
GPG Key ID: 8C461CCD293F6011
9 changed files with 289 additions and 91 deletions
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110
include/secp256k1.h
View File

@ -14,7 +14,7 @@ extern "C" {
* 2. Array lengths always immediately the follow the argument whose length
* they describe, even if this violates rule 1.
* 3. Within the OUT/OUTIN/IN groups, pointers to data that is typically generated
* later go first. This means: signatures, public nonces, private nonces,
* later go first. This means: signatures, public nonces, secret nonces,
* messages, public keys, secret keys, tweaks.
* 4. Arguments that are not data pointers go last, from more complex to less
* complex: function pointers, algorithm names, messages, void pointers,
@ -531,7 +531,7 @@ SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_def
/** Create an ECDSA signature.
*
* Returns: 1: signature created
* 0: the nonce generation function failed, or the private key was invalid.
* 0: the nonce generation function failed, or the secret key was invalid.
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
@ -552,6 +552,11 @@ SECP256K1_API int secp256k1_ecdsa_sign(
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Verify an ECDSA secret key.
*
* A secret key is valid if it is not 0 and less than the secp256k1 curve order
* when interpreted as an integer (most significant byte first). The
* probability of choosing a 32-byte string uniformly at random which is an
* invalid secret key is negligible.
*
* Returns: 1: secret key is valid
* 0: secret key is invalid
@ -569,7 +574,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(
* 0: secret was invalid, try again
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: pubkey: pointer to the created public key (cannot be NULL)
* In: seckey: pointer to a 32-byte private key (cannot be NULL)
* In: seckey: pointer to a 32-byte secret key (cannot be NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
const secp256k1_context* ctx,
@ -577,12 +582,24 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
const unsigned char *seckey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Negates a private key in place.
/** Negates a secret key in place.
*
* Returns: 1 always
* Returns: 0 if the given secret key is invalid according to
* secp256k1_ec_seckey_verify. 1 otherwise
* Args: ctx: pointer to a context object
* In/Out: seckey: pointer to the 32-byte private key to be negated (cannot be NULL)
* In/Out: seckey: pointer to the 32-byte secret key to be negated. If the
* secret key is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0 and
* seckey will be set to some unspecified value. (cannot be
* NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_negate(
const secp256k1_context* ctx,
unsigned char *seckey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Same as secp256k1_ec_seckey_negate, but DEPRECATED. Will be removed in
* future versions. */
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_negate(
const secp256k1_context* ctx,
unsigned char *seckey
@ -599,15 +616,29 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
secp256k1_pubkey *pubkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Tweak a private key by adding tweak to it.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or if the resulting private key
* would be invalid (only when the tweak is the complement of the
* private key). 1 otherwise.
/** Tweak a secret key by adding tweak to it.
*
* Returns: 0 if the arguments are invalid or the resulting secret key would be
* invalid (only when the tweak is the negation of the secret key). 1
* otherwise.
* Args: ctx: pointer to a context object (cannot be NULL).
* In/Out: seckey: pointer to a 32-byte private key.
* In: tweak: pointer to a 32-byte tweak.
* In/Out: seckey: pointer to a 32-byte secret key. If the secret key is
* invalid according to secp256k1_ec_seckey_verify, this
* function returns 0. seckey will be set to some unspecified
* value if this function returns 0. (cannot be NULL)
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_add(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Same as secp256k1_ec_seckey_tweak_add, but DEPRECATED. Will be removed in
* future versions. */
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
const secp256k1_context* ctx,
unsigned char *seckey,
@ -615,14 +646,18 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Tweak a public key by adding tweak times the generator to it.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or if the resulting public key
* would be invalid (only when the tweak is the complement of the
* corresponding private key). 1 otherwise.
*
* Returns: 0 if the arguments are invalid or the resulting public key would be
* invalid (only when the tweak is the negation of the corresponding
* secret key). 1 otherwise.
* Args: ctx: pointer to a context object initialized for validation
* (cannot be NULL).
* In/Out: pubkey: pointer to a public key object.
* In: tweak: pointer to a 32-byte tweak.
* In/Out: pubkey: pointer to a public key object. pubkey will be set to an
* invalid value if this function returns 0 (cannot be NULL).
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
const secp256k1_context* ctx,
@ -630,13 +665,27 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Tweak a private key by multiplying it by a tweak.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or equal to zero. 1 otherwise.
/** Tweak a secret key by multiplying it by a tweak.
*
* Returns: 0 if the arguments are invalid. 1 otherwise.
* Args: ctx: pointer to a context object (cannot be NULL).
* In/Out: seckey: pointer to a 32-byte private key.
* In: tweak: pointer to a 32-byte tweak.
* In/Out: seckey: pointer to a 32-byte secret key. If the secret key is
* invalid according to secp256k1_ec_seckey_verify, this
* function returns 0. seckey will be set to some unspecified
* value if this function returns 0. (cannot be NULL)
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_mul(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Same as secp256k1_ec_seckey_tweak_mul, but DEPRECATED. Will be removed in
* future versions. */
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
const secp256k1_context* ctx,
unsigned char *seckey,
@ -644,12 +693,16 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Tweak a public key by multiplying it by a tweak value.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or equal to zero. 1 otherwise.
*
* Returns: 0 if the arguments are invalid. 1 otherwise.
* Args: ctx: pointer to a context object initialized for validation
* (cannot be NULL).
* In/Out: pubkey: pointer to a public key object.
* In: tweak: pointer to a 32-byte tweak.
* In/Out: pubkey: pointer to a public key object. pubkey will be set to an
* invalid value if this function returns 0 (cannot be NULL).
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
const secp256k1_context* ctx,
@ -688,6 +741,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
) SECP256K1_ARG_NONNULL(1);
/** Add a number of public keys together.
*
* Returns: 1: the sum of the public keys is valid.
* 0: the sum of the public keys is not valid.
* Args: ctx: pointer to a context object

