Objective-C

Get EC Public Key from EC Private Key

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Demonstrates how to get an EC public key from an EC private key. Objective-C

#import <CkoPrivateKey.h>
#import <CkoPublicKey.h>

BOOL success = NO;

// We have an ECC private key...
// The contents of the private key PEM file look like this:

// 	-----BEGIN PRIVATE KEY-----
// 	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
// 	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
// 	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
// 	-----END PRIVATE KEY-----

CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];
success = [privKey LoadPemFile: @"qa_data/ecc/secp256r1-key-pkcs8.pem"];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

// Get the public key.
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
[privKey ToPublicKey: pubKey];

// Save the public key to a PEM file.
success = [pubKey SavePemFile: NO path: @"qa_data/ecc/secp256r1-pubkey.pem"];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

// The contents of the ECC public key PEM file look like this:

// 	-----BEGIN PUBLIC KEY-----
// 	MIIBSzCCAQMGByqGSM49AgEwgfcCAQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAA
// 	AAAAAAAAAAAA////////////////MFsEIP////8AAAABAAAAAAAAAAAAAAAA////
// 	///////////8BCBaxjXYqjqT57PrvVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSd
// 	NgiG5wSTamZ44ROdJreBn36QBEEEaxfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5
// 	RdiYwpZP40Li/hp/m47n60p8D54WK84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA
// 	//////////+85vqtpxeehPO5ysL8YyVRAgEBA0IABOVKaiLPKEDChhkA64UEBOXT
// 	v/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=
// 	-----END PUBLIC KEY-----

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