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authorJack Lloyd <[email protected]>2016-04-04 23:30:13 -0400
committerJack Lloyd <[email protected]>2016-04-09 12:57:47 -0400
commit088e85ea774e9035c0b951c27a1a00d0793fa01e (patch)
tree9254702508469a6148c5c5ba28d78239cb1eb028 /src/lib
parent8dd6eb9252ad91f59630e2889fa6803f6e3bf554 (diff)
Add support for ChaCha(12)
Diffstat (limited to 'src/lib')
-rw-r--r--src/lib/stream/chacha/chacha.cpp25
-rw-r--r--src/lib/stream/chacha/chacha.h15
-rw-r--r--src/lib/stream/stream_cipher.cpp2
3 files changed, 33 insertions, 9 deletions
diff --git a/src/lib/stream/chacha/chacha.cpp b/src/lib/stream/chacha/chacha.cpp
index 0a32c720b..ac81fd70d 100644
--- a/src/lib/stream/chacha/chacha.cpp
+++ b/src/lib/stream/chacha/chacha.cpp
@@ -10,8 +10,18 @@
namespace Botan {
-void ChaCha::chacha(byte output[64], const u32bit input[16])
+ChaCha::ChaCha(size_t rounds) : m_rounds(rounds)
{
+ if(m_rounds != 12 && m_rounds != 20)
+ throw Invalid_Argument("ChaCha only supports 12 or 20 rounds");
+ }
+
+namespace {
+
+void chacha(byte output[64], const u32bit input[16], size_t rounds)
+ {
+ BOTAN_ASSERT(rounds % 2 == 0, "Valid rounds");
+
u32bit x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3],
x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7],
x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11],
@@ -25,7 +35,7 @@ void ChaCha::chacha(byte output[64], const u32bit input[16])
c += d; b ^= c; b = rotate_left(b, 7); \
} while(0)
- for(size_t i = 0; i != 10; ++i)
+ for(size_t i = 0; i != rounds / 2; ++i)
{
CHACHA_QUARTER_ROUND(x00, x04, x08, x12);
CHACHA_QUARTER_ROUND(x01, x05, x09, x13);
@@ -58,6 +68,8 @@ void ChaCha::chacha(byte output[64], const u32bit input[16])
store_le(x15 + input[15], output + 4 * 15);
}
+}
+
/*
* Combine cipher stream with message
*/
@@ -69,7 +81,7 @@ void ChaCha::cipher(const byte in[], byte out[], size_t length)
length -= (m_buffer.size() - m_position);
in += (m_buffer.size() - m_position);
out += (m_buffer.size() - m_position);
- chacha(m_buffer.data(), m_state.data());
+ chacha(m_buffer.data(), m_state.data(), m_rounds);
++m_state[12];
m_state[13] += (m_state[12] == 0);
@@ -142,7 +154,7 @@ void ChaCha::set_iv(const byte iv[], size_t length)
m_state[15] = load_le<u32bit>(iv, 2);
}
- chacha(m_buffer.data(), m_state.data());
+ chacha(m_buffer.data(), m_state.data(), m_rounds);
++m_state[12];
m_state[13] += (m_state[12] == 0);
@@ -156,4 +168,9 @@ void ChaCha::clear()
m_position = 0;
}
+std::string ChaCha::name() const
+ {
+ return "ChaCha(" + std::to_string(m_rounds) + ")";
+ }
+
}
diff --git a/src/lib/stream/chacha/chacha.h b/src/lib/stream/chacha/chacha.h
index 92f8ef035..ba93d6260 100644
--- a/src/lib/stream/chacha/chacha.h
+++ b/src/lib/stream/chacha/chacha.h
@@ -18,6 +18,14 @@ namespace Botan {
class BOTAN_DLL ChaCha final : public StreamCipher
{
public:
+ StreamCipher* clone() const override { return new ChaCha(m_rounds); }
+
+ /**
+ * Currently only 12 or 20 rounds are supported, all others
+ * will throw an exception
+ */
+ ChaCha(size_t rounds);
+
void cipher(const byte in[], byte out[], size_t length) override;
void set_iv(const byte iv[], size_t iv_len) override;
@@ -31,14 +39,13 @@ class BOTAN_DLL ChaCha final : public StreamCipher
}
void clear() override;
- std::string name() const override { return "ChaCha"; }
- StreamCipher* clone() const override { return new ChaCha; }
- protected:
- virtual void chacha(byte output[64], const u32bit input[16]);
+ std::string name() const override;
+
private:
void key_schedule(const byte key[], size_t key_len) override;
+ size_t m_rounds;
secure_vector<u32bit> m_state;
secure_vector<byte> m_buffer;
size_t m_position = 0;
diff --git a/src/lib/stream/stream_cipher.cpp b/src/lib/stream/stream_cipher.cpp
index 03ef5e329..6f98df1fb 100644
--- a/src/lib/stream/stream_cipher.cpp
+++ b/src/lib/stream/stream_cipher.cpp
@@ -51,7 +51,7 @@ void StreamCipher::set_iv(const byte[], size_t iv_len)
}
#if defined(BOTAN_HAS_CHACHA)
-BOTAN_REGISTER_T_NOARGS(StreamCipher, ChaCha);
+BOTAN_REGISTER_T_1LEN(StreamCipher, ChaCha, 20);
#endif
#if defined(BOTAN_HAS_SALSA20)