diff options
Diffstat (limited to 'cipher/ecc-misc.c')
| -rw-r--r-- | cipher/ecc-misc.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/cipher/ecc-misc.c b/cipher/ecc-misc.c index 67e3b3d8..33af6f74 100644 --- a/cipher/ecc-misc.c +++ b/cipher/ecc-misc.c @@ -322,7 +322,9 @@ _gcry_ecc_mont_decodepoint (gcry_mpi_t pk, mpi_ec_t ctx, mpi_point_t result) } else { - a = rawmpi = _gcry_mpi_get_buffer (pk, ctx->nbits/8, &rawmpilen, NULL); + unsigned int nbytes = (ctx->nbits+7)/8; + + a = rawmpi = _gcry_mpi_get_buffer (pk, nbytes, &rawmpilen, NULL); if (!a) return gpg_err_code_from_syserror (); /* @@ -339,16 +341,17 @@ _gcry_ecc_mont_decodepoint (gcry_mpi_t pk, mpi_ec_t ctx, mpi_point_t result) * So, we need to check if it's really the prefix or not. * Only when it's the prefix, we remove it. */ - if (ctx->nbits/8 == rawmpilen - 1) - rawmpi++; - else if (rawmpilen < ctx->nbits/8) + if (rawmpilen > nbytes) + {/* Prefix 0x40 or 0x00 */ + rawmpi++; + rawmpilen = nbytes; + } + else if (rawmpilen < nbytes) {/* * It is possible for data created by older implementation * to have shorter length when it was parsed as MPI. */ - unsigned int new_rawmpilen = ctx->nbits/8; - - rawmpi = xtrymalloc (new_rawmpilen); + rawmpi = xtrymalloc (nbytes); if (!rawmpi) { gpg_err_code_t err = gpg_err_code_from_syserror (); @@ -356,8 +359,8 @@ _gcry_ecc_mont_decodepoint (gcry_mpi_t pk, mpi_ec_t ctx, mpi_point_t result) return err; } - memset (rawmpi, 0, new_rawmpilen - rawmpilen); - memcpy (rawmpi + new_rawmpilen - rawmpilen, a, rawmpilen); + memset (rawmpi, 0, nbytes - rawmpilen); + memcpy (rawmpi + nbytes - rawmpilen, a, rawmpilen); } } |