diff --git a/Makefile.am b/Makefile.am index 8480651e7d7..b89bfdb211c 100644 --- a/Makefile.am +++ b/Makefile.am @@ -40,6 +40,7 @@ noinst_HEADERS += src/hash_impl.h noinst_HEADERS += src/field.h noinst_HEADERS += src/field_impl.h noinst_HEADERS += src/bench.h +noinst_HEADERS += contrib/lax_der_parsing.h pkgconfigdir = $(libdir)/pkgconfig pkgconfig_DATA = libsecp256k1.pc @@ -64,7 +65,7 @@ endif if USE_TESTS noinst_PROGRAMS += tests tests_SOURCES = src/tests.c -tests_CPPFLAGS = -DVERIFY -I$(top_srcdir)/src $(SECP_INCLUDES) $(SECP_TEST_INCLUDES) +tests_CPPFLAGS = -DVERIFY -I$(top_srcdir)/src -I$(top_srcdir)/include $(SECP_INCLUDES) $(SECP_TEST_INCLUDES) tests_LDADD = $(SECP_LIBS) $(SECP_TEST_LIBS) tests_LDFLAGS = -static TESTS = tests diff --git a/contrib/lax_der_parsing.h b/contrib/lax_der_parsing.h new file mode 100644 index 00000000000..53aafbc4b49 --- /dev/null +++ b/contrib/lax_der_parsing.h @@ -0,0 +1,191 @@ +/********************************************************************** + * Copyright (c) 2015 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or http://www.opensource.org/licenses/mit-license.php.* + **********************************************************************/ + +/* This file contains a code snippet that parses DER with various errors and + * violations. This is not a part of the library itself, because the allowed + * violations are chosen arbitrarily and do not follow or establish any + * standard. + * + * In many places it matters that different implementations do not only accept + * the same set of valid signatures, but also reject the same set of signatures. + * The only means to accomplish that is by strictly obeying a standard, and not + * accepting anything else. + * + * Nonetheless, sometimes there is a need for compatibility with systems that + * use signatures which do not strictly obey DER. The snippet below shows how + * certain violations are easily supported. You may need to adapt it. + * + * Do not use this for new systems. Use well-defined DER or compact signatures + * instead if you have the choice (see secp256k1_ecdsa_signature_parse_der and + * secp256k1_ecdsa_signature_parse_compact). + * + * The supported violations are: + * - All numbers are parsed as nonnegative integers, even though X.609-0207 + * section 8.3.3 specifies that integers are always encoded as two's + * complement. + * - Integers can have length 0, even though section 8.3.1 says they can't. + * - Integers with overly long padding are accepted, violation section + * 8.3.2. + * - 127-byte long length descriptors are accepted, even though section + * 8.1.3.5.c says that they are not. + * - Trailing garbage data inside or after the signature is ignored. + * - The length descriptor of the sequence is ignored. + * + * Compared to for example OpenSSL, many violations are NOT supported: + * - Using overly long tag descriptors for the sequence or integers inside, + * violating section 8.1.2.2. + * - Encoding primitive integers as constructed values, violating section + * 8.3.1. + */ + +#ifndef _SECP256K1_CONTRIB_LAX_DER_PARSING_H_ +#define _SECP256K1_CONTRIB_LAX_DER_PARSING_H_ + +#include +#include + +static int secp256k1_ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen); + +static int secp256k1_ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen) { + size_t rpos, rlen, spos, slen; + size_t pos = 0; + size_t lenbyte; + unsigned char tmpsig[64] = {0}; + int overflow = 0; + + /* Hack to initialize sig with a correctly-parsed but invalid signature. */ + secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig); + + /* Sequence tag byte */ + if (pos == inputlen || input[pos] != 0x30) { + return 0; + } + pos++; + + /* Sequence length bytes */ + if (pos == inputlen) { + return 0; + } + lenbyte = input[pos++]; + if (lenbyte & 0x80) { + lenbyte -= 0x80; + if (pos + lenbyte > inputlen) { + return 0; + } + pos += lenbyte; + } + + /* Integer tag byte for R */ + if (pos == inputlen || input[pos] != 0x02) { + return 0; + } + pos++; + + /* Integer length for R */ + if (pos == inputlen) { + return 0; + } + lenbyte = input[pos++]; + if (lenbyte & 0x80) { + lenbyte -= 0x80; + if (pos + lenbyte > inputlen) { + return 0; + } + while (lenbyte > 0 && input[pos] == 0) { + pos++; + lenbyte--; + } + if (lenbyte >= sizeof(size_t)) { + return 0; + } + rlen = 0; + while (lenbyte > 0) { + rlen = (rlen << 8) + input[pos]; + pos++; + lenbyte--; + } + } else { + rlen = lenbyte; + } + if (rlen > inputlen - pos) { + return 0; + } + rpos = pos; + pos += rlen; + + /* Integer tag byte for S */ + if (pos == inputlen || input[pos] != 0x02) { + return 0; + } + pos++; + + /* Integer length for S */ + if (pos == inputlen) { + return 0; + } + lenbyte = input[pos++]; + if (lenbyte & 0x80) { + lenbyte -= 0x80; + if (pos + lenbyte > inputlen) { + return 0; + } + while (lenbyte > 0 && input[pos] == 0) { + pos++; + lenbyte--; + } + if (lenbyte >= sizeof(size_t)) { + return 0; + } + slen = 0; + while (lenbyte > 0) { + slen = (slen << 8) + input[pos]; + pos++; + lenbyte--; + } + } else { + slen = lenbyte; + } + if (slen > inputlen - pos) { + return 0; + } + spos = pos; + pos += slen; + + /* Ignore leading zeroes in R */ + while (rlen > 0 && input[rpos] == 0) { + rlen--; + rpos++; + } + /* Copy R value */ + if (rlen > 32) { + overflow = 1; + } else { + memcpy(tmpsig + 32 - rlen, input + rpos, rlen); + } + + /* Ignore leading zeroes in S */ + while (slen > 0 && input[spos] == 0) { + slen--; + spos++; + } + /* Copy S value */ + if (slen > 32) { + overflow = 1; + } else { + memcpy(tmpsig + 64 - slen, input + spos, slen); + } + + if (!overflow) { + overflow = !secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig); + } + if (overflow) { + memset(tmpsig, 0, 64); + secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig); + } + return 1; +} + +#endif diff --git a/include/secp256k1.h b/include/secp256k1.h index ba076014c70..61e8dd6b13f 100644 --- a/include/secp256k1.h +++ b/include/secp256k1.h @@ -271,6 +271,27 @@ SECP256K1_API int secp256k1_ec_pubkey_serialize( unsigned int flags ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); +/** Parse an ECDSA signature in compact (64 bytes) format. + * + * Returns: 1 when the signature could be parsed, 0 otherwise. + * Args: ctx: a secp256k1 context object + * Out: sig: a pointer to a signature object + * In: input64: a pointer to the 64-byte array to parse + * + * The signature must consist of a 32-byte big endian R value, followed by a + * 32-byte big endian S value. If R or S fall outside of [0..order-1], the + * encoding is invalid. R and S with value 0 are allowed in the encoding. + * + * After the call, sig will always be initialized. If parsing failed or R or + * S are zero, the resulting sig value is guaranteed to fail validation for any + * message and public key. + */ +SECP256K1_API int secp256k1_ecdsa_signature_parse_compact( + const secp256k1_context* ctx, + secp256k1_ecdsa_signature* sig, + const unsigned char *input64 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + /** Parse a DER ECDSA signature. * * Returns: 1 when the signature could be parsed, 0 otherwise. @@ -279,7 +300,12 @@ SECP256K1_API