Signatures

Foxit PDF SDK for iOS provides digital signature create, verify, remove, and property APIs via Core SDK. Recipients can verify document origin and whether content was altered.

UI Extensions built-in signatures

With the full reader (UI Extensions), the SignatureModule handles signing and verification—no extra code required.

Default signature types

The SDK includes default signature callbacks for:

• Adobe.PPKLite + adbe.pkcs7.detached
• Adobe.PPKLite + adbe.pkcs7.sha1

Core class

Class	Description
FSSignature	Signature object. Create with [FSPDFPage addSignature:], retrieve with [FSPDFDoc getSignature:]

Digest algorithm constants

Constant	Description
FSSignatureDigestSHA1	SHA-1
FSSignatureDigestSHA256	SHA-256
FSSignatureDigestSHA384	SHA-384
FSSignatureDigestSHA512	SHA-512

Signature key constants

Use setKeyValue:value::

Constant	Description
FSSignatureKeyNameSigner	Signer
FSSignatureKeyNameLocation	Location
FSSignatureKeyNameReason	Reason
FSSignatureKeyNameContactInfo	Contact info
FSSignatureKeyNameDN	Distinguished name
FSSignatureKeyNameText	Custom text

Appearance flag constants

Use setAppearanceFlags::

Constant	Description
FSSignatureAPFlagSigner	Show signer
FSSignatureAPFlagReason	Show reason
FSSignatureAPFlagSigningTime	Show signing time
FSSignatureAPFlagDN	Show DN
FSSignatureAPFlagLocation	Show location
FSSignatureAPFlagBitmap	Show image
FSSignatureAPFlagText	Show custom text

Example: sign and verify

#import <FoxitRDK/FSPDFObjC.h>

FSPDFDoc *doc = [[FSPDFDoc alloc] initWithPath:@"path/to/Sample.pdf"];
[doc load:nil];
FSPDFPage *page = [doc getPage:0];

// Add signature field
FSRectF *rect = [[FSRectF alloc] initWithLeft1:100 bottom1:600 right1:300 top1:700];
FSSignature *signature = [page addSignature:rect];

// Appearance
[signature setAppearanceFlags:
    FSSignatureAPFlagSigner | FSSignatureAPFlagDN |
    FSSignatureAPFlagReason | FSSignatureAPFlagSigningTime |
    FSSignatureAPFlagLocation];

// Signature metadata
[signature setKeyValue:FSSignatureKeyNameSigner value:@"John Smith"];
[signature setKeyValue:FSSignatureKeyNameLocation value:@"Beijing"];
[signature setKeyValue:FSSignatureKeyNameReason value:@"Document approval"];
[signature setFilter:@"Adobe.PPKLite"];
[signature setSubFilter:@"adbe.pkcs7.detached"];

// Sign
NSString *certPath = @"path/to/cert.pfx";
NSString *savePath = @"path/to/signed.pdf";
FSProgressive *progressive = [signature startSign:certPath
                                    cert_password:@"123"
                                 digest_algorithm:FSSignatureDigestSHA256
                                        save_path:savePath
                                      client_data:nil
                                            pause:nil];

FSProgressState state = FSProgressiveToBeContinued;
while (state == FSProgressiveToBeContinued) {
    state = [progressive resume];
}

// Verify all signatures in signed document
FSPDFDoc *signedDoc = [[FSPDFDoc alloc] initWithPath:savePath];
[signedDoc load:nil];

int count = [signedDoc getSignatureCount];
for (int i = 0; i < count; i++) {
    FSSignature *sig = [signedDoc getSignature:i];
    if (!sig || [sig isEmpty]) continue;

    FSProgressive *verifyProgress = [sig startVerify:nil pause:nil];
    FSProgressState vState = FSProgressiveToBeContinued;
    while (vState == FSProgressiveToBeContinued) {
        vState = [verifyProgress resume];
    }

    unsigned int verifiedState = [sig getState];
    if (verifiedState & FSSignatureStateVerifyValid) {
        NSLog(@"Signature %d is valid", i);
    }
}

API reference

See the API reference for FSSignature.