4
include/secp256k1_ecdh.h
View File

@ -41,7 +41,7 @@ SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_func
* Out: output: pointer to an array to be filled by hashfp
* In: pubkey: a pointer to a secp256k1_pubkey containing an
* initialized public key
* privkey: a 32-byte scalar with which to multiply the point
* seckey: a 32-byte scalar with which to multiply the point
* hashfp: pointer to a hash function. If NULL, secp256k1_ecdh_hash_function_sha256 is used
* (in which case, 32 bytes will be written to output)
* data: arbitrary data pointer that is passed through to hashfp
@ -50,7 +50,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh(
const secp256k1_context* ctx,
unsigned char *output,
const secp256k1_pubkey *pubkey,
const unsigned char *privkey,
const unsigned char *seckey,
secp256k1_ecdh_hash_function hashfp,
void *data
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);

2
include/secp256k1_recovery.h
View File

@ -70,7 +70,7 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact(
/** Create a recoverable ECDSA signature.
*
* Returns: 1: signature created
* 0: the nonce generation function failed, or the private key was invalid.
* 0: the nonce generation function failed, or the secret key was invalid.
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msg32: the 32-byte message hash being signed (cannot be NULL)

5
src/eckey_impl.h
View File

@ -54,10 +54,7 @@ static int secp256k1_eckey_pubkey_serialize(secp256k1_ge *elem, unsigned char *p
static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
secp256k1_scalar_add(key, key, tweak);
if (secp256k1_scalar_is_zero(key)) {
return 0;
}
return 1;
return !secp256k1_scalar_is_zero(key);
}
static int secp256k1_eckey_pubkey_tweak_add(const secp256k1_ecmult_context *ctx, secp256k1_ge *key, const secp256k1_scalar *tweak) {

