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cts128.c: add support for NIST "Ciphertext Stealing" proposal.

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This commit is contained in:
Andy Polyakov 2010-04-10 14:01:02 +00:00
parent 6c83629bd9
commit 67a315b60b
2 changed files with 227 additions and 9 deletions
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223
crypto/modes/cts128.c
View File

@ -23,8 +23,9 @@
* deviates from mentioned RFCs. Most notably it allows input to be
* of block length and it doesn't flip the order of the last two
* blocks. CTS is being discussed even in ECB context, but it's not
* adopted for any known application. This implementation complies
* with mentioned RFCs and [as such] extends CBC mode.
* adopted for any known application. This implementation provides
* two interfaces: one compliant with above mentioned RFCs and one
* compliant with the NIST proposal, both extending CBC mode.
*/
size_t CRYPTO_cts128_encrypt_block(const unsigned char *in, unsigned char *out,
@ -54,6 +55,34 @@ size_t CRYPTO_cts128_encrypt_block(const unsigned char *in, unsigned char *out,
return len+residue;
}
size_t CRYPTO_nistcts128_encrypt_block(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], block128_f block)
{ size_t residue, n;
assert (in && out && key && ivec);
if (len < 16) return 0;
residue=len%16;
len -= residue;
CRYPTO_cbc128_encrypt(in,out,len,key,ivec,block);
if (residue==0) return len;
in += len;
out += len;
for (n=0; n<residue; ++n)
ivec[n] ^= in[n];
(*block)(ivec,ivec,key);
memcpy(out-16+residue,ivec,16);
return len+residue;
}
size_t CRYPTO_cts128_encrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc)
@ -90,6 +119,41 @@ size_t CRYPTO_cts128_encrypt(const unsigned char *in, unsigned char *out,
return len+residue;
}
size_t CRYPTO_nistcts128_encrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc)
{ size_t residue;
union { size_t align; unsigned char c[16]; } tmp;
assert (in && out && key && ivec);
if (len < 16) return 0;
residue=len%16;
len -= residue;
(*cbc)(in,out,len,key,ivec,1);
if (residue==0) return len;
in += len;
out += len;
#if defined(CBC_HANDLES_TRUNCATED_IO)
(*cbc)(in,out-16+residue,residue,key,ivec,1);
#else
{
size_t n;
for (n=0; n<16; n+=sizeof(size_t))
*(size_t *)(tmp.c+n) = 0;
memcpy(tmp.c,in,residue);
}
(*cbc)(tmp.c,out-16+residue,16,key,ivec,1);
#endif
return len+residue;
}
size_t CRYPTO_cts128_decrypt_block(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], block128_f block)
@ -125,7 +189,51 @@ size_t CRYPTO_cts128_decrypt_block(const unsigned char *in, unsigned char *out,
for(residue+=16; n<residue; ++n)
out[n] = tmp.c[n] ^ in[n];
return len+residue-16;
return 16+len+residue;
}
size_t CRYPTO_nistcts128_decrypt_block(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], block128_f block)
{ size_t residue, n;
union { size_t align; unsigned char c[32]; } tmp;
assert (in && out && key && ivec);
if (len<16) return 0;
residue=len%16;
if (residue==0) {
CRYPTO_cbc128_decrypt(in,out,len,key,ivec,block);
return len;
}
len -= 16+residue;
if (len) {
CRYPTO_cbc128_decrypt(in,out,len,key,ivec,block);
in += len;
out += len;
}
(*block)(in+residue,tmp.c+16,key);
for (n=0; n<16; n+=sizeof(size_t))
*(size_t *)(tmp.c+n) = *(size_t *)(tmp.c+16+n);
memcpy(tmp.c,in,residue);
(*block)(tmp.c,tmp.c,key);
for(n=0; n<16; ++n) {
unsigned char c = in[n];
out[n] = tmp.c[n] ^ ivec[n];
ivec[n] = in[n+residue];
tmp.c[n] = c;
}
for(residue+=16; n<residue; ++n)
out[n] = tmp.c[n] ^ tmp.c[n-16];
return 16+len+residue;
}
size_t CRYPTO_cts128_decrypt(const unsigned char *in, unsigned char *out,
@ -160,7 +268,47 @@ size_t CRYPTO_cts128_decrypt(const unsigned char *in, unsigned char *out,
(*cbc)(tmp.c,tmp.c,32,key,ivec,0);
memcpy(out,tmp.c,16+residue);
#endif
return len+residue;
return 16+len+residue;
}
size_t CRYPTO_nistcts128_decrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc)
{ size_t residue, n;
union { size_t align; unsigned char c[32]; } tmp;
assert (in && out && key && ivec);
if (len<16) return 0;
residue=len%16;
if (residue==0) {
