下面是加密文件的代码示例：
代码语言：javascript复制LOCAL oEnc As EncryptDecrypt
oEnc = CREATEOBJECT("EncryptDecrypt")
WITH oEnc
IF NOT .GenerateKey("foxpro") && a password
? .errorno, .errormessage
ELSE
IF NOT .EncryptFile("c:myfilessomefile.txt",;
"c:myfilessomefile.enc")
? .errorno, .errormessage
ENDIF
ENDIF
ENDWITH解密同样简单：
代码语言：javascript复制WITH oEnc
IF NOT .GenerateKey("foxpro") && use same password
? .errorno, .errormessage
ELSE
IF NOT .DecryptFile("c:myfilessomefile.enc",;
"c:myfilessomefile.enc.txt")
? .errorno, .errormessage
ENDIF
ENDIF
ENDWITH类代码如下
代码语言：javascript复制#DEFINE PROV_RSA_FULL 1
#DEFINE CRYPT_VERIFYCONTEXT 0xf0000000
#DEFINE KEYLENGTH 0x00800000
#DEFINE CRYPT_EXPORTABLE 1
#DEFINE ALG_CLASS_HASH BITLSHIFT(4, 13)
#DEFINE ALG_TYPE_ANY 0
#DEFINE ALG_SID_MD5 3
#DEFINE CALG_MD5 BITOR(ALG_CLASS_HASH, ALG_TYPE_ANY, ALG_SID_MD5)
#DEFINE ALG_CLASS_DATA_ENCRYPT BITLSHIFT(3, 13)
#DEFINE ALG_TYPE_STREAM BITLSHIFT(4, 9)
#DEFINE ALG_SID_RC4 1
#DEFINE CALG_RC4 BITOR(ALG_CLASS_DATA_ENCRYPT, ALG_TYPE_STREAM, ALG_SID_RC4)
#DEFINE CALG_3DES 0x6603 && Triple DES encryption algorithm.
#DEFINE CALG_DES 0x6601 && DES encryption algorithm.
DEFINE CLASS EncryptDecrypt As Session
PROTECTED hProvider, hKey, signature
hProvider=0
hKey=0
signature="VFP_ENCRYPT_DECRYPT"
errorno=0
errormessage=""
PROCEDURE Init
THIS.declare
THIS.AcquireContext
PROCEDURE Destroy
THIS.DestroyKey
THIS.ReleaseContext
FUNCTION EncryptFile(cSourceFile, cTargetFile) As Boolean
RETURN THIS.ProcessFile(cSourceFile, cTargetFile, .T.)
FUNCTION DecryptFile(cSourceFile, cTargetFile) As Boolean
RETURN THIS.ProcessFile(cSourceFile, cTargetFile, .F.)
PROTECTED PROCEDURE ReleaseContext
IF THIS.hProvider <> 0
= CryptReleaseContext(THIS.hProvider, 0)
THIS.hProvider=0
ENDIF
PROTECTED PROCEDURE DestroyKey
IF THIS.hKey <> 0
= CryptDestroyKey(THIS.hKey)
THIS.hKey=0
ENDIF
PROTECTED PROCEDURE AcquireContext
THIS.ReleaseContext
THIS.ClearError
LOCAL hProvider, nResult
hProvider=0
IF CryptAcquireContext(@hProvider, NULL, NULL,;
PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) = 0
THIS.SetError(GetLastError(),;
"Call to CryptAcquireContext failed.")
RETURN .F.
ELSE
THIS.hProvider = m.hProvider
ENDIF
RETURN .T.
PROCEDURE GenerateKey(cPassword)
THIS.ClearError
THIS.DestroyKey
LOCAL hHash, hKey, lResult
STORE 0 TO hHash, hKey
IF CryptCreateHash(THIS.hProvider, CALG_MD5, 0, 0, @hHash)=0
THIS.SetError(GetLastError(),;
"Call to CryptCreateHash failed.")
lResult=.F.
ELSE
IF CryptHashData(m.hHash, @cPassword, LEN(cPassword), 0)=0
THIS.SetError(GetLastError(),;
"Call to CryptHashData failed.")
lResult=.F.
ELSE
IF CryptDeriveKey(THIS.hProvider, CALG_RC4,;
m.hHash, KEYLENGTH, @hKey)=0
THIS.SetError(GetLastError(),;
"Call to CryptDeriveKey failed.")
lResult=.F.
ELSE
THIS.hKey = m.hKey
lResult=.T.
ENDIF
ENDIF
ENDIF
IF (m.hHash <> 0)
= CryptDestroyHash(m.hHash)
ENDIF
RETURN m.lResult
FUNCTION EncryptBuffer(cBuffer) As Boolean
THIS.ClearError
IF THIS.hProvider=0
THIS.SetError(-1,;
"Cryptographic Service Provider handle is invalid.")
