563 lines
16 KiB
C
563 lines
16 KiB
C
/*
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* Copyright 2014-2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <string.h>
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#include <openssl/crypto.h>
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#include <openssl/err.h>
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#include "modes_local.h"
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#ifndef OPENSSL_NO_OCB
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/*
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* Calculate the number of binary trailing zero's in any given number
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*/
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static u32 ocb_ntz(u64 n)
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{
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u32 cnt = 0;
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/*
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* We do a right-to-left simple sequential search. This is surprisingly
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* efficient as the distribution of trailing zeros is not uniform,
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* e.g. the number of possible inputs with no trailing zeros is equal to
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* the number with 1 or more; the number with exactly 1 is equal to the
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* number with 2 or more, etc. Checking the last two bits covers 75% of
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* all numbers. Checking the last three covers 87.5%
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*/
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while (!(n & 1)) {
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n >>= 1;
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cnt++;
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}
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return cnt;
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}
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/*
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* Shift a block of 16 bytes left by shift bits
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*/
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static void ocb_block_lshift(const unsigned char *in, size_t shift,
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unsigned char *out)
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{
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int i;
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unsigned char carry = 0, carry_next;
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for (i = 15; i >= 0; i--) {
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carry_next = in[i] >> (8 - shift);
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out[i] = (in[i] << shift) | carry;
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carry = carry_next;
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}
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}
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/*
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* Perform a "double" operation as per OCB spec
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*/
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static void ocb_double(OCB_BLOCK *in, OCB_BLOCK *out)
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{
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unsigned char mask;
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/*
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* Calculate the mask based on the most significant bit. There are more
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* efficient ways to do this - but this way is constant time
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*/
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mask = in->c[0] & 0x80;
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mask >>= 7;
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mask = (0 - mask) & 0x87;
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ocb_block_lshift(in->c, 1, out->c);
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out->c[15] ^= mask;
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}
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/*
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* Perform an xor on in1 and in2 - each of len bytes. Store result in out
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*/
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static void ocb_block_xor(const unsigned char *in1,
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const unsigned char *in2, size_t len,
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unsigned char *out)
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{
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size_t i;
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for (i = 0; i < len; i++) {
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out[i] = in1[i] ^ in2[i];
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}
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}
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/*
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* Lookup L_index in our lookup table. If we haven't already got it we need to
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* calculate it
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*/
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static OCB_BLOCK *ocb_lookup_l(OCB128_CONTEXT *ctx, size_t idx)
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{
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size_t l_index = ctx->l_index;
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if (idx <= l_index) {
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return ctx->l + idx;
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}
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/* We don't have it - so calculate it */
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if (idx >= ctx->max_l_index) {
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void *tmp_ptr;
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/*
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* Each additional entry allows to process almost double as
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* much data, so that in linear world the table will need to
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* be expanded with smaller and smaller increments. Originally
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* it was doubling in size, which was a waste. Growing it
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* linearly is not formally optimal, but is simpler to implement.
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* We grow table by minimally required 4*n that would accommodate
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* the index.