int secp256k1_ec_pubkey_serialize( * In: input: a pointer to the signature to be parsed * inputlen: the length of the array pointed to be input * - * Note that this function also supports some violations of DER and even BER. + * This function will accept any valid DER encoded signature, even if the + * encoded numbers are out of range. + * + * After the call, sig will always be initialized. If parsing failed or the + * encoded numbers are out of range, signature validation with it is + * guaranteed to fail for every message and public key. */ SECP256K1_API int secp256k1_ecdsa_signature_parse_der( const secp256k1_context* ctx, @@ -306,6 +332,21 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_der( const secp256k1_ecdsa_signature* sig ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); +/** Serialize an ECDSA signature in compact (64 byte) format. + * + * Returns: 1 + * Args: ctx: a secp256k1 context object + * Out: output64: a pointer to a 64-byte array to store the compact serialization + * In: sig: a pointer to an initialized signature object + * + * See secp256k1_ecdsa_signature_parse_compact for details about the encoding. + */ +SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact( + const secp256k1_context* ctx, + unsigned char *output64, + const secp256k1_ecdsa_signature* sig +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + /** Verify an ECDSA signature. * * Returns: 1: correct signature @@ -314,6 +355,15 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_der( * In: sig: the signature being verified (cannot be NULL) * msg32: the 32-byte message hash being verified (cannot be NULL) * pubkey: pointer to an initialized public key to verify with (cannot be NULL) + * + * To avoid accepting malleable signatures, only ECDSA signatures in lower-S + * form are accepted. + * + * If you need to accept ECDSA signatures from sources that do not obey this + * rule, apply secp256k1_ecdsa_signature_normalize to the signature prior to + * validation, but be aware that doing so results in malleable signatures. + * + * For details, see the comments for that function. */ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify( const secp256k1_context* ctx, @@ -322,6 +372,54 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify( const secp256k1_pubkey *pubkey ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); +/** Convert a signature to a normalized lower-S form. + * + * Returns: 1 if sigin was not normalized, 0 if it already was. + * Args: ctx: a secp256k1 context object + * Out: sigout: a pointer to a signature to fill with the normalized form, + * or copy if the input was already normalized. (can be NULL if + * you're only interested in whether the input was already + * normalized). + * In: sigin: a pointer to a signature to check/normalize (cannot be NULL, + * can be identical to sigout) + * + * With ECDSA a third-party can forge a second distinct signature of the same + * message, given a single initial signature, but without knowing the key. This + * is done by negating the S value modulo the order of the curve, 'flipping' + * the sign of the random point R which is not included in the signature. + * + * Forgery of the same message isn't universally problematic, but in systems + * where message malleability or uniqueness of signatures is important this can + * cause issues. This forgery can be blocked by all verifiers forcing signers + * to use a normalized form. + * + * The lower-S form reduces the size of signatures slightly on average when + * variable length encodings (such as DER) are used and is cheap to verify, + * making it a good choice. Security of always using lower-S is assured because + * anyone can trivially modify a signature after the fact to enforce this + * property anyway. + * + * The lower S value is always between 0x1 and + * 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, + * inclusive. + * + * No other forms of ECDSA malleability are known and none seem likely, but + * there is no formal proof that ECDSA, even with this additional restriction, + * is free of other malleability. Commonly used serialization schemes will also + * accept various non-unique encodings, so care should be taken when this + * property is required for an application. + * + * The secp256k1_ecdsa_sign function will by default create signatures in the + * lower-S form, and secp256k1_ecdsa_verify will not accept others. In case + * signatures come from a system that cannot enforce this property, + * secp256k1_ecdsa_signature_normalize must be called before verification. + */ +SECP256K1_API int secp256k1_ecdsa_signature_normalize( + const secp256k1_context* ctx, + secp256k1_ecdsa_signature *sigout, + const secp256k1_ecdsa_signature *sigin +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3); + /** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function. * If a data pointer is passed, it is assumed to be a pointer to 32 bytes of * extra entropy. @@ -342,32 +440,8 @@ SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_def * noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used * ndata: pointer to arbitrary data used by the nonce generation function (can be NULL) * - * The sig always has an s value in the lower half of the range (From 0x1 - * to 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, - * inclusive), unlike many other implementations. - * - * With ECDSA a third-party can can forge a second distinct signature - * of the same message given a single initial signature without knowing - * the key by setting s to its additive inverse mod-order, 'flipping' the - * sign of the random point R which is not included in the signature. - * Since the forgery is of the same message this isn't universally - * problematic, but in systems where message malleability or uniqueness - * of signatures is important this can cause issues. This forgery can be - * blocked by all verifiers forcing signers to use a canonical form. The - * lower-S form reduces the size of signatures slightly on average when - * variable length encodings (such as DER) are used and is cheap to - * verify, making it a good choice. Security of always using lower-S is - * assured because anyone can trivially modify a signature after the - * fact to enforce this property. Adjusting it inside the signing - * function avoids the need to re-serialize or have curve specific - * constants outside of the library. By always using a canonical form - * even in applications where it isn't needed it becomes possible to - * impose a requirement later if a need is discovered. - * No other forms of ECDSA malleability are known and none seem likely, - * but there is no formal proof that ECDSA, even with this additional - * restriction, is free of other malleability. Commonly used serialization - * schemes will also accept various non-unique encodings, so care should - * be taken when this property is required for an application. + * The created signature is always in lower-S form. See + * secp256k1_ecdsa_signature_normalize for more details. */ SECP256K1_API int secp256k1_ecdsa_sign( const secp256k1_context* ctx, diff --git a/include/secp256k1_recovery.h b/include/secp256k1_recovery.h index c9b8c0a3069..2283df6c9d5 100644 --- a/include/secp256k1_recovery.h +++ b/include/secp256k1_recovery.h @@ -65,7 +65,7 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact( unsigned char *output64, int *recid, const secp256k1_ecdsa_recoverable_signature* sig -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4); +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); /** Create a recoverable ECDSA signature. * diff --git a/src/ecdsa_impl.h b/src/ecdsa_impl.h index 4a172b3c511..5fe84e2cf3b 100644 --- a/src/ecdsa_impl.h +++ b/src/ecdsa_impl.h @@ -1,5 +1,5 @@ /********************************************************************** - * Copyright (c) 2013, 2014 Pieter Wuille * + * Copyright (c) 2013-2015 Pieter Wuille * * Distributed under the MIT software license, see the accompanying * * file COPYING or http://www.opensource.org/licenses/mit-license.php.