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MatasanoCrypto
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PKCS7 padding improved

master
Krzysztof Kwiatkowski před 9 roky
rodič
16deb8a259
revize
8345e52541
8 změnil soubory, kde provedl 504 přidání a 227 odebrání
Rozdělené zobrazení
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Zobrazit statistiky Stáhněte soubor opravy Stáhněte rozdílový soubor
  1. +199
    -206
      prj/Matasano.sublime-workspace
  2. +176
    -6
      sol/set2.c
  3. +4
    -0
      sol/set2.h
  4. +1
    -0
      src/common.c
  5. +6
    -0
      src/common.h
  6. +29
    -7
      src/enc_modes.c
  7. +73
    -7
      src/pkcs7.c
  8. +16
    -1
      src/pkcs7.h

+ 199
- 206
prj/Matasano.sublime-workspace Zobrazit soubor

@@ -4,29 +4,77 @@
"selected_items":
[
[
"test",
"test_text"
"i_buf",
"i_padded_buf"
],
[
"inpu",
"input"
"Re",
"Result_OK"
],
[
"TCASE",
"TCASE_E"
"Resu",
"Result_t"
],
[
"out",
"output_len"
"padded",
"padded_input_len"
],
[
"Resu",
"Result_OK"
"inpu",
"input_len"
],
[
"unp",
"unpad_len"
],
[
"padd",
"padding_value"
],
[
"inp",
"input_len"
],
[
"Res",
"Result_Error"
],
[
"random",
"random_bytes"
],
[
"uint",
"uint8_t"
],
[
"uin",
"uint8_t"
],
[
"u",
"uint32_t"
],
[
"at",
"attribs_openssl_enc"
],
[
"out",
"out_len"
],
[
"attri",
"attribs"
],
[
"test",
"test_text"
],
[
"TCASE",
"TCASE_E"
],
[
"ou",
"output_len"
@@ -99,10 +147,6 @@
"co",
"concatenated_blocks"
],
[
"uint",
"uint8_t"
],
[
"o_",
"o_buff_ptr"
@@ -470,50 +514,6 @@
[
"aMappingBy",
"aMappingByNumber"
],
[
"ConnectionHan",
"ConnectionHandlerInterfacePtr"
],
[
"CCNa",
"CCNBackRoutingKeyStorage::Value::Value"
],
[
"ConvI",
"CMG_ConvIndex"
],
[
"AMD_UIN",
"AMD_UInt16"
],
[
"AMD_UI",
"AMD_UInt16"
],
[
"AMD_U",
"AMD_UInt16"
],
[
"Excep",
"Exception"
],
[
"getOrigin",
"getOriginConvID"
],
[
"SEI_TRACE_",
"SEI_TRACE_WARNING"
],
[
"isCon",
"isCloseOnReply"
],
[
"TrafficEve",
"TrafficEventHandlerBase"
]
]
},
@@ -536,74 +536,75 @@
}
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"contents": "\n\n\n /// TO NIE DZIALA\n\n\n\n printf(\"DUPA\");\n CryptoAttribs_t attr;\n CryptoAttribs_t::Init(&attr);\n attr.input = (uint8_t*)malloc(16);\n memcpy(attr.input, out, 16);\n assert( ecb_decrypt(&attr, key) == Result_OK );\n printf(\"%s \\n %d\\n\", attr.output, attr.output_len);\n printf(\"DUPA\");\n\n\n\n\n\n",
"file": "/home/flowher/repos/MatasanoCrypto/src/pkcs7.c",
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@@ -645,7 +646,7 @@
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@@ -1051,18 +1052,24 @@
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@@ -1076,11 +1083,9 @@
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"/home/flowher/repos/MatasanoCrypto/sol/main.cpp",
"/home/flowher/repos/notes/crypto/eliptic.md",
@@ -1174,11 +1179,7 @@
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"/home/kkwiatkowski/valgrind.suppr",
"/home/kkwiatkowski/storage/91_Repositories/openssl101j/ssl/ssl.h",
"/home/kkwiatkowski/storage/91_Repositories/openssl101j/crypto/s390xcpuid.S",
"/home/kkwiatkowski/storage/91_Repositories/srp_client_server_implementation_with_openssl/server.cpp",
"/home/kkwiatkowski/storage/91_Repositories/openssl101j/include/openssl/symhacks.h",
"/home/kkwiatkowski/storage/91_Repositories/openssl101j/crypto/symhacks.h"
"/home/kkwiatkowski/storage/91_Repositories/openssl101j/ssl/ssl.h"
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@@ -1253,6 +1254,32 @@
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"attribs",
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@@ -1354,33 +1381,7 @@
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@@ -1446,7 +1447,7 @@
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@@ -1605,26 +1590,27 @@
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@@ -1635,148 +1621,151 @@
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@@ -1911,6 +1900,10 @@
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@@ -1931,7 +1924,7 @@
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@@ -1940,6 +1933,10 @@
"last_filter": "",
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[
"common",
"MatasanoCrypto/src/common.c"
],
[
"common.c",
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@@ -2447,10 +2444,6 @@
[
"timer",
"HPT-13/src/TimersManager.cpp"
],
[
"cmdnewsetdelbasepeakversiontest",
"SI/masteragent/test/src/CmdNewSetDelBasePeakVersionTest.cpp"
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@@ -2757,7 +2750,7 @@
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+ 176
- 6
sol/set2.c Zobrazit soubor

