diff options
author | lloyd <[email protected]> | 2012-02-15 16:53:08 +0000 |
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committer | lloyd <[email protected]> | 2012-02-15 16:53:08 +0000 |
commit | 718d9503e3bad05fa58d61af11784976a495e21a (patch) | |
tree | 8724b0002fc444ea5e6d9703656cd827052abc67 /src/rng/hmac_rng/hmac_rng.cpp | |
parent | 88626b546863966ba6cf100d68fb9d73bc2a9fb9 (diff) |
Force a reseed in HMAC_RNG after 20 bytes have been added, rather than
waiting for a full kilobyte. This is for the benefit of DSA/ECDSA
which want a call to add_entropy to update the state in some way,
passing just a hash input which might be as small as 20 bytes.
Diffstat (limited to 'src/rng/hmac_rng/hmac_rng.cpp')
-rw-r--r-- | src/rng/hmac_rng/hmac_rng.cpp | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/src/rng/hmac_rng/hmac_rng.cpp b/src/rng/hmac_rng/hmac_rng.cpp index 7912e58af..55503382a 100644 --- a/src/rng/hmac_rng/hmac_rng.cpp +++ b/src/rng/hmac_rng/hmac_rng.cpp @@ -110,7 +110,11 @@ void HMAC_RNG::reseed(size_t poll_bits) counter = 0; user_input_len = 0; - if(accum.bits_collected() >= 128) + /* + Consider ourselves seeded once we've collected an estimated 128 bits of + entropy in a single poll. + */ + if(seeded == false && accum.bits_collected() >= 128) seeded = true; } @@ -119,15 +123,18 @@ void HMAC_RNG::reseed(size_t poll_bits) */ void HMAC_RNG::add_entropy(const byte input[], size_t length) { + const size_t USER_ENTROPY_WATERSHED = 20; + extractor->update(input, length); user_input_len += length; /* - * After we've accumulated >= 1024 bytes of user input, reseed. - * This input will automatically have been included if reseed was - * called already, as it's just included in the extractor input. + * After we've accumulated at least USER_ENTROPY_WATERSHED bytes of + * user input, reseed. This input will automatically have been + * included if reseed was called already, as it's just included in + * the extractor input. */ - if(user_input_len >= 1024) + if(user_input_len >= USER_ENTROPY_WATERSHED) reseed(128); } |