Generating Keys with Secure Enclave on MacOS
Secure Enclave is a hardware-based key manager introduced by Apple in its MacOS operating system. It provides a secure environment for generating and storing cryptographic keys, making it an ideal tool for developers looking to enhance the security of their applications.
What is Secure Enclave?
Secure Enclave is a coprocessor found in Apple’s system-on-chips (SoCs) used in Mac computers. It is designed to provide a secure environment for critical operations such as key generation, storage, and management. Secure Enclave is isolated from the main processor, making it resistant to attacks such as malware, viruses, and other threats.
Generating Keys with Secure Enclave
Secure Enclave provides an API for generating cryptographic keys. The API allows developers to generate keys securely, store them in the Secure Enclave, and use them for encryption and decryption operations. To generate a key pair with Secure Enclave, you need to use the SecKeyCreateRandomKey() function.
const char \*tags[] = {\"kSecAttrKeyType\", \"kSecAttrKeySizeInBits\", \"kSecPrivateKeyAttrs\", \"kSecPublicKeyAttrs\"};
const void \*values[] = {
&kSecAttrKeyTypeRSA,
&kSecAttrKeySizeInBits\_2048,
NULL,
NULL
};
The above code sets up the parameters for the key generation. The kSecAttrKeyType parameter specifies the type of key to generate, while the kSecAttrKeySizeInBits parameter specifies the size of the key. The kSecPrivateKeyAttrs and kSecPublicKeyAttrs parameters are used to specify any additional attributes for the private and public keys, respectively.
NSError \*error = NULL;
SecKeyRef privateKey = NULL;
SecKeyRef publicKey = NULL;
The above code initializes the variables for the key generation. The SecKeyRef type is used to reference the generated keys.
privateKey = SecKeyCreateRandomKey(¶ms, error);
publicKey = SecKeyCopyPublicKey(privateKey);
The above code generates the key pair using the SecKeyCreateRandomKey() function. The private key is then used to generate the public key using the SecKeyCopyPublicKey() function.
Storing Keys in Secure Enclave
After generating the key pair, you can store them securely in the Secure Enclave using the SecKeyAddAttribute() function.
const char \*keyTags[] = {\"kSecAttrIsPermanent\", \"kSecAttrApplicationTag\"};
const void \*keyValues[] = {
&kCFBooleanTrue,
(const void \*)&applicationTag
};
The above code sets up the parameters for storing the key pair. The kSecAttrIsPermanent parameter specifies that the key pair should be stored permanently in the Secure Enclave. The kSecAttrApplicationTag parameter specifies an application-specific tag for the key pair.
error = NULL;
SecKeyAddAttribute(privateKey,
&keyTags[0],
&keyValues[0],
keyCount);
The above code stores the private key in the Secure Enclave. The public key is stored by setting its kSecAttrApplicationTag attribute to the same value as the private key.
References
- Apple Developer: Generating Keys
- Apple Developer: Storing