(Objective-C) CAdES BES Attached (Opaque) Signature

Demonstrates how to create a CAdES BES attached signature file (.p7m). This is a PKCS7 signature format (known as an opaque, or "attached" signature) where the file data is embedded within the signature file. The signature verification both verifies the signature and extracts the original data.

(A "detached" signature is where the original data is NOT included within the PKCS7 signature format.)

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

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

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

// Use a digital certificate and private key from a PFX file (.pfx or .p12).
NSString *pfxPath = @"qa_data/pfx/myCertAndPrivateKey.p12";
NSString *pfxPassword = @"password";

CkoCert *cert = [[CkoCert alloc] init];
BOOL success = [cert LoadPfxFile: pfxPath password: pfxPassword];
if (success != YES) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Tell the crypt component to use this cert.
success = [crypt SetSigningCert: cert];
if (success != YES) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

// The CadesEnabled property applies to all methods that create PKCS7 signatures. 
// To create a CAdES-BES signature, set this property equal to true. 
crypt.CadesEnabled = YES;

// To sign with SHA1, set the HashAlgorithm property to "sha1"
crypt.HashAlgorithm = @"sha1";

// To sign with SHA256, set the HashAlgorithm property to "SHA256".
crypt.HashAlgorithm = @"sha256";

// Other hash algorithm choices are "md5", "md2", "sha384", and "sha512"

// We can sign any type of file, creating a .p7m as output.
// The .p7m contains the signature and also embeds the data of the file that is signed.
NSString *inFile = @"qa_data/json/sample.json";
NSString *sigFile = @"qa_output/signature.p7m";

// -----------------------------------------------------------------------------------------
// Also see Chilkat's online tool to examine a .p7m and generate code to duplicate the .p7m
// -----------------------------------------------------------------------------------------

// Create the CAdES-BES attached signature, which contains the original data.
success = [crypt CreateP7M: inFile p7mPath: sigFile];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

// Verify the .p7m file and extract the original file from the .p7m. 
NSString *extractedToFilePath = @"qa_output/sample.json";
success = [crypt VerifyP7M: sigFile destPath: extractedToFilePath];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

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