59 lines
1.3 KiB
C
59 lines
1.3 KiB
C
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// Circular Hash
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//
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// This code implements a circular hash algorithm, intended as a variable
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// length hash function that is fast to update. (The hash function will be
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// called many times.) This is done by SHA-1'ing each of the inputs, then
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// circularly XORing this value into a buffer.
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#ifndef __CIRCHASH_H__
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#define __CIRCHASH_H__
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typedef struct {
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DWORD dwCircHashVer;
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DWORD dwCircSize;
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DWORD dwMode;
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DWORD dwCircInc;
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DWORD dwCurCircPos;
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DWORD dwAlgId;
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DWORD dwPad1;
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DWORD dwPad2;
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BYTE CircBuf[ 256 ];
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} CircularHash;
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// mode flags
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#define CH_MODE_FEEDBACK 0x01
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// alg flags
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#define CH_ALG_SHA1_NS 0 // SHA-1 without endian transform
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#define CH_ALG_MD4 1 // RSA MD4
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BOOL
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InitCircularHash(
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IN CircularHash *NewHash,
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IN DWORD dwUpdateInc,
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IN DWORD dwAlgId,
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IN DWORD dwMode
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);
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VOID
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DestroyCircularHash(
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IN CircularHash *OldHash
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);
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BOOL
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GetCircularHashValue(
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IN CircularHash *CurrentHash,
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OUT BYTE **ppbHashValue,
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OUT DWORD *pcbHashValue
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);
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BOOL
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UpdateCircularHash(
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IN CircularHash *CurrentHash,
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IN VOID *pvData,
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IN DWORD cbData
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);
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#endif // __CIRCHASH_H__
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