* **********************************************************************/ @@ -46,66 +46,132 @@ static const secp256k1_fe secp256k1_ecdsa_const_p_minus_order = SECP256K1_FE_CON 0, 0, 0, 1, 0x45512319UL, 0x50B75FC4UL, 0x402DA172UL, 0x2FC9BAEEUL ); +static int secp256k1_der_read_len(const unsigned char **sigp, const unsigned char *sigend) { + int lenleft, b1; + size_t ret = 0; + if (*sigp >= sigend) { + return -1; + } + b1 = *((*sigp)++); + if (b1 == 0xFF) { + /* X.690-0207 8.1.3.5.c the value 0xFF shall not be used. */ + return -1; + } + if ((b1 & 0x80) == 0) { + /* X.690-0207 8.1.3.4 short form length octets */ + return b1; + } + if (b1 == 0x80) { + /* Indefinite length is not allowed in DER. */ + return -1; + } + /* X.690-207 8.1.3.5 long form length octets */ + lenleft = b1 & 0x7F; + if (lenleft > sigend - *sigp) { + return -1; + } + if (**sigp == 0) { + /* Not the shortest possible length encoding. */ + return -1; + } + if ((size_t)lenleft > sizeof(size_t)) { + /* The resulthing length would exceed the range of a size_t, so + certainly longer than the passed array size. */ + return -1; + } + while (lenleft > 0) { + if ((ret >> ((sizeof(size_t) - 1) * 8)) != 0) { + } + ret = (ret << 8) | **sigp; + if (ret + lenleft > (size_t)(sigend - *sigp)) { + /* Result exceeds the length of the passed array. */ + return -1; + } + (*sigp)++; + lenleft--; + } + if (ret < 128) { + /* Not the shortest possible length encoding. */ + return -1; + } + return ret; +} + +static int secp256k1_der_parse_integer(secp256k1_scalar *r, const unsigned char **sig, const unsigned char *sigend) { + int overflow = 0; + unsigned char ra[32] = {0}; + int rlen; + + if (*sig == sigend || **sig != 0x02) { + /* Not a primitive integer (X.690-0207 8.3.1). */ + return 0; + } + (*sig)++; + rlen = secp256k1_der_read_len(sig, sigend); + if (rlen <= 0 || (*sig) + rlen > sigend) { + /* Exceeds bounds or not at least length 1 (X.690-0207 8.3.1). */ + return 0; + } + if (**sig == 0x00 && rlen > 1 && (((*sig)[1]) & 0x80) == 0x00) { + /* Excessive 0x00 padding. */ + return 0; + } + if (**sig == 0xFF && rlen > 1 && (((*sig)[1]) & 0x80) == 0x80) { + /* Excessive 0xFF padding. */ + return 0; + } + if ((**sig & 0x80) == 0x80) { + /* Negative. */ + overflow = 1; + } + while (rlen > 0 && **sig == 0) { + /* Skip leading zero bytes */ + rlen--; + (*sig)++; + } + if (rlen > 32) { + overflow = 1; + } + if (!overflow) { + memcpy(ra + 32 - rlen, *sig, rlen); + secp256k1_scalar_set_b32(r, ra, &overflow); + } + if (overflow) { + secp256k1_scalar_set_int(r, 0); + } + (*sig) += rlen; + return 1; +} + static int secp256k1_ecdsa_sig_parse(secp256k1_scalar *rr, secp256k1_scalar *rs, const unsigned char *sig, size_t size) { - unsigned char ra[32] = {0}, sa[32] = {0}; - const unsigned char *rp; - const unsigned char *sp; - size_t lenr; - size_t lens; - int overflow; - if (sig[0] != 0x30) { + const unsigned char *sigend = sig + size; + int rlen; + if (sig == sigend || *(sig++) != 0x30) { + /* The encoding doesn't start with a constructed sequence (X.690-0207 8.9.1). */ return 0; } - lenr = sig[3]; - if (5+lenr >= size) { + rlen = secp256k1_der_read_len(&sig, sigend); + if (rlen < 0 || sig + rlen > sigend) { + /* Tuple exceeds bounds */ return 0; } - lens = sig[lenr+5]; - if (sig[1] != lenr+lens+4) { + if (sig + rlen != sigend) { + /* Garbage after tuple. */ return 0; } - if (lenr+lens+6 > size) { + + if (!secp256k1_der_parse_integer(rr, &sig, sigend)) { return 0; } - if (sig[2] != 0x02) { + if (!secp256k1_der_parse_integer(rs, &sig, sigend)) { return 0; } - if (lenr == 0) { - return 0; - } - if (sig[lenr+4] != 0x02) { - return 0; - } - if (lens == 0) { - return 0; - } - sp = sig + 6 + lenr; - while (lens > 0 && sp[0] == 0) { - lens--; - sp++; - } - if (lens > 32) { - return 0; - } - rp = sig + 4; - while (lenr > 0 && rp[0] == 0) { - lenr--; - rp++; - } - if (lenr > 32) { - return 0; - } - memcpy(ra + 32 - lenr, rp, lenr); - memcpy(sa + 32 - lens, sp, lens); - overflow = 0; - secp256k1_scalar_set_b32(rr, ra, &overflow); - if (overflow) { - return 0; - } - secp256k1_scalar_set_b32(rs, sa, &overflow); - if (overflow) { + + if (sig != sigend) { + /* Trailing garbage inside tuple. */ return 0; } + return 1; } diff --git a/src/modules/recovery/main_impl.h b/src/modules/recovery/main_impl.h index 193abd44de9..eec57b6bfb7 100644 --- a/src/modules/recovery/main_impl.h +++ b/src/modules/recovery/main_impl.h @@ -63,6 +63,7 @@ int secp256k1_ecdsa_recoverable_signature_serialize_compact(const secp256k1_cont (void)ctx; ARG_CHECK(output64 != NULL); ARG_CHECK(sig != NULL); + ARG_CHECK(recid != NULL); secp256k1_ecdsa_recoverable_signature_load(ctx, &r, &s, recid, sig); secp256k1_scalar_get_b32(&output64[0], &r); diff --git a/src/modules/recovery/tests_impl.h b/src/modules/recovery/tests_impl.h index 6af108ae4c6..8932d5f0afc 100644 --- a/src/modules/recovery/tests_impl.h +++ b/src/modules/recovery/tests_impl.h @@ -56,7 +56,7 @@ void test_ecdsa_recovery_end_to_end(void) { CHECK(memcmp(&pubkey, &recpubkey, sizeof(pubkey)) == 0); /* Serialize/destroy/parse signature and verify again. */ CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, &rsignature[4]) == 1); - sig[secp256k1_rand32() % 64] += 1 + (secp256k1_rand32() % 255); + sig[secp256k1_rand_bits(6)] += 1 + secp256k1_rand_int(255); CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsignature[4], sig, recid) == 1); CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &signature[4], &rsignature[4]) == 1); CHECK(secp256k1_ecdsa_verify(ctx, &signature[4], message, &pubkey) == 0); @@ -163,25 +163,24 @@ void test_ecdsa_recovery_edge_cases(void) { CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigb64, recid2) == 1); CHECK(secp256k1_ecdsa_recover(ctx, &pubkey2b, &rsig, msg32) == 1); /* Verifying with (order + r,4) should always fail. */ - CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderlong, sizeof(sigbderlong)) == 0); + CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderlong, sizeof(sigbderlong)) == 1); + CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0); } /* DER parsing tests. */ /* Zero length r/s. */ CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder_zr, sizeof(sigcder_zr)) == 0); CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder_zs, sizeof(sigcder_zs)) == 