3
* Exampel entropy estimator for key-like input events. */
5
/* nettle, low-level cryptographics library
7
* Copyright (C) 2001 Niels M�ller
9
* The nettle library is free software; you can redistribute it and/or modify
10
* it under the terms of the GNU Lesser General Public License as published by
11
* the Free Software Foundation; either version 2.1 of the License, or (at your
12
* option) any later version.
14
* The nettle library is distributed in the hope that it will be useful, but
15
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17
* License for more details.
19
* You should have received a copy of the GNU Lesser General Public License
20
* along with the nettle library; see the file COPYING.LIB. If not, write to
21
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
32
yarrow_key_event_init(struct yarrow_key_event_ctx *ctx)
39
for (i = 0; i < YARROW_KEY_EVENT_BUFFER; i++)
44
yarrow_key_event_estimate(struct yarrow_key_event_ctx *ctx,
45
unsigned key, unsigned time)
50
/* Look at timing first. */
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if (ctx->previous && (time > ctx->previous) )
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if ( (time - ctx->previous) >= 256)
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for (i = 0; i < YARROW_KEY_EVENT_BUFFER; i++)
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if (key == ctx->chars[i])
63
/* This is a recent character. Ignore it. */
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/* Count one bit of entropy, unless this was one of the initial 16
68
if (ctx->chars[ctx->index])
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/* Remember the character. */
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ctx->chars[ctx->index] = key;
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ctx->index = (ctx->index + 1) % YARROW_KEY_EVENT_BUFFER;
added
removed
yarrow_key_event.c