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*/
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ctx->max_l_index += (idx - ctx->max_l_index + 4) & ~3;
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tmp_ptr = OPENSSL_realloc(ctx->l, ctx->max_l_index * sizeof(OCB_BLOCK));
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if (tmp_ptr == NULL) /* prevent ctx->l from being clobbered */
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return NULL;
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ctx->l = tmp_ptr;
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}
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while (l_index < idx) {
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ocb_double(ctx->l + l_index, ctx->l + l_index + 1);
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l_index++;
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}
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ctx->l_index = l_index;
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return ctx->l + idx;
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}
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/*
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* Create a new OCB128_CONTEXT
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*/
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OCB128_CONTEXT *CRYPTO_ocb128_new(void *keyenc, void *keydec,
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block128_f encrypt, block128_f decrypt,
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ocb128_f stream)
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{
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OCB128_CONTEXT *octx;
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int ret;
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if ((octx = OPENSSL_malloc(sizeof(*octx))) != NULL) {
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ret = CRYPTO_ocb128_init(octx, keyenc, keydec, encrypt, decrypt,
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stream);
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if (ret)
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return octx;
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OPENSSL_free(octx);
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}
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return NULL;
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}
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/*
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* Initialise an existing OCB128_CONTEXT
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*/
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int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
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block128_f encrypt, block128_f decrypt,
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ocb128_f stream)
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{
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memset(ctx, 0, sizeof(*ctx));
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ctx->l_index = 0;
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ctx->max_l_index = 5;
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if ((ctx->l = OPENSSL_malloc(ctx->max_l_index * 16)) == NULL) {
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CRYPTOerr(CRYPTO_F_CRYPTO_OCB128_INIT, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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/*
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* We set both the encryption and decryption key schedules - decryption
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* needs both. Don't really need decryption schedule if only doing
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* encryption - but it simplifies things to take it anyway
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*/
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ctx->encrypt = encrypt;
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ctx->decrypt = decrypt;
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ctx->stream = stream;
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ctx->keyenc = keyenc;
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ctx->keydec = keydec;
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/* L_* = ENCIPHER(K, zeros(128)) */
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ctx->encrypt(ctx->l_star.c, ctx->l_star.c, ctx->keyenc);
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/* L_$ = double(L_*) */
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ocb_double(&ctx->l_star, &ctx->l_dollar);
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/* L_0 = double(L_$) */
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ocb_double(&ctx->l_dollar, ctx->l);
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/* L_{i} = double(L_{i-1}) */
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ocb_double(ctx->l, ctx->l+1);
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ocb_double(ctx->l+1, ctx->l+2);
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ocb_double(ctx->l+2, ctx->l+3);
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ocb_double(ctx->l+3, ctx->l+4);
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ctx->l_index = 4; /* enough to process up to 496 bytes */
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return 1;
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}
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/*
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* Copy an OCB128_CONTEXT object
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*/
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int CRYPTO_ocb128_copy_ctx(OCB128_CONTEXT *dest, OCB128_CONTEXT *src,
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void *keyenc, void *keydec)
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{
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memcpy(dest, src, sizeof(OCB128_CONTEXT));
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if (keyenc)
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dest->keyenc = keyenc;
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if (keydec)
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dest->keydec = keydec;
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if (src->l) {
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if ((dest->l = OPENSSL_malloc(src->max_l_index * 16)) == NULL) {
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CRYPTOerr(CRYPTO_F_CRYPTO_OCB128_COPY_CTX, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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memcpy(dest->l, src->l, (src->l_index + 1) * 16);
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}
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return 1;
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}
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/*
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* Set the IV to be used for this operation. Must be 1 - 15 bytes.
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*/
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int CRYPTO_ocb128_setiv(OCB128_CONTEXT *ctx, const unsigned char *iv,
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size_t len, size_t taglen)
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{
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unsigned char ktop[16], tmp[16], mask;
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unsigned char stretch[24], nonce[16];
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size_t bottom, shift;
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/*
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* Spec says IV is 120 bits or fewer - it allows non byte aligned lengths.
