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Fixed bug in bit length computation (implied some wrong RSA signatures in case of carry propagation with some specific key/factor lengths).

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This commit is contained in:
Thomas Pornin 2018-05-02 17:32:35 +02:00
parent 7d313ccce7
commit c1e540575c
3 changed files with 60 additions and 2 deletions
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11
src/int/i15_mulacc.c
View file

@ -29,10 +29,19 @@ void
br_i15_mulacc(uint16_t *d, const uint16_t *a, const uint16_t *b) br_i15_mulacc(uint16_t *d, const uint16_t *a, const uint16_t *b)
{ {
size_t alen, blen, u; size_t alen, blen, u;
unsigned dl, dh;
alen = (a[0] + 15) >> 4; alen = (a[0] + 15) >> 4;
blen = (b[0] + 15) >> 4; blen = (b[0] + 15) >> 4;
d[0] = a[0] + b[0];
/*
* Announced bit length of d[] will be the sum of the announced
* bit lengths of a[] and b[]; but the lengths are encoded.
*/
dl = (a[0] & 15) + (d[0] & 15);
dh = (a[0] >> 4) + (b[0] >> 4);
d[0] = (dh << 4) + dl + (~(uint16_t)(dl - 15) >> 15);
for (u = 0; u < blen; u ++) { for (u = 0; u < blen; u ++) {
uint32_t f; uint32_t f;
size_t v; size_t v;

11
src/int/i31_mulacc.c
View file

@ -29,10 +29,19 @@ void
br_i31_mulacc(uint32_t *d, const uint32_t *a, const uint32_t *b) br_i31_mulacc(uint32_t *d, const uint32_t *a, const uint32_t *b)
{ {
size_t alen, blen, u; size_t alen, blen, u;
uint32_t dl, dh;
alen = (a[0] + 31) >> 5; alen = (a[0] + 31) >> 5;
blen = (b[0] + 31) >> 5; blen = (b[0] + 31) >> 5;
d[0] = a[0] + b[0];
/*
* We want to add the two bit lengths, but these are encoded,
* which requires some extra care.
*/
dl = (a[0] & 31) + (b[0] & 31);
dh = (a[0] >> 5) + (b[0] >> 5);
d[0] = (dh << 5) + dl + (~(uint32_t)(dl - 31) >> 31);
for (u = 0; u < blen; u ++) { for (u = 0; u < blen; u ++) {
uint32_t f; uint32_t f;
size_t v; size_t v;

40
test/test_crypto.c
View file

@ -4759,6 +4759,11 @@ test_RSA_sign(const char *name, br_rsa_private fpriv,
{ {
unsigned char t1[128], t2[128]; unsigned char t1[128], t2[128];
unsigned char hv[20], tmp[20]; unsigned char hv[20], tmp[20];
unsigned char rsa_n[128], rsa_e[3], rsa_p[64], rsa_q[64];
unsigned char rsa_dp[64], rsa_dq[64], rsa_iq[64];
br_rsa_public_key rsa_pk;
br_rsa_private_key rsa_sk;
unsigned char hv2[64], tmp2[64], sig[128];
br_sha1_context hc; br_sha1_context hc;
size_t u; size_t u;
@ -4812,6 +4817,41 @@ test_RSA_sign(const char *name, br_rsa_private fpriv,
fflush(stdout); fflush(stdout);
} }
/*
* Another KAT test, which historically showed a bug.
*/
rsa_pk.n = rsa_n;
rsa_pk.nlen = hextobin(rsa_n, "E65DAEF196D22C300B3DAE1CE5157EDF821BB6038E419D8D363A8B2DA84A1321042330E6F87A8BD8FE6BA1D2A17031955ED2315CC5FD2397197E238A5E0D2D0AFD25717E814EC4D2BBA887327A3C5B3A450FD8D547BDFCBB0F73B997CA13DD5E7572C4D5BAA764A349BAB2F868ACF4574AE2C7AEC94B77D2EE00A21B6CB175BB");
rsa_pk.e = rsa_e;
rsa_pk.elen = hextobin(rsa_e, "010001");
rsa_sk.n_bitlen = 1024;
rsa_sk.p = rsa_p;
rsa_sk.plen = hextobin(rsa_p, "FF58513DBA4F3F42DFDFD3E6AFB6BD62DE27E06BA3C9D9F9B542CB21228C2AAE67936514161C8FDC1A248A50195CAF22ADC50DA89BFED1B9EEFBB37304241357");
rsa_sk.q = rsa_q;
rsa_sk.qlen = hextobin(rsa_q, "E6F4F66818B7442297DDEB45E9B3D438E5B57BB5EF86EFF2462AD6B9C10F383517CDD2E7E36EAD4BEBCC57CFE8AA985F7E7B38B96D30FFBE9ED9FE21B1CFB63D");
rsa_sk.dp = rsa_dp;
rsa_sk.dplen = hextobin(rsa_dp, "6F89517B682D83919F9EF2BDBA955526A1A9C382E139A3A84AC01160B8E9871F458901C7035D988D6931FAE4C01F57350BB89E9DBEFE50F829E6F25CD43B39E3");
rsa_sk.dq = rsa_dq;
rsa_sk.dqlen = hextobin(rsa_dq, "409E08D2D7176F58BE64B88EB6F4394C31F8B4C412600E821A5FA1F416AFCB6A0F5EE6C33A3E9CFDC0DB4B3640427A9F3D23FC9AE491F0FBC435F98433DB8981");
rsa_sk.iq = rsa_iq;
rsa_sk.iqlen = hextobin(rsa_iq, "CF333D6AD66D02B4D11C8C23CA669D14D71803ADC3943BE03B1E48F52F385BCFDDFD0F85AD02A984E504FC6612549D4E7867B7D09DD13196BFC3FAA4B57393A9");
hextobin(sig, "CFB84D161E6DB130736FC6212EBE575571AF341CEF5757C19952A5364C90E3C47549E520E26253DAE70F645F31FA8B5DA9AE282741D3CA4B1CC365B7BD75D6D61D4CFD9AD9EDD17D23E0BA7D9775138DBABC7FF2A57587FE1EA1B51E8F3C68326E26FF89D8CF92BDD4C787D04857DFC3266E6B33B92AA08809929C72642F35C2");
hextobin(hv2, "F66C62B38E1CC69C378C0E16574AE5C6443FDFA3E85C6205C00B3231CAA3074EC1481BDC22AB575E6CF3CCD9EDA6B39F83923FC0E6475C799D257545F77233B4");
if (!fsign(BR_HASH_OID_SHA512, hv2, 64, &rsa_sk, t2)) {
fprintf(stderr, "Signature generation failed (2)\n");
exit(EXIT_FAILURE);
}
check_equals("Regenerated signature (2)", t2, sig, sizeof t2);
if (!fvrfy(t2, sizeof t2, BR_HASH_OID_SHA512,
sizeof tmp2, &rsa_pk, tmp2))
{
fprintf(stderr, "Signature verification failed (2)\n");
exit(EXIT_FAILURE);
}
check_equals("Extracted hash value (2)", hv2, tmp2, sizeof tmp2);
printf(" done.\n"); printf(" done.\n");
fflush(stdout); fflush(stdout);
} }