Adding StreamCipher::seek interface, supporting seek in ChaCha, and also adding ChaCha8 support

16 files changed, 583 insertions, 5 deletions

diff --git a/doc/credits.rst b/doc/credits.rst
index 6d62b6380..af78680a4 100644
--- a/doc/credits.rst
+++ b/doc/credits.rst
@@ -104,3 +104,10 @@ snail-mail address (S), and Bitcoin address (B).
   W: https://www.kullo.net
   D: Build system
   S: Germany
+
+  N: Simon Cogliani
+  E: [email protected]
+  W: https://www.tanker.io/
+  P: EA73 D0AF 5A81 A61A 8931  C2CA C9AB F2E4 3820 4F25
+  D: Getting keystream of ChaCha
+  S: Paris, France
diff --git a/doc/license.txt b/doc/license.txt
index ef0b97ac1..fd4fd0a7b 100644
--- a/doc/license.txt
+++ b/doc/license.txt
@@ -29,6 +29,7 @@ Copyright (C) 1999-2013,2014,2015,2016 Jack Lloyd
               2015,2016 Daniel Neus
               2015 Uri Blumenthal
               2015,2016 Kai Michaelis
+              2016 Simon Cogliani
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
diff --git a/src/lib/prov/openssl/openssl_rc4.cpp b/src/lib/prov/openssl/openssl_rc4.cpp
index e36535e08..070cdb14d 100644
--- a/src/lib/prov/openssl/openssl_rc4.cpp
+++ b/src/lib/prov/openssl/openssl_rc4.cpp
@@ -45,6 +45,11 @@ class OpenSSL_RC4 : public StreamCipher
 
       explicit OpenSSL_RC4(size_t skip = 0) : m_skip(skip) { clear(); }
       ~OpenSSL_RC4() { clear(); }
+
+      void seek(u64bit) override
+         {
+         throw Exception("RC4 does not support seeking");
+         }
    private:
       void cipher(const byte in[], byte out[], size_t length) override
          {
diff --git a/src/lib/stream/chacha/chacha.cpp b/src/lib/stream/chacha/chacha.cpp
index ac81fd70d..40da93029 100644
--- a/src/lib/stream/chacha/chacha.cpp
+++ b/src/lib/stream/chacha/chacha.cpp
@@ -12,8 +12,8 @@ namespace Botan {
 
 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");
+   if(m_rounds != 8 && m_rounds != 12 && m_rounds != 20)
+      throw Invalid_Argument("ChaCha only supports 8, 12 or 20 rounds");
    }
 
 namespace {
@@ -67,7 +67,6 @@ void chacha(byte output[64], const u32bit input[16], size_t rounds)
    store_le(x14 + input[14], output + 4 * 14);
    store_le(x15 + input[15], output + 4 * 15);
    }
-
 }
 
 /*
@@ -173,4 +172,27 @@ std::string ChaCha::name() const
    return "ChaCha(" + std::to_string(m_rounds) + ")";
    }
 
+void ChaCha::seek(u64bit offset)
+   {
+   if (m_state.size() == 0 && m_buffer.size() == 0)
+      {
+         throw Invalid_State("You have to setup the stream cipher (key and iv)");
+      }
+
+   m_position = offset % m_buffer.size();
+
+   u64bit counter = offset / m_buffer.size();
+
+   byte out[8];
+
+   store_le(counter, out);
+
+   m_state[12] = load_le<u32bit>(out, 0);
+   m_state[13] += load_le<u32bit>(out, 1);
+
+   chacha(m_buffer.data(), m_state.data(), m_rounds);
+
+   ++m_state[12];
+   m_state[13] += (m_state[12] == 0);
+   }
 }
diff --git a/src/lib/stream/chacha/chacha.h b/src/lib/stream/chacha/chacha.h
index ba93d6260..f8f42e41d 100644
--- a/src/lib/stream/chacha/chacha.h
+++ b/src/lib/stream/chacha/chacha.h
@@ -21,7 +21,7 @@ class BOTAN_DLL ChaCha final : public StreamCipher
       StreamCipher* clone() const override { return new ChaCha(m_rounds); }
 