4
src/scalar.h
View File

@ -39,6 +39,10 @@ static unsigned int secp256k1_scalar_get_bits_var(const secp256k1_scalar *a, uns
*/
static void secp256k1_scalar_set_b32(secp256k1_scalar *r, const unsigned char *bin, int *overflow);
/** Set a scalar from a big endian byte array and returns 1 if it is a valid
* seckey and 0 otherwise. */
static int secp256k1_scalar_set_b32_seckey(secp256k1_scalar *r, const unsigned char *bin);
/** Set a scalar to an unsigned integer. */
static void secp256k1_scalar_set_int(secp256k1_scalar *r, unsigned int v);

6
src/scalar_impl.h
View File

@ -55,6 +55,12 @@ static void secp256k1_scalar_order_get_num(secp256k1_num *r) {
}
#endif
static int secp256k1_scalar_set_b32_seckey(secp256k1_scalar *r, const unsigned char *bin) {
int overflow;
secp256k1_scalar_set_b32(r, bin, &overflow);
return (!overflow) & (!secp256k1_scalar_is_zero(r));
}
static void secp256k1_scalar_inverse(secp256k1_scalar *r, const secp256k1_scalar *x) {
#if defined(EXHAUSTIVE_TEST_ORDER)
int i;

70
src/secp256k1.c
View File

@ -471,7 +471,7 @@ int secp256k1_ecdsa_sign(const secp256k1_context* ctx, secp256k1_ecdsa_signature
secp256k1_scalar r, s;
secp256k1_scalar sec, non, msg;
int ret = 0;
int overflow = 0;
int is_sec_valid;
unsigned char nonce32[32];
unsigned int count = 0;
VERIFY_CHECK(ctx != NULL);
@ -483,22 +483,20 @@ int secp256k1_ecdsa_sign(const secp256k1_context* ctx, secp256k1_ecdsa_signature
noncefp = secp256k1_nonce_function_default;
}
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
/* Fail if the secret key is invalid. */
overflow |= secp256k1_scalar_is_zero(&sec);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_one, overflow);
is_sec_valid = secp256k1_scalar_set_b32_seckey(&sec, seckey);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_one, !is_sec_valid);
secp256k1_scalar_set_b32(&msg, msg32, NULL);
while (1) {
int koverflow;
ret = noncefp(nonce32, msg32, seckey, NULL, (void*)noncedata, count);
int is_nonce_valid;
ret = !!noncefp(nonce32, msg32, seckey, NULL, (void*)noncedata, count);
if (!ret) {
break;
}
secp256k1_scalar_set_b32(&non, nonce32, &koverflow);
koverflow |= secp256k1_scalar_is_zero(&non);
/* The nonce is still secret here, but it overflowing or being zero is is less likely than 1:2^255. */
secp256k1_declassify(ctx, &koverflow, sizeof(koverflow));
if (!koverflow) {
is_nonce_valid = secp256k1_scalar_set_b32_seckey(&non, nonce32);
/* The nonce is still secret here, but it being invalid is is less likely than 1:2^255. */
secp256k1_declassify(ctx, &is_nonce_valid, sizeof(is_nonce_valid));
if (is_nonce_valid) {
ret = secp256k1_ecdsa_sig_sign(&ctx->ecmult_gen_ctx, &r, &s, &sec, &msg, &non, NULL);
/* The final signature is no longer a secret, nor is the fact that we were successful or not. */
secp256k1_declassify(ctx, &ret, sizeof(ret));
@ -508,25 +506,27 @@ int secp256k1_ecdsa_sign(const secp256k1_context* ctx, secp256k1_ecdsa_signature
}
count++;
}
/* We don't want to declassify is_sec_valid and therefore the range of
* seckey. As a result is_sec_valid is included in ret only after ret was
* used as a branching variable. */
ret &= is_sec_valid;
memset(nonce32, 0, 32);
secp256k1_scalar_clear(&msg);
secp256k1_scalar_clear(&non);
secp256k1_scalar_clear(&sec);
secp256k1_scalar_cmov(&r, &secp256k1_scalar_zero, (!ret) | overflow);
secp256k1_scalar_cmov(&s, &secp256k1_scalar_zero, (!ret) | overflow);
secp256k1_scalar_cmov(&r, &secp256k1_scalar_zero, !ret);
secp256k1_scalar_cmov(&s, &secp256k1_scalar_zero, !ret);
secp256k1_ecdsa_signature_save(signature, &r, &s);
return !!ret & !overflow;
return ret;
}
int secp256k1_ec_seckey_verify(const secp256k1_context* ctx, const unsigned char *seckey) {
secp256k1_scalar sec;
int ret;
int overflow;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(seckey != NULL);
