Rename S2K to PBKDF, because that is by far the most common name - S2K

really is only used by OpenPGP, and largely it was named S2K here
because the OpenPGP S2K was implemented years before the ones in PKCS
#5. We have a typedef of PBKDF to S2K, and an inlined get_s2k that
calls get_pbkdf for source compatability.

There doesn't seem to be any reason to have a forward for the renamed
s2k.h header - to actually use a PBKDF, you'd have to either include
lookup.h and call get_s2k / get_pbkdf, or else include an
algorithm-specific header and use it directly. In either case,
including s2k.h is neither necessary nor sufficient.

3 files changed, 120 insertions, 0 deletions

diff --git a/src/pbkdf/pbkdf2/info.txt b/src/pbkdf/pbkdf2/info.txt
new file mode 100644
index 000000000..5462b2e1b
--- /dev/null
+++ b/src/pbkdf/pbkdf2/info.txt
@@ -0,0 +1,5 @@
+define PBKDF2
+
+<requires>
+mac
+</requires>
diff --git a/src/pbkdf/pbkdf2/pbkdf2.cpp b/src/pbkdf/pbkdf2/pbkdf2.cpp
new file mode 100644
index 000000000..e88a5749a
--- /dev/null
+++ b/src/pbkdf/pbkdf2/pbkdf2.cpp
@@ -0,0 +1,62 @@
+/*
+* PBKDF2
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/pbkdf2.h>
+#include <botan/get_byte.h>
+#include <botan/internal/xor_buf.h>
+
+namespace Botan {
+
+/*
+* Return a PKCS #5 PBKDF2 derived key
+*/
+OctetString PKCS5_PBKDF2::derive_key(u32bit key_len,
+                                     const std::string& passphrase,
+                                     const byte salt[], u32bit salt_size,
+                                     u32bit iterations) const
+   {
+   if(iterations == 0)
+      throw Invalid_Argument("PKCS#5 PBKDF2: Invalid iteration count");
+
+   if(passphrase.length() == 0)
+      throw Invalid_Argument("PKCS#5 PBKDF2: Empty passphrase is invalid");
+
+   mac->set_key(reinterpret_cast<const byte*>(passphrase.data()),
+                passphrase.length());
+
+   SecureVector<byte> key(key_len);
+
+   byte* T = key.begin();
+
+   u32bit counter = 1;
+   while(key_len)
+      {
+      u32bit T_size = std::min(mac->OUTPUT_LENGTH, key_len);
+      SecureVector<byte> U(mac->OUTPUT_LENGTH);
+
+      mac->update(salt, salt_size);
+      for(u32bit j = 0; j != 4; ++j)
+         mac->update(get_byte(j, counter));
+      mac->final(U);
+      xor_buf(T, U, T_size);
+
+      for(u32bit j = 1; j != iterations; ++j)
+         {
+         mac->update(U);
+         mac->final(U);
+         xor_buf(T, U, T_size);
+         }
+
+      key_len -= T_size;
+      T += T_size;
+      ++counter;
+      }
+
+   return key;
+   }
+
+}
diff --git a/src/pbkdf/pbkdf2/pbkdf2.h b/src/pbkdf/pbkdf2/pbkdf2.h
new file mode 100644
index 000000000..2b25a7b1d
--- /dev/null
+++ b/src/pbkdf/pbkdf2/pbkdf2.h
@@ -0,0 +1,53 @@
+/*
+* PBKDF2
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_PBKDF2_H__
+#define BOTAN_PBKDF2_H__
+
+#include <botan/pbkdf.h>
+#include <botan/mac.h>
+
+namespace Botan {
+
+/**
+* PKCS #5 PBKDF2
+*/
+class BOTAN_DLL PKCS5_PBKDF2 : public PBKDF
+   {
+   public:
+      std::string name() const
+         {
+         return "PBKDF2(" + mac->name() + ")";
+         }
+
+      PBKDF* clone() const
+         {
+         return new PKCS5_PBKDF2(mac->clone());
+         }
+
+      OctetString derive_key(u32bit output_len,
+                             const std::string& passphrase,
+                             const byte salt[], u32bit salt_len,
+                             u32bit iterations) const;
+
+      /**
+      * Create a PKCS #5 instance using the specified message auth code
+      * @param mac the MAC to use
+      */
+      PKCS5_PBKDF2(MessageAuthenticationCode* m) : mac(m) {}
+
+      /**
+      * Destructor
+      */
+      ~PKCS5_PBKDF2() { delete mac; }
+   private:
+      MessageAuthenticationCode* mac;
+   };
+
+}
+
+#endif