eme / pubkey test improvements

- add test for EME::maximum_input_size()
- additionally use maximum_input_size() before pad() in OAEP and PKCS1 (remove code duplication)
- prevent C4800 MSVC warning

2 files changed, 13 insertions, 11 deletions

diff --git a/src/lib/pk_pad/eme_oaep/oaep.cpp b/src/lib/pk_pad/eme_oaep/oaep.cpp
index 0ae0d8554..1ae1068a7 100644
--- a/src/lib/pk_pad/eme_oaep/oaep.cpp
+++ b/src/lib/pk_pad/eme_oaep/oaep.cpp
@@ -35,8 +35,10 @@ secure_vector<byte> OAEP::pad(const byte in[], size_t in_length,
    {
    key_length /= 8;
 
-   if(key_length < in_length + 2*m_Phash.size() + 1)
+   if(in_length > maximum_input_size(key_length * 8))
+      {
       throw Invalid_Argument("OAEP: Input is too large");
+      }
 
    secure_vector<byte> out(key_length);
 
diff --git a/src/lib/pk_pad/eme_pkcs1/eme_pkcs.cpp b/src/lib/pk_pad/eme_pkcs1/eme_pkcs.cpp
index 8148b7bc9..9bab8eb95 100644
--- a/src/lib/pk_pad/eme_pkcs1/eme_pkcs.cpp
+++ b/src/lib/pk_pad/eme_pkcs1/eme_pkcs.cpp
@@ -14,22 +14,22 @@ namespace Botan {
 * PKCS1 Pad Operation
 */
 secure_vector<byte> EME_PKCS1v15::pad(const byte in[], size_t inlen,
-                                     size_t olen,
+                                     size_t key_length,
                                      RandomNumberGenerator& rng) const
    {
-   olen /= 8;
+   key_length /= 8;
 
-   if(olen < 10)
-      throw Encoding_Error("PKCS1: Output space too small");
-   if(inlen > olen - 10)
-      throw Encoding_Error("PKCS1: Input is too large");
+   if(inlen > maximum_input_size(key_length * 8))
+      {
+      throw Invalid_Argument("PKCS1: Input is too large");
+      }
 
-   secure_vector<byte> out(olen);
+   secure_vector<byte> out(key_length);
 
    out[0] = 0x02;
-   rng.randomize(out.data() + 1, (olen - inlen - 2));
+   rng.randomize(out.data() + 1, (key_length - inlen - 2));
 
-   for(size_t j = 1; j != olen - inlen - 1; ++j)
+   for(size_t j = 1; j != key_length - inlen - 1; ++j)
       {
       if(out[j] == 0)
          {
@@ -37,7 +37,7 @@ secure_vector<byte> EME_PKCS1v15::pad(const byte in[], size_t inlen,
          }
       }
 
-   buffer_insert(out, olen - inlen, in, inlen);
+   buffer_insert(out, key_length - inlen, in, inlen);
 
    return out;
    }