@@ -3,7 +3,10 @@
#include "src/enc_modes.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <time.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <assert.h>
@@ -42,6 +45,8 @@ struct OpenSSL
}
};



TCASE(ecb_encrypt_decrypt_single_block)
{
static const uint8_t expected_result[17] = "0123456789123456";
@@ -77,21 +82,28 @@ TCASE_E

TCASE(pkcs7_test)
{
// int pkcs7_pad(const char* i_buff, const size_t i_len, char* o_buff );
const char text1[] = "Text1";
const char text2[] = "Text2ToPad";
const uint8_t text1[] = "Text1";
uint8_t unpadded[32] = {0};
uint8_t* p_unpadded = &unpadded[0];

int ret;
char buff1[32];
uint8_t buff1[32];
uint8_t* p_buff1 = &buff1[0];
char buff2[10];

ret = pkcs7_pad(text1, 5, buff1, 32);
CHECK(ret==0, (const unsigned char* const) "Padding operation failed");
ret = pkcs7_pad(text1, 5, &p_buff1, 32);
CHECK(ret==true, (const unsigned char* const) "Padding operation failed");
ret = memcmp(text1, buff1, 5);
CHECK(ret==0, (const unsigned char* const) "Content differs");
for(int i=5; i<32; i++)
{
CHECK(buff1[i] == 27, (const unsigned char* const) "Wrong padding");
}

size_t unpad_len = 0;
CHECK( true == pkcs7_unpad(&buff1[0], 32, &p_unpadded, &unpad_len) );
CHECK(unpad_len == 5, (const uint8_t*) "Unpadded length wrong");
CHECK( 0==memcmp(text1, unpadded, unpad_len) );
}
TCASE_E

@@ -250,3 +262,161 @@ TCASE(encode_decode_openssl)
}
}
TCASE_E

/* -------------------------------------------------------------------------
Checks if ciphertext is encrypted with ECB or CBC.
Requirement: In order to work, plaintext must encrypt to 6 blocks
and all the letters in the PT must be exactly the same.
Returns:
* 0 : if ciphertext encrypted with ECB
* 1 : if ciphertext encrypted with CBC
* 0xFF: in case wrong input parameters provided
-------------------------------------------------------------------------*/
uint8_t check_ciphertext(const uint8_t* ciphertext, uint32_t len )
{
uint32_t bs = 16;
if( (len < 6*bs) || (len>7*bs) )
return 0xFF;

for(uint32_t i=1; i<6; ++i)
{
if( memcmp(ciphertext+(bs*i), ciphertext+(bs*(i+1)), bs) != 0)
return 1; // Two blocks differ -> must be CBC
}
return 0; // All checked blocks are the same -> ECB
}

Result_t encryption_oracle(
const uint8_t* pt,
uint32_t pt_len,
uint8_t* ct,
uint32_t* ct_len,
uint8_t* mode)
{
uint8_t iv1[16] = {0};
uint8_t key[16] = {0};
uint8_t prepend_byte_size;
uint8_t append_byte_size;
uint8_t random_bytes[10];
uint8_t encryption_mode = 0xFF;
struct timespec tv;
CryptoAttribs_t attribs;
Key_t keyObj;

