Mercurial > dropbear
view libtommath/bn_mp_sub_d.c @ 1855:35d504d59c05
Implement server-side support for sk-ecdsa U2F-backed keys (#142)
* Implement server-side support for sk-ecdsa U2F-backed keys
* Fix out-of-bounds read on normal ecdsa-sha2-[identifier] keys
* Fix one more potential out-of-bounds read
* Check if nistp256 curve is used in sk-ecdsa-sha2- key
It's the only allowed curve per PROTOCOL.u2f specification
* Implement server-side support for sk-ed25519 FIDO2-backed keys
* Keys with type sk-* make no sense as host keys, so they should be
disabled
* fix typo
* Make sk-ecdsa call buf_ecdsa_verify
This reduces code duplication, the SK code just handles the
different message format.
* Reduce sk specific code
The application id can be stored in signkey, then we don't need
to call sk-specific functions from svr-authpubkey
* Remove debugging output, which causes compilation errors with DEBUG_TRACE disabled
* Proper cleanup of sk_app
Co-authored-by: Matt Johnston <[email protected]>
author | egor-duda <egor-duda@users.noreply.github.com> |
---|---|
date | Sat, 22 Jan 2022 16:53:04 +0300 |
parents | 1051e4eea25a |
children |
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#include "tommath_private.h" #ifdef BN_MP_SUB_D_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* single digit subtraction */ mp_err mp_sub_d(const mp_int *a, mp_digit b, mp_int *c) { mp_digit *tmpa, *tmpc; mp_err err; int ix, oldused; /* grow c as required */ if (c->alloc < (a->used + 1)) { if ((err = mp_grow(c, a->used + 1)) != MP_OKAY) { return err; } } /* if a is negative just do an unsigned * addition [with fudged signs] */ if (a->sign == MP_NEG) { mp_int a_ = *a; a_.sign = MP_ZPOS; err = mp_add_d(&a_, b, c); c->sign = MP_NEG; /* clamp */ mp_clamp(c); return err; } /* setup regs */ oldused = c->used; tmpa = a->dp; tmpc = c->dp; /* if a <= b simply fix the single digit */ if (((a->used == 1) && (a->dp[0] <= b)) || (a->used == 0)) { if (a->used == 1) { *tmpc++ = b - *tmpa; } else { *tmpc++ = b; } ix = 1; /* negative/1digit */ c->sign = MP_NEG; c->used = 1; } else { mp_digit mu = b; /* positive/size */ c->sign = MP_ZPOS; c->used = a->used; /* subtract digits, mu is carry */ for (ix = 0; ix < a->used; ix++) { *tmpc = *tmpa++ - mu; mu = *tmpc >> (MP_SIZEOF_BITS(mp_digit) - 1u); *tmpc++ &= MP_MASK; } } /* zero excess digits */ MP_ZERO_DIGITS(tmpc, oldused - ix); mp_clamp(c); return MP_OKAY; } #endif