0); /* Leading zeros. */ - CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt1, sizeof(sigbderalt1)) == 1); - CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 1); - CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt2, sizeof(sigbderalt2)) == 1); - CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 1); - CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt3, sizeof(sigbderalt3)) == 1); - CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 1); - CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt4, sizeof(sigbderalt4)) == 1); - CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 1); - sigbderalt3[4] = 1; + CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt1, sizeof(sigbderalt1)) == 0); + CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt2, sizeof(sigbderalt2)) == 0); CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt3, sizeof(sigbderalt3)) == 0); - sigbderalt4[7] = 1; CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt4, sizeof(sigbderalt4)) == 0); + sigbderalt3[4] = 1; + CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt3, sizeof(sigbderalt3)) == 1); + CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0); + sigbderalt4[7] = 1; + CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt4, sizeof(sigbderalt4)) == 1); + CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0); /* Damage signature. */ sigbder[7]++; CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, sizeof(sigbder)) == 1); diff --git a/src/modules/schnorr/tests_impl.h b/src/modules/schnorr/tests_impl.h index 79737f74873..5bd14a03e3c 100644 --- a/src/modules/schnorr/tests_impl.h +++ b/src/modules/schnorr/tests_impl.h @@ -33,7 +33,7 @@ void test_schnorr_end_to_end(void) { CHECK(secp256k1_schnorr_recover(ctx, &recpubkey, schnorr_signature, message) == 1); CHECK(memcmp(&pubkey, &recpubkey, sizeof(pubkey)) == 0); /* Destroy signature and verify again. */ - schnorr_signature[secp256k1_rand32() % 64] += 1 + (secp256k1_rand32() % 255); + schnorr_signature[secp256k1_rand_bits(6)] += 1 + secp256k1_rand_int(255); CHECK(secp256k1_schnorr_verify(ctx, schnorr_signature, message, &pubkey) == 0); CHECK(secp256k1_schnorr_recover(ctx, &recpubkey, schnorr_signature, message) != 1 || memcmp(&pubkey, &recpubkey, sizeof(pubkey)) != 0); @@ -73,8 +73,8 @@ void test_schnorr_sign_verify(void) { CHECK(secp256k1_schnorr_sig_verify(&ctx->ecmult_ctx, sig64[k], &pubkey[k], &test_schnorr_hash, msg32)); for (i = 0; i < 4; i++) { - int pos = secp256k1_rand32() % 64; - int mod = 1 + (secp256k1_rand32() % 255); + int pos = secp256k1_rand_bits(6); + int mod = 1 + secp256k1_rand_int(255); sig64[k][pos] ^= mod; CHECK(secp256k1_schnorr_sig_verify(&ctx->ecmult_ctx, sig64[k], &pubkey[k], &test_schnorr_hash, msg32) == 0); sig64[k][pos] ^= mod; @@ -97,9 +97,9 @@ void test_schnorr_threshold(void) { int damage; int ret = 0; - damage = (secp256k1_rand32() % 2) ? (1 + (secp256k1_rand32() % 4)) : 0; + damage = secp256k1_rand_bits(1) ? (1 + secp256k1_rand_int(4)) : 0; secp256k1_rand256_test(msg); - n = 2 + (secp256k1_rand32() % 4); + n = 2 + secp256k1_rand_int(4); for (i = 0; i < n; i++) { do { secp256k1_rand256_test(sec[i]); @@ -109,9 +109,9 @@ void test_schnorr_threshold(void) { pubs[i] = &pub[i]; } if (damage == 1) { - nonce[secp256k1_rand32() % n][secp256k1_rand32() % 32] ^= 1 + (secp256k1_rand32() % 255); + nonce[secp256k1_rand_int(n)][secp256k1_rand_int(32)] ^= 1 + secp256k1_rand_int(255); } else if (damage == 2) { - sec[secp256k1_rand32() % n][secp256k1_rand32() % 32] ^= 1 + (secp256k1_rand32() % 255); + sec[secp256k1_rand_int(n)][secp256k1_rand_int(32)] ^= 1 + secp256k1_rand_int(255); } for (i = 0; i < n; i++) { secp256k1_pubkey allpubnonce; @@ -128,14 +128,14 @@ void test_schnorr_threshold(void) { sigs[i] = sig[i]; } if (damage == 3) { - sig[secp256k1_rand32() % n][secp256k1_rand32() % 64] ^= 1 + (secp256k1_rand32() % 255); + sig[secp256k1_rand_int(n)][secp256k1_rand_bits(6)] ^= 1 + secp256k1_rand_int(255); } ret |= (secp256k1_ec_pubkey_combine(ctx, &allpub, pubs, n) != 1) * 2; if ((ret & 1) == 0) { ret |= (secp256k1_schnorr_partial_combine(ctx, allsig, sigs, n) != 1) * 4; } if (damage == 4) { - allsig[secp256k1_rand32() % 32] ^= 1 + (secp256k1_rand32() % 255); + allsig[secp256k1_rand_int(32)] ^= 1 + secp256k1_rand_int(255); } if ((ret & 7) == 0) { ret |= (secp256k1_schnorr_verify(ctx, allsig, msg, &allpub) != 1) * 8; diff --git a/src/secp256k1.c b/src/secp256k1.c index 8ef16ac9a78..9529d9f6bc2 100644 --- a/src/secp256k1.c +++ b/src/secp256k1.c @@ -210,6 +210,27 @@ int secp256k1_ecdsa_signature_parse_der(const secp256k1_context* ctx, secp256k1_ } } +int secp256k1_ecdsa_signature_parse_compact(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input64) { + secp256k1_scalar r, s; + int ret = 1; + int overflow = 0; + + (void)ctx; + ARG_CHECK(sig != NULL); + ARG_CHECK(input64 != NULL); + + secp256k1_scalar_set_b32(&r, &input64[0], &overflow); + ret &= !overflow; + secp256k1_scalar_set_b32(&s, &input64[32], &overflow); + ret &= !overflow; + if (ret) { + secp256k1_ecdsa_signature_save(sig, &r, &s); + } else { + memset(sig, 0, sizeof(*sig)); + } + return ret; +} + int secp256k1_ecdsa_signature_serialize_der(const secp256k1_context* ctx, unsigned char *output, size_t *outputlen, const secp256k1_ecdsa_signature* sig) { secp256k1_scalar r, s; @@ -222,6 +243,38 @@ int secp256k1_ecdsa_signature_serialize_der(const secp256k1_context* ctx, unsign return secp256k1_ecdsa_sig_serialize(output, outputlen, &r, &s); } +int secp256k1_ecdsa_signature_serialize_compact(const secp256k1_context* ctx, unsigned char *output64, const secp256k1_ecdsa_signature* sig) { + secp256k1_scalar r, s; + + (void)ctx; + ARG_CHECK(output64 != NULL); + ARG_CHECK(sig != NULL); + + secp256k1_ecdsa_signature_load(ctx, &r, &s, sig); + secp256k1_scalar_get_b32(&output64[0], &r); + secp256k1_scalar_get_b32(&output64[32], &s); + return 1; +} + +int secp256k1_ecdsa_signature_normalize(const secp256k1_context* ctx, secp256k1_ecdsa_signature *sigout, const secp256k1_ecdsa_signature *sigin) { + secp256k1_scalar r, s; + int ret = 0; + + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(sigin != NULL); + + secp256k1_ecdsa_signature_load(ctx, &r, &s, sigin); + ret = secp256k1_scalar_is_high(&s); + if (sigout != NULL) { + if (ret) { + secp256k1_scalar_negate(&s, &s); + } + secp256k1_ecdsa_signature_save(sigout, &r, &s); + } + + return ret; +} + int secp256k1_ecdsa_verify(const secp256k1_context* ctx, const secp256k1_ecdsa_signature *sig, const unsigned char *msg32, const secp256k1_pubkey *pubkey) { secp256k1_ge q; secp256k1_scalar r, s; @@ -234,7 +287,8 @@ int secp256k1_ecdsa_verify(const secp256k1_context* ctx, const secp256k1_ecdsa_s secp256k1_scalar_set_b32(&m, msg32, NULL); secp256k1_ecdsa_signature_load(ctx, &r, &s, sig); - return (secp256k1_pubkey_load(ctx, &q, pubkey) && + return (!secp256k1_scalar_is_high(&s) && + secp256k1_pubkey_load(ctx, &q, pubkey) && secp256k1_ecdsa_sig_verify(&ctx->ecmult_ctx, &r, &s, &q, &m)); } diff --git a/src/testrand.h b/src/testrand.h index 041bb92c47a..f8efa93c7c3 100644 --- a/src/testrand.h +++ b/src/testrand.h @@ -16,13 +16,23 @@ /** Seed the pseudorandom number generator for testing. */ SECP256K1_INLINE static void secp256k1_rand_seed(const unsigned char *seed16); -/** Generate a pseudorandom 32-bit number. */ +/** Generate a pseudorandom number in the range [0..2**32-1]. */ static uint32_t secp256k1_rand32(void); +/** Generate a pseudorandom number in the range [0..2**bits-1]. Bits must be 1 or + * more. */ +static uint32_t secp256k1_rand_bits(int bits); + +/** Generate a pseudorandom number in the range [0..range-1]. */ +static uint32_t secp256k1_rand_int(uint32_t range); + /** Generate a pseudorandom 32-byte array. */ static void secp256k1_rand256(unsigned char *b32); /** Generate a pseudorandom 32-byte array with long sequences of zero and one bits. */ static void secp256k1_rand256_test(unsigned char *b32); +/** Generate pseudorandom bytes with long sequences of zero and one bits. */ +static void secp256k1_rand_bytes_test(unsigned char *bytes, size_t len); + #endif diff --git a/src/testrand_impl.h b/src/testrand_impl.h index 7c35542662c..15c7b9f12df 100644 --- a/src/testrand_impl.h +++ b/src/testrand_impl.h @@ -1,5 +1,5 @@ /********************************************************************** - * Copyright (c) 2013, 2014 Pieter Wuille * + * Copyright (c) 2013-2015 Pieter Wuille * * Distributed under the MIT software license, see the accompanying * * file COPYING or http://www.opensource.org/licenses/mit-license.php.* **********************************************************************/ @@ -16,6 +16,8 @@ static secp256k1_rfc6979_hmac_sha256_t secp256k1_test_rng; static uint32_t secp256k1_test_rng_precomputed[8]; static int secp256k1_test_rng_precomputed_used = 8; +static uint64_t secp256k1_test_rng_integer; +static int secp256k1_test_rng_integer_bits_left = 0; SECP256K1_INLINE static void secp256k1_rand_seed(const unsigned char *seed16) { secp256k1_rfc6979_hmac_sha256_initialize(&secp256k1_test_rng, seed16, 16); @@ -29,32 +31,80 @@ SECP256K1_INLINE static uint32_t secp256k1_rand32(void) { return secp256k1_test_rng_precomputed[secp256k1_test_rng_precomputed_used++]; } +static uint32_t secp256k1_rand_bits(int bits) { + uint32_t ret; + if (secp256k1_test_rng_integer_bits_left < bits) { + secp256k1_test_rng_integer |= (((uint64_t)secp256k1_rand32()) << secp256k1_test_rng_integer_bits_left); + secp256k1_test_rng_integer_bits_left += 32; + } + ret = secp256k1_test_rng_integer; + secp256k1_test_rng_integer >>= bits; + secp256k1_test_rng_integer_bits_left -= bits; + ret &= ((~((uint32_t)0)) >> (32 - bits)); + return ret; +} + +static uint32_t secp256k1_rand_int(uint32_t range) { + /* We want a uniform integer between 0 and range-1, inclusive. + * B is the smallest number such that range <= 2**B. + * two mechanisms implemented here: + * - generate B bits numbers until one below range is found, and return it + * - find the largest multiple M of range that is <= 2**(B+A), generate B+A + * bits numbers until one below M is found, and return it modulo range + * The second mechanism consumes A more bits of entropy in every iteration, + * but may need fewer iterations due to M being closer to 2**(B+A) then + * range is to 2**B. The array below (indexed by B) contains a 0 when the + * first mechanism is to be used, and the number A otherwise. + */ + static const int addbits[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 1, 0}; + uint32_t trange, mult; + int bits = 0; + if (range <= 1) { + return 0; + } + trange = range - 1; + while (trange > 0) { + trange >>= 1; + bits++; + } + if (addbits[bits]) { + bits = bits + addbits[bits]; + mult = ((~((uint32_t)0)) >> (32 - bits)) / range; + trange = range * mult; + } else { + trange = range; + mult = 1; + } + while(1) { + uint32_t x = secp256k1_rand_bits(bits); + if (x < trange) { + return (mult == 1) ? x : (x % range); + } + } +} + static void secp256k1_rand256(unsigned char *b32) { secp256k1_rfc6979_hmac_sha256_generate(&secp256k1_test_rng, b32, 32); } -static void secp256k1_rand256_test(unsigned char *b32) { - int bits=0; - uint64_t ent = 0; - int entleft = 0; - memset(b32, 0, 32); - while (bits < 256) { +static void secp256k1_rand_bytes_test(unsigned char *bytes, size_t len) { + size_t bits = 0; + memset(bytes, 0, len); + while (bits < len * 8) { int now; uint32_t val; - if (entleft < 12) { - ent |= ((uint64_t)secp256k1_rand32()) << entleft; - entleft += 32; - } - now = 1 + ((ent % 64)*((ent >> 6) % 32)+16)/31; - val = 1 & (ent >> 11); - ent >>= 12; - entleft -= 12; - while (now > 0 && bits < 256) { - b32[bits / 8] |= val << (bits % 8); + now = 1 + (secp256k1_rand_bits(6) * secp256k1_rand_bits(5) + 16) / 31; + val = secp256k1_rand_bits(1); + while (now > 0 && bits < len * 8) { + bytes[bits / 8] |= val << (bits % 8); now--; bits++; } } } +static void secp256k1_rand256_test(unsigned char *b32) { + secp256k1_rand_bytes_test(b32, 32); +} + #endif diff --git a/src/tests.c b/src/tests.c index 13048f6c728..0e047173fff 100644 --- a/src/tests.c +++ b/src/tests.c @@ -24,6 +24,8 @@ #include "openssl/obj_mac.h" #endif +#include "contrib/lax_der_parsing.h" + #if !defined(VG_CHECK) # if defined(VALGRIND) # include @@ -50,7 +52,7 @@ void random_field_element_test(secp256k1_fe *fe) { void random_field_element_magnitude(secp256k1_fe *fe) { secp256k1_fe zero; - int n = secp256k1_rand32() % 9; + int n = secp256k1_rand_int(9); secp256k1_fe_normalize(fe); if (n == 0) { return; @@ -66,7 +68,7 @@ void random_group_element_test(secp256k1_ge *ge) { secp256k1_fe fe; do { random_field_element_test(&fe); - if (secp256k1_ge_set_xo_var(ge, &fe, secp256k1_rand32() & 1)) { + if (secp256k1_ge_set_xo_var(ge, &fe, secp256k1_rand_bits(1))) { secp256k1_fe_normalize(&ge->y); break; } @@ -189,7 +191,7 @@ void run_sha256_tests(void) { secp256k1_sha256_finalize(&hasher, out); CHECK(memcmp(out, outputs[i], 32) == 0); if (strlen(inputs[i]) > 0) { - int split = secp256k1_rand32() % strlen(inputs[i]); + int split = secp256k1_rand_int(strlen(inputs[i])); secp256k1_sha256_initialize(&hasher); secp256k1_sha256_write(&hasher, (const unsigned char*)(inputs[i]), split); secp256k1_sha256_write(&hasher, (const unsigned char*)(inputs[i] + split), strlen(inputs[i]) - split); @@ -233,7 +235,7 @@ void run_hmac_sha256_tests(void) { secp256k1_hmac_sha256_finalize(&hasher, out); CHECK(memcmp(out, outputs[i], 32) == 0); if (strlen(inputs[i]) > 0) { - int split = secp256k1_rand32() % strlen(inputs[i]); + int split = secp256k1_rand_int(strlen(inputs[i])); secp256k1_hmac_sha256_initialize(&hasher, (const unsigned char*)(keys[i]), strlen(keys[i])); secp256k1_hmac_sha256_write(&hasher, (const unsigned char*)(inputs[i]), split); secp256k1_hmac_sha256_write(&hasher, (const unsigned char*)(inputs[i] + split), strlen(inputs[i]) - split); @@ -284,11 +286,83 @@ void run_rfc6979_hmac_sha256_tests(void) { secp256k1_rfc6979_hmac_sha256_finalize(&rng); } +/***** RANDOM TESTS *****/ + +void test_rand_bits(int rand32, int bits) { + /* (1-1/2^B)^rounds[B] < 1/10^9, so rounds is the number of iterations to + * get a false negative chance below once in a billion */ + static const unsigned int rounds[7] = {1, 30, 73, 156, 322, 653, 1316}; + /* We try multiplying the results with various odd numbers, which shouldn't + * influence the uniform distribution modulo a power of 2. */ + static const uint32_t mults[6] = {1, 3, 21, 289, 0x9999, 0x80402011}; + /* We only select up to 6 bits from the output to analyse */ + unsigned int usebits = bits > 6 ? 