Is there any example for use ECC in iOS?
I noticed that the kSecAttrKeyTypeEC in Apple Developer Documents, but I can't use it to generic Key pair.
Below code is modified from the example CryptoExercise
// Container dictionaries.
NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];
// Set top level dictionary for the keypair.
[keyPairAttr setObject:(id)kSecAttrKeyTypeEC forKey:(id)kSecAttrKeyType];
[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(id)kSecAttrKeySizeInBits];
// Set the private key dictionary.
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
[privateKeyAttr setObject:privateTag forKey:(id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set the public key dictionary.
[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
[publicKeyAttr setObject:publicTag forKey:(id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set attributes to top level dictionary.
[keyPairAttr setObject:privateKeyAttr forKey:(id)kSecPrivateKeyAttrs];
[keyPairAttr setObject:publicKeyAttr forKey:(id)kSecPublicKeyAttrs];
// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
sanityCheck = SecKeyGeneratePair((CFDictionaryRef)keyPairAttr, &publicKeyRef, &privateKeyRef);
LOGGING_FACILITY( sanityCheck == noErr && publicKeyRef != NULL && privateKeyRef != NULL, #"Something really bad went wrong with generating the key pair." );
The sanityCheck always return -50 which means 'errSecParam'.
I really don't know how to use it, thank you for read this.
NSDictionary *parameters = #{
(__bridge id)kSecAttrKeyType: (__bridge id)kSecAttrKeyTypeEC,
(__bridge id)kSecAttrKeySizeInBits: #256,
(__bridge id)kSecPrivateKeyAttrs: #{
(__bridge id)kSecAttrIsPermanent: #YES,
(__bridge id)kSecAttrApplicationTag: [#"my.key.tag" dataUsingEncoding:NSUTF8StringEncoding],
},
(__bridge id)kSecPublicKeyAttrs: #{
(__bridge id)kSecAttrIsPermanent: #YES,
(__bridge id)kSecAttrApplicationTag: [#"my.key.pubtag" dataUsingEncoding:NSUTF8StringEncoding],
}
};
SecKeyRef publicKey, privateKey;
OSStatus status = SecKeyGeneratePair((__bridge CFDictionaryRef)parameters, &publicKey, &privateKey);
This works, double check your key size parameter.
Just a note, currently EC keys can only be used for signing/verifying data. Encryption/decryption returns errSecUnimplemented = -4.
CryptoKit now supports Ed25519 in iOS13+
https://developer.apple.com/documentation/cryptokit/curve25519/signing
Related
I am generating a RSA keypair on the iphone, but how can I store the generated private and public key in a file? I need to encrypt the private key with AES and transmit it to my server, but I can't find any methods to get the bytes of the keys.
My code for generating the keypair:
-(void)generateKeyPair {
OSStatus sanityCheck = noErr;
SecKeyRef localPublicKey = NULL;
SecKeyRef localPrivateKey = NULL;
self.publicTag = [#"com.crap.pub" dataUsingEncoding:NSUTF8StringEncoding];
self.privateTag = [#"com.crap.pri" dataUsingEncoding:NSUTF8StringEncoding];
// Container dictionaries.
NSMutableDictionary * privateKeyAttr = [NSMutableDictionary dictionaryWithCapacity:0];
NSMutableDictionary * publicKeyAttr = [NSMutableDictionary dictionaryWithCapacity:0];
NSMutableDictionary * keyPairAttr = [NSMutableDictionary dictionaryWithCapacity:0];
// Set top level dictionary for the keypair.
[keyPairAttr setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:2048] forKey:(__bridge id)kSecAttrKeySizeInBits];
// Set the private key dictionary.
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecAttrIsPermanent];
[privateKeyAttr setObject:self.privateTag forKey:(__bridge id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set the public key dictionary.
[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecAttrIsPermanent];
[publicKeyAttr setObject:self.publicTag forKey:(__bridge id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set attributes to top level dictionary.
[keyPairAttr setObject:privateKeyAttr forKey:(__bridge id)kSecPrivateKeyAttrs];
[keyPairAttr setObject:publicKeyAttr forKey:(__bridge id)kSecPublicKeyAttrs];
// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
sanityCheck = SecKeyGeneratePair((__bridge CFDictionaryRef)keyPairAttr, &localPublicKey, &localPrivateKey);
}
I am at a loss here, I create a keychain query, add the item if it does not already exist, then I try and update kSecValueData with a test string and it returns error code -50, which means there was an error with one or more parameters I entered...
NSString *initial = #"";
NSData *initData = [initial dataUsingEncoding:NSUTF8StringEncoding];
//Create Search Dictionary For Phone Number...