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
ret = !overflow & !secp256k1_scalar_is_zero(&sec);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
secp256k1_scalar_clear(&sec);
return ret;
}
@ -535,7 +535,6 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
secp256k1_gej pj;
secp256k1_ge p;
secp256k1_scalar sec;
int overflow;
int ret = 0;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL);
@ -543,8 +542,7 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(seckey != NULL);
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
ret = !overflow & !secp256k1_scalar_is_zero(&sec);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_one, !ret);
secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pj, &sec);
@ -556,17 +554,23 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
return ret;
}
int secp256k1_ec_privkey_negate(const secp256k1_context* ctx, unsigned char *seckey) {
int secp256k1_ec_seckey_negate(const secp256k1_context* ctx, unsigned char *seckey) {
secp256k1_scalar sec;
int ret = 0;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(seckey != NULL);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret);
secp256k1_scalar_negate(&sec, &sec);
secp256k1_scalar_get_b32(seckey, &sec);
secp256k1_scalar_clear(&sec);
return 1;
return ret;
}
int secp256k1_ec_privkey_negate(const secp256k1_context* ctx, unsigned char *seckey) {
return secp256k1_ec_seckey_negate(ctx, seckey);
}
int secp256k1_ec_pubkey_negate(const secp256k1_context* ctx, secp256k1_pubkey *pubkey) {
@ -584,7 +588,7 @@ int secp256k1_ec_pubkey_negate(const secp256k1_context* ctx, secp256k1_pubkey *p
return ret;
}
int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
int secp256k1_ec_seckey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar term;
secp256k1_scalar sec;
int ret = 0;
@ -594,9 +598,9 @@ int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *
ARG_CHECK(tweak != NULL);
secp256k1_scalar_set_b32(&term, tweak, &overflow);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
ret = (!overflow) & secp256k1_eckey_privkey_tweak_add(&sec, &term);
ret &= (!overflow) & secp256k1_eckey_privkey_tweak_add(&sec, &term);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret);
secp256k1_scalar_get_b32(seckey, &sec);
@ -605,6 +609,10 @@ int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *
return ret;
}
int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
return secp256k1_ec_seckey_tweak_add(ctx, seckey, tweak);
}
int secp256k1_ec_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *tweak) {
secp256k1_ge p;
secp256k1_scalar term;
@ -629,7 +637,7 @@ int secp256k1_ec_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey
return ret;
}
int secp256k1_ec_privkey_tweak_mul(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
int secp256k1_ec_seckey_tweak_mul(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar factor;
secp256k1_scalar sec;
int ret = 0;
@ -639,8 +647,8 @@ int secp256k1_ec_privkey_tweak_mul(const secp256k1_context* ctx, unsigned char *
ARG_CHECK(tweak != NULL);
secp256k1_scalar_set_b32(&factor, tweak, &overflow);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
ret = (!overflow) & secp256k1_eckey_privkey_tweak_mul(&sec, &factor);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
ret &= (!overflow) & secp256k1_eckey_privkey_tweak_mul(&sec, &factor);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret);
secp256k1_scalar_get_b32(seckey, &sec);
@ -649,6 +657,10 @@ int secp256k1_ec_privkey_tweak_mul(const secp256k1_context* ctx, unsigned char *
return ret;
}
int secp256k1_ec_privkey_tweak_mul(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
return secp256k1_ec_seckey_tweak_mul(ctx, seckey, tweak);
}
int secp256k1_ec_pubkey_tweak_mul(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *tweak) {
secp256k1_ge p;
secp256k1_scalar factor;