// seed randomnes
clock_gettime(CLOCK_MONOTONIC, &tv);
srand((unsigned int)tv.tv_nsec);

// choose random sizes and enc mode (0 ECB, 1 CBC)
prepend_byte_size = 5+(rand() % 6);
append_byte_size = 5+(rand() % 6);
encryption_mode = rand() % 2;

// generate rando data
RAND_bytes(iv1, 16);
RAND_bytes(key, 16);

// initialize encryption attribs
CryptoAttribs_t::Init(&attribs);
attribs.operation = kEncrypt;
attribs.input_len = (5*16) + prepend_byte_size + append_byte_size;
attribs.input = (uint8_t*)malloc(attribs.input_len);
attribs.output_len = 7*16;
attribs.output = (uint8_t*)malloc(7*16);
attribs.padding = kPadding_PKCS7;

// copy input to the input buffer
RAND_bytes(random_bytes, prepend_byte_size);
int tmplen=0;
memcpy(attribs.input+tmplen, random_bytes, prepend_byte_size);
tmplen+=prepend_byte_size;
memcpy(attribs.input+tmplen, pt, pt_len);
tmplen+=pt_len;
RAND_bytes(random_bytes, append_byte_size);
memcpy(attribs.input+tmplen, random_bytes, append_byte_size);
tmplen+=append_byte_size;

// key
Key_t::Init(&keyObj);
keyObj.key = key;
keyObj.len = 16;

if(encryption_mode)
{
attribs.iv = (uint8_t*)malloc(16);
attribs.iv_len = 16;
RAND_bytes(attribs.iv, 16);
if( Result_OK!=cbc_encrypt(&attribs, &keyObj) )
return Result_Error;
}
else
{
if( Result_OK!=ecb_encrypt(&attribs, &keyObj) )
return Result_Error;
}

// Copy results
memcpy(ct, attribs.output, attribs.output_len);
*ct_len = attribs.output_len;
*mode = encryption_mode;

CryptoAttribs_t::Free(&attribs);
return Result_OK;
}

TCASE(encode_oracle_test)
{
uint8_t plaintext[5*16] = {0};
uint8_t ciphertext[7*16] = {0};
uint8_t mode = 0xFF;
uint8_t guessed_mode = 0xFF;
uint32_t ciphertext_len = 7*16;

// set data in blocks so that
// first block will be filled with 111...
// second block with 2222...
// ...
memset(plaintext, 1, 5*16);
Result_t ret = encryption_oracle(plaintext, 5*16, ciphertext, &ciphertext_len, &mode);
CHECK(ret == Result_OK, (uint8_t*)"Error occured on encryption");
CHECK(mode != 0xFF);

guessed_mode = check_ciphertext(ciphertext, ciphertext_len);
CHECK(mode == guessed_mode);
}
TCASE_E

TCASE(encrypt_padding_pkcs7)
{
/* char text[] = "ABC";
char iv[16] = {0};

CryptoAttribs_t attribs_enc;
CryptoAttribs_t::Init(&attribs_enc);
attribs_enc.input = &text[0];
attribs_enc.input_len = sizeof(text);
attribs_enc.iv = &iv1[0];
attribs_enc.iv_len = sizeof(iv1);
attribs_enc.operation = kEncrypt;
attribs_enc.padding = kPadding_PKCS7;
CHECK( Result_OK == cbc_encrypt(&attribs_enc, &keyObj) );

CryptoAttribs_t attribs_openssl_dec;
CryptoAttribs_t::Init(&attribs_openssl_dec);
attribs_openssl_dec.input = attribs_enc.output;
attribs_openssl_dec.input_len = attribs_enc.output_len;
attribs_openssl_dec.iv = &iv1[0];
attribs_openssl_dec.iv_len = sizeof(iv1);
attribs_openssl_dec.operation = kDecrypt;
CHECK(OpenSSL::Cbc(&attribs_openssl_dec, &keyObj)==Result_OK);
CHECK(attribs_openssl_dec.output_len==48, (uint8_t*)"Ciphertext has wrong size");
CHECK(
memcmp( concatenated_blocks,
attribs_openssl_dec.output,
attribs_openssl_dec.output_len) == 0,
(uint8_t*)"Input/Output differs");
::free(attribs_enc.output);
::free(attribs_openssl_dec.output);
*/
}
TCASE_E

