Password hashing is a pretty useful service, really. Move the guts of

the passhash example to the library. Support variable work factors;
default work factor of 10 takes about half a second to do one password
on my Core2. Switch to using SHA-512 instead of SHA-1 in PBKDF2. To keep
the output evenly sized for base64 purposes, reduce PBKDF2 output size by
one byte (to 112 bits).

2 files changed, 8 insertions, 58 deletions

diff --git a/doc/examples/passhash.cpp b/doc/examples/passhash.cpp
index 8c50de072..0949e944c 100644
--- a/doc/examples/passhash.cpp
+++ b/doc/examples/passhash.cpp
@@ -5,17 +5,11 @@
 */
 
 #include <botan/botan.h>
-#include <botan/pbkdf2.h>
-#include <botan/hmac.h>
-#include <botan/sha160.h>
+#include <botan/passhash.h>
 #include <iostream>
 #include <memory>
 
-using namespace Botan;
-
-std::string password_hash(const std::string& pass,
-                          RandomNumberGenerator& rng);
-bool password_hash_ok(const std::string& pass, const std::string& hash);
+#include <stdio.h>
 
 int main(int argc, char* argv[])
    {
@@ -33,14 +27,16 @@ int main(int argc, char* argv[])
 
       if(argc == 2)
          {
-         AutoSeeded_RNG rng;
+         Botan::AutoSeeded_RNG rng;
+
+         Botan::u32bit work_factor = 10;
 
          std::cout << "H('" << argv[1] << "') = "
-                   << password_hash(argv[1], rng) << '\n';
+                   << Botan::password_hash(argv[1], rng, work_factor) << '\n';
          }
       else
          {
-         bool ok = password_hash_ok(argv[1], argv[2]);
+         bool ok = Botan::password_hash_ok(argv[1], argv[2]);
          if(ok)
             std::cout << "Password and hash match\n";
          else
@@ -54,50 +50,3 @@ int main(int argc, char* argv[])
       }
    return 0;
    }
-
-const u32bit SALT_BYTES = 8; // 64 bits of salt
-const u32bit PBKDF_OUTPUT_LEN = 16; // 128 bits output
-const u32bit KDF_ITERATIONS = 100000;
-
-std::string password_hash(const std::string& pass,
-                          RandomNumberGenerator& rng)
-   {
-   PKCS5_PBKDF2 kdf(new HMAC(new SHA_160));
-
-   SecureVector<byte> salt(SALT_BYTES);
-   rng.randomize(&salt[0], salt.size());
-
-   // Encode the salt plus 96 bits of PBKDF2 output
-
-   Pipe pipe(new Base64_Encoder);
-   pipe.start_msg();
-   pipe.write(salt);
-   pipe.write(kdf.derive_key(PBKDF_OUTPUT_LEN, pass,
-                             &salt[0], salt.size(),
-                             KDF_ITERATIONS).bits_of());
-   pipe.end_msg();
-
-   return pipe.read_all_as_string();
-   }
-
-bool password_hash_ok(const std::string& pass, const std::string& hash)
-   {
-   Pipe pipe(new Base64_Decoder);
-   pipe.start_msg();
-   pipe.write(hash);
-   pipe.end_msg();
-
-   SecureVector<byte> hash_bin = pipe.read_all();
-
-   if(hash_bin.size() != (PBKDF_OUTPUT_LEN + SALT_BYTES))
-      return false;
-
-   PKCS5_PBKDF2 kdf(new HMAC(new SHA_160));
-
-   SecureVector<byte> cmp = kdf.derive_key(
-      PBKDF_OUTPUT_LEN, pass,
-      &hash_bin[0], SALT_BYTES,
-      KDF_ITERATIONS).bits_of();
-
-   return same_mem(cmp.begin(), hash_bin.begin() + 6, 12);
-   }
diff --git a/doc/log.txt b/doc/log.txt
index 652ce7054..2e93cf207 100644
--- a/doc/log.txt
+++ b/doc/log.txt
@@ -6,6 +6,7 @@
  - Perform CBC decryption in parallel where possible
  - Add SQLite3 db encryption codec, contributed by Olivier de Gaalon
  - Add a block cipher cascade construction
+ - Add support for password hashing for authentication (passhash.h)
  - Add support for Win32 high resolution system timers
  - Changed S2K interface: derive_key now takes salt, iteration count
  - Fix crash in GMP_Engine if library is shutdown and reinitialized