161
src/tests.c
View File

@ -140,6 +140,12 @@ void random_scalar_order(secp256k1_scalar *num) {
} while(1);
}
void random_scalar_order_b32(unsigned char *b32) {
secp256k1_scalar num;
random_scalar_order(&num);
secp256k1_scalar_get_b32(b32, &num);
}
void run_context_tests(int use_prealloc) {
secp256k1_pubkey pubkey;
secp256k1_pubkey zero_pubkey;
@ -1077,11 +1083,31 @@ void scalar_test(void) {
}
void run_scalar_set_b32_seckey_tests(void) {
unsigned char b32[32];
secp256k1_scalar s1;
secp256k1_scalar s2;
/* Usually set_b32 and set_b32_seckey give the same result */
random_scalar_order_b32(b32);
secp256k1_scalar_set_b32(&s1, b32, NULL);
CHECK(secp256k1_scalar_set_b32_seckey(&s2, b32) == 1);
CHECK(secp256k1_scalar_eq(&s1, &s2) == 1);
memset(b32, 0, sizeof(b32));
CHECK(secp256k1_scalar_set_b32_seckey(&s2, b32) == 0);
memset(b32, 0xFF, sizeof(b32));
CHECK(secp256k1_scalar_set_b32_seckey(&s2, b32) == 0);
}
void run_scalar_tests(void) {
int i;
for (i = 0; i < 128 * count; i++) {
scalar_test();
}
for (i = 0; i < count; i++) {
run_scalar_set_b32_seckey_tests();
}
{
/* (-1)+1 should be zero. */
@ -1097,16 +1123,43 @@ void run_scalar_tests(void) {
#ifndef USE_NUM_NONE
{
/* A scalar with value of the curve order should be 0. */
/* Test secp256k1_scalar_set_b32 boundary conditions */
secp256k1_num order;
secp256k1_scalar zero;
secp256k1_scalar scalar;
unsigned char bin[32];
unsigned char bin_tmp[32];
int overflow = 0;
/* 2^256-1 - order */
static const secp256k1_scalar all_ones_minus_order = SECP256K1_SCALAR_CONST(
0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000001UL,
0x45512319UL, 0x50B75FC4UL, 0x402DA173UL, 0x2FC9BEBEUL
);
/* A scalar set to 0s should be 0. */
memset(bin, 0, 32);
secp256k1_scalar_set_b32(&scalar, bin, &overflow);
CHECK(overflow == 0);
CHECK(secp256k1_scalar_is_zero(&scalar));
/* A scalar with value of the curve order should be 0. */
secp256k1_scalar_order_get_num(&order);
secp256k1_num_get_bin(bin, 32, &order);
secp256k1_scalar_set_b32(&zero, bin, &overflow);
secp256k1_scalar_set_b32(&scalar, bin, &overflow);
CHECK(overflow == 1);
CHECK(secp256k1_scalar_is_zero(&zero));
CHECK(secp256k1_scalar_is_zero(&scalar));
/* A scalar with value of the curve order minus one should not overflow. */
bin[31] -= 1;
secp256k1_scalar_set_b32(&scalar, bin, &overflow);
CHECK(overflow == 0);
secp256k1_scalar_get_b32(bin_tmp, &scalar);
CHECK(memcmp(bin, bin_tmp, 32) == 0);
/* A scalar set to all 1s should overflow. */
memset(bin, 0xFF, 32);
secp256k1_scalar_set_b32(&scalar, bin, &overflow);
CHECK(overflow == 1);
CHECK(secp256k1_scalar_eq(&scalar, &all_ones_minus_order));
}
#endif
@ -3936,37 +3989,57 @@ void run_eckey_edge_case_test(void) {
pubkey_negone = pubkey;
/* Tweak of zero leaves the value unchanged. */