NSDictionary *secPhoneItem = #{ (__bridge id)kSecClass : (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecReturnData : (__bridge id)kCFBooleanTrue,
(__bridge id)kSecValueData : initData
};
//Check to see if keychain already exists by using secItemCopyMatching and associated status code
OSStatus PhoneCheckStatus = SecItemCopyMatching((__bridge CFDictionaryRef)secPhoneItem, NULL);
//Check Status Code Phone
if (PhoneCheckStatus == errSecItemNotFound) //If Phone Keychain Item Does Not already Exist
{
//Add Phone Number To Keychain
SecItemAdd((__bridge CFDictionaryRef)secPhoneItem, NULL);
}
//Update Phone Number to String
NSString *string = #"Test String";
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *attributesForUpdate = #{
(__bridge id)kSecValueData : data
};
OSStatus news = SecItemUpdate((__bridge CFDictionaryRef)secPhoneItem, (__bridge CFDictionaryRef)attributesForUpdate);
NSLog(#"Update Status Code: %ld", news);
If anyone knows why or can shed some info, the only lead I have right now from Apples Documentation is that you can only pass real attributes into secItemUpdate(), not "meta" attributes.
So after rereading the documentation, I found out that the key-value pair (__bridge id)kSecReturnData : (__bridge id)kCFBooleanTrue cannot be used in the secItemUpdate()' query parameter. To fix my problem and help better refine the search, I added the key-value pair(__bridge id)kSecAttrDescription : someUniqueData` to the search query along with the class item specification then making my attributes dictionary returned status 0: SUCCESS!!!
Key and certificate Attribute Update-----------
for the normal SecItemUpdate code gave two error:-25300(item not found),-50(trying to update more than one item in one update method)
here is the code for update method:
//Search Dictionary.....
NSMutableDictionary *searchDict = [[NSMutableDictionary alloc] init];
NSData *privateKeyTag = [NSData dataWithBytes:[keyIdentifier UTF8String] length:keyIdentifier.length];
[searchDict setObject:privateKeyTag forKey:(__bridge id)kSecAttrApplicationTag];
[searchDict setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[searchDict setObject:(__bridge id)(kSecAttrKeyTypeRSA) forKey:(__bridge id<NSCopying>)(kSecAttrKeyType)];
[searchDict setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
[searchDict setObject:(__bridge id)kCFBooleanTrue forKey:(__bridge id<NSCopying>)(kSecReturnData)];
status = SecItemCopyMatching((__bridge CFDictionaryRef)searchDict, (CFTypeRef*)&item);
if (status != errSecSuccess)
{//your code for error handling }
//dictionary for the attribute that are going to update in key of certificate
//if youwant to update your passward the add the passward attribute
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly,kSecAttrAccessible, nil];
/*removing the some of the from the searching dictionary*/
[searchDict removeObjectForKey:(__bridge id)kSecReturnData];
[searchDict removeObjectForKey:(__bridge id)kSecMatchLimit];
//Creating the Array for every item in the keychain that is cert of key as Search Dictionary
NSArray *secItemclasses= #[(__bridge id)kSecClassKey,(__bridge id)kSecClassCertificate];
for (id secitemclass in secItemclasses) {
//updating the key as well as certificate attribute....//
status = SecItemUpdate((__bridge CFDictionaryRef)searchDict,(__bridge CFDictionaryRef)dict);
}
if(status != errSecSuccess)
I have a exponent and a modulus. How do i encrypt a NSString using RSA algorithm. I have gone through many forums. But still find it confusing. Can anyone give me the right way to encrypt a NSString using RSA algorithm with the exponent and modulus?
I currently try this. But still get a wrong encrypted string
publicTag = [self PublicKeyItems];
SecKeyRef publicKeyData = [self getPublicKeyRef];
NSString* result = (NSString*)[self encryptRSA:#"Shob" key:publicKeyData];
And the following implementations
- (NSData *)PublicKeyItems
{
NSMutableArray *publicarray = [[NSMutableArray alloc] init];
[publicarray addObject:encryptionExponent];
[publicarray addObject:encryptionModulus];
NSData *testData = [publicarray berData];
NSLog(#"testdata = %#",testData);
return testData;
}
-(SecKeyRef)getPublicKeyRef
{
OSStatus sanityCheck = noErr;
SecKeyRef publicKeyReference = NULL;
if (publicKeyReference == NULL) {
[self generateKeyPair:512];
NSMutableDictionary *queryPublicKey = [[NSMutableDictionary alloc] init];
// Set the public key query dictionary.
[queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
// Get the key.
sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyReference);
if (sanityCheck != noErr)
{
publicKeyReference = NULL;
}
// [queryPublicKey release];
} else { publicKeyReference = publicKey; }
return publicKeyReference;
}
- (void)generateKeyPair:(NSUInteger)keySize {
OSStatus sanityCheck = noErr;
publicKey = NULL;
privateKey = NULL;
// LOGGING_FACILITY1( keySize == 512 || keySize == 1024 || keySize == 2048, #"%d is an invalid and unsupported key size.", keySize );
// First delete current keys.
// [self deleteAsymmetricKeys];
// Container dictionaries.
NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];
// Set top level dictionary for the keypair.
[keyPairAttr setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(__bridge id)kSecAttrKeySizeInBits];
// Set the public key dictionary.
[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecAttrIsPermanent];
[publicKeyAttr setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set attributes to top level dictionary.
[keyPairAttr setObject:publicKeyAttr forKey:(__bridge id)kSecPublicKeyAttrs];
// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
sanityCheck = SecKeyGeneratePair((__bridge CFDictionaryRef)keyPairAttr, &publicKey, &privateKey);
// LOGGING_FACILITY( sanityCheck == noErr && publicKey != NULL && privateKey != NULL, #"Something really bad went wrong with generating the key pair." );
if(sanityCheck == noErr && publicKey != NULL && privateKey != NULL)
{
NSLog(#"Successful");
}
// [privateKeyAttr release];
// [publicKeyAttr release];
// [keyPairAttr release];
}
-(NSString *)encryptRSA:(NSString *)plainTextString key:(SecKeyRef)publicKeyNext {
size_t cipherBufferSize = SecKeyGetBlockSize(publicKeyNext);
uint8_t *cipherBuffer = malloc(cipherBufferSize);
uint8_t *nonce = (uint8_t *)[plainTextString UTF8String];
SecKeyEncrypt(publicKeyNext,
kSecPaddingOAEP,
nonce,
strlen( (char*)nonce ),
&cipherBuffer[0],
&cipherBufferSize);
NSData *encryptedData = [NSData dataWithBytes:cipherBuffer length:cipherBufferSize];
NSString* encryptedString = [NSString stringWithFormat:#"%#",encryptedData];
return encryptedString;
}
The easy way
Use Chilkat iOS RSA Library. One major downside: cost $189! :O
The hard way
Parse the XML, use SCZ-BasicEncodingRules-iOS to generate a public key data out of the modulus and exponent. If that works, create a dummy keychain using that public key (follow sample code here), extract the public key now in SecKeyRef format and pass it to the encryptRSA method in the question. Finally, cleanup, remove the dummy keychain. Sounds good in theory, but I have never tested this thoroughly, if you do, let me know!
i want to generate same asymmetric key pair every time i apply same seed.
i have used iOS RSA crypto exercise to generarte RSA Asymmetric key pair.
i also apply same seed every time. (public and private tags)
However, i receive different keys each time i generate.
- (void)generateKeyPair:(NSUInteger)keySize {
OSStatus sanityCheck = noErr;
publicKeyRef = NULL;
privateKeyRef = NULL;
LOGGING_FACILITY1( keySize == 512 || keySize == 1024 || keySize == 2048, #"%d is an invalid and unsupported key size.", keySize );
// First delete current keys.
[self deleteAsymmetricKeys];
// Container dictionaries.
NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];
// Set top level dictionary for the keypair.
[keyPairAttr setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(id)kSecAttrKeySizeInBits];
// Set the private key dictionary.
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrCanEncrypt];
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrCanDecrypt];
[privateKeyAttr setObject:privateTag forKey:(id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set the public key dictionary.
[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
[publicKeyAttr setObject:publicTag forKey:(id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set attributes to top level dictionary.
[keyPairAttr setObject:privateKeyAttr forKey:(id)kSecPrivateKeyAttrs];
[keyPairAttr setObject:publicKeyAttr forKey:(id)kSecPublicKeyAttrs];
// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
sanityCheck = SecKeyGeneratePair((CFDictionaryRef)keyPairAttr, &publicKeyRef, &privateKeyRef);
LOGGING_FACILITY( sanityCheck == noErr && publicKeyRef != NULL && privateKeyRef != NULL, #"Something really bad went wrong with generating the key pair." );
NSLog(#"getPublicKeyBits: %#", [self getPublicKeyBits]);
NSLog(#"getPublicKeyExp: %#", [self getPublicKeyExp]);
NSLog(#"getPublicKeyMod: %#", [self getPublicKeyMod]);
// NSLog(#"keyPairAttr: %#" , keyPairAttr);
[privateKeyAttr release];
[publicKeyAttr release];
[keyPairAttr release];
}
The "public and private tags" that you are setting are simply identifiers that you can search for later using SecItemCopyMatching if you store the key pair in the key chain.