       /**
-      * Currently only 12 or 20 rounds are supported, all others
+      * Currently only 8, 12 or 20 rounds are supported, all others
       * will throw an exception
       */
       ChaCha(size_t rounds);
@@ -42,6 +42,8 @@ class BOTAN_DLL ChaCha final : public StreamCipher
 
       std::string name() const override;
 
+      void seek(u64bit offset) override;
+
    private:
       void key_schedule(const byte key[], size_t key_len) override;
 
diff --git a/src/lib/stream/ctr/ctr.cpp b/src/lib/stream/ctr/ctr.cpp
index f5301c099..43609ba2d 100644
--- a/src/lib/stream/ctr/ctr.cpp
+++ b/src/lib/stream/ctr/ctr.cpp
@@ -125,4 +125,8 @@ void CTR_BE::increment_counter()
    m_pad_pos = 0;
    }
 
+void CTR_BE::seek(u64bit)
+   {
+   throw Not_Implemented("CTR_BE::seek");
+   }
 }
diff --git a/src/lib/stream/ctr/ctr.h b/src/lib/stream/ctr/ctr.h
index 003297b92..5d5556254 100644
--- a/src/lib/stream/ctr/ctr.h
+++ b/src/lib/stream/ctr/ctr.h
@@ -46,6 +46,8 @@ class BOTAN_DLL CTR_BE final : public StreamCipher
       explicit CTR_BE(BlockCipher* cipher);
 
       CTR_BE(BlockCipher* cipher, size_t ctr_size);
+
+      void seek(u64bit offset) override;
    private:
       void key_schedule(const byte key[], size_t key_len) override;
       void increment_counter();
diff --git a/src/lib/stream/ofb/ofb.cpp b/src/lib/stream/ofb/ofb.cpp
index e8cb463db..3337a0c14 100644
--- a/src/lib/stream/ofb/ofb.cpp
+++ b/src/lib/stream/ofb/ofb.cpp
@@ -73,4 +73,9 @@ void OFB::set_iv(const byte iv[], size_t iv_len)
    m_buf_pos = 0;
    }
 
+
+void OFB::seek(u64bit)
+   {
+   throw Exception("OFB does not support seeking");
+   }
 }
diff --git a/src/lib/stream/ofb/ofb.h b/src/lib/stream/ofb/ofb.h
index fecd47d9d..127a06578 100644
--- a/src/lib/stream/ofb/ofb.h
+++ b/src/lib/stream/ofb/ofb.h
@@ -44,6 +44,8 @@ class BOTAN_DLL OFB final : public StreamCipher
       * @param cipher the underlying block cipher to use
       */
       explicit OFB(BlockCipher* cipher);
+
+      void seek(u64bit offset) override;
    private:
       void key_schedule(const byte key[], size_t key_len) override;
 
diff --git a/src/lib/stream/rc4/rc4.cpp b/src/lib/stream/rc4/rc4.cpp
index 895f38091..a4dea9e2b 100644
--- a/src/lib/stream/rc4/rc4.cpp
+++ b/src/lib/stream/rc4/rc4.cpp
@@ -113,4 +113,8 @@ void RC4::clear()
 */
 RC4::RC4(size_t s) : m_SKIP(s) {}
 
+void RC4::seek(u64bit)
+   {
+   throw Exception("RC4 does not support seeking");
+   }
 }
diff --git a/src/lib/stream/rc4/rc4.h b/src/lib/stream/rc4/rc4.h
index f166a2772..88798fae6 100644
--- a/src/lib/stream/rc4/rc4.h
+++ b/src/lib/stream/rc4/rc4.h
@@ -39,6 +39,8 @@ class BOTAN_DLL RC4 final : public StreamCipher
       explicit RC4(size_t skip = 0);
 
       ~RC4() { clear(); }
+
+      void seek(u64bit offset) override;
    private:
       void key_schedule(const byte[], size_t) override;
       void generate();
diff --git a/src/lib/stream/salsa20/salsa20.cpp b/src/lib/stream/salsa20/salsa20.cpp
index 1d3fe3d28..f11fe5e59 100644
--- a/src/lib/stream/salsa20/salsa20.cpp
+++ b/src/lib/stream/salsa20/salsa20.cpp
@@ -227,4 +227,8 @@ void Salsa20::clear()
    m_position = 0;
    }
 