memset(ctmp2, 0, 32);
CHECK(secp256k1_ec_privkey_tweak_add(ctx, ctmp, ctmp2) == 1);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp, ctmp2) == 1);
CHECK(memcmp(orderc, ctmp, 31) == 0 && ctmp[31] == 0x40);
memcpy(&pubkey2, &pubkey, sizeof(pubkey));
CHECK(secp256k1_ec_pubkey_tweak_add(ctx, &pubkey, ctmp2) == 1);
CHECK(memcmp(&pubkey, &pubkey2, sizeof(pubkey)) == 0);
/* Multiply tweak of zero zeroizes the output. */
CHECK(secp256k1_ec_privkey_tweak_mul(ctx, ctmp, ctmp2) == 0);
CHECK(secp256k1_ec_seckey_tweak_mul(ctx, ctmp, ctmp2) == 0);
CHECK(memcmp(zeros, ctmp, 32) == 0);
CHECK(secp256k1_ec_pubkey_tweak_mul(ctx, &pubkey, ctmp2) == 0);
CHECK(memcmp(&pubkey, zeros, sizeof(pubkey)) == 0);
memcpy(&pubkey, &pubkey2, sizeof(pubkey));
/* Overflowing key tweak zeroizes. */
/* If seckey_tweak_add or seckey_tweak_mul are called with an overflowing
seckey, the seckey is zeroized. */
memcpy(ctmp, orderc, 32);
memset(ctmp2, 0, 32);
ctmp2[31] = 0x01;
CHECK(secp256k1_ec_seckey_verify(ctx, ctmp2) == 1);
CHECK(secp256k1_ec_seckey_verify(ctx, ctmp) == 0);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp, ctmp2) == 0);
CHECK(memcmp(zeros, ctmp, 32) == 0);
memcpy(ctmp, orderc, 32);
CHECK(secp256k1_ec_seckey_tweak_mul(ctx, ctmp, ctmp2) == 0);
CHECK(memcmp(zeros, ctmp, 32) == 0);
/* If seckey_tweak_add or seckey_tweak_mul are called with an overflowing
tweak, the seckey is zeroized. */
memcpy(ctmp, orderc, 32);
ctmp[31] = 0x40;
CHECK(secp256k1_ec_privkey_tweak_add(ctx, ctmp, orderc) == 0);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp, orderc) == 0);
CHECK(memcmp(zeros, ctmp, 32) == 0);
memcpy(ctmp, orderc, 32);
ctmp[31] = 0x40;
CHECK(secp256k1_ec_privkey_tweak_mul(ctx, ctmp, orderc) == 0);
CHECK(secp256k1_ec_seckey_tweak_mul(ctx, ctmp, orderc) == 0);
CHECK(memcmp(zeros, ctmp, 32) == 0);
memcpy(ctmp, orderc, 32);
ctmp[31] = 0x40;
/* If pubkey_tweak_add or pubkey_tweak_mul are called with an overflowing
tweak, the pubkey is zeroized. */
CHECK(secp256k1_ec_pubkey_tweak_add(ctx, &pubkey, orderc) == 0);
CHECK(memcmp(&pubkey, zeros, sizeof(pubkey)) == 0);
memcpy(&pubkey, &pubkey2, sizeof(pubkey));
CHECK(secp256k1_ec_pubkey_tweak_mul(ctx, &pubkey, orderc) == 0);
CHECK(memcmp(&pubkey, zeros, sizeof(pubkey)) == 0);
memcpy(&pubkey, &pubkey2, sizeof(pubkey));
/* Private key tweaks results in a key of zero. */
/* If the resulting key in secp256k1_ec_seckey_tweak_add and
* secp256k1_ec_pubkey_tweak_add is 0 the functions fail and in the latter
* case the pubkey is zeroized. */
memcpy(ctmp, orderc, 32);
ctmp[31] = 0x40;
memset(ctmp2, 0, 32);
ctmp2[31] = 1;
CHECK(secp256k1_ec_privkey_tweak_add(ctx, ctmp2, ctmp) == 0);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp2, ctmp) == 0);
CHECK(memcmp(zeros, ctmp2, 32) == 0);
