• Crea un archivo llamada AAAA.txt de 512 bytes lleno de AAAAAAAAAA's para ejempliciar el plain text.
• Genera un par de llaves RSA (Parte tardada)
• Guarda las claves creadas en archivo en archivo para su posterior uso
• Genera apartir de la llave publica y algunos otros datos 5  "Key Message" para fines didacticos solo usaremos el ultimo
• usa el campo pass del KeyMessage para cifrar el AES en modo CBC con el iv correspondiente
• Guarda la salida en un archivo llamada AAES.txt

Key df9701195198737faf7c163298704e2c5b583532cf8fc20595c8512b5b65e8db2ef1683d4e7399132d719a38cdf14b32d100a73e84f338ae4d8c43dc43c408222e2278d005332bca737d55b5a7a24897
Key b858d2f07d002deeb2afd730078b8f38904725e37f98d31dd15c11a404e22777c1813ea5982db9324e9fc8f85b60720fa709f62baaab81034f9090cf4ad37609858b5d5c7b285f8f0baf241fcd405c28
Key 4df7986bfb598832b552860e7e03bb67a661c75d6a571656ac6b5e31ea60755f984964eafaf78e79e83a66589c2993dd7fc67de37467c6c3e56a565e8167305271079d6902c6cbfdd7ee8c3799d58b79
Key a8d81e45dfcec1e6cb5b9be014626311f42c38f88ceb6f4ef6494d4c7281c92c0e92cdc6cb296231322909b8634af89b15807235b7fcd27c7103e4df89e6163cf809a342ce4004145e3d7f19643d2133
Key 420341bb215e4393c4fb364ed05331bb4ab51e81355d767fe7ac4fe33012c15fcc66740840cc8b0981a9d6e98b925f408e9c16e0b559993b368fb749f337bae3dfe9797fdced844f1d227dbce12bda05

/*
	twitter: @albertobsd
	cc -o ejemplos ejemplos.c `libgcrypt-config --cflags --libs`
*/
 
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<gcrypt.h>
 
void libgcrypt_init();
int createRSA_4096(char *prefix,char *bufferPkey);
unsigned char *my_kdf(char *passphrase,size_t passphraselen,unsigned int iterations,size_t keysize);
int encrypt(char *buffer,char *pass,char *iv,int length);
 
 
 
typedef struct str_KeyMessage {
	unsigned char pass[32];
	unsigned char hmac[32];
	unsigned char iv[16];
}*KeyMessage;
 
int main()	{
 
	FILE *archivo = NULL;
	char *buffer = NULL;
	char *pkey = NULL;
	char *digest = NULL;
	unsigned char *key = NULL;
	int length,i,j;
	buffer = calloc(512,1);
	if(!buffer)	{
		printf("calloc\n");
		exit(0);
	}
	memset(buffer,'A',512);
	archivo = fopen("AAAA.txt","w");
	if(!archivo)	{
		printf("calloc\n");
		exit(0);
	}
	fwrite(buffer,1,512,archivo);
	fclose(archivo);
	libgcrypt_init();
	pkey = calloc(2048,1);
	length = createRSA_4096("UsuarioA",pkey);
	j = 0;
	while(j < 5)	{
		key = my_kdf(pkey,length,1024,80);
		if(!key)	{
			printf("my_kdf\n");
			exit(0);
		}
		printf("Key ");
		i = 0;
		while(i < 80)	{
			printf("%.2x",key[i]);
			i++;
		}
		printf("\n");
		j++;
	}
	KeyMessage km = (KeyMessage)key;
	encrypt(buffer,(char*)km->pass,(char*)km->iv,512);
	archivo = fopen("AAES.txt","w");
	if(!archivo)	{
		printf("fopen 2");
		exit(0);
	}
	fwrite(buffer,1,512,archivo);
	fclose(archivo);
 