+ 4
- 0
sol/set2.h Zobrazit soubor

@@ -6,6 +6,8 @@ void cbc_decrypt_test();
void cbc_enc_dec_test();
void ecb_encrypt_decrypt_single_block();
void encode_decode_openssl();
void encode_oracle_test();
void encrypt_padding_pkcs7();

struct SET2
{
@@ -16,6 +18,8 @@ struct SET2
encode_decode_openssl();
cbc_decrypt_test();
cbc_enc_dec_test();
encode_oracle_test();
encrypt_padding_pkcs7();
}
};



+ 1
- 0
src/common.c Zobrazit soubor

@@ -115,6 +115,7 @@ void CryptoAttribs_t::Init(CryptoAttribs_t* ctx)
ctx->input = NULL;
ctx->input_len = 0;
ctx->operation = kEncrypt;
ctx->padding = kPadding_None;
}

void CryptoAttribs_t::Free(CryptoAttribs_t* ctx)


+ 6
- 0
src/common.h Zobrazit soubor

@@ -42,6 +42,11 @@ typedef enum {
kDecrypt = 1
} CryptoOperation;

typedef enum {
kPadding_None = 0,
kPadding_PKCS7
} PaddingType;

/* -------------------------------------------------------------------------
Struct used for symmetric encryption
-------------------------------------------------------------------------*/
@@ -53,6 +58,7 @@ struct CryptoAttribs_t {
uint8_t* iv;
size_t iv_len;
CryptoOperation operation;
PaddingType padding;

static void Init(CryptoAttribs_t* ctx);
static void Free(CryptoAttribs_t* ctx);


+ 29
- 7
src/enc_modes.c Zobrazit soubor

@@ -7,6 +7,7 @@
#include "xor.h"
#include "base64.h" // to del
#include <openssl/err.h>
#include "pkcs7.h"

static Result_t crypt( CryptoAttribs_t* attribs,
const Key_t* const key)
@@ -33,8 +34,10 @@ static Result_t crypt( CryptoAttribs_t* attribs,
(attribs->operation == kEncrypt ? 1 : 0)) );
OP_CHECK( EVP_CIPHER_CTX_iv_length(&ctx) == 0);
EVP_CIPHER_CTX_set_padding(&ctx, 0);
// printf("ZZ %d\n", ret);
OP_CHECK( EVP_CipherUpdate(&ctx, &out[ret], &ret, attribs->input, attribs->input_len) );
attribs->output_len = ret;
// printf("OO %d\n", ret);
OP_CHECK( EVP_CipherFinal_ex(&ctx, &out[ret], &ret) );
attribs->output_len += ret;
EVP_CIPHER_CTX_cleanup(&ctx);
@@ -105,18 +108,32 @@ Result_t cbc_encrypt(
CryptoAttribs_t* attribs,
const Key_t* const key)
{

if((attribs->input_len % key->len) != 0 )
return Result_Error;

if( attribs->iv_len != key->len )
return Result_Error;

if( key->len == 0 )
return Result_Error;

const size_t bc = attribs->input_len / key->len;
uint8_t* padded_input = NULL;
size_t new_buf_len = 0;
if( attribs->padding == kPadding_PKCS7 )
{
new_buf_len = ROUNDUP_16_BYTES(attribs->input_len);
// one block extra if size aligned
if(new_buf_len == attribs->input_len)
new_buf_len += 16;
pkcs7_pad(attribs->input, attribs->input_len, &padded_input, new_buf_len);
}
else
{
if((attribs->input_len % key->len) != 0 )
return Result_Error;
}

const size_t bc_without_last = (size_t)( attribs->input_len / key->len );
const size_t bc = bc_without_last + 1;
const size_t bs = key->len;
const size_t last_bs = attribs->input_len % bs;

if( attribs->output == NULL)
{
@@ -133,6 +150,7 @@ Result_t cbc_encrypt(
ecb_attribs.input_len = 0;
ecb_attribs.output = (uint8_t*)malloc(bs);
ecb_attribs.output_len = 0;
Result_t ret = Result_OK;
for(int i=0; i<bc; ++i)
{
uint8_t* buffptr = (attribs->input)+(bs*i);
@@ -147,7 +165,10 @@ Result_t cbc_encrypt(
// 2. Encrypt
ecb_attribs.operation = kEncrypt;
if( crypt(&ecb_attribs, key) != Result_OK )
return Result_Error;
{
ret = Result_Error;
break;
}