ctmp2[31] = 1;
CHECK(secp256k1_ec_pubkey_tweak_add(ctx, &pubkey, ctmp2) == 0);
@ -3974,7 +4047,7 @@ void run_eckey_edge_case_test(void) {
memcpy(&pubkey, &pubkey2, sizeof(pubkey));
/* Tweak computation wraps and results in a key of 1. */
ctmp2[31] = 2;
CHECK(secp256k1_ec_privkey_tweak_add(ctx, ctmp2, ctmp) == 1);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp2, ctmp) == 1);
CHECK(memcmp(ctmp2, zeros, 31) == 0 && ctmp2[31] == 1);
ctmp2[31] = 2;
CHECK(secp256k1_ec_pubkey_tweak_add(ctx, &pubkey, ctmp2) == 1);
@ -4022,16 +4095,16 @@ void run_eckey_edge_case_test(void) {
CHECK(ecount == 2);
ecount = 0;
memset(ctmp2, 0, 32);
CHECK(secp256k1_ec_privkey_tweak_add(ctx, NULL, ctmp2) == 0);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, NULL, ctmp2) == 0);
CHECK(ecount == 1);
CHECK(secp256k1_ec_privkey_tweak_add(ctx, ctmp, NULL) == 0);
CHECK(secp256k1_ec_seckey_tweak_add(ctx, ctmp, NULL) == 0);
CHECK(ecount == 2);
ecount = 0;
memset(ctmp2, 0, 32);
ctmp2[31] = 1;
CHECK(secp256k1_ec_privkey_tweak_mul(ctx, NULL, ctmp2) == 0);
CHECK(secp256k1_ec_seckey_tweak_mul(ctx, NULL, ctmp2) == 0);
CHECK(ecount == 1);
CHECK(secp256k1_ec_privkey_tweak_mul(ctx, ctmp, NULL) == 0);
CHECK(secp256k1_ec_seckey_tweak_mul(ctx, ctmp, NULL) == 0);
CHECK(ecount == 2);
ecount = 0;
CHECK(secp256k1_ec_pubkey_create(ctx, NULL, ctmp) == 0);
@ -4104,6 +4177,41 @@ void run_eckey_edge_case_test(void) {
secp256k1_context_set_illegal_callback(ctx, NULL, NULL);
}
void run_eckey_negate_test(void) {
unsigned char seckey[32];
unsigned char seckey_tmp[32];
random_scalar_order_b32(seckey);
memcpy(seckey_tmp, seckey, 32);
/* Verify negation changes the key and changes it back */
CHECK(secp256k1_ec_seckey_negate(ctx, seckey) == 1);
CHECK(memcmp(seckey, seckey_tmp, 32) != 0);
CHECK(secp256k1_ec_seckey_negate(ctx, seckey) == 1);
CHECK(memcmp(seckey, seckey_tmp, 32) == 0);
/* Check that privkey alias gives same result */
CHECK(secp256k1_ec_seckey_negate(ctx, seckey) == 1);
CHECK(secp256k1_ec_privkey_negate(ctx, seckey_tmp) == 1);
CHECK(memcmp(seckey, seckey_tmp, 32) == 0);
/* Negating all 0s fails */
memset(seckey, 0, 32);
memset(seckey_tmp, 0, 32);
CHECK(secp256k1_ec_seckey_negate(ctx, seckey) == 0);
/* Check that seckey is not modified */
CHECK(memcmp(seckey, seckey_tmp, 32) == 0);
/* Negating an overflowing seckey fails and the seckey is zeroed. In this
* test, the seckey has 16 random bytes to ensure that ec_seckey_negate
* doesn't just set seckey to a constant value in case of failure. */
random_scalar_order_b32(seckey);
memset(seckey, 0xFF, 16);
memset(seckey_tmp, 0, 32);
CHECK(secp256k1_ec_seckey_negate(ctx, seckey) == 0);
CHECK(memcmp(seckey, seckey_tmp, 32) == 0);
}