RETURN .F.
ENDIF
IF THIS.hKey=0
THIS.SetError(-1,;
"Cryptographic session key is invalid.")
RETURN .F.
ENDIF
LOCAL nTextSize, nBufsize, lResult
nTextSize = LEN(m.cBuffer)
* call the function first time to determine
* the correct buffer size
= CryptEncrypt(THIS.hKey, 0, 1, 0,;
NULL, @nTextSize, nBufsize)
nBufsize = nTextSize
nTextSize = LEN(m.cBuffer)
cBuffer = PADR(cBuffer, nBufsize, CHR(0))
IF CryptEncrypt(THIS.hKey, 0, 1, 0, @cBuffer,;
@nTextSize, nBufsize)=0
THIS.SetError(GetLastError(), "Call to CryptEncrypt failed.")
RETURN .F.
ENDIF
RETURN .T.
FUNCTION DecryptBuffer(cBuffer) As Boolean
THIS.ClearError
IF THIS.hProvider=0
THIS.SetError(-1,;
"Cryptographic Service Provider handle is invalid.")
RETURN .F.
ENDIF
IF THIS.hKey=0
THIS.SetError(-1,;
"Cryptographic session key is invalid.")
RETURN .F.
ENDIF
LOCAL nBufsize, lResult
nBufsize = LEN(m.cBuffer)
IF CryptDecrypt(THIS.hKey, 0, 1, 0,;
@cBuffer, @nBufsize)=0
THIS.SetError(GetLastError(),;
"Call to CryptDecrypt failed.")
RETURN .F.
ENDIF
cBuffer = PADR(m.cBuffer, m.nBufsize)
RETURN .T.
PROTECTED FUNCTION ProcessFile(cSourceFile,;
cTargetFile, lEncrypt) As Boolean
LOCAL cBuffer, ex As Exception, lResult
TRY
cBuffer = FILETOSTR(m.cSourceFile)
CATCH TO ex
ENDTRY
IF VARTYPE(m.ex) = "O"
THIS.SetError(ex.ErrorNo, ex.Message)
RETURN .F.
ENDIF
IF m.lEncrypt
cBuffer = THIS.signature cBuffer
lResult = THIS.EncryptBuffer(@cBuffer)
ELSE
lResult = THIS.DecryptBuffer(@cBuffer)
IF lResult
IF AT(THIS.signature, m.cBuffer) <> 1
THIS.SetError(-1, "Invalid password")
RETURN .F.
ENDIF
cBuffer = SUBSTR(cBuffer, LEN(THIS.signature) 1)
ENDIF
ENDIF
IF m.lResult
TRY
STRTOFILE(m.cBuffer, m.cTargetFile)
CATCH TO ex
ENDTRY
IF VARTYPE(m.ex) = "O"
THIS.SetError(ex.ErrorNo, ex.Message)
RETURN .F.
ENDIF
RETURN .T.
ENDIF
RETURN .F.
PROTECTED PROCEDURE SetError(nError, cMsg)
THIS.errorno = m.nError
THIS.errormessage = m.cMsg
PROTECTED PROCEDURE ClearError
THIS.SetError(0, "")
PROCEDURE declare
DECLARE INTEGER GetLastError IN kernel32
DECLARE INTEGER CryptDestroyHash IN advapi32 INTEGER hHash
DECLARE INTEGER CryptDestroyKey IN advapi32 INTEGER hKey
DECLARE INTEGER CryptCreateHash IN advapi32;
INTEGER hProv, INTEGER Algid, INTEGER hKey,;
INTEGER dwFlags, INTEGER @phHash
DECLARE INTEGER CryptAcquireContext IN advapi32;
INTEGER @hProvHandle, STRING cContainer, ;
STRING cProvider, INTEGER nProvType, INTEGER nFlags
DECLARE INTEGER CryptReleaseContext IN advapi32;
INTEGER hProvHandle, INTEGER nReserved
DECLARE INTEGER CryptHashData IN advapi32;
INTEGER hHash, STRING @pbData,;
LONG dwDataLen, LONG dwFlags
DECLARE INTEGER CryptDeriveKey IN advapi32;
INTEGER hProv, INTEGER Algid, INTEGER hBaseData,;
LONG dwFlags, INTEGER @phKey
DECLARE INTEGER CryptEncrypt IN advapi32;
INTEGER hKey, INTEGER hHash, INTEGER Final,;
LONG dwFlags, STRING @pbData,;
LONG @pdwDataLen, LONG dwBufLen
DECLARE INTEGER CryptDecrypt IN advapi32;
INTEGER hKey, INTEGER hHash, INTEGER Final,;
LONG dwFlags, STRING @pbData, LONG @pdwDataLen
ENDDEFINE 