+void Salsa20::seek(u64bit)
+   {
+   throw Not_Implemented("Salsa20::seek");
+   }
 }
diff --git a/src/lib/stream/salsa20/salsa20.h b/src/lib/stream/salsa20/salsa20.h
index 7e75470da..8256ea4db 100644
--- a/src/lib/stream/salsa20/salsa20.h
+++ b/src/lib/stream/salsa20/salsa20.h
@@ -33,6 +33,8 @@ class BOTAN_DLL Salsa20 final : public StreamCipher
       void clear() override;
       std::string name() const override;
       StreamCipher* clone() const override { return new Salsa20; }
+
+      void seek(u64bit offset) override;
    private:
       void key_schedule(const byte key[], size_t key_len) override;
 
diff --git a/src/lib/stream/stream_cipher.h b/src/lib/stream/stream_cipher.h
index bff1fd1a6..56bd2d5d9 100644
--- a/src/lib/stream/stream_cipher.h
+++ b/src/lib/stream/stream_cipher.h
@@ -80,6 +80,12 @@ class BOTAN_DLL StreamCipher : public SymmetricAlgorithm
       */
       virtual StreamCipher* clone() const = 0;
 
+      /**
+      * Set the offset and the state used later to generate the keystream
+      * @param offset the offset where we begin to generate the keystream
+      */
+      virtual void seek(u64bit offset) = 0;
+
       StreamCipher();
       virtual ~StreamCipher();
    };
diff --git a/src/tests/data/stream/chacha.vec b/src/tests/data/stream/chacha.vec
index 1c3c18c7c..f51ff0812 100644
--- a/src/tests/data/stream/chacha.vec
+++ b/src/tests/data/stream/chacha.vec
@@ -1,3 +1,104 @@
+[ChaCha(8)]
+
+# Tests got from the original implementation of Daniel J. Bernstein
+
+Key = 00000000000000000000000000000000
+Nonce = 0000000000000000
+In  = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = E28A5FA4A67F8C5DEFED3E6FB7303486AA8427D31419A729572D777953491120B64AB8E72B8DEB85CD6AEA7CB6089A101824BEEB08814A428AAB1FA2C816081B
+
+Key = 0000000000000000000000000000000000000000000000000000000000000000
+Nonce = 000000000000000000000002
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out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
+
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out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
+
+# Test vector in a draft "Test Vectors for the Stream Cipher ChaCha draft-strombergson-chacha-test-vectors-00" available at the following link: http://tools.ietf.org/html/draft-strombergson-chacha-test-vectors-00.
+# The document links a github repo where you can find all the vectors https://github.com/secworks/chacha_testvectors/
+
+Key = 00000000000000000000000000000000
+Nonce = 0000000000000000
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = E28A5FA4A67F8C5DEFED3E6FB7303486AA8427D31419A729572D777953491120B64AB8E72B8DEB85CD6AEA7CB6089A101824BEEB08814A428AAB1FA2C816081B8A26AF448A1BA906368FD8C83831C18CEC8CED811A028E675B8D2BE8FCE081165CEAE9F1D1B7A975497749480569CEB83DE6A0A587D4984F19925F5D338E430D
+
+Key = 0000000000000000000000000000000000000000000000000000000000000000
+Nonce = 0000000000000000
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 3E00EF2F895F40D67F5BB8E81F09A5A12C840EC3CE9A7F3B181BE188EF711A1E984CE172B9216F419F445367456D5619314A42A3DA86B001387BFDB80E0CFE42D2AEFA0DEAA5C151BF0ADB6C01F2A5ADC0FD581259F9A2AADCF20F8FD566A26B5032EC38BBC5DA98EE0C6F568B872A65A08ABF251DEB21BB4B56E5D8821E68AA
+
+Key = 01000000000000000000000000000000
+Nonce = 0000000000000000
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 03A7669888605A0765E8357475E58673F94FC8161DA76C2A3AA2F3CAF9FE5449E0FCF38EB882656AF83D430D410927D55C972AC4C92AB9DA3713E19F761EAA147138C25C8A7CE3D5E7546746FFD2E3515CE6A4B1B2D3F380138668ED39FA92F8A1AEE36258E05FAE6F566673511765FDB59E05163D55A708C5F9BC45045124CB