}
 
void libgcrypt_init()	{
	if(!gcry_check_version(GCRYPT_VERSION))	{
		fprintf(stderr,"libgrypt version mismatch %s\n",GCRYPT_VERSION);
		exit(0);
	}
	gcry_control(GCRYCTL_SUSPEND_SECMEM_WARN);
	gcry_control(GCRYCTL_INIT_SECMEM,1638,0);
	gcry_control(GCRYCTL_INITIALIZATION_FINISHED,0);
	if(!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))	{
		fprintf(stderr,"libgrypt has not been initialized\n");
		exit(0);
	}
}
 
int createRSA_4096(char *prefix,char *publickey)	{
	FILE *p;
	FILE *s;
	gcry_sexp_t rsa_parms = NULL;
	gcry_sexp_t rsa_keypair = NULL;
	gcry_sexp_t rsa_skey = NULL;
	gcry_sexp_t rsa_pkey = NULL;
	gcry_error_t err = 0;
	int temp = 0;
	char *nombre_p,*nombre_s;
	size_t length = 2048;
	size_t offset = 0;
	char *bufferkey;
	nombre_p = calloc(strlen(prefix) + 2,sizeof(char));
	nombre_s = calloc(strlen(prefix) + 2,sizeof(char));
	sprintf(nombre_p,"%sp",prefix);
	sprintf(nombre_s,"%ss",prefix);
	err = gcry_sexp_build(&rsa_parms, NULL, "(genkey (rsa (nbits 4:4096)(rsa-use-e 1:1)))");
	if(err) {
		fprintf(stderr,"gcry_sexp_build: failed to build\n");
		fclose(stderr);
		exit(0);
	}
	err = gcry_pk_genkey(&rsa_keypair, rsa_parms);
	gcry_sexp_release(rsa_parms);
	if(err) {
		fprintf(stderr,"gcry_pk_genkey: failed to genkey\n");
		fclose(stderr);
		exit(0);
	}
	rsa_pkey = gcry_sexp_find_token(rsa_keypair, "public-key", 0);
	rsa_skey = gcry_sexp_find_token(rsa_keypair, "private-key", 0);
	gcry_sexp_release(rsa_keypair);
	bufferkey = calloc(length,sizeof(char));
	if(bufferkey == NULL)	{
		fprintf(stderr,"unable to alloc memory\n");
		fclose(stderr);
		exit(0);
	}
	offset = gcry_sexp_sprint(rsa_pkey,GCRYSEXP_FMT_CANON,bufferkey,length);
	gcry_sexp_release(rsa_pkey);
	p = fopen(nombre_p,"w");
	if(p == NULL)	{
		fprintf(stderr,"unable to create file\n");
		fclose(stderr);
		exit(0);
	}
	temp = offset;
	memcpy(publickey,bufferkey,offset);
	fwrite(bufferkey,sizeof(char),offset,p);
	fclose(p);
	memset(bufferkey,0,length);
	offset = gcry_sexp_sprint(rsa_skey,GCRYSEXP_FMT_CANON,bufferkey,length);
	gcry_sexp_release(rsa_skey);
	s = fopen(nombre_s,"w");
	if(s == NULL)	{
		fprintf(stderr,"unable to create file\n");
		fclose(stderr);
		exit(0);
	}
	fwrite(bufferkey,sizeof(char),offset,s);
	fclose(s);
	memset(bufferkey,0,length);
	return temp;
}
 
unsigned char *my_kdf(char *passphrase,size_t passphraselen,unsigned int iterations,size_t keysize)	{
	gpg_error_t err;
	unsigned char *bufferkey = NULL;
	char *salt = NULL;
	bufferkey = calloc(keysize,1);
	salt = calloc(8,1);
	gcry_randomize(salt,8,GCRY_VERY_STRONG_RANDOM);
	err = gcry_kdf_derive(passphrase,passphraselen,GCRY_KDF_ITERSALTED_S2K,GCRY_MD_SHA512,salt,8,iterations,keysize,bufferkey);
	if(err != 0)	{
		free(bufferkey);
		free(salt);
		return NULL;
	}
	else	{
		free(salt);
		return bufferkey;
	}	
}
 
 
int encrypt(char *buffer,char *pass,char *iv,int length)	{
	gcry_error_t err = 0;
	gcry_cipher_hd_t aes_hd;
	gcry_cipher_open(&aes_hd, GCRY_CIPHER_AES256,GCRY_CIPHER_MODE_CBC, GCRY_CIPHER_SECURE);
	err = gcry_cipher_setkey(aes_hd, pass, 32);
	if (err) {
		fprintf(stderr,"gcry_cipher_setkey(): could not set cipher key\n");
		fclose(stderr);
		exit(0);
	}
	err = gcry_cipher_setiv(aes_hd, iv, 16);
	if (err) {
		fprintf(stderr,"gcry_cipher_setiv(): could not set cipher initialization vector\n");
		fclose(stderr);
		exit(0);
	}
	err = gcry_cipher_encrypt(aes_hd, (unsigned char*) buffer, length, NULL, 0);
	if (err) {
		fprintf(stderr,"gcry_cipher_encrypt(): unable to encrypt file\n");
		fclose(stderr);
		exit(0);
	}
	err = gcry_cipher_reset(aes_hd);
	gcry_cipher_close(aes_hd);
	return err;
}
 