void random_sign(secp256k1_scalar *sigr, secp256k1_scalar *sigs, const secp256k1_scalar *key, const secp256k1_scalar *msg, int *recid) {
secp256k1_scalar nonce;
do {
@ -4243,15 +4351,22 @@ void test_ecdsa_end_to_end(void) {
if (secp256k1_rand_int(3) == 0) {
int ret1;
int ret2;
int ret3;
unsigned char rnd[32];
unsigned char privkey_tmp[32];
secp256k1_pubkey pubkey2;
secp256k1_rand256_test(rnd);
ret1 = secp256k1_ec_privkey_tweak_add(ctx, privkey, rnd);
memcpy(privkey_tmp, privkey, 32);
ret1 = secp256k1_ec_seckey_tweak_add(ctx, privkey, rnd);
ret2 = secp256k1_ec_pubkey_tweak_add(ctx, &pubkey, rnd);
/* Check that privkey alias gives same result */
ret3 = secp256k1_ec_privkey_tweak_add(ctx, privkey_tmp, rnd);
CHECK(ret1 == ret2);
CHECK(ret2 == ret3);
if (ret1 == 0) {
return;
}
CHECK(memcmp(privkey, privkey_tmp, 32) == 0);
CHECK(secp256k1_ec_pubkey_create(ctx, &pubkey2, privkey) == 1);
CHECK(memcmp(&pubkey, &pubkey2, sizeof(pubkey)) == 0);
}
@ -4260,15 +4375,22 @@ void test_ecdsa_end_to_end(void) {
if (secp256k1_rand_int(3) == 0) {
int ret1;
int ret2;
int ret3;
unsigned char rnd[32];
unsigned char privkey_tmp[32];
secp256k1_pubkey pubkey2;
secp256k1_rand256_test(rnd);
ret1 = secp256k1_ec_privkey_tweak_mul(ctx, privkey, rnd);
memcpy(privkey_tmp, privkey, 32);
ret1 = secp256k1_ec_seckey_tweak_mul(ctx, privkey, rnd);
ret2 = secp256k1_ec_pubkey_tweak_mul(ctx, &pubkey, rnd);
/* Check that privkey alias gives same result */
ret3 = secp256k1_ec_privkey_tweak_mul(ctx, privkey_tmp, rnd);
CHECK(ret1 == ret2);
CHECK(ret2 == ret3);
if (ret1 == 0) {
return;
}
CHECK(memcmp(privkey, privkey_tmp, 32) == 0);
CHECK(secp256k1_ec_pubkey_create(ctx, &pubkey2, privkey) == 1);
CHECK(memcmp(&pubkey, &pubkey2, sizeof(pubkey)) == 0);
}
@ -5294,6 +5416,9 @@ int main(int argc, char **argv) {
/* EC key edge cases */
run_eckey_edge_case_test();
/* EC key arithmetic test */
run_eckey_negate_test();
#ifdef ENABLE_MODULE_ECDH
/* ecdh tests */
run_ecdh_tests();

6
src/valgrind_ctime_test.c
View File

@ -73,19 +73,19 @@ int main(void) {
CHECK(ret == 1);
VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
ret = secp256k1_ec_privkey_negate(ctx, key);
ret = secp256k1_ec_seckey_negate(ctx, key);
VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
CHECK(ret == 1);
VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
VALGRIND_MAKE_MEM_UNDEFINED(msg, 32);
ret = secp256k1_ec_privkey_tweak_add(ctx, key, msg);
ret = secp256k1_ec_seckey_tweak_add(ctx, key, msg);
VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
CHECK(ret == 1);
VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
VALGRIND_MAKE_MEM_UNDEFINED(msg, 32);
ret = secp256k1_ec_privkey_tweak_mul(ctx, key, msg);
ret = secp256k1_ec_seckey_tweak_mul(ctx, key, msg);
VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
CHECK(ret == 1);