6 : bits; + unsigned int maxshift = bits - usebits; + /* For each of the maxshift+1 usebits-bit sequences inside a bits-bit + number, track all observed outcomes, one per bit in a uint64_t. */ + uint64_t x[6][27] = {{0}}; + unsigned int i, shift, m; + /* Multiply the output of all rand calls with the odd number m, which + should not change the uniformity of its distribution. */ + for (i = 0; i < rounds[usebits]; i++) { + uint32_t r = (rand32 ? secp256k1_rand32() : secp256k1_rand_bits(bits)); + CHECK((((uint64_t)r) >> bits) == 0); + for (m = 0; m < sizeof(mults) / sizeof(mults[0]); m++) { + uint32_t rm = r * mults[m]; + for (shift = 0; shift <= maxshift; shift++) { + x[m][shift] |= (((uint64_t)1) << ((rm >> shift) & ((1 << usebits) - 1))); + } + } + } + for (m = 0; m < sizeof(mults) / sizeof(mults[0]); m++) { + for (shift = 0; shift <= maxshift; shift++) { + /* Test that the lower usebits bits of x[shift] are 1 */ + CHECK(((~x[m][shift]) << (64 - (1 << usebits))) == 0); + } + } +} + +/* Subrange must be a whole divisor of range, and at most 64 */ +void test_rand_int(uint32_t range, uint32_t subrange) { + /* (1-1/subrange)^rounds < 1/10^9 */ + int rounds = (subrange * 2073) / 100; + int i; + uint64_t x = 0; + CHECK((range % subrange) == 0); + for (i = 0; i < rounds; i++) { + uint32_t r = secp256k1_rand_int(range); + CHECK(r < range); + r = r % subrange; + x |= (((uint64_t)1) << r); + } + /* Test that the lower subrange bits of x are 1. */ + CHECK(((~x) << (64 - subrange)) == 0); +} + +void run_rand_bits(void) { + size_t b; + test_rand_bits(1, 32); + for (b = 1; b <= 32; b++) { + test_rand_bits(0, b); + } +} + +void run_rand_int(void) { + static const uint32_t ms[] = {1, 3, 17, 1000, 13771, 999999, 33554432}; + static const uint32_t ss[] = {1, 3, 6, 9, 13, 31, 64}; + unsigned int m, s; + for (m = 0; m < sizeof(ms) / sizeof(ms[0]); m++) { + for (s = 0; s < sizeof(ss) / sizeof(ss[0]); s++) { + test_rand_int(ms[m] * ss[s], ss[s]); + } + } +} + /***** NUM TESTS *****/ #ifndef USE_NUM_NONE void random_num_negate(secp256k1_num *num) { - if (secp256k1_rand32() & 1) { + if (secp256k1_rand_bits(1)) { secp256k1_num_negate(num); } } @@ -329,13 +403,12 @@ void test_num_add_sub(void) { secp256k1_num n1; secp256k1_num n2; secp256k1_num n1p2, n2p1, n1m2, n2m1; - int r = secp256k1_rand32(); random_num_order_test(&n1); /* n1 = R1 */ - if (r & 1) { + if (secp256k1_rand_bits(1)) { random_num_negate(&n1); } random_num_order_test(&n2); /* n2 = R2 */ - if (r & 2) { + if (secp256k1_rand_bits(1)) { random_num_negate(&n2); } secp256k1_num_add(&n1p2, &n1, &n2); /* n1p2 = R1 + R2 */ @@ -420,7 +493,7 @@ void scalar_test(void) { while (i < 256) { secp256k1_scalar t; int j; - int now = (secp256k1_rand32() % 15) + 1; + int now = secp256k1_rand_int(15) + 1; if (now + i > 256) { now = 256 - i; } @@ -497,7 +570,7 @@ void scalar_test(void) { secp256k1_num rnum; secp256k1_num rnum2; unsigned char cone[1] = {0x01}; - unsigned int shift = 256 + (secp256k1_rand32() % 257); + unsigned int shift = 256 + secp256k1_rand_int(257); secp256k1_scalar_mul_shift_var(&r, &s1, &s2, shift); secp256k1_num_mul(&rnum, &s1num, &s2num); secp256k1_num_shift(&rnum, shift - 1); @@ -515,7 +588,7 @@ void scalar_test(void) { random_scalar_order_test(&r); for (i = 0; i < 100; ++i) { int low; - int shift = 1 + (secp256k1_rand32() % 15); + int shift = 1 + secp256k1_rand_int(15); int expected = r.d[0] % (1 << shift); low = secp256k1_scalar_shr_int(&r, shift); CHECK(expected == low); @@ -559,7 +632,7 @@ void scalar_test(void) { secp256k1_scalar b; int i; /* Test add_bit. */ - int bit = secp256k1_rand32() % 256; + int bit = secp256k1_rand_bits(8); secp256k1_scalar_set_int(&b, 1); CHECK(secp256k1_scalar_is_one(&b)); for (i = 0; i < bit; i++) { @@ -874,7 +947,7 @@ void run_field_inv_all_var(void) { secp256k1_fe_inv_all_var(0, xi, x); for (i = 0; i < count; i++) { size_t j; - size_t len = (secp256k1_rand32() & 15) + 1; + size_t len = secp256k1_rand_int(15) + 1; for (j = 0; j < len; j++) { random_fe_non_zero(&x[j]); } @@ -1163,7 +1236,7 @@ void test_ge(void) { gej_shuffled[i] = gej[i]; } for (i = 0; i < 4 * runs + 1; i++) { - int swap = i + secp256k1_rand32() % (4 * runs + 1 - i); + int swap = i + secp256k1_rand_int(4 * runs + 1 - i); if (swap != i) { secp256k1_gej t = gej_shuffled[i]; gej_shuffled[i] = gej_shuffled[swap]; @@ -2174,7 +2247,7 @@ void test_ecdsa_sign_verify(void) { random_scalar_order_test(&key); secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pubj, &key); secp256k1_ge_set_gej(&pub, &pubj); - getrec = secp256k1_rand32()&1; + getrec = secp256k1_rand_bits(1); random_sign(&sigr, &sigs, &key, &msg, getrec?&recid:NULL); if (getrec) { CHECK(recid >= 0 && recid < 4); @@ -2249,7 +2322,8 @@ void test_ecdsa_end_to_end(void) { unsigned char privkey[32]; unsigned char message[32]; unsigned char privkey2[32]; - secp256k1_ecdsa_signature signature[5]; + secp256k1_ecdsa_signature signature[6]; + secp256k1_scalar r, s; unsigned char sig[74]; size_t siglen = 74; unsigned char pubkeyc[65]; @@ -2272,17 +2346,17 @@ void test_ecdsa_end_to_end(void) { CHECK(secp256k1_ec_pubkey_create(ctx, &pubkey, privkey) == 1); /* Verify exporting and importing public key. */ - CHECK(secp256k1_ec_pubkey_serialize(ctx, pubkeyc, &pubkeyclen, &pubkey, secp256k1_rand32() % 2) == 1); + CHECK(secp256k1_ec_pubkey_serialize(ctx, pubkeyc, &pubkeyclen, &pubkey, secp256k1_rand_bits(1)) == 1); memset(&pubkey, 0, sizeof(pubkey)); CHECK(secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeyc, pubkeyclen) == 1); /* Verify private key import and export. */ - CHECK(secp256k1_ec_privkey_export(ctx, seckey, &seckeylen, privkey, (secp256k1_rand32() % 2) == 1) ? SECP256K1_EC_COMPRESSED : 0); + CHECK(secp256k1_ec_privkey_export(ctx, seckey, &seckeylen, privkey, secp256k1_rand_bits(1) == 1) ? SECP256K1_EC_COMPRESSED : 0); CHECK(secp256k1_ec_privkey_import(ctx, privkey2, seckey, seckeylen) == 1); CHECK(memcmp(privkey, privkey2, 32) == 0); /* Optionally tweak the keys using addition. */ - if (secp256k1_rand32() % 3 == 0) { + if (secp256k1_rand_int(3) == 0) { int ret1; int ret2; unsigned char rnd[32]; @@ -2299,7 +2373,7 @@ void test_ecdsa_end_to_end(void) { } /* Optionally tweak the keys using multiplication. */ - if (secp256k1_rand32() % 3 == 0) { + if (secp256k1_rand_int(3) == 0) { int ret1; int ret2; unsigned char rnd[32]; @@ -2336,6 +2410,21 @@ void test_ecdsa_end_to_end(void) { CHECK(secp256k1_ecdsa_verify(ctx, &signature[1], message, &pubkey) == 1); CHECK(secp256k1_ecdsa_verify(ctx, &signature[2], message, &pubkey) == 1); CHECK(secp256k1_ecdsa_verify(ctx, &signature[3], message, &pubkey) == 1); + /* Test lower-S form, malleate, verify and fail, test again, malleate again */ + CHECK(!secp256k1_ecdsa_signature_normalize(ctx, NULL, &signature[0])); + secp256k1_ecdsa_signature_load(ctx, &r, &s, &signature[0]); + secp256k1_scalar_negate(&s, &s); + secp256k1_ecdsa_signature_save(&signature[5], &r, &s); + CHECK(secp256k1_ecdsa_verify(ctx, &signature[5], message, &pubkey) == 