Clean up PK decryption encoding.

Previously RSA and ElGamal stripped off leading zeros which were then
assumed by the padding decoders. Instead have them produce ciphertexts
with leading zeros. Changes EME_Raw to strip leading zeros to match
existing behavior.

1 files changed, 9 insertions, 5 deletions

diff --git a/src/lib/utils/ct_utils.h b/src/lib/utils/ct_utils.h
index ec055374a..5a1d03d4f 100644
--- a/src/lib/utils/ct_utils.h
+++ b/src/lib/utils/ct_utils.h
@@ -177,20 +177,24 @@ inline T min(T a, T b)
    return select(expand_top_bit(b), b, a);
    }
 
-template<typename T, typename Alloc>
-std::vector<T, Alloc> strip_leading_zeros(const std::vector<T, Alloc>& input)
+inline secure_vector<uint8_t> strip_leading_zeros(const uint8_t in[], size_t length)
    {
    size_t leading_zeros = 0;
 
    uint8_t only_zeros = 0xFF;
 
-   for(size_t i = 0; i != input.size(); ++i)
+   for(size_t i = 0; i != length; ++i)
       {
-      only_zeros &= CT::is_zero(input[i]);
+      only_zeros &= CT::is_zero(in[i]);
       leading_zeros += CT::select<uint8_t>(only_zeros, 1, 0);
       }
 
-   return secure_vector<byte>(input.begin() + leading_zeros, input.end());
+   return secure_vector<byte>(in + leading_zeros, in + length);
+   }
+
+inline secure_vector<byte> strip_leading_zeros(const secure_vector<uint8_t>& in)
+   {
+   return strip_leading_zeros(in.data(), in.size());
    }
 
 }