Unfortunately, you cannot set the "seed" value for assymetric key pairs using SecKeyGeneratePair or SecKeyGeneratePairAsync. You will always get "randomly generated" key pairs.
If you must do this, you will have to look at other libraries that provide that functionality.
I have two keys, public and private, that are both stored in SecKeyRef-variables. For simplicity's sake, let's start with the public one. What I wanna do is export it to an NSData object. For that, there is an almost famous code snippet provide by Apple, which is here:
- (NSData *)getPublicKeyBits {
OSStatus sanityCheck = noErr;
NSData * publicKeyBits = nil;
NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
// Set the public key query dictionary.
[queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag];
[queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
[queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnData];
// Get the key bits.
sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyBits);
if (sanityCheck != noErr)
{
publicKeyBits = nil;
}
[queryPublicKey release];
return publicKeyBits;
}
I have Xcode 4.6.2, however, and the code appears erroneous ("__bridge" is added before each conversion to id). The new version looks like this:
- (NSData *)getPublicKeyBitsFromKey:(SecKeyRef)givenKey {
OSStatus sanityCheck = noErr;
NSData * publicKeyBits = nil;
NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
// Set the public key query dictionary.
[queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnData];
// Get the key bits.
sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyBits);
if (sanityCheck != noErr)
{
publicKeyBits = nil;
}
return publicKeyBits;
}
There are still two errors, though:
use of undeclared identifier 'publicTag'
Cast of an indirect pointer to an Objective-C pointer to 'CFTypeRef ' (aka 'const void *') is disallowed with ARC
Now, I hope that after your help, the first issue will no longer be a problem, for I do not want to build a query or whatnot to extract the key from the keychain. I have it in a variable and I wish to extract it from there. The variable's name is givenPublicKey, and that's the key I wish to convert to NSData.
So, how would I go about doing this and solving this ARC-issue?
Follow-up: How can I export a private key to NSData, since I've read several time that the function I'm trying to work with only works for public keys.
use of undeclared identifier 'publicTag'
The publicTag is just some unique identifier added to the Keychain items. In the CryptoExercise sample project it is defined as
#define kPublicKeyTag "com.apple.sample.publickey"
static const uint8_t publicKeyIdentifier[] = kPublicKeyTag;
NSData *publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:sizeof(publicKeyIdentifier)];
Cast of an indirect pointer to an Objective-C pointer to 'CFTypeRef ' (aka 'const void *') is disallowed with ARC
This can be solved by using a temporary CFTypeRef variable:
CFTypeRef result;
sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)queryPublicKey, &result);
if (sanityCheck == errSecSuccess) {
publicKeyBits = CFBridgingRelease(result);
}
I do not want to build a query or whatnot to extract the key from the keychain. I have it in a variable and I wish to extract it from there ...
As far as I know, you have to store the SecKeyRef to the Keychain temporarily. SecItemAdd
has the option to return the added item as data. From the documentation:
To obtain the data of the added item as an object of type CFDataRef,
specify the return type key kSecReturnData with a value of
kCFBooleanTrue.
Putting all that together, the following code should do what you want:
- (NSData *)getPublicKeyBitsFromKey:(SecKeyRef)givenKey {
static const uint8_t publicKeyIdentifier[] = "com.your.company.publickey";
NSData *publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:sizeof(publicKeyIdentifier)];
OSStatus sanityCheck = noErr;
NSData * publicKeyBits = nil;
NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
[queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
// Temporarily add key to the Keychain, return as data:
NSMutableDictionary * attributes = [queryPublicKey mutableCopy];
[attributes setObject:(__bridge id)givenKey forKey:(__bridge id)kSecValueRef];
[attributes setObject:#YES forKey:(__bridge id)kSecReturnData];
CFTypeRef result;
sanityCheck = SecItemAdd((__bridge CFDictionaryRef) attributes, &result);
if (sanityCheck == errSecSuccess) {
publicKeyBits = CFBridgingRelease(result);
// Remove from Keychain again:
(void)SecItemDelete((__bridge CFDictionaryRef) queryPublicKey);
}
return publicKeyBits;
}
I hope that this works, I cannot test it at the moment.
Follow-up: How can I export a private key to NSData, since I've read several time that the function I'm trying to work with only works for public keys.
I don't know.