+
+Key = 0100000000000000000000000000000000000000000000000000000000000000
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+
+Key = 00000000000000000000000000000000
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+
+Key = 0000000000000000000000000000000000000000000000000000000000000000
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+
+Key = FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
+Nonce = FFFFFFFFFFFFFFFF
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 2204D5B81CE662193E00966034F91302F14A3FB047F58B6E6EF0D721132304163E0FB640D76FF9C3B9CD99996E6E38FAD13F0E31C82244D33ABBC1B11E8BF12D9A81D78E9E56604DDFAE136921F51C9D81AE15119DB8E756DD28024493EE571D363AE4BBCD6E7D300F99D2673AEB92CCFC6E43A38DC31BACD66B28F17B22B28A
+
+Key = FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
+Nonce = FFFFFFFFFFFFFFFF
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = E163BBF8C9A739D18925EE8362DAD2CDC973DF05225AFB2AA26396F2A9849A4A445E0547D31C1623C537DF4BA85C70A9884A35BCBF3DFAB077E98B0F68135F5481D4933F8B322AC0CD762C27235CE2B31534E0244A9A2F1FD5E94498D47FF108790C009CF9E1A348032A7694CB28024CD96D3498361EDB1785AF752D187AB54B
+
+Key = 55555555555555555555555555555555
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+
+Key = 5555555555555555555555555555555555555555555555555555555555555555
+Nonce = 5555555555555555
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
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+
+Key = AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+Nonce = AAAAAAAAAAAAAAAA
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+
+Key = AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+Nonce = AAAAAAAAAAAAAAAA
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 40F9AB86C8F9A1A0CDC05A75E5531B612D71EF7F0CF9E387DF6ED6972F0AAE21311AA581F816C90E8A99DE990B6B95AAC92450F4E112712667B804C99E9C6EDAF8D144F560C8C0EA36880D3B77874C9A9103D147F6DED386284801A4EE158E5EA4F9C093FC55FD344C33349DC5B699E21DC83B4296F92EE3ECABF3D51F95FE3F
+
+Key = 00112233445566778899AABBCCDDEEFF
+Nonce = 0F1E2D3C4B5A6978
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 29560D280B4528400A8F4B795369FB3A01105599E9F1ED58279CFC9ECE2DC5F99F1C2E52C98238F542A5C0A881D850B615D3ACD9FBDB026E9368565DA50E0D49DD5BE8EF74248B3E251D965D8FCB21E7CFE204D4007806FBEE3CE94C74BFBAD2C11C621BA048147C5CAA94D182CCFF6FD5CF44ADF96E3D68281BB49676AF87E7
+
+Key = 00112233445566778899AABBCCDDEEFFFFEEDDCCBBAA99887766554433221100
+Nonce = 0F1E2D3C4B5A6978
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = DB43AD9D1E842D1272E4530E276B3F568F8859B3F7CF6D9D2C74FA53808CB5157A8EBF46AD3DCC4B6C7DADDE131784B0120E0E22F6D5F9FFA7407D4A21B695D9C5DD30BF55612FAB9BDD118920C19816470C7F5DCD42325DBBED8C57A56281C144CB0F03E81B3004624E0650A1CE5AFAF9A7CD8163F6DBD72602257DD96E471E
+
+Key = C46EC1B18CE8A878725A37E780DFB735
+Nonce = 1ADA31D5CF688221
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 6A870108859F679118F3E205E2A56A6826EF5A60A4102AC8D4770059FCB7C7BAE02F5CE004A6BFBBEA53014DD82107C0AA1C7CE11B7D78F2D50BD3602BBD25940560BB6A84289E0B38F5DD21D6EF6D7737E3EC0FB772DA2C71C2397762E5DBBBF449E3D1639CCBFA3E069C4D871ED6395B22AAF35C8DA6DE2DEC3D77880DA8E8
+
+Key = C46EC1B18CE8A878725A37E780DFB7351F68ED2E194C79FBC6AEBEE1A667975D
+Nonce = 1ADA31D5CF688221
+In = 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 838751B42D8DDD8A3D77F48825A2BA752CF4047CB308A5978EF274973BE374C96AD848065871417B08F034E681FE46A93F7D5C61D1306614D4AAF257A7CFF08B16F2FDA170CC18A4B58A2667ED962774AF792A6E7F3C77992540711A7A136D7E8A2F8D3F93816709D45A3FA5F8CE72FDE15BE7B841ACBA3A2ABD557228D9FE4F
 