(*cbc)(in,out,len,key,ivec,0);
return len;
}
len -= 16+residue;
if (len) {
(*cbc)(in,out,len,key,ivec,0);
in += len;
out += len;
}
for (n=16; n<32; n+=sizeof(size_t))
*(size_t *)(tmp.c+n) = 0;
/* this places in[16] at &tmp.c[16] and decrypted block at &tmp.c[0] */
(*cbc)(in+residue,tmp.c,16,key,tmp.c+16,0);
memcpy(tmp.c,in,residue);
#if defined(CBC_HANDLES_TRUNCATED_IO)
(*cbc)(tmp.c,out,16+residue,key,ivec,0);
#else
(*cbc)(tmp.c,tmp.c,32,key,ivec,0);
memcpy(out,tmp.c,16+residue);
#endif
return 16+len+residue;
}
#if defined(SELFTEST)
@ -200,9 +348,8 @@ static const unsigned char vector_64[64] =
static AES_KEY encks, decks;
void test_vector(const unsigned char *vector,size_t len)
{ unsigned char cleartext[64];
unsigned char iv[sizeof(test_iv)];
unsigned char ciphertext[64];
{ unsigned char iv[sizeof(test_iv)];
unsigned char cleartext[64],ciphertext[64];
size_t tail;
printf("vector_%d\n",len); fflush(stdout);
@ -243,7 +390,57 @@ void test_vector(const unsigned char *vector,size_t len)
fprintf(stderr,"iv_%d mismatch\n",len), exit(4);
}
main()
void test_nistvector(const unsigned char *vector,size_t len)
{ unsigned char iv[sizeof(test_iv)];
unsigned char cleartext[64],ciphertext[64],nistvector[64];
size_t tail;
printf("nistvector_%d\n",len); fflush(stdout);
if ((tail=len%16) == 0) tail = 16;
len -= 16 + tail;
memcpy(nistvector,vector,len);
/* flip two last blocks */
memcpy(nistvector+len,vector+len+16,tail);
memcpy(nistvector+len+tail,vector+len,16);
len += 16 + tail;
tail = 16;
/* test block-based encryption */
memcpy(iv,test_iv,sizeof(test_iv));
CRYPTO_nistcts128_encrypt_block(test_input,ciphertext,len,&encks,iv,(block128_f)AES_encrypt);
if (memcmp(ciphertext,nistvector,len))
fprintf(stderr,"output_%d mismatch\n",len), exit(1);
if (memcmp(iv,nistvector+len-tail,sizeof(iv)))
fprintf(stderr,"iv_%d mismatch\n",len), exit(1);
/* test block-based decryption */
memcpy(iv,test_iv,sizeof(test_iv));
CRYPTO_nistcts128_decrypt_block(ciphertext,cleartext,len,&decks,iv,(block128_f)AES_decrypt);
if (memcmp(cleartext,test_input,len))
fprintf(stderr,"input_%d mismatch\n",len), exit(2);
if (memcmp(iv,nistvector+len-tail,sizeof(iv)))
fprintf(stderr,"iv_%d mismatch\n",len), exit(2);
/* test streamed encryption */
memcpy(iv,test_iv,sizeof(test_iv));
CRYPTO_nistcts128_encrypt(test_input,ciphertext,len,&encks,iv,(cbc128_f)AES_cbc_encrypt);
if (memcmp(ciphertext,nistvector,len))
fprintf(stderr,"output_%d mismatch\n",len), exit(3);
if (memcmp(iv,nistvector+len-tail,sizeof(iv)))
fprintf(stderr,"iv_%d mismatch\n",len), exit(3);
/* test streamed decryption */
memcpy(iv,test_iv,sizeof(test_iv));
CRYPTO_nistcts128_decrypt(ciphertext,cleartext,len,&decks,iv,(cbc128_f)AES_cbc_encrypt);
if (memcmp(cleartext,test_input,len))
fprintf(stderr,"input_%d mismatch\n",len), exit(4);
if (memcmp(iv,nistvector+len-tail,sizeof(iv)))
fprintf(stderr,"iv_%d mismatch\n",len), exit(4);
}
int main()
{
AES_set_encrypt_key(test_key,128,&encks);
AES_set_decrypt_key(test_key,128,&decks);
@ -254,6 +451,14 @@ main()
test_vector(vector_47,sizeof(vector_47));
test_vector(vector_48,sizeof(vector_48));
test_vector(vector_64,sizeof(vector_64));
exit(0);
test_nistvector(vector_17,sizeof(vector_17));
test_nistvector(vector_31,sizeof(vector_31));
test_nistvector(vector_32,sizeof(vector_32));
test_nistvector(vector_47,sizeof(vector_47));
test_nistvector(vector_48,sizeof(vector_48));
test_nistvector(vector_64,sizeof(vector_64));
return 0;
}
#endif

13
crypto/modes/modes.h
View File

@ -57,3 +57,16 @@ size_t CRYPTO_cts128_decrypt_block(const unsigned char *in, unsigned char *out,
size_t CRYPTO_cts128_decrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc);
size_t CRYPTO_nistcts128_encrypt_block(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], block128_f block);
size_t CRYPTO_nistcts128_encrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc);
size_t CRYPTO_nistcts128_decrypt_block(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], block128_f block);
size_t CRYPTO_nistcts128_decrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], cbc128_f cbc);