kSecAttrKeyType
and kSecAttrKeySizeInBits
parameters, respectively. The above example indicates 2048-bit RSA keys, though other options are available.kSecPrivateKeyAttrs
parameter with a subdictionary that characterizes the private key. By assigning a value of true
to the private key’s kSecAttrIsPermanent
attribute, you store it in the default keychain while creating it. You also specify the kSecAttrApplicationTag
attribute with a unique NSData
value so that you can find and retrieve it from the keychain later. The tag data is constructed from a string, using reverse DNS notation, though any unique tag will do.kSecPublicKeyAttrs
attribute to the attributes dictionary, specifying a distinct tag and keychain storage for the public key. However, it’s typically easier to store only the private key and then generate the public key from it when needed. That way you don’t need to keep track of another tag or clutter your keychain.SecItemDelete(_:)
before creating a new one with that tag.SecKeyCreateRandomKey(_:_:)
function with the attributes dictionary:NULL
return value, it fills in the error
parameter to indicate the reason for failure. Otherwise, the key reference points to a new private key that’s ready for use. The key is also stored in the default keychain, from where you can read it later, as described in Storing Keys in the Keychain. If you need the corresponding public key (now or later), call the SecKeyCopyPublicKey(_:)
function with the private key reference:SecKeyCreateEncryptedData(_:_:_:_:)
to create a symmetric key for you. This function creates the symmetric key, uses it to encrypt your data, and then encrypts the key itself with the public key that you provide. It then packages all of this data together and returns it to you. You then transmit it to a receiver, who uses the corresponding private key in a call to SecKeyCreateDecryptedData(_:_:_:_:)
to reverse the operation. For more details, see Using Keys for Encryption.func SecKeyCreateRandomKey(CFDictionary, UnsafeMutablePointer<Unmanaged<CFError>?>?) -> SecKey?
func SecKeyCopyPublicKey(SecKey) -> SecKey?