Don't artificially limit very small RSA keys.

Keys smaller than 384 bits are trivially breakable, but that's true
for 512 as well so no reason to draw the line there. Just do 5 bits
since the smallest legal RSA key is 3*5 and that handles the integer
overflow warning from Coverity which was the original reason for it.

GH #1953

1 files changed, 6 insertions, 1 deletions

diff --git a/src/lib/pubkey/rsa/rsa.cpp b/src/lib/pubkey/rsa/rsa.cpp
index 0cd8bbdf4..9bb03dff8 100644
--- a/src/lib/pubkey/rsa/rsa.cpp
+++ b/src/lib/pubkey/rsa/rsa.cpp
@@ -397,7 +397,12 @@ class RSA_Public_Operation
       size_t get_max_input_bits() const
          {
          const size_t n_bits = m_n.bits();
-         BOTAN_ASSERT_NOMSG(n_bits >= 384);
+         /*
+         Make Coverity happy that n_bits - 1 won't underflow
+
+         5 bit minimum: smallest possible RSA key is 3*5
+         */
+         BOTAN_ASSERT_NOMSG(n_bits >= 5);
          return n_bits - 1;
          }