diff options
| author | Jack Lloyd <[email protected]> | 2017-02-02 22:43:38 -0500 |
|---|---|---|
| committer | Jack Lloyd <[email protected]> | 2017-02-02 22:43:38 -0500 |
| commit | 23a96ca126ebfddb2259386f12a00a8e783226ed (patch) | |
| tree | 03b8bb5224a2ae7de2c0a94e54bd28631717ddf8 | |
| parent | ae8d2bd859120839ee08bc35daebda7ef4971ea6 (diff) | |
Support zero-length IV in ChaCha
Equivalent to an 8 byte all-zero IV, same handling as Salsa.
| -rw-r--r-- | src/lib/stream/chacha/chacha.cpp | 13 | ||||
| -rw-r--r-- | src/lib/stream/chacha/chacha.h | 7 | ||||
| -rw-r--r-- | src/tests/data/stream/chacha.vec | 3 |
3 files changed, 20 insertions, 3 deletions
diff --git a/src/lib/stream/chacha/chacha.cpp b/src/lib/stream/chacha/chacha.cpp index 4befe1981..d56f9e60a 100644 --- a/src/lib/stream/chacha/chacha.cpp +++ b/src/lib/stream/chacha/chacha.cpp @@ -171,6 +171,11 @@ void ChaCha::key_schedule(const uint8_t key[], size_t length) set_iv(ZERO, sizeof(ZERO)); } +bool ChaCha::valid_iv_length(size_t iv_len) const + { + return (iv_len == 0 || iv_len == 8 || iv_len == 12); + } + void ChaCha::set_iv(const uint8_t iv[], size_t length) { if(!valid_iv_length(length)) @@ -179,7 +184,13 @@ void ChaCha::set_iv(const uint8_t iv[], size_t length) m_state[12] = 0; m_state[13] = 0; - if(length == 8) + if(length == 0) + { + // Treat zero length IV same as an all-zero IV + m_state[14] = 0; + m_state[15] = 0; + } + else if(length == 8) { m_state[14] = load_le<uint32_t>(iv, 0); m_state[15] = load_le<uint32_t>(iv, 1); diff --git a/src/lib/stream/chacha/chacha.h b/src/lib/stream/chacha/chacha.h index 876b9ca33..64a387ec5 100644 --- a/src/lib/stream/chacha/chacha.h +++ b/src/lib/stream/chacha/chacha.h @@ -33,8 +33,11 @@ class BOTAN_DLL ChaCha final : public StreamCipher void set_iv(const uint8_t iv[], size_t iv_len) override; - bool valid_iv_length(size_t iv_len) const override - { return (iv_len == 8 || iv_len == 12); } + /* + * ChaCha accepts 0, 8, or 12 byte IVs. The default IV is a 8 zero bytes. + * An IV of length 0 is treated the same as the default zero IV. + */ + bool valid_iv_length(size_t iv_len) const override; Key_Length_Specification key_spec() const override { diff --git a/src/tests/data/stream/chacha.vec b/src/tests/data/stream/chacha.vec index f7ba701ba..a361a913a 100644 --- a/src/tests/data/stream/chacha.vec +++ b/src/tests/data/stream/chacha.vec @@ -6,6 +6,9 @@ # Tests got from the original implementation of Daniel J. Bernstein Key = 00000000000000000000000000000000 +Out = E28A5FA4A67F8C5DEFED3E6FB7303486AA8427D31419A729572D777953491120B64AB8E72B8DEB85CD6AEA7CB6089A101824BEEB08814A428AAB1FA2C816081B + +Key = 00000000000000000000000000000000 Nonce = 0000000000000000 Out = E28A5FA4A67F8C5DEFED3E6FB7303486AA8427D31419A729572D777953491120B64AB8E72B8DEB85CD6AEA7CB6089A101824BEEB08814A428AAB1FA2C816081B |