[Chris Torr]

Here is an example of generating an RSA key and performing encryption with it.

#include <multos.h>

#define MODULUS_LENGTH ((WORD)256)
#define EXPONENT_LENGTH 1
#define KEYGEN_METHOD_DEFAULT 0
#define KEYGEN_MODE_BALANCED 1

typedef struct
{
	BYTE privateKey[(MODULUS_LENGTH)/2 * 5];// Formatted as dp|dq|p|q|u
	BYTE publicKey[MODULUS_LENGTH];
	BYTE exponent[1];
} rsa_t;

#pragma melstatic
rsa_t keyPair;

#pragma melsession
BYTE ciphertext[MODULUS_LENGTH];
BYTE deciphered[MODULUS_LENGTH];

	// ... in the code ...
	// Generate a key pair
	keyPair.exponent[0] = 3;	
	genOK = multosGenerateRsaKeyPair(KEYGEN_METHOD_DEFAULT,
					KEYGEN_MODE_BALANCED,
					MODULUS_LENGTH,
					keyPair.publicKey,
					keyPair.privateKey,
					keyPair.exponent,
					EXPONENT_LENGTH,
					MODULUS_LENGTH);
									
	if(!genOK)	// a BOOL
		multosExitSW(0x90FD);

	// Encrypt
	multosRsaVerify(ciphertext,
			cleartext,		// A BYTE array of size MODULUS_LENGTH containing the data to encipher
			keyPair.publicKey,
			keyPair.exponent,
			MODULUS_LENGTH,
			EXPONENT_LENGTH);

	// Decrypt
	multosModularExponentiationCRT(deciphered,
					ciphertext,
					keyPair.privateKey+MODULUS_LENGTH,	//pquAddr
					keyPair.privateKey,			//dpdqAddr
					MODULUS_LENGTH);

	// Compare deciphered with original cleartext - should be the same
	if(multosCompare(deciphered,cleartext,MODULUS_LENGTH) != MULTOS_BLOCK1_EQ_BLOCK2)
		multosExitSW(0x90FF);
}

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