--- /dev/null
+/*
+ * Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <string.h>
+#include <openssl/crypto.h>
+#include "modes_lcl.h"
+
+#ifndef OPENSSL_NO_OCB
+
+/*
+ * Calculate the number of binary trailing zero's in any given number
+ */
+static u32 ocb_ntz(u64 n)
+{
+ u32 cnt = 0;
+
+ /*
+ * We do a right-to-left simple sequential search. This is surprisingly
+ * efficient as the distribution of trailing zeros is not uniform,
+ * e.g. the number of possible inputs with no trailing zeros is equal to
+ * the number with 1 or more; the number with exactly 1 is equal to the
+ * number with 2 or more, etc. Checking the last two bits covers 75% of
+ * all numbers. Checking the last three covers 87.5%
+ */
+ while (!(n & 1)) {
+ n >>= 1;
+ cnt++;
+ }
+ return cnt;
+}
+
+/*
+ * Shift a block of 16 bytes left by shift bits
+ */
+static void ocb_block_lshift(const unsigned char *in, size_t shift,
+ unsigned char *out)
+{
+ unsigned char shift_mask;
+ int i;
+ unsigned char mask[15];
+
+ shift_mask = 0xff;
+ shift_mask <<= (8 - shift);
+ for (i = 15; i >= 0; i--) {
+ if (i > 0) {
+ mask[i - 1] = in[i] & shift_mask;
+ mask[i - 1] >>= 8 - shift;
+ }
+ out[i] = in[i] << shift;
+
+ if (i != 15) {
+ out[i] ^= mask[i];
+ }
+ }
+}
+
+/*
+ * Perform a "double" operation as per OCB spec
+ */
+static void ocb_double(OCB_BLOCK *in, OCB_BLOCK *out)
+{
+ unsigned char mask;
+
+ /*
+ * Calculate the mask based on the most significant bit. There are more
+ * efficient ways to do this - but this way is constant time
+ */
+ mask = in->c[0] & 0x80;
+ mask >>= 7;
+ mask *= 135;
+
+ ocb_block_lshift(in->c, 1, out->c);
+
+ out->c[15] ^= mask;
+}
+
+/*
+ * Perform an xor on in1 and in2 - each of len bytes. Store result in out
+ */
+static void ocb_block_xor(const unsigned char *in1,
+ const unsigned char *in2, size_t len,
+ unsigned char *out)
+{
+ size_t i;
+ for (i = 0; i < len; i++) {
+ out[i] = in1[i] ^ in2[i];
+ }
+}
+
+/*
+ * Lookup L_index in our lookup table. If we haven't already got it we need to
+ * calculate it
+ */
+static OCB_BLOCK *ocb_lookup_l(OCB128_CONTEXT *ctx, size_t idx)
+{
+ size_t l_index = ctx->l_index;
+
+ if (idx <= l_index) {
+ return ctx->l + idx;
+ }
+
+ /* We don't have it - so calculate it */
+ if (idx >= ctx->max_l_index) {
+ void *tmp_ptr;
+ /*
+ * Each additional entry allows to process almost double as
+ * much data, so that in linear world the table will need to
+ * be expanded with smaller and smaller increments. Originally
+ * it was doubling in size, which was a waste. Growing it
+ * linearly is not formally optimal, but is simpler to implement.
+ * We grow table by minimally required 4*n that would accommodate
+ * the index.