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* We don't support this at this stage
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*/
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if ((len > 15) || (len < 1) || (taglen > 16) || (taglen < 1)) {
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return -1;
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}
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/* Reset nonce-dependent variables */
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memset(&ctx->sess, 0, sizeof(ctx->sess));
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/* Nonce = num2str(TAGLEN mod 128,7) || zeros(120-bitlen(N)) || 1 || N */
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nonce[0] = ((taglen * 8) % 128) << 1;
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memset(nonce + 1, 0, 15);
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memcpy(nonce + 16 - len, iv, len);
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nonce[15 - len] |= 1;
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/* Ktop = ENCIPHER(K, Nonce[1..122] || zeros(6)) */
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memcpy(tmp, nonce, 16);
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tmp[15] &= 0xc0;
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ctx->encrypt(tmp, ktop, ctx->keyenc);
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/* Stretch = Ktop || (Ktop[1..64] xor Ktop[9..72]) */
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memcpy(stretch, ktop, 16);
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ocb_block_xor(ktop, ktop + 1, 8, stretch + 16);
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/* bottom = str2num(Nonce[123..128]) */
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bottom = nonce[15] & 0x3f;
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/* Offset_0 = Stretch[1+bottom..128+bottom] */
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shift = bottom % 8;
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ocb_block_lshift(stretch + (bottom / 8), shift, ctx->sess.offset.c);
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mask = 0xff;
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mask <<= 8 - shift;
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ctx->sess.offset.c[15] |=
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(*(stretch + (bottom / 8) + 16) & mask) >> (8 - shift);
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return 1;
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}
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/*
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* Provide any AAD. This can be called multiple times. Only the final time can
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* have a partial block
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*/
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int CRYPTO_ocb128_aad(OCB128_CONTEXT *ctx, const unsigned char *aad,
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size_t len)
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{
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u64 i, all_num_blocks;
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size_t num_blocks, last_len;
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OCB_BLOCK tmp;
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/* Calculate the number of blocks of AAD provided now, and so far */
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num_blocks = len / 16;
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all_num_blocks = num_blocks + ctx->sess.blocks_hashed;
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/* Loop through all full blocks of AAD */
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for (i = ctx->sess.blocks_hashed + 1; i <= all_num_blocks; i++) {
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OCB_BLOCK *lookup;
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/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
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lookup = ocb_lookup_l(ctx, ocb_ntz(i));
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if (lookup == NULL)
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return 0;
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ocb_block16_xor(&ctx->sess.offset_aad, lookup, &ctx->sess.offset_aad);
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memcpy(tmp.c, aad, 16);
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aad += 16;
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/* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
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ocb_block16_xor(&ctx->sess.offset_aad, &tmp, &tmp);
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ctx->encrypt(tmp.c, tmp.c, ctx->keyenc);
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ocb_block16_xor(&tmp, &ctx->sess.sum, &ctx->sess.sum);
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}
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/*
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* Check if we have any partial blocks left over. This is only valid in the
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* last call to this function
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*/
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last_len = len % 16;
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if (last_len > 0) {
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/* Offset_* = Offset_m xor L_* */
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ocb_block16_xor(&ctx->sess.offset_aad, &ctx->l_star,
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&ctx->sess.offset_aad);
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/* CipherInput = (A_* || 1 || zeros(127-bitlen(A_*))) xor Offset_* */
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memset(tmp.c, 0, 16);
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memcpy(tmp.c, aad, last_len);
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tmp.c[last_len] = 0x80;
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ocb_block16_xor(&ctx->sess.offset_aad, &tmp, &tmp);
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/* Sum = Sum_m xor ENCIPHER(K, CipherInput) */
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ctx->encrypt(tmp.c, tmp.c, ctx->keyenc);
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ocb_block16_xor(&tmp, &ctx->sess.sum, &ctx->sess.sum);
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}
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ctx->sess.blocks_hashed = all_num_blocks;
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return 1;
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}
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/*
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* Provide any data to be encrypted. This can be called multiple times. Only
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* the final time can have a partial block
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*/
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int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
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const unsigned char *in, unsigned char *out,
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size_t len)
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{
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u64 i, all_num_blocks;
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size_t num_blocks, last_len;
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/*
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* Calculate the number of blocks of data to be encrypted provided now, and
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* so far
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*/
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num_blocks = len / 16;
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all_num_blocks = num_blocks + ctx->sess.blocks_processed;
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if (num_blocks && all_num_blocks == (size_t)all_num_blocks
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&& ctx->stream != NULL) {
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size_t max_idx = 0, top = (size_t)all_num_blocks;
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/*
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* See how many L_{i} entries we need to process data at hand
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* and pre-compute missing entries in the table [if any]...
