cryptopals_c

commit 61013081552caa361b5c0e39a0448f4a441fedb4
parent 56ee190384a567da636a3bcc669ea6e738e9c1f7
Author: superpozycja <anna@superpozycja.net>
Date:   Sun, 23 Feb 2025 01:34:36 +0100

lib/aes: implement plain aes part 1; working key expansion

Diffstat:
A
lib/aes.c
 | 
177
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
lib/aes.h
 | 
14
++++++++++++++
M
src/s1/c7.c
 | 
14
++++++++++++--

3 files changed, 203 insertions(+), 2 deletions(-)
diff --git a/lib/aes.c b/lib/aes.c
@@ -0,0 +1,177 @@
+/* adapted from https://csrc.nist.gov/pubs/fips/197/final */
+
+#include "aes.h"
+
+static uint8_t sbox[0x100] = {
+	0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
+	0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
+	0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
+	0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
+	0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
+	0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
+	0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
+	0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
+	0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
+	0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
+	0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
+	0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
+	0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
+	0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
+	0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
+	0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
+};
+
+static uint8_t sbox_inv[0x100] = {
+	0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
+	0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
+	0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
+	0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
+	0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
+	0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
+	0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
+	0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
+	0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
+	0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
+	0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
+	0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
+	0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
+	0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
+	0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
+	0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
+};
+
+static int rot_word(ba *input, ba **output, unsigned int amt) {
+	*output = ba_alloc(4);
+	for (int i = 0; i < 4; i++) {
+		(*output)->val[i] = input->val[(i+amt)%4];
+	}
+}
+
+static int sub_word(ba *input, ba **output) {
+	*output = ba_alloc(4);
+	for (int i = 0; i < 4; i++) {
+		(*output)->val[i] = sbox[input->val[i]];
+	}
+}
+
+static int key_expansion(ba *key, unsigned int keylen, unsigned int rounds,
+			 ba *round_keys[4*(rounds + 1)])
+{
+	ba *rcon[10] = {
+		ba_from_hex("01000000"),
+		ba_from_hex("02000000"),
+		ba_from_hex("04000000"),
+		ba_from_hex("08000000"),
+		ba_from_hex("10000000"),
+		ba_from_hex("20000000"),
+		ba_from_hex("40000000"),
+		ba_from_hex("80000000"),
+		ba_from_hex("1b000000"),
+		ba_from_hex("36000000")
+	};
+
+	const int nk = keylen / 4;
+
+	for (int i = 0; i < nk; i++) {
+		round_keys[i] = ba_alloc(4);
+		for (int j = 0; j < 4; j++)
+			(round_keys[i])->val[j] = key->val[i*4+j];
+	}
+
+	for (int i = nk; i < 4 * (rounds + 1); i++) {
+		ba *tmp = ba_alloc(4);
+		ba *tmp2 = ba_alloc(4);
+		round_keys[i] = ba_alloc(4);
+
+		ba_copy(tmp, round_keys[i - 1]);
+		ba_copy(tmp2, round_keys[i - nk]);
+
+		if (i % nk == 0) {
+			ba *tmp3;
+			rot_word(tmp, &tmp3, 1);
+			sub_word(tmp3, &tmp);
+			ba_xor(tmp, rcon[(i-1) / nk]);
+			ba_free(tmp3);
+		} else if (nk > 6 && i % nk == 4) {
+			ba *tmp3 = ba_alloc(4);
+			ba_copy(tmp3, tmp);
+			sub_word(tmp3, &tmp);
+			ba_free(tmp3);
+		}
+
+		ba_xor(tmp, tmp2);
+		ba_copy(round_keys[i], tmp);
+		ba_free(tmp);
+		ba_free(tmp2);
+	}
+
+	return 0;
+}
+
+static int aes_generic(unsigned int rounds, unsigned int keylen,
+		       ba *plaintext, ba *key, ba* ciphertext)
+{
+	if (plaintext->len != 16) {
+		printf("invalid block len\n");
+		return -EINVAL;
+	}
+	if (key->len != keylen) {
+		printf("invalid keylen\n");
+		return -EINVAL;
+	}
+
+	ba *state[4] = {
+		ba_alloc(4),
+		ba_alloc(4),
+		ba_alloc(4),
+		ba_alloc(4),
+	};
+
+	for (int i = 0; i < 16; i++) {
+		(state[i/4]->val)[i%4] = plaintext->val[i];
+	}
+
+	ba *round_keys[4*(rounds + 1)];
+	key_expansion(key, keylen, rounds, round_keys);
+
+	for (int i = 0; i < 4*(rounds + 1); i++) {
+		ba_fprint(round_keys[i], stdout, 0);
+		printf("\n");
+	}
+
+
+	/*
+	add_round_key(state, round_keys[0]);
+	for round
+		sub_bytes
+		shift_rows
+		mix_columns
+		add_round_key
+	sub_bytes
+	shift_rows
+	add_round_key(state, round_keys[rounds]);
+	*/
+
+	ciphertext = ba_alloc(16);
+	for (int i = 0; i < 16; i++) {
+		 ciphertext->val[i] = (state[i/4]->val)[i%4];
+	}
+
+	return 0;
+}
+
+int aes_128_encrypt(ba *plaintext, ba *key, ba *ciphertext)
+{
+	return aes_generic(10, 16, plaintext, key, ciphertext);
+}
+
+int aes_192_encrypt(ba *plaintext, ba *key, ba *ciphertext)
+{
+	return aes_generic(12, 24, plaintext, key, ciphertext);
+}
+
+int aes_256_encrypt(ba *plaintext, ba *key, ba *ciphertext)
+{
+	return aes_generic(14, 32, plaintext, key, ciphertext);
+}
+
diff --git a/lib/aes.h b/lib/aes.h
@@ -0,0 +1,14 @@
+#ifndef AES_H_1e491544
+#define AES_H_1e491544
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include "ba.h"
+
+int aes_128_encrypt(ba *plaintext, ba *key, ba *ciphertext);
+int aes_192_encrypt(ba *plaintext, ba *key, ba *ciphertext);
+int aes_256_encrypt(ba *plaintext, ba *key, ba *ciphertext);
+
+#endif
diff --git a/src/s1/c7.c b/src/s1/c7.c
@@ -3,10 +3,11 @@
 #include <string.h>
 #include <ba.h>
 #include <util.h>
+#include <aes.h>
 
 int main(int argc, char *argv[])
 {
-	unsigned char *key = (unsigned char*) "YELLOW SUBMARINE";
+	char *key = "YELLOW SUBMARINE";
 	char line[256];
 	int pt_len;
 	char *b64;
@@ -27,6 +28,15 @@ int main(int argc, char *argv[])
 	}
 
 	base64_to_hex(&hex, b64);
-	printf("%s\n", hex);
+	//printf("%s\n", hex);
+
+	ba *pt_ba = ba_from_string("yoyoyoyoyoyoyoyo");
+	ba *key_ba = ba_from_hex("2b7e151628aed2a6abf7158809cf4f3c");
+	ba *key_192_ba = ba_from_hex("8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b");
+	ba *ct_ba;
+
+	aes_128_encrypt(pt_ba, key_ba, ct_ba);
+	aes_192_encrypt(pt_ba, key_192_ba, ct_ba);
+
 	return 0;
 }