(Objective-C) Ed25519ph Sign and Verify

Demonstrates how to create an Ed25519ph signature, and then to verify it.

Note: This example requires Chilkat v9.5.0.91 or greater.

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#import <NSString.h>
#import <CkoPrivateKey.h>
#import <CkoBinData.h>
#import <CkoEdDSA.h>
#import <CkoPublicKey.h>

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

// Use the following test vector from https://www.rfc-editor.org/rfc/rfc8032#page-30

//    -----TEST abc
// 
//    ALGORITHM:
//    Ed25519ph
// 
//    SECRET KEY:
//    833fe62409237b9d62ec77587520911e
//    9a759cec1d19755b7da901b96dca3d42
// 
//    PUBLIC KEY:
//    ec172b93ad5e563bf4932c70e1245034
//    c35467ef2efd4d64ebf819683467e2bf
// 
//    MESSAGE (length 3 bytes):
//    616263
// 
//    SIGNATURE:
//    98a70222f0b8121aa9d30f813d683f80
//    9e462b469c7ff87639499bb94e6dae41
//    31f85042463c2a355a2003d062adf5aa
//    a10b8c61e636062aaad11c2a26083406

NSString *privKeyHex = @"833fe62409237b9d62ec77587520911e9a759cec1d19755b7da901b96dca3d42";
NSString *pubKeyHex = @"ec172b93ad5e563bf4932c70e1245034c35467ef2efd4d64ebf819683467e2bf";

CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];
BOOL success = [privKey LoadEd25519: privKeyHex pubKey: pubKeyHex];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

// The data to be signed...
CkoBinData *bd = [[CkoBinData alloc] init];
[bd AppendEncoded: @"616263" encoding: @"hex"];

CkoEdDSA *eddsa = [[CkoEdDSA alloc] init];
// Indicate we want the Ed25519ph instance.
eddsa.Algorithm = @"Ed25519ph";

NSString *hexSig = [eddsa SignBdENC: bd encoding: @"hexlower" privkey: privKey];

NSLog(@"%@%@",@"signature = ",hexSig);

// The expected output is: 98a70222f0b8121aa9d30f813d683f80....

// Verify the signature..
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
success = [pubKey LoadEd25519: pubKeyHex];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

BOOL bVerified = [eddsa VerifyBdENC: bd encodedSig: hexSig enocding: @"hexlower" pubkey: pubKey];
if (bVerified == NO) {
    NSLog(@"%@",eddsa.LastErrorText);
    NSLog(@"%@",@"Failed to verify the signature.");
    return;
}

NSLog(@"%@",@"The Ed25519ph signature is verified!");