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*/
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while (top >>= 1)
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max_idx++;
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if (ocb_lookup_l(ctx, max_idx) == NULL)
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return 0;
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ctx->stream(in, out, num_blocks, ctx->keyenc,
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(size_t)ctx->sess.blocks_processed + 1, ctx->sess.offset.c,
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(const unsigned char (*)[16])ctx->l, ctx->sess.checksum.c);
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} else {
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/* Loop through all full blocks to be encrypted */
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for (i = ctx->sess.blocks_processed + 1; i <= all_num_blocks; i++) {
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OCB_BLOCK *lookup;
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OCB_BLOCK tmp;
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/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
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lookup = ocb_lookup_l(ctx, ocb_ntz(i));
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if (lookup == NULL)
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return 0;
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ocb_block16_xor(&ctx->sess.offset, lookup, &ctx->sess.offset);
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memcpy(tmp.c, in, 16);
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in += 16;
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/* Checksum_i = Checksum_{i-1} xor P_i */
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ocb_block16_xor(&tmp, &ctx->sess.checksum, &ctx->sess.checksum);
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/* C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i) */
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ocb_block16_xor(&ctx->sess.offset, &tmp, &tmp);
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ctx->encrypt(tmp.c, tmp.c, ctx->keyenc);
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ocb_block16_xor(&ctx->sess.offset, &tmp, &tmp);
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memcpy(out, tmp.c, 16);
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out += 16;
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}
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}
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/*
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* Check if we have any partial blocks left over. This is only valid in the
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* last call to this function
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*/
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last_len = len % 16;
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if (last_len > 0) {
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OCB_BLOCK pad;
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/* Offset_* = Offset_m xor L_* */
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ocb_block16_xor(&ctx->sess.offset, &ctx->l_star, &ctx->sess.offset);
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/* Pad = ENCIPHER(K, Offset_*) */
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ctx->encrypt(ctx->sess.offset.c, pad.c, ctx->keyenc);
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/* C_* = P_* xor Pad[1..bitlen(P_*)] */
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ocb_block_xor(in, pad.c, last_len, out);
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/* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
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memset(pad.c, 0, 16); /* borrow pad */
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memcpy(pad.c, in, last_len);
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pad.c[last_len] = 0x80;
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ocb_block16_xor(&pad, &ctx->sess.checksum, &ctx->sess.checksum);
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}
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ctx->sess.blocks_processed = all_num_blocks;
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return 1;
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}
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/*
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* Provide any data to be decrypted. This can be called multiple times. Only
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* the final time can have a partial block
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*/
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int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
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const unsigned char *in, unsigned char *out,
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size_t len)
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{
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u64 i, all_num_blocks;
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size_t num_blocks, last_len;
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/*
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* Calculate the number of blocks of data to be decrypted provided now, and
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* so far
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*/
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num_blocks = len / 16;
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all_num_blocks = num_blocks + ctx->sess.blocks_processed;
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if (num_blocks && all_num_blocks == (size_t)all_num_blocks
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&& ctx->stream != NULL) {
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size_t max_idx = 0, top = (size_t)all_num_blocks;
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/*
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* See how many L_{i} entries we need to process data at hand
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* and pre-compute missing entries in the table [if any]...
