From 04bf8dc51861bab37d6260de8b318dc71ea4bba7 Mon Sep 17 00:00:00 2001
From: Jack Lloyd <lloyd@randombit.net>
Date: Thu, 15 Sep 2016 09:16:46 -0400
Subject: Add T::provider() to allow user to inquire about implementation used

For block ciphers, stream ciphers, hashes, MACs, and cipher modes.
Cipher_Mode already had it, with a slightly different usage.
---
 src/lib/stream/chacha/chacha.cpp | 12 ++++++++++++
 src/lib/stream/chacha/chacha.h   |  2 ++
 src/lib/stream/stream_cipher.h   |  7 +++++++
 3 files changed, 21 insertions(+)

(limited to 'src/lib/stream')

diff --git a/src/lib/stream/chacha/chacha.cpp b/src/lib/stream/chacha/chacha.cpp
index c35363112..66d7ad90d 100644
--- a/src/lib/stream/chacha/chacha.cpp
+++ b/src/lib/stream/chacha/chacha.cpp
@@ -17,6 +17,18 @@ ChaCha::ChaCha(size_t rounds) : m_rounds(rounds)
       throw Invalid_Argument("ChaCha only supports 8, 12 or 20 rounds");
    }
 
+const char* ChaCha::provider() const
+   {
+#if defined(BOTAN_HAS_CHACHA_SSE2)
+   if(CPUID::has_sse2())
+      {
+      return "sse2";
+      }
+#endif
+
+   return "base";
+   }
+
 //static
 void ChaCha::chacha_x4(byte output[64*4], u32bit input[16], size_t rounds)
    {
diff --git a/src/lib/stream/chacha/chacha.h b/src/lib/stream/chacha/chacha.h
index 7e9e54768..19ed6d25f 100644
--- a/src/lib/stream/chacha/chacha.h
+++ b/src/lib/stream/chacha/chacha.h
@@ -26,6 +26,8 @@ class BOTAN_DLL ChaCha final : public StreamCipher
       */
       ChaCha(size_t rounds = 20);
 
+      const char* provider() const override;
+
       void cipher(const byte in[], byte out[], size_t length) override;
 
       void set_iv(const byte iv[], size_t iv_len) override;
diff --git a/src/lib/stream/stream_cipher.h b/src/lib/stream/stream_cipher.h
index e08bee0ce..e41cdaa6d 100644
--- a/src/lib/stream/stream_cipher.h
+++ b/src/lib/stream/stream_cipher.h
@@ -86,6 +86,13 @@ class BOTAN_DLL StreamCipher : public SymmetricAlgorithm
       */
       virtual void seek(u64bit offset) = 0;
 
+      /**
+      * @return provider information about this implementation. Default is "base",
+      * might also return "sse2", "avx2", "openssl", or some other arbitrary string.
+      * The return value is guaranteed to point to a string literal constant.
+      */
+      virtual const char* provider() const { return "base"; }
+
       StreamCipher();
       virtual ~StreamCipher();
    };
-- 
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