5 // Created by Jens Alfke on 3/25/09.
6 // Copyright 2009 Jens Alfke. All rights reserved.
13 #import <Security/SecKey.h>
17 /** A public key, which can be used for encrypting data and verifying signatures.
18 MYPublicKeys are created as part of generating a MYKeyPair,
19 or by being imported into a MYKeychain. */
20 @interface MYPublicKey : MYKey <MYEncryption>
23 MYSHA1Digest *_digest;
26 /** The public key's SHA-1 digest. This is a convenient short (20-byte) identifier for the key. */
27 @property (readonly) MYSHA1Digest *publicKeyDigest;
29 /** Returns the receiver as a MYPublicKey.
30 If the receiver already is a MYPublicKey, this just returns self.
31 If it's a MYKeyPair, it returns a new MYPublicKey containing just the public key. */
32 @property (readonly) MYPublicKey *asPublicKey;
34 /** Encrypts a short piece of data using this key, returning the raw encrypted result.
35 An RSA key can encrypt only blocks smaller than its own key size; this
36 method will fail and return nil if the data is too long.
37 RSA encryption is also much slower than regular symmetric-key encryption, so the correct
38 way to encrypt a large block of data using a public key is to first generate a random
39 symmetric key, called the "session key" (using a Cryptor), encrypt that session key with the
40 public key, and then encrypt your data with the session key. Send the encrypted session key
41 and the encrypted data. */
42 - (NSData*) encryptData: (NSData*)data;
44 /** Verifies the signature of a block of data. If the result is YES, you can be assured that
45 the signature was generated from the data by using this key's matching private key.
46 If the result is NO, something is wrong: either the data or the signature was modified,
47 or the signature was generated by a different private key.
48 (What's actually verified using RSA is the SHA-256 digest of the data.) */
49 - (BOOL) verifySignature: (NSData*)signature ofData: (NSData*)data;