 [ChaCha(12)]
 
@@ -43,8 +144,413 @@ In  = 00000000000000000000000000000000000000000000000000000000000000000000000000
 Out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
 
 # From draft-irtf-cfrg-chacha20-poly1305-03
+#
 Key = 0000000000000000000000000000000000000000000000000000000000000000
 Nonce = 000000000000000000000002
 In  = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 Out = C2C64D378CD536374AE204B9EF933FCD1A8B2288B3DFA49672AB765B54EE27C78A970E0E955C14F3A88E741B97C286F75F8FC299E8148362FA198A39531BED6D
 
+# Test seek offset
+# Tests got from the original implementation of Daniel J. Bernstein
+#
+Seek = 0
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 103AF111C18B549D39248FB07D60C29A95D1DB88D892F7B4AF709A5FD47A9E4BD5FF9A658DD52C708BEF1F0F622B3747040FA3551300B1F293150A88620D5FED
+
+Seek = 1
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+
+Seek = 51
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 551300B1F293150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A9
+
+Seek = 52
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 1300B1F293150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974
+
+Seek = 53
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 00B1F293150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD
+
+Seek = 54
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = B1F293150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28
+
+Seek = 55
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = F293150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B8
+
+Seek = 56
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 93150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B
+
+Seek = 57
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 150A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12
+
+Seek = 58
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 0A88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8
+
+Seek = 59
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 88620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D9
+
+Seek = 60
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 620D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D907
+
+Seek = 61
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 0D5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D90790
+
+Seek = 62
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 5FED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D907904F
+
+Seek = 63
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = ED89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D907904F9E
+
+Seek = 64
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = 89FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D907904F9ED6
+
+Seek = 65
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = FB08002917A540B7833FF3981D0E63C970B2E75174ADB9E6972FC575C0A63CEC802CF3E61EB198373276D865948F237E84A974FD28B89B12B8D907904F9ED679
+
+Seek = 4294967232
+Key = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F
+Nonce = 000102030405060708090A0B
+In = 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+Out = DBF81BB406517BE1A54F4740E5DDDF2B7965747B757FA9D5B7EDD6B27FEDDB89D5D47F9B24E57DF393017A5079F61852CD8B86859884120AF867D25D3B259E2B
diff --git a/src/tests/test_stream.cpp b/src/tests/test_stream.cpp
index 232fdcdd9..d3d83c26c 100644
--- a/src/tests/test_stream.cpp
+++ b/src/tests/test_stream.cpp
@@ -18,7 +18,7 @@ class Stream_Cipher_Tests : public Text_Based_Test
    {
    public:
       Stream_Cipher_Tests(): Text_Based_Test("stream",
-                                             {"Key", "In", "Out"}, {"Nonce"}) {}
+                                             {"Key", "In", "Out"}, {"Nonce", "Seek"}) {}
 
       Test::Result run_one_test(const std::string& algo, const VarMap& vars) override
          {
@@ -26,6 +26,7 @@ class Stream_Cipher_Tests : public Text_Based_Test
          const std::vector<uint8_t> input    = get_req_bin(vars, "In");
          const std::vector<uint8_t> expected = get_req_bin(vars, "Out");
          const std::vector<uint8_t> nonce    = get_opt_bin(vars, "Nonce");
+         const size_t seek                   = get_opt_sz(vars, "Seek", 0);
 
          Test::Result result(algo);
 
@@ -53,6 +54,9 @@ class Stream_Cipher_Tests : public Text_Based_Test
             if(nonce.size())
                cipher->set_iv(nonce.data(), nonce.size());
 
+            if (seek != 0)
+               cipher->seek(seek);
+
             std::vector<uint8_t> buf = input;
             cipher->encrypt(buf);