// Encrypted block is my new IV
iv = ecb_attribs.output;
@@ -159,7 +180,8 @@ Result_t cbc_encrypt(
attribs->output_len += ecb_attribs.output_len;
}
CryptoAttribs_t::Free(&ecb_attribs);
return Result_OK;
::free(padded_input);
return ret;
}

Result_t ecb_encrypt( CryptoAttribs_t* attribs, const Key_t* const key )


+ 73
- 7
src/pkcs7.c Zobrazit soubor

@@ -1,17 +1,83 @@
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>

int pkcs7_pad(const char* i_buff, size_t i_len, char* o_buff, size_t i_obuff_len )

/* -----------------------------------------------------------------------------
* @brief Produces PKCS7 padded buffer from unpadded buffer
*
* @param i_buff: unpadded buffer
* i_len : length of unpadded buffer
* o_buff: padded output. If pointer *o_buff NULL then memory is allocated
* i_obuff_len: requested size of the output buffer
*
* @returns false if:
* * pad value is bigger then 0xFF. In such case o_buff is unchanged.
* * i_obuff_len < i_len
* * o_buff: NULL
* Otherwise true.
*
-------------------------------------------------------------------------------- */
bool pkcs7_pad(const uint8_t* i_buff, size_t i_len, uint8_t** o_buff, size_t i_obuff_len )
{
if(i_obuff_len < i_len )
if( (i_obuff_len < i_len ) ||
(i_obuff_len - i_len > 0xFF) ||
(o_buff == NULL) )
{
return -1;
return false;
}
if(NULL == *o_buff )
{
*o_buff = (uint8_t*) malloc(i_obuff_len);
}

const unsigned pad_value = i_obuff_len - i_len;
memset(o_buff, pad_value, i_obuff_len);
memcpy(o_buff, i_buff, i_len);
memset(*o_buff, pad_value, i_obuff_len);
memcpy(*o_buff, i_buff, i_len);

return true;
}

/* -----------------------------------------------------------------------------
* @brief Removes padding from PKCS7 padded buffer
*
* @param i_padded_buf: padded buffer
* i_len : length of padded buffer
* o_unpad_buf: unpadded output. If pointer *o_buff NULL then memory is allocated
* unpad_len: length of unpadded buffer
*
* @returns false if:
* * any of pointers NULL
* * i_len == 0
* * pad_value > 0xFF
* Otherwise true.
*
-------------------------------------------------------------------------------- */
bool pkcs7_unpad( const uint8_t* i_padded_buf,
size_t i_len,
uint8_t** o_unpad_buf,
size_t* unpad_len)
{
if( i_padded_buf== NULL ||
unpad_len == NULL ||
o_unpad_buf == NULL ||
i_len == 0)
{
return false;
}

const unsigned pad_val = i_padded_buf[i_len - 1];
if(pad_val > 0xFF)
{
return false;
}

*unpad_len = i_len - pad_val;
if(*o_unpad_buf == NULL)
{
*o_unpad_buf = (uint8_t*) malloc(*unpad_len);
}

return 0;
memcpy(*o_unpad_buf, i_padded_buf, *unpad_len);
return true;
}

+ 16
- 1
src/pkcs7.h Zobrazit soubor

@@ -1,2 +1,17 @@
#ifndef __pkcs7_h__
#define __pkcs7_h__

#include <stdlib.h>
int pkcs7_pad(const char* i_buff, size_t i_len, char* o_buff, size_t i_obuff_len );
#include <stdint.h>

bool pkcs7_pad( const uint8_t* i_buff,
size_t i_len,
uint8_t** o_buff,
size_t i_obuff_len );

bool pkcs7_unpad( const uint8_t* i_padded_buf,
size_t i_len,
uint8_t** o_unpad_buf,
size_t* unpad_len);

#endif // __pkcs7_h__

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