3DES CBC encryption decryption

[dushantha12]

Hi,

I have to build a application that can do encryption and decryption using Triple Des CBC mode. Can anybody give me a sample code for this. I trid with google. But it's not poroperly suited.

Thank you.

[histrungalot]

Maybe
http://bradconte.com/3des_c which points to https://github.com/B-Con/crypto-algorithms

Some explanation:
http://orlingrabbe.com/des.htm

[dushantha12]

Hi,

Thank you. I tried with open ssl. But It's not working properly.

#include <openssl/des.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
	
	DES_cblock cb1 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE };
	DES_cblock cb2 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE };
	DES_cblock cb3 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE };

	DES_key_schedule ks1;
	DES_key_schedule ks2;
	DES_key_schedule ks3;

	DES_cblock cblock = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

	char string[] = "I am a software developer";

	printf("Plain Text : %s\n",string);

	char* cipher = (char *) malloc(32);
	char* text = (char *) malloc(strlen(string));

	DES_set_odd_parity(&cblock);

	if (DES_set_key_checked(&cb1, &ks1) || DES_set_key_checked(&cb2, &ks2) || DES_set_key_checked(&cb3, &ks3)) {
		printf("Key error, exiting ....\n");
		return 1;
	}

	DES_ede3_cbc_encrypt(string, cipher, strlen(string), &ks1, &ks2, &ks3,&cblock, 1);

	printf("Encrypted : %s+\n",cipher);

	DES_ede3_cbc_encrypt(cipher, text, strlen(cipher), &ks1, &ks2, &ks3, &cblock,0);

	printf("Decrypted : %s\n",text);
}

Oputput :

Plain Text : I am a software developer
Encrypted : 0}�~i���:����u�8O<`�l���s�[q+
Decrypted : $���R�7oftware developer

Can you please help me to do this.

Thank you.

[histrungalot]

This works but be careful with the sizes of your arrays. Didn't check to much if you were going outside of your array boundaries.

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#include <openssl/des.h> #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { DES_cblock cb1 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE }; DES_cblock cb2 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE }; DES_cblock cb3 = { 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE, 0xAE }; DES_key_schedule ks1,ks2,ks3; DES_cblock cblock = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; char string[] = "I am a software developer"; // --------------------------------------------- // I use sizeof instead of strlen because I want // to count the '\0' at the end, strlen would // not count it int stringLen(sizeof(string)); printf("Plain Text : %s\n",string); char* cipher(new char[32]); char* text(new char[stringLen]); memset(cipher,0,32); memset(text,0,stringLen); DES_set_odd_parity(&cblock); if (DES_set_key_checked(&cb1, &ks1) || DES_set_key_checked(&cb2, &ks2) || DES_set_key_checked(&cb3, &ks3)) { printf("Key error, exiting ....\n"); return 1; } DES_ede3_cbc_encrypt((const unsigned char*)string, (unsigned char*)cipher, stringLen, &ks1, &ks2, &ks3, &cblock, DES_ENCRYPT); printf("Encrypted : %32.32s\n",cipher); //----------------------------------------------- // You need to start with the same cblock value memset(cblock,0,sizeof(DES_cblock)); DES_set_odd_parity(&cblock); //----------------------------------------------- // I think you need to use 32 for the cipher len. // You can't use strlen(cipher) because if there // is a 0x00 in the middle of the cipher strlen // will stop there and the length would be short DES_ede3_cbc_encrypt((const unsigned char*)cipher, (unsigned char*)text, 32, &ks1, &ks2, &ks3, &cblock,DES_DECRYPT); printf("Decrypted : %s\n",text); }

Plain Text : I am a software developer Encrypted : 0}¶~iúÌ:¾Èu8O`¾l³×âs¢q Decrypted : I am a software developer

[dushantha12]

Hi,

Thank you very much..