How to decrypt a file with PGPsdk

I am trying to decide which SDK is the best for decrypting
a lot of files. The PGPsdk has excellent documentation, as
can be seen in this sample code taken from the manual.

-Ramon

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/* ==== Decrypt a File code fragment ========================== */

/*
* Demonstrates simple file decryption with the PGPsdk.
*
* Decrypts file "testEncrypted.pgp" encrypted with key
* "test@pgp.com", producing decrypted file "testDecrypted.txt".
*
*/

/* Specify the input filename, output filename,
and key passphrase to use */

char const *inFileName = "testEncrypted.asc";
char const *outFileName = "testDecrypted.txt";
char const *keyPassphrase = "testPassphrase";


/* Declare and initialize variables */

PGPError err = kPGPError_NoErr;

PGPContextRef context = kInvalidPGPContextRef;

PGPKeySetRef defaultKeyRing = kInvalidPGPKeySetRef;

PGPFileSpecRef inFileRef = kInvalidPGPFileSpecRef;

PGPFileSpecRef outFileRef = kInvalidPGPFileSpecRef;

/* ---- PGP Setup ------------------------------------------- */

/* NOTE: These calls appear here for clarity only.
* In a real-world application, you would call PGPsdkInit()
* and PGPNewContext() at application startup time, not on
* an operation-by-operation basis.
*/

/* Initialize the PGPsdk libs */

err = PGPsdkInit();
if (IsPGPError(err))
goto Exit;

/* Create the PGPContext */

err = PGPNewContext(kPGPsdkAPIVersion, &context);

if (IsPGPError(err))
goto Exit;

/* ---- Prepare Decryption Operation Parameters ------------- */

/* Open the default keyring */

err = PGPOpenDefaultKeyRings(context, kPGPKeyRingOpenFlags_Mutable,
&defaultKeyRing);

if (IsPGPError(err))
goto Exit;

/* Create the file descriptions */

err = PGPNewFileSpecFromFullPath(context, inFileName, &inFileRef);

if (IsPGPError(err))
goto Exit;

err = PGPNewFileSpecFromFullPath(context, outFileName, &outFileRef);

if (IsPGPError(err))
goto Exit;

/* ---- Perform the Decryption operation ------------- */

/* This is the main event; everything above and
* below exists only to support this call.
*
* Produces the decrypted output file in the default directory.
*/

err = PGPDecode(context,
PGPOInputFile(context, inFileRef),
PGPOOutputFile(context, outFileRef),
PGPOKeySetRef(context, defaultKeyRing),
PGPOPassphrase(context, keyPassphrase),
PGPOLastOption(context));

/* ---- Release resources used in this operation ------------- */

Exit:

if (PGPFileSpecRefIsValid(inFileRef))
PGPFreeFileSpec(inFileRef);

if (PGPFileSpecRefIsValid(outFileRef))
PGPFreeFileSpec(outFileRef);

if (PGPKeySetRefIsValid(defaultKeyRing))
PGPFreeKeySet(defaultKeyRing);

/* ---- PGP Shutdown ----------------------------------------- */

/* NOTE: These calls appear here for clarity only.
* In a real-world application, you would make these calls to
* PGPFreeContext() and PGPsdkInit() at application shutdown time,
* and not on an operation-by-operation basis.
*/

/* Release the PGP context we've been using */

if (PGPContextRefIsValid(context))
PGPFreeContext(context);

/* PGP library shutdown */

PGPsdkCleanup();

/* ========== End of Decrypt a File code fragment ========== */

exit(0);