388 lines
7.7 KiB
C
388 lines
7.7 KiB
C
/*++
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Copyright (c) 1994-1998 Microsoft Corporation
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Module Name:
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encrypt.c
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Abstract:
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Contains functions that encrypt and decrypt data sent accross client and
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server.
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Author:
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Madan Appiah (madana) 24-Jan-1998
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Environment:
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User Mode - Win32
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Revision History:
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--*/
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#include <seccom.h>
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VOID
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GenerateMACSignature(
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LPBYTE pbData,
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DWORD dwDataLen,
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LPBYTE pbMACSaltKey,
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DWORD dwMACSaltKey,
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LPBYTE pbSignature,
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BOOL fIncludeEncryptionCount,
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DWORD dwEncryptionCount
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)
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/*++
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Routine Description:
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This function generates a message authentication signature.
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Arguments:
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pbData - pointer to a data buffer.
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dwDataLen - length of the above data.
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pbMACSaltKey - pointer to a MAC salt key.
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pbSignature - pointer a signature buffer.
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fIncludeEncryptionCount - TRUE to salt in the encryption count
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dwEncryptionCount - total encryption count
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Return Value:
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None.
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--*/
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{
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A_SHA_CTX SHAHash;
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MD5_CTX MD5Hash;
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BYTE abSHADigest[A_SHA_DIGEST_LEN];
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//
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// make a SHA(MACSalt + g_abPad1 + Length + Content) hash.
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//
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A_SHAInit(&SHAHash);
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A_SHAUpdate(&SHAHash, pbMACSaltKey, dwMACSaltKey);
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A_SHAUpdate(&SHAHash, (unsigned char *)g_abPad1, 40);
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A_SHAUpdate(&SHAHash, (LPBYTE)&dwDataLen, sizeof(DWORD));
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A_SHAUpdate(&SHAHash, pbData, dwDataLen);
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if (fIncludeEncryptionCount) {
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A_SHAUpdate(&SHAHash, (LPBYTE)&dwEncryptionCount, sizeof(DWORD));
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}
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A_SHAFinal(&SHAHash, abSHADigest);
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//
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// make a MD5(MACSalt + g_abPad2 + SHAHash) hash.
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//
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MD5Init(&MD5Hash);
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MD5Update(&MD5Hash, pbMACSaltKey, dwMACSaltKey);
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MD5Update(&MD5Hash, g_abPad2, 48);
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MD5Update(&MD5Hash, abSHADigest, A_SHA_DIGEST_LEN);
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MD5Final(&MD5Hash);
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ASSERT( DATA_SIGNATURE_SIZE <= MD5DIGESTLEN );
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memcpy(pbSignature, MD5Hash.digest, DATA_SIGNATURE_SIZE);
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return;
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}
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BOOL
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EncryptData(
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DWORD dwEncryptionLevel,
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LPBYTE pSessionKey,
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struct RC4_KEYSTRUCT FAR *prc4EncryptKey,
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DWORD dwKeyLength,
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LPBYTE pbData,
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DWORD dwDataLen,
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LPBYTE pbMACSaltKey,
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LPBYTE pbSignature,
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BOOL fSecureChecksum,
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DWORD dwEncryptionCount
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)
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/*++
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Routine Description:
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Encrypt the given data buffer in place.
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Arguments:
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dwEncryptionLevel - encryption level, used to select the encryption
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algorithm.
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pSessionKey - pointer to the session key.
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prc4EncryptKey - pointer to a RC4 key.
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dwKeyLength - length of the session key.
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pbData - pointer to the data buffer being encrypted, encrypted data is
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returned in the same buffer.
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dwDataLen - length of the data buffer.
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pbMACSaltKey - pointer to a message authentication key buffer.
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pbSignature - pointer to a signature buffer where the data signature is
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returned.
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fSecureChecksum - TRUE if the checksum is to be salted with the encryption
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count
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dwDecryptionCount - running counter of all encryptions
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Return Value:
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TRUE - if successfully encrypted the data.
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FALSE - otherwise.
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--*/
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{
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//
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// generate the MAC signature first.
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//
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GenerateMACSignature (
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pbData,
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dwDataLen,
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pbMACSaltKey,
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dwKeyLength,
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pbSignature,
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fSecureChecksum,
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dwEncryptionCount
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);
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//
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// encrypt data.
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//
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//
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// use microsoft version of rc4 algorithm (super fast!) for level 1 and
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// level 2 encryption, for level 3 use RSA rc4 algorithm.
