c-libp2p/include/libp2p/crypto/rsa.h

#ifndef rsa_h
#define rsa_h

#include <stddef.h>

struct RsaPublicKey {
	unsigned char* der;
	size_t der_length;
};

struct RsaPrivateKey {
	// the basics of a key pair
	unsigned long long QP;
	unsigned long long DQ;
	unsigned long long DP;
	unsigned long long Q;
	unsigned long long P;
	unsigned long long D;
	unsigned long long E;
	unsigned long long N;
	// the keys in DER format
	// private
	unsigned char* der;
	size_t der_length;
	// public
	char* public_key_der;
	size_t public_key_length;
};

/**
 * Convert a struct RsaPrivateKey to a struct PrivateKey
 * @param in the RsaPrivateKey
 * @returns a struct PrivateKey
 */
struct PrivateKey* libp2p_crypto_rsa_to_private_key(struct RsaPrivateKey* in);

/***
 * Convert a PrivateKey struct to an RsaPrivateKey struct
 * @param in the PrivateKey (NOTE: Must be of type KEYTYPE_RSA
 * @returns the RsaPrivateKey or NULL on error
 */
struct RsaPrivateKey* libp2p_crypto_private_key_to_rsa(struct PrivateKey* in);

/**
 * generate a new private key
 * @param private_key the new private key
 * @param num_bits_for_keypair the size of the key (1024 minimum)
 * @returns true(1) on success
 */
int libp2p_crypto_rsa_generate_keypair(struct RsaPrivateKey* private_key, unsigned long num_bits_for_keypair);

/**
 * Use the private key DER to fill in the public key DER
 * @param private_key the private key to use
 * @reutrns true(1) on success
 */
int libp2p_crypto_rsa_private_key_fill_public_key(struct RsaPrivateKey* private_key);


/***
 * Free resources used by RsaPrivateKey
 * @param private_key the resources
 * @returns 0
 */
int libp2p_crypto_rsa_rsa_private_key_free(struct RsaPrivateKey* private_key);
struct RsaPrivateKey* libp2p_crypto_rsa_rsa_private_key_new();
/**
 * sign a message
 * @param private_key the private key
 * @param message the message to be signed
 * @param message_length the length of message
 * @param result the resultant signature. Note: should be pre-allocated and be the size of the private key (i.e. 2048)
 * @returns true(1) on successs, otherwise false(0)
 */
int libp2p_crypto_rsa_sign(struct RsaPrivateKey* private_key, const char* message, size_t message_length, unsigned char** result, size_t* result_size);

int libp2p_crypto_rsa_verify(struct RsaPublicKey* public_key, const unsigned char* message, size_t message_length, const unsigned char* signature);

#endif /* rsa_h */