diff options
Diffstat (limited to 'crypto/rsa.c')
| -rw-r--r-- | crypto/rsa.c | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/crypto/rsa.c b/crypto/rsa.c index b9cd11fb7d..d9be9e8609 100644 --- a/crypto/rsa.c +++ b/crypto/rsa.c @@ -24,14 +24,38 @@ struct rsa_mpi_key { MPI qinv; }; +static int rsa_check_payload(MPI x, MPI n) +{ + MPI n1; + + if (mpi_cmp_ui(x, 1) <= 0) + return -EINVAL; + + n1 = mpi_alloc(0); + if (!n1) + return -ENOMEM; + + if (mpi_sub_ui(n1, n, 1) || mpi_cmp(x, n1) >= 0) { + mpi_free(n1); + return -EINVAL; + } + + mpi_free(n1); + return 0; +} + /* * RSAEP function [RFC3447 sec 5.1.1] * c = m^e mod n; */ static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m) { - /* (1) Validate 0 <= m < n */ - if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0) + /* + * Even though (1) in RFC3447 only requires 0 <= m <= n - 1, we are + * slightly more conservative and require 1 < m < n - 1. This is in line + * with SP 800-56Br2, Section 7.1.1. + */ + if (rsa_check_payload(m, key->n)) return -EINVAL; /* (2) c = m^e mod n */ @@ -50,8 +74,12 @@ static int _rsa_dec_crt(const struct rsa_mpi_key *key, MPI m_or_m1_or_h, MPI c) MPI m2, m12_or_qh; int ret = -ENOMEM; - /* (1) Validate 0 <= c < n */ - if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0) + /* + * Even though (1) in RFC3447 only requires 0 <= c <= n - 1, we are + * slightly more conservative and require 1 < c < n - 1. This is in line + * with SP 800-56Br2, Section 7.1.2. + */ + if (rsa_check_payload(c, key->n)) return -EINVAL; m2 = mpi_alloc(0); |