How to find out the modulus and exponent of RSA Public Key on iPhone/Objective C

Question

Is there a possible way to find out the modulus and exponent of the Public Key, created with SecKeyGeneratePair (the Security Framework in general)?

Answer 1

I removed that extra byte at the beginning, now it works fine. In my case it was always extracting 129 bytes modulus.

- (NSData *)getPublicKeyModFromKeyData:(NSData*)pk
{
if (pk == NULL) return NULL;

int iterator = 0;

iterator++; // TYPE - bit stream - mod + exp
[self derEncodingGetSizeFrom:pk at:&iterator]; // Total size

iterator++; // TYPE - bit stream mod
int mod_size = [self derEncodingGetSizeFrom:pk at:&iterator];

// return [pk subdataWithRange:NSMakeRange(iterator, mod_size)];
NSData* subData=[pk subdataWithRange:NSMakeRange(iterator, mod_size)];
return  [subData subdataWithRange:NSMakeRange(1, subData.length-1)];

}