0); + CHECK(secp256k1_ecdsa_signature_normalize(ctx, NULL, &signature[5])); + CHECK(secp256k1_ecdsa_signature_normalize(ctx, &signature[5], &signature[5])); + CHECK(!secp256k1_ecdsa_signature_normalize(ctx, NULL, &signature[5])); + CHECK(secp256k1_ecdsa_verify(ctx, &signature[5], message, &pubkey) == 1); + secp256k1_scalar_negate(&s, &s); + secp256k1_ecdsa_signature_save(&signature[5], &r, &s); + CHECK(!secp256k1_ecdsa_signature_normalize(ctx, NULL, &signature[5])); + CHECK(secp256k1_ecdsa_verify(ctx, &signature[5], message, &pubkey) == 1); + CHECK(memcmp(&signature[5], &signature[0], 64) == 0); /* Serialize/parse DER and verify again */ CHECK(secp256k1_ecdsa_signature_serialize_der(ctx, sig, &siglen, &signature[0]) == 1); @@ -2345,7 +2434,7 @@ void test_ecdsa_end_to_end(void) { /* Serialize/destroy/parse DER and verify again. */ siglen = 74; CHECK(secp256k1_ecdsa_signature_serialize_der(ctx, sig, &siglen, &signature[0]) == 1); - sig[secp256k1_rand32() % siglen] += 1 + (secp256k1_rand32() % 255); + sig[secp256k1_rand_int(siglen)] += 1 + secp256k1_rand_int(255); CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &signature[0], sig, siglen) == 0 || secp256k1_ecdsa_verify(ctx, &signature[0], message, &pubkey) == 0); } @@ -2355,23 +2444,18 @@ void test_random_pubkeys(void) { secp256k1_ge elem2; unsigned char in[65]; /* Generate some randomly sized pubkeys. */ - uint32_t r = secp256k1_rand32(); - size_t len = (r & 3) == 0 ? 65 : 33; - r>>=2; - if ((r & 3) == 0) { - len = (r & 252) >> 3; + size_t len = secp256k1_rand_bits(2) == 0 ? 65 : 33; + if (secp256k1_rand_bits(2) == 0) { + len = secp256k1_rand_bits(6); } - r>>=8; if (len == 65) { - in[0] = (r & 2) ? 4 : ((r & 1)? 6 : 7); + in[0] = secp256k1_rand_bits(1) ? 4 : (secp256k1_rand_bits(1) ? 6 : 7); } else { - in[0] = (r & 1) ? 2 : 3; + in[0] = secp256k1_rand_bits(1) ? 2 : 3; } - r>>=2; - if ((r & 7) == 0) { - in[0] = (r & 2040) >> 3; + if (secp256k1_rand_bits(3) == 0) { + in[0] = secp256k1_rand_bits(8); } - r>>=11; if (len > 1) { secp256k1_rand256(&in[1]); } @@ -2398,7 +2482,7 @@ void test_random_pubkeys(void) { CHECK(secp256k1_eckey_pubkey_parse(&elem2, in, size)); ge_equals_ge(&elem,&elem2); /* Check that the X9.62 hybrid type is checked. */ - in[0] = (r & 1) ? 6 : 7; + in[0] = secp256k1_rand_bits(1) ? 6 : 7; res = secp256k1_eckey_pubkey_parse(&elem2, in, size); if (firstb == 2 || firstb == 3) { if (in[0] == firstb + 4) { @@ -2429,6 +2513,332 @@ void run_ecdsa_end_to_end(void) { } } +int test_ecdsa_der_parse(const unsigned char *sig, size_t siglen, int certainly_der, int certainly_not_der) { + static const unsigned char zeroes[32] = {0}; + static const unsigned char max_scalar[32] = { + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, + 0xba, 0xae, 0xdc, 0xe6, 0xaf, 0x48, 0xa0, 0x3b, + 0xbf, 0xd2, 0x5e, 0x8c, 0xd0, 0x36, 0x41, 0x40 + }; + + int ret = 0; + + secp256k1_ecdsa_signature sig_der; + unsigned char roundtrip_der[2048]; + unsigned char compact_der[64]; + size_t len_der = 2048; + int parsed_der = 0, valid_der = 0, roundtrips_der = 0; + + secp256k1_ecdsa_signature sig_der_lax; + unsigned char roundtrip_der_lax[2048]; + unsigned char compact_der_lax[64]; + size_t len_der_lax = 2048; + int parsed_der_lax = 0, valid_der_lax = 0, roundtrips_der_lax = 0; + +#ifdef ENABLE_OPENSSL_TESTS + ECDSA_SIG *sig_openssl; + const unsigned char *sigptr; + unsigned char roundtrip_openssl[2048]; + int len_openssl = 2048; + int parsed_openssl, valid_openssl = 0, roundtrips_openssl = 0; +#endif + + parsed_der = secp256k1_ecdsa_signature_parse_der(ctx, &sig_der, sig, siglen); + if (parsed_der) { + ret |= (!secp256k1_ecdsa_signature_serialize_compact(ctx, compact_der, &sig_der)) << 0; + valid_der = (memcmp(compact_der, zeroes, 32) != 0) && (memcmp(compact_der + 32, zeroes, 32) != 0); + } + if (valid_der) { + ret |= (!secp256k1_ecdsa_signature_serialize_der(ctx, roundtrip_der, &len_der, &sig_der)) << 1; + roundtrips_der = (len_der == siglen) && memcmp(roundtrip_der, sig, siglen) == 0; + } + + parsed_der_lax = secp256k1_ecdsa_signature_parse_der_lax(ctx, &sig_der_lax, sig, siglen); + if (parsed_der_lax) { + ret |= (!secp256k1_ecdsa_signature_serialize_compact(ctx, compact_der_lax, &sig_der_lax)) << 10; + valid_der_lax = (memcmp(compact_der_lax, zeroes, 32) != 0) && (memcmp(compact_der_lax + 32, zeroes, 32) != 0); + } + if (valid_der_lax) { + ret |= (!secp256k1_ecdsa_signature_serialize_der(ctx, roundtrip_der_lax, &len_der_lax, &sig_der_lax)) << 11; + roundtrips_der_lax = (len_der_lax == siglen) && memcmp(roundtrip_der_lax, sig, siglen) == 0; + } + + if (certainly_der) { + ret |= (!parsed_der) << 2; + } + if (certainly_not_der) { + ret |= (parsed_der) << 17; + } + if (valid_der) { + ret |= (!roundtrips_der) << 3; + } + + if (valid_der) { + ret |= (!roundtrips_der_lax) << 12; + ret |= (len_der != len_der_lax) << 13; + ret |= (memcmp(roundtrip_der_lax, roundtrip_der, len_der) != 0) << 14; + } + ret |= (roundtrips_der != roundtrips_der_lax) << 15; + if (parsed_der) { + ret |= (!parsed_der_lax) << 16; + } + +#ifdef ENABLE_OPENSSL_TESTS + sig_openssl = ECDSA_SIG_new(); + sigptr = sig; + parsed_openssl = (d2i_ECDSA_SIG(&sig_openssl, &sigptr, siglen) != NULL); + if (parsed_openssl) { + valid_openssl = !BN_is_negative(sig_openssl->r) && !BN_is_negative(sig_openssl->s) && BN_num_bits(sig_openssl->r) > 0 && BN_num_bits(sig_openssl->r) <= 256 && BN_num_bits(sig_openssl->s) > 0 && BN_num_bits(sig_openssl->s) <= 256; + if (valid_openssl) { + unsigned char tmp[32] = {0}; + BN_bn2bin(sig_openssl->r, tmp + 32 - BN_num_bytes(sig_openssl->r)); + valid_openssl = memcmp(tmp, max_scalar, 32) < 0; + } + if (valid_openssl) { + unsigned char tmp[32] = {0}; + BN_bn2bin(sig_openssl->s, tmp + 32 - BN_num_bytes(sig_openssl->s)); + valid_openssl = memcmp(tmp, max_scalar, 32) < 0; + } + } + len_openssl = i2d_ECDSA_SIG(sig_openssl, NULL); + if (len_openssl <= 2048) { + unsigned char *ptr = roundtrip_openssl; + CHECK(i2d_ECDSA_SIG(sig_openssl, &ptr) == len_openssl); + roundtrips_openssl = valid_openssl && ((size_t)len_openssl == siglen) && (memcmp(roundtrip_openssl, sig, siglen) == 0); + } else { + len_openssl = 0; + } + ECDSA_SIG_free(sig_openssl); + + ret |= (parsed_der && !parsed_openssl) << 4; + ret |= (valid_der && !valid_openssl) << 5; + ret |= (roundtrips_openssl && !parsed_der) << 6; + ret |= (roundtrips_der != roundtrips_openssl) << 7; + if (roundtrips_openssl) { + ret |= (len_der != (size_t)len_openssl) << 8; + ret |= (memcmp(roundtrip_der, roundtrip_openssl, len_der) != 0) << 9; + } +#endif + return ret; +} + +static void assign_big_endian(unsigned char *ptr, size_t ptrlen, uint32_t val) { + size_t i; + for (i = 0; i < ptrlen; i++) { + int shift = ptrlen - 1 - i; + if (shift >= 4) { + ptr[i] = 0; + } else { + ptr[i] = (val >> shift) & 0xFF; + } + } +} + +static void damage_array(unsigned char *sig, size_t *len) { + int pos; + int action = secp256k1_rand_bits(3); + if (action < 1) { + /* Delete a byte. */ + pos = secp256k1_rand_int(*len); + memmove(sig + pos, sig + pos + 1, *len - pos - 1); + (*len)--; + return; + } else if (action < 2) { + /* Insert a byte. */ + pos = secp256k1_rand_int(1 + *len); + memmove(sig + pos + 1, sig + pos, *len - pos); + sig[pos] = secp256k1_rand_bits(8); + (*len)++; + return; + } else if (action < 4) { + /* Modify a byte. */ + sig[secp256k1_rand_int(*len)] += 1 + secp256k1_rand_int(255); + return; + } else { /* action < 8 */ + /* Modify a bit. */ + sig[secp256k1_rand_int(*len)] ^= 1 << secp256k1_rand_bits(3); + return; + } +} + +static void random_ber_signature(unsigned char *sig, size_t *len, int* certainly_der, int* certainly_not_der) { + int der; + int nlow[2], nlen[2], nlenlen[2], nhbit[2], nhbyte[2], nzlen[2]; + size_t tlen, elen, glen; + int indet; + int n; + + *len = 0; + der = secp256k1_rand_bits(2) == 0; + *certainly_der = der; + *certainly_not_der = 0; + indet = der ? 