+ */
+ ctx->max_l_index += (idx - ctx->max_l_index + 4) & ~3;
+ tmp_ptr =
+ OPENSSL_realloc(ctx->l, ctx->max_l_index * sizeof(OCB_BLOCK));
+ if (tmp_ptr == NULL) /* prevent ctx->l from being clobbered */
+ return NULL;
+ ctx->l = tmp_ptr;
+ }
+ while (l_index < idx) {
+ ocb_double(ctx->l + l_index, ctx->l + l_index + 1);
+ l_index++;
+ }
+ ctx->l_index = l_index;
+
+ return ctx->l + idx;
+}
+
+/*
+ * Create a new OCB128_CONTEXT
+ */
+OCB128_CONTEXT *CRYPTO_ocb128_new(void *keyenc, void *keydec,
+ block128_f encrypt, block128_f decrypt,
+ ocb128_f stream)
+{
+ OCB128_CONTEXT *octx;
+ int ret;
+
+ if ((octx = OPENSSL_malloc(sizeof(*octx))) != NULL) {
+ ret = CRYPTO_ocb128_init(octx, keyenc, keydec, encrypt, decrypt,
+ stream);
+ if (ret)
+ return octx;
+ OPENSSL_free(octx);
+ }
+
+ return NULL;
+}
+
+/*
+ * Initialise an existing OCB128_CONTEXT
+ */
+int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
+ block128_f encrypt, block128_f decrypt,
+ ocb128_f stream)
+{
+ memset(ctx, 0, sizeof(*ctx));
+ ctx->l_index = 0;
+ ctx->max_l_index = 5;
+ ctx->l = OPENSSL_malloc(ctx->max_l_index * 16);
+ if (ctx->l == NULL)
+ return 0;
+
+ /*
+ * We set both the encryption and decryption key schedules - decryption
+ * needs both. Don't really need decryption schedule if only doing
+ * encryption - but it simplifies things to take it anyway
+ */
+ ctx->encrypt = encrypt;
+ ctx->decrypt = decrypt;
+ ctx->stream = stream;
+ ctx->keyenc = keyenc;
+ ctx->keydec = keydec;
+
+ /* L_* = ENCIPHER(K, zeros(128)) */
+ ctx->encrypt(ctx->l_star.c, ctx->l_star.c, ctx->keyenc);
+
+ /* L_$ = double(L_*) */
+ ocb_double(&ctx->l_star, &ctx->l_dollar);
+
+ /* L_0 = double(L_$) */
+ ocb_double(&ctx->l_dollar, ctx->l);
+
+ /* L_{i} = double(L_{i-1}) */
+ ocb_double(ctx->l, ctx->l+1);
+ ocb_double(ctx->l+1, ctx->l+2);
+ ocb_double(ctx->l+2, ctx->l+3);
+ ocb_double(ctx->l+3, ctx->l+4);
+ ctx->l_index = 4; /* enough to process up to 496 bytes */
+
+ return 1;
+}
+
+/*
+ * Copy an OCB128_CONTEXT object
+ */
+int CRYPTO_ocb128_copy_ctx(OCB128_CONTEXT *dest, OCB128_CONTEXT *src,
+ void *keyenc, void *keydec)
+{
+ memcpy(dest, src, sizeof(OCB128_CONTEXT));
+ if (keyenc)
+ dest->keyenc = keyenc;
+ if (keydec)
+ dest->keydec = keydec;
+ if (src->l) {
+ dest->l = OPENSSL_malloc(src->max_l_index * 16);
+ if (dest->l == NULL)
+ return 0;
+ memcpy(dest->l, src->l, (src->l_index + 1) * 16);
+ }
+ return 1;
+}
+
+/*
+ * Set the IV to be used for this operation. Must be 1 - 15 bytes.
+ */
+int CRYPTO_ocb128_setiv(OCB128_CONTEXT *ctx, const unsigned char *iv,
+ size_t len, size_t taglen)
+{
+ unsigned char ktop[16], tmp[16], mask;
+ unsigned char stretch[24], nonce[16];
+ size_t bottom, shift;
+
+ /*
+ * Spec says IV is 120 bits or fewer - it allows non byte aligned lengths.
