iOS How can I use externally generated keys to encrypt and decrypt the data in iPhone?

[sspbond007]

I am working on an application, in which I need to encrypt and decrypt the data, with the keys generated by server. I viewed the sample code of Crypto Exercise. In that keys are automatically generated. How can I use externally generated keys in the code? Please help.

 

[jnic]

I am working on an application, in which I need to encrypt and decrypt the data, with the keys generated by server. I viewed the sample code of Crypto Exercise. In that keys are automatically generated. How can I use externally generated keys in the code? Please help.

I suppose you could do CGI programming in Objective-C, but if you're generating keys on the server then you now need to also encrypt their transit to your client. Depending on your needs, SSL should be strong enough for this.

Perhaps you could tell us a little more about what you're trying to achieve so we can suggest a more appropriate scheme?

 

[sspbond007]

I suppose you could do CGI programming in Objective-C, but if you're generating keys on the server then you now need to also encrypt their transit to your client. Depending on your needs, SSL should be strong enough for this.

Perhaps you could tell us a little more about what you're trying to achieve so we can suggest a more appropriate scheme?

Thanks for reply.
Actually we would save the key to the application before distributing iphone with application installed, application will be of no use without keys.
As the admin will have the details of key.

Key example generated at server:

Public Key = Sun RSA public key, 1024 bits
modulus: 124023351056468614901533017072321247442755935604055880454060007476890164438816752725874372294674015042581755934271759902049502111005389711791135502487008186937382304689292437368682143846990300465923690895265303828247563983908120112048903925521720479908415043670044545880379949571719973833044267594283578037267
public exponent: 65537


Private Key = Sun RSA private CRT key, 1024 bits
modulus: 124023351056468614901533017072321247442755935604055880454060007476890164438816752725874372294674015042581755934271759902049502111005389711791135502487008186937382304689292437368682143846990300465923690895265303828247563983908120112048903925521720479908415043670044545880379949571719973833044267594283578037267
public exponent: 65537
private exponent: 114890545279601844443397943138649850519510438476857905583814289850458195725239236991936753534369197968325998817852095997884055154511927839122200092947323690104719921979672421871813387130149834682490921697661392281141856629258926789279733883254021403658980049918631649289303454629969269203849499935133081811361
prime p: 12286772546456233633275173954900435004671958267370681732506625760473826004732448434908366238181160639947248110138614224358839989172329264022644016028973059
prime q: 10094054446563315404837804379878204754449128284698017797970347835729750012713048675775291259987608136883717196181912050395526837190859701170692738982862513
prime exponent p: 6258591756082036824688727469008975414818560245962364286987025462897260074705636908960525964404865734521857632493970713517114841365028423956969729879231695
prime exponent q: 9594257283447854543206990103779134390712804966818879788076489729210638079129670691539045778219144697846415178976206805975832853842761073978436487735484865
crt coefficient: 9270409267843644570790177803648197918946915567779960231096993691473748233824775338016370226367676538314640135208758120690734790651897457694493986394969199



using this info we have to do all kind of cryptographic operation.

Any suggestion.

 

[jnic]

Thanks for reply.
Actually we would save the key to the application before distributing iphone with application installed, application will be of no use without keys.

Wouldn't that mean that all instances of your app were doing their encryption/decryption with the same key pair? This would render such encryption moot, as anyone could simply extract the private key from memory and decrypt all data for all instances of your app.

 

[Cromulent]

Wouldn't that mean that all instances of your app were doing their encryption/decryption with the same key pair? This would render such encryption moot, as anyone could simply extract the private key from memory and decrypt all data for all instances of your app.

Exactly.

Your best bet is to have the application create a key pair on first launch then have it securely transmit the keys with a unique ID to the server so that it can associate each key with a specific instance of the application.

 

[sspbond007]

Wouldn't that mean that all instances of your app were doing their encryption/decryption with the same key pair? This would render such encryption moot, as anyone could simply extract the private key from memory and decrypt all data for all instances of your app.

Sorry, the logic behind is somewhat different. The main problem is of how to create SecKeyRef with the keys? Or is there any other way to encrypt data with the key information?