0 : secp256k1_rand_int(10) == 0; + + for (n = 0; n < 2; n++) { + /* We generate two classes of numbers: nlow==1 "low" ones (up to 32 bytes), nlow==0 "high" ones (32 bytes with 129 top bits set, or larger than 32 bytes) */ + nlow[n] = der ? 1 : (secp256k1_rand_bits(3) != 0); + /* The length of the number in bytes (the first byte of which will always be nonzero) */ + nlen[n] = nlow[n] ? secp256k1_rand_int(33) : 32 + secp256k1_rand_int(200) * secp256k1_rand_int(8) / 8; + CHECK(nlen[n] <= 232); + /* The top bit of the number. */ + nhbit[n] = (nlow[n] == 0 && nlen[n] == 32) ? 1 : (nlen[n] == 0 ? 0 : secp256k1_rand_bits(1)); + /* The top byte of the number (after the potential hardcoded 16 0xFF characters for "high" 32 bytes numbers) */ + nhbyte[n] = nlen[n] == 0 ? 0 : (nhbit[n] ? 128 + secp256k1_rand_bits(7) : 1 + secp256k1_rand_int(127)); + /* The number of zero bytes in front of the number (which is 0 or 1 in case of DER, otherwise we extend up to 300 bytes) */ + nzlen[n] = der ? ((nlen[n] == 0 || nhbit[n]) ? 1 : 0) : (nlow[n] ? secp256k1_rand_int(3) : secp256k1_rand_int(300 - nlen[n]) * secp256k1_rand_int(8) / 8); + if (nzlen[n] > ((nlen[n] == 0 || nhbit[n]) ? 1 : 0)) { + *certainly_not_der = 1; + } + CHECK(nlen[n] + nzlen[n] <= 300); + /* The length of the length descriptor for the number. 0 means short encoding, anything else is long encoding. */ + nlenlen[n] = nlen[n] + nzlen[n] < 128 ? 0 : (nlen[n] + nzlen[n] < 256 ? 1 : 2); + if (!der) { + /* nlenlen[n] max 127 bytes */ + int add = secp256k1_rand_int(127 - nlenlen[n]) * secp256k1_rand_int(16) * secp256k1_rand_int(16) / 256; + nlenlen[n] += add; + if (add != 0) { + *certainly_not_der = 1; + } + } + CHECK(nlen[n] + nzlen[n] + nlenlen[n] <= 427); + } + + /* The total length of the data to go, so far */ + tlen = 2 + nlenlen[0] + nlen[0] + nzlen[0] + 2 + nlenlen[1] + nlen[1] + nzlen[1]; + CHECK(tlen <= 856); + + /* The length of the garbage inside the tuple. */ + elen = (der || indet) ? 0 : secp256k1_rand_int(980 - tlen) * secp256k1_rand_int(8) / 8; + if (elen != 0) { + *certainly_not_der = 1; + } + tlen += elen; + CHECK(tlen <= 980); + + /* The length of the garbage after the end of the tuple. */ + glen = der ? 0 : secp256k1_rand_int(990 - tlen) * secp256k1_rand_int(8) / 8; + if (glen != 0) { + *certainly_not_der = 1; + } + CHECK(tlen + glen <= 990); + + /* Write the tuple header. */ + sig[(*len)++] = 0x30; + if (indet) { + /* Indeterminate length */ + sig[(*len)++] = 0x80; + *certainly_not_der = 1; + } else { + int tlenlen = tlen < 128 ? 0 : (tlen < 256 ? 1 : 2); + if (!der) { + int add = secp256k1_rand_int(127 - tlenlen) * secp256k1_rand_int(16) * secp256k1_rand_int(16) / 256; + tlenlen += add; + if (add != 0) { + *certainly_not_der = 1; + } + } + if (tlenlen == 0) { + /* Short length notation */ + sig[(*len)++] = tlen; + } else { + /* Long length notation */ + sig[(*len)++] = 128 + tlenlen; + assign_big_endian(sig + *len, tlenlen, tlen); + *len += tlenlen; + } + tlen += tlenlen; + } + tlen += 2; + CHECK(tlen + glen <= 1119); + + for (n = 0; n < 2; n++) { + /* Write the integer header. */ + sig[(*len)++] = 0x02; + if (nlenlen[n] == 0) { + /* Short length notation */ + sig[(*len)++] = nlen[n] + nzlen[n]; + } else { + /* Long length notation. */ + sig[(*len)++] = 128 + nlenlen[n]; + assign_big_endian(sig + *len, nlenlen[n], nlen[n] + nzlen[n]); + *len += nlenlen[n]; + } + /* Write zero padding */ + while (nzlen[n] > 0) { + sig[(*len)++] = 0x00; + nzlen[n]--; + } + if (nlen[n] == 32 && !nlow[n]) { + /* Special extra 16 0xFF bytes in "high" 32-byte numbers */ + int i; + for (i = 0; i < 16; i++) { + sig[(*len)++] = 0xFF; + } + nlen[n] -= 16; + } + /* Write first byte of number */ + if (nlen[n] > 0) { + sig[(*len)++] = nhbyte[n]; + nlen[n]--; + } + /* Generate remaining random bytes of number */ + secp256k1_rand_bytes_test(sig + *len, nlen[n]); + *len += nlen[n]; + nlen[n] = 0; + } + + /* Generate random garbage inside tuple. */ + secp256k1_rand_bytes_test(sig + *len, elen); + *len += elen; + + /* Generate end-of-contents bytes. */ + if (indet) { + sig[(*len)++] = 0; + sig[(*len)++] = 0; + tlen += 2; + } + CHECK(tlen + glen <= 1121); + + /* Generate random garbage outside tuple. */ + secp256k1_rand_bytes_test(sig + *len, glen); + *len += glen; + tlen += glen; + CHECK(tlen <= 1121); + CHECK(tlen == *len); +} + +void run_ecdsa_der_parse(void) { + int i,j; + for (i = 0; i < 200 * count; i++) { + unsigned char buffer[2048]; + size_t buflen = 0; + int certainly_der = 0; + int certainly_not_der = 0; + random_ber_signature(buffer, &buflen, &certainly_der, &certainly_not_der); + for (j = 0; j < 16; j++) { + int ret = 0; + if (j > 0) { + damage_array(buffer, &buflen); + /* We don't know anything anymore about the DERness of the result */ + certainly_der = 0; + certainly_not_der = 0; + } + ret = test_ecdsa_der_parse(buffer, buflen, certainly_der, certainly_not_der); + if (ret != 0) { + size_t k; + fprintf(stderr, "Failure %x on ", ret); + for (k = 0; k < buflen; k++) { + fprintf(stderr, "%02x ", buffer[k]); + } + fprintf(stderr, "\n"); + } + CHECK(ret == 0); + } + } +} + + /* Tests several edge cases. */ void test_ecdsa_edge_cases(void) { int t; @@ -2575,7 +2985,7 @@ EC_KEY *get_openssl_key(const secp256k1_scalar *key) { unsigned char privkey[300]; size_t privkeylen; const unsigned char* pbegin = privkey; - int compr = secp256k1_rand32() & 1; + int compr = secp256k1_rand_bits(1); EC_KEY *ec_key = EC_KEY_new_by_curve_name(NID_secp256k1); CHECK(secp256k1_eckey_privkey_serialize(&ctx->ecmult_gen_ctx, privkey, &privkeylen, key, compr ? SECP256K1_EC_COMPRESSED : 0)); CHECK(d2i_ECPrivateKey(&ec_key, &pbegin, privkeylen)); @@ -2681,11 +3091,14 @@ int main(int argc, char **argv) { /* initialize */ run_context_tests(); ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); - - if (secp256k1_rand32() & 1) { + if (secp256k1_rand_bits(1)) { secp256k1_rand256(run32); - CHECK(secp256k1_context_randomize(ctx, (secp256k1_rand32() & 1) ? run32 : NULL)); + CHECK(secp256k1_context_randomize(ctx, secp256k1_rand_bits(1) ? run32 : NULL)); } + + run_rand_bits(); + run_rand_int(); + run_sha256_tests(); run_hmac_sha256_tests(); run_rfc6979_hmac_sha256_tests(); @@ -2734,6 +3147,7 @@ int main(int argc, char **argv) { /* ecdsa tests */ run_random_pubkeys(); + run_ecdsa_der_parse(); run_ecdsa_sign_verify(); run_ecdsa_end_to_end(); run_ecdsa_edge_cases();