(Objective-C) Extract PKCS7 from MIME and Decrypt

Extracts the base64-encoded PKCS7 body of a MIME message to a file, and then decrypts using Chilkat Crypt2.

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#import <CkoMime.h>
#import <CkoCrypt2.h>
#import <NSString.h>

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoMime *mime = [[CkoMime alloc] init];

BOOL success = [mime LoadMimeFile: @"c:/aaworkarea/EmailInBytes.txt"];
if (success != YES) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

success = [mime SaveBody: @"c:/aaworkarea/smime.p7m"];
if (success != YES) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];

success = [crypt AddPfxSourceFile: @"c:/aaworkarea/my.pfx" password: @"pfxPassword"];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

// Indicate the public-key (PKCS7) encryption/decryption should be used:
crypt.CryptAlgorithm = @"pki";

NSString *inPath = @"c:/aaworkarea/smime.p7m";
NSString *outPath = @"c:/aaworkarea/decrypted.dat";

success = [crypt CkDecryptFile: inPath destFile: outPath];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

NSLog(@"%@",@"Success.");