cryptopals_c

commit 8c2929ed7d6bb1c047d706435311b412ef62d0dd
parent aa869ba8f72fa5f749a3d814f0b037bfff1e58a6
Author: anna <anna@brokenlove.online>
Date:   Sat, 31 Aug 2024 20:09:03 +0200

clean up thoseee

Diffstat:
R
s1/c1.c -> src/s1/c1.c
 | 
0

R
s1/c2.c -> src/s1/c2.c
 | 
0

R
s1/c3.c -> src/s1/c3.c
 | 
0

R
s1/c4.c -> src/s1/c4.c
 | 
0

R
s1/c5.c -> src/s1/c5.c
 | 
0

R
s1/c6.c -> src/s1/c6.c
 | 
0

A
src/s1/c7.c
 | 
119
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

7 files changed, 119 insertions(+), 0 deletions(-)
diff --git a/s1/c1.c b/src/s1/c1.c
diff --git a/s1/c2.c b/src/s1/c2.c
diff --git a/s1/c3.c b/src/s1/c3.c
diff --git a/s1/c4.c b/src/s1/c4.c
diff --git a/s1/c5.c b/src/s1/c5.c
diff --git a/s1/c6.c b/src/s1/c6.c
diff --git a/src/s1/c7.c b/src/s1/c7.c
@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ba.h>
+#include <openssl/aes.h>
+#include <openssl/conf.h>
+#include <openssl/evp.h>
+#include <openssl/err.h>
+
+const char b64table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+int b64_chunk_to_hex(char **hex, char *b64)
+{
+	unsigned int val;
+	unsigned int sz;
+	unsigned int i;
+
+	if (strlen(b64) != 4)
+		return -1;
+
+	val = 0;
+	for (i = 0; i < 4; i++) {
+		int j = 0;
+		val <<= 6;
+
+		while (b64[i] != '=' && b64table[j] != b64[i])
+			j++;
+
+		val += j;
+	}
+
+	sz = 3 - ((b64[2] == '=') + (b64[3] == '='));
+
+	*hex = (char *) malloc(sizeof(char) * sz);
+	i = 0;
+	while (val > 0) {
+		(*hex)[i] = val % 256;
+		val /= 8;
+		i++;
+	}
+	return 0;
+}
+
+int base64_to_hex(char **hex, char *b64)
+{
+	unsigned int len;
+
+	len = (strlen(b64) * 3 / 4) + 1;
+	*hex = (char *) malloc(sizeof(char *) * len);
+
+	for (int i = 0; i < strlen(b64)/4; i++) {
+		char b64_chunk[5];
+		char *hex_chunk;
+
+		b64_chunk[4] = '\0';
+		memcpy(b64_chunk, b64+4*i, 4);
+		b64_chunk_to_hex(&hex_chunk, b64_chunk);
+		strcat(*hex, hex_chunk);
+	}
+	(*hex)[len-1] = '\0';
+}
+
+int decrypt(unsigned char *ct, int ct_len, unsigned char *key,
+	    unsigned char *pt)
+{
+	EVP_CIPHER_CTX *ctx;
+	int pt_len;
+	int len;
+
+	if (!(ctx = EVP_CIPHER_CTX_new()))
+		return -1;
+
+	if(EVP_DecryptInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, NULL) != 1)
+		return -1;
+
+	if(EVP_DecryptUpdate(ctx, pt, &len, ct, ct_len) != 1)
+		return -1;
+
+	pt_len = len;
+
+	if(EVP_DecryptFinal_ex(ctx, pt + len, &len) != 1)
+		return -1;
+	pt_len += len;
+
+	EVP_CIPHER_CTX_free(ctx);
+	return pt_len;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned char *key = (unsigned char*) "YELLOW SUBMARINE";
+	char line[256];
+	int pt_len;
+	char *b64;
+	char *hex;
+	char *pt;
+	FILE *f;
+	ba *ct;
+	int sz;
+
+	b64 = (char *) malloc(sizeof(char));
+
+	f = fopen(argv[1], "r");
+	sz = 0;
+	while (fgets(line, sizeof(line), f)) {
+		sz += strlen(line) - 1;
+		b64 = (char *) realloc(b64, sz);
+		strncat(b64, line, strlen(line) - 1);
+	}
+
+	base64_to_hex(&hex, b64);
+	
+	pt = (char *) malloc(sizeof(char) * strlen(hex) + 1);
+
+	pt_len = decrypt(hex, strlen(hex), key, pt);
+
+	/* Add a NULL terminator. We are expecting printable text */
+	//pt[pt_len] = '\0';
+}