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*/
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while (top >>= 1)
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max_idx++;
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if (ocb_lookup_l(ctx, max_idx) == NULL)
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return 0;
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ctx->stream(in, out, num_blocks, ctx->keydec,
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(size_t)ctx->sess.blocks_processed + 1, ctx->sess.offset.c,
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(const unsigned char (*)[16])ctx->l, ctx->sess.checksum.c);
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} else {
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OCB_BLOCK tmp;
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/* Loop through all full blocks to be decrypted */
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for (i = ctx->sess.blocks_processed + 1; i <= all_num_blocks; i++) {
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/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
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OCB_BLOCK *lookup = ocb_lookup_l(ctx, ocb_ntz(i));
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if (lookup == NULL)
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return 0;
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ocb_block16_xor(&ctx->sess.offset, lookup, &ctx->sess.offset);
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memcpy(tmp.c, in, 16);
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in += 16;
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/* P_i = Offset_i xor DECIPHER(K, C_i xor Offset_i) */
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ocb_block16_xor(&ctx->sess.offset, &tmp, &tmp);
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ctx->decrypt(tmp.c, tmp.c, ctx->keydec);
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ocb_block16_xor(&ctx->sess.offset, &tmp, &tmp);
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/* Checksum_i = Checksum_{i-1} xor P_i */
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ocb_block16_xor(&tmp, &ctx->sess.checksum, &ctx->sess.checksum);
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memcpy(out, tmp.c, 16);
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out += 16;
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}
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}
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/*
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* Check if we have any partial blocks left over. This is only valid in the
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* last call to this function
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*/
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last_len = len % 16;
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if (last_len > 0) {
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OCB_BLOCK pad;
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/* Offset_* = Offset_m xor L_* */
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ocb_block16_xor(&ctx->sess.offset, &ctx->l_star, &ctx->sess.offset);
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|
/* Pad = ENCIPHER(K, Offset_*) */
|
|
ctx->encrypt(ctx->sess.offset.c, pad.c, ctx->keyenc);
|
|
|
|
/* P_* = C_* xor Pad[1..bitlen(C_*)] */
|
|
ocb_block_xor(in, pad.c, last_len, out);
|
|
|
|
/* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
|
|
memset(pad.c, 0, 16); /* borrow pad */
|
|
memcpy(pad.c, out, last_len);
|
|
pad.c[last_len] = 0x80;
|
|
ocb_block16_xor(&pad, &ctx->sess.checksum, &ctx->sess.checksum);
|
|
}
|
|
|
|
ctx->sess.blocks_processed = all_num_blocks;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int ocb_finish(OCB128_CONTEXT *ctx, unsigned char *tag, size_t len,
|
|
int write)
|
|
{
|
|
OCB_BLOCK tmp;
|
|
|
|
if (len > 16 || len < 1) {
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A)
|
|
*/
|
|
ocb_block16_xor(&ctx->sess.checksum, &ctx->sess.offset, &tmp);
|
|
ocb_block16_xor(&ctx->l_dollar, &tmp, &tmp);
|
|
ctx->encrypt(tmp.c, tmp.c, ctx->keyenc);
|
|
ocb_block16_xor(&tmp, &ctx->sess.sum, &tmp);
|
|
|
|
if (write) {
|
|
memcpy(tag, &tmp, len);
|
|
return 1;
|
|
} else {
|
|
return CRYPTO_memcmp(&tmp, tag, len);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Calculate the tag and verify it against the supplied tag
|
|
*/
|
|
int CRYPTO_ocb128_finish(OCB128_CONTEXT *ctx, const unsigned char *tag,
|
|
size_t len)
|
|
{
|
|
return ocb_finish(ctx, (unsigned char*)tag, len, 0);
|
|
}
|
|
|
|
/*
|
|
* Retrieve the calculated tag
|
|
*/
|
|
int CRYPTO_ocb128_tag(OCB128_CONTEXT *ctx, unsigned char *tag, size_t len)
|
|
{
|
|
return ocb_finish(ctx, tag, len, 1);
|
|
}
|
|
|
|
/*
|
|
* Release all resources
|
|
*/
|
|
void CRYPTO_ocb128_cleanup(OCB128_CONTEXT *ctx)
|
|
{
|
|
if (ctx) {
|
|
OPENSSL_clear_free(ctx->l, ctx->max_l_index * 16);
|
|
OPENSSL_cleanse(ctx, sizeof(*ctx));
|
|
}
|
|
}
|
|
|
|
#endif /* OPENSSL_NO_OCB */
|