 
 

• 32 bytes AES password
• 32 bytes HMAC
• 16 bytes IV

int IDtableLoad( char DNI[] )
 {
 FILE *fptr;
 char mot[BUFSIZ];
 int i;
 fptr = fopen( "DNIList.txt", "rt" );
 if( fptr != NULL ) {
 i = 0;
 fscanf( fptr, " %s", mot );
 while( !feof( fptr ) ) {
//Aqui deberias de agregar la variable leida a la variable  global
 fscanf( fptr, " %s", mot );
 } /* while */
 fclose( fptr );
 } else {
i = -1;
 } /* if */
 return i;
} /* IDtableLoad */
 

char IDtable[MAXID][IDLEN+1];

/*
	Twitter @albertobsd
cc -o iterative_sha512 iterative_sha512.c `libgcrypt-config --cflags --libs`
*/
 
#include<stdio.h>
#include<gcrypt.h>
 
int main()	{
	unsigned char *buffer,*digest,*temp = NULL;
	register int i = 0,j;
	buffer = calloc(64,sizeof(unsigned char));
	digest = calloc(64,sizeof(unsigned char));
	memset(buffer,'A',64);
	while(i < 5200)	{
		gcry_md_hash_buffer(GCRY_MD_SHA512,digest,buffer,64);
		printf("sha512: ");
		j = 0;
		while(j < 64)	{
			printf("%.2x",digest[j++]);
		}
		printf("\n");
		temp = buffer;
		buffer = digest;
		digest = temp;
		i++;
	}
	free(buffer);
	free(digest);
}
 
 

sha512: 4f86b77580f55fdb90493042738915127aaa4fa2f1302a52b647b7a179b9c49b06f3cf67d0b1cc6e50dc7519bbb30c207b87be46eb60c8c78da0a18be7ee7b7a
sha512: 08726cc621866ffce20525d3e06d369aa73efae405d452ecdb426dfa00784637b2d0287e8702c50853741c34aac4768765d2e8395188351e9c5b5c6793d4759b
sha512: 16687e52fd941f0ccd8f70ce64c6802688c135482ec01c03e16cf0bb60490774b86ffab6fc7d19b65a22519d38807ee5b88277847a875f011c05ea2f47ae7e3b
sha512: bc83d85641f7588c15a023f8fe3617baacc67a758d148829ea8e10e3123d684f710b7d085de99fea5be9913db9a67145d181de39d7b19fc664780477f5e2253b
sha512: 13bd175d39ab444f808a09dc49a823f76720a36a48bf8e1f321ba9a16303325003fb41fb80d40fd2a82cf8c2904168dc6160491e0be48ef60a6e8ed63137ee4f
sha512: 36d743bb4e26669d09c96e4f82213105f5d34e4fcbcb7e5d385bf278b30e2083d9d8dfd9516a28e5e4096078a5ee7ab160da16aff39c19062eddfce4282190d7
sha512: dee957067e6ca41113242e06e9a42532c0806a577fb665ed6d9e45a8f60762ab0c8c4511ef720a0edaf3758cf40bf6f85e10237f2821ec3213451b8aa34a3a2f
sha512: fd3172c5314f26e48a6f94d243e428be4bb28379c5536e943fa33c8a7b87564c46b23359dc113f547b21f64a6b8ca3d8b655f4f743c533aeffd84c38f10ceced
sha512: a2c5ce5e4342863ca31dfbf0ff204d94636fd2da00c539df97ab6ce193791c5dd4a4136686ef7e37ca25c547fe12cea80192f06c1e6c33450e730f73a9d170ba
sha512: 467bb8f325dcb319ebfb9f60464a4d54cf4078fc3c5ad8ee70ab214e999a2fb39873d430a51cb96e5ca2929d8c485105b3095463f4790ba4709deb425512cb2e
sha512: 82776272e658cbc37b73258da6d5283baa027f85c27ee1538c47aaccde688ee510652e2e47fb8bcfa7eb02f3797bfffa44cf20f9274f401d8668467632459928
sha512: 5387ba3de50479e2b15c466d0bec62252bccaace8a207c53d5591283fb799ef7d1480aebdefeaff30e92436633d519e9a494d3db6a578e1da84b452372aa1b71