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//
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if( dwEncryptionLevel <= 2 ) {
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msrc4(prc4EncryptKey, (UINT)dwDataLen, pbData );
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}
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else {
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rc4(prc4EncryptKey, (UINT)dwDataLen, pbData );
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}
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return( TRUE );
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}
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BOOL
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DecryptData(
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DWORD dwEncryptionLevel,
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LPBYTE pSessionKey,
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struct RC4_KEYSTRUCT FAR *prc4DecryptKey,
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DWORD dwKeyLength,
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LPBYTE pbData,
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DWORD dwDataLen,
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LPBYTE pbMACSaltKey,
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LPBYTE pbSignature,
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BOOL fSecureChecksum,
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DWORD dwDecryptionCount
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)
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/*++
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Routine Description:
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Decrypt the given data buffer in place.
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Arguments:
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dwEncryptionLevel - encryption level, used to select the encryption
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algorithm.
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pSessionKey - pointer to the session key.
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prc4DecryptKey - pointer to a RC4 key.
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dwKeyLength - length of the session key.
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pbData - pointer to the data buffer being decrypted, decrypted data is
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returned in the same buffer.
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dwDataLen - length of the data buffer.
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pbMACSaltKey - pointer to a message authentication key buffer.
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pbSignature - pointer to a signature buffer where the data signature is
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returned.
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fSecureChecksum - TRUE if the checksum is to be salted with the encryption
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count
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dwDecryptionCount - running counter of all encryptions
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Return Value:
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TRUE - if successfully encrypted the data.
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FALSE - otherwise.
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--*/
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{
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BYTE abSignature[DATA_SIGNATURE_SIZE];
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//
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// decrypt data.
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//
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//
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// use microsoft version of rc4 algorithm (super fast!) for level 1 and
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// level 2 encryption, for level 3 use RSA rc4 algorithm.
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//
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if( dwEncryptionLevel <= 2 ) {
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msrc4(prc4DecryptKey, (UINT)dwDataLen, pbData );
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}
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else {
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rc4(prc4DecryptKey, (UINT)dwDataLen, pbData );
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}
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GenerateMACSignature (
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pbData,
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dwDataLen,
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pbMACSaltKey,
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dwKeyLength,
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(LPBYTE)abSignature,
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fSecureChecksum,
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dwDecryptionCount
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);
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//
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// check to see the sigature match.
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//
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if( memcmp(
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(LPBYTE)abSignature,
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pbSignature,
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sizeof(abSignature) ) ) {
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return( FALSE );
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}
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return( TRUE );
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}
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#ifdef USE_MSRC4
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VOID
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msrc4_key(
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struct RC4_KEYSTRUCT FAR *pKS,
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DWORD dwLen,
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LPBYTE pbKey
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)
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/*++
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Routine Description:
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Generate the key control structure. Key can be any size.
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Assumes pKS is locked against simultaneous use.
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Arguments:
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pKS - pointer to a KEYSTRUCT structure that will be initialized.
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dwLen - Size of the key, in bytes.
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pbKey - Pointer to the key.
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Return Value:
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NONE.
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--*/
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{
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#define SWAP(_x_, _y_) { BYTE _t_; _t_ = (_x_); (_x_) = (_y_); (_y_) = _t_; }
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BYTE index1;
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BYTE index2;
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UINT counter;
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BYTE bLen;
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ASSERT( dwLen < 256 );
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bLen = ( dwLen >= 256 ) ? 255 : (BYTE)dwLen;
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for (counter = 0; counter < 256; counter++) {
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pKS->S[counter] = (BYTE) counter;
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}
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pKS->i = 0;
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pKS->j = 0;
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index1 = 0;
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index2 = 0;
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for (counter = 0; counter < 256; counter++) {
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index2 = (pbKey[index1] + pKS->S[counter] + index2);
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SWAP(pKS->S[counter], pKS->S[index2]);
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index1 = (index1 + 1) % bLen;
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}
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}
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VOID
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msrc4(
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struct RC4_KEYSTRUCT FAR *pKS,
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DWORD dwLen,
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LPBYTE pbuf
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)
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/*++
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Routine Description:
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Performs the actual encryption or decryption.
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Assumes pKS is locked against simultaneous use.
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Arguments:
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pKS - Pointer to the KEYSTRUCT created using msrc4_key().
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dwLen - Size of buffer, in bytes.
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pbuf - Buffer to be encrypted.
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Return Value:
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NONE.
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--*/
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{
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BYTE FAR *const s = pKS->S;
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BYTE a, b;
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while(dwLen--) {
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a = s[++(pKS->i)];
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pKS->j += a;
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b = s[pKS->j];
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s[pKS->j] = a;
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a += b;
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s[pKS->i] = b;
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*pbuf++ ^= s[a];
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}
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}
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#endif // USE_MSRC4
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