+ * We don't support this at this stage
+ */
+ if ((len > 15) || (len < 1) || (taglen > 16) || (taglen < 1)) {
+ return -1;
+ }
+
+ /* Nonce = num2str(TAGLEN mod 128,7) || zeros(120-bitlen(N)) || 1 || N */
+ nonce[0] = ((taglen * 8) % 128) << 1;
+ memset(nonce + 1, 0, 15);
+ memcpy(nonce + 16 - len, iv, len);
+ nonce[15 - len] |= 1;
+
+ /* Ktop = ENCIPHER(K, Nonce[1..122] || zeros(6)) */
+ memcpy(tmp, nonce, 16);
+ tmp[15] &= 0xc0;
+ ctx->encrypt(tmp, ktop, ctx->keyenc);
+
+ /* Stretch = Ktop || (Ktop[1..64] xor Ktop[9..72]) */
+ memcpy(stretch, ktop, 16);
+ ocb_block_xor(ktop, ktop + 1, 8, stretch + 16);
+
+ /* bottom = str2num(Nonce[123..128]) */
+ bottom = nonce[15] & 0x3f;
+
+ /* Offset_0 = Stretch[1+bottom..128+bottom] */
+ shift = bottom % 8;
+ ocb_block_lshift(stretch + (bottom / 8), shift, ctx->offset.c);
+ mask = 0xff;
+ mask <<= 8 - shift;
+ ctx->offset.c[15] |=
+ (*(stretch + (bottom / 8) + 16) & mask) >> (8 - shift);
+
+ return 1;
+}
+
+/*
+ * Provide any AAD. This can be called multiple times. Only the final time can
+ * have a partial block
+ */
+int CRYPTO_ocb128_aad(OCB128_CONTEXT *ctx, const unsigned char *aad,
+ size_t len)
+{
+ u64 i, all_num_blocks;
+ size_t num_blocks, last_len;
+ OCB_BLOCK tmp1;
+ OCB_BLOCK tmp2;
+
+ /* Calculate the number of blocks of AAD provided now, and so far */
+ num_blocks = len / 16;
+ all_num_blocks = num_blocks + ctx->blocks_hashed;
+
+ /* Loop through all full blocks of AAD */
+ for (i = ctx->blocks_hashed + 1; i <= all_num_blocks; i++) {
+ OCB_BLOCK *lookup;
+ OCB_BLOCK *aad_block;
+
+ /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
+ lookup = ocb_lookup_l(ctx, ocb_ntz(i));
+ if (lookup == NULL)
+ return 0;
+ ocb_block16_xor(&ctx->offset_aad, lookup, &ctx->offset_aad);
+
+ /* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
+ aad_block = (OCB_BLOCK *)(aad + ((i - ctx->blocks_hashed - 1) * 16));
+ ocb_block16_xor(&ctx->offset_aad, aad_block, &tmp1);
+ ctx->encrypt(tmp1.c, tmp2.c, ctx->keyenc);
+ ocb_block16_xor(&ctx->sum, &tmp2, &ctx->sum);
+ }
+
+ /*
+ * Check if we have any partial blocks left over. This is only valid in the
+ * last call to this function
+ */
+ last_len = len % 16;
+
+ if (last_len > 0) {
+ /* Offset_* = Offset_m xor L_* */
+ ocb_block16_xor(&ctx->offset_aad, &ctx->l_star, &ctx->offset_aad);
+
+ /* CipherInput = (A_* || 1 || zeros(127-bitlen(A_*))) xor Offset_* */
+ memset(&tmp1, 0, 16);
+ memcpy(&tmp1, aad + (num_blocks * 16), last_len);
+ ((unsigned char *)&tmp1)[last_len] = 0x80;
+ ocb_block16_xor(&ctx->offset_aad, &tmp1, &tmp2);
+
+ /* Sum = Sum_m xor ENCIPHER(K, CipherInput) */
+ ctx->encrypt(tmp2.c, tmp1.c, ctx->keyenc);
+ ocb_block16_xor(&ctx->sum, &tmp1, &ctx->sum);
+ }
+
+ ctx->blocks_hashed = all_num_blocks;
+
+ return 1;
+}
+
+/*
+ * Provide any data to be encrypted. This can be called multiple times. Only
+ * the final time can have a partial block
+ */
+int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
+ const unsigned char *in, unsigned char *out,
+ size_t len)
+{
+ u64 i, all_num_blocks;
+ size_t num_blocks, last_len;
+ OCB_BLOCK tmp1;
+ OCB_BLOCK tmp2;
+ OCB_BLOCK pad;
+
+ /*
+ * Calculate the number of blocks of data to be encrypted provided now, and
+ * so far
+ */
+ num_blocks = len / 16;
+ all_num_blocks = num_blocks + ctx->blocks_processed;
+
+ if (num_blocks && all_num_blocks == (size_t)all_num_blocks
+ && ctx->stream != NULL) {
+ size_t max_idx = 0, top = (size_t)all_num_blocks;
+
+ /*
+ * See how many L_{i} entries we need to process data at hand
+ * and pre-compute missing entries in the table [if any]...
+ */
+ while (top >>= 1)
+ max_idx++;
+ if (ocb_lookup_l(ctx, max_idx) == NULL)
+ return 0;
+
+ ctx->stream(in, out, num_blocks, ctx->keyenc,
+ (size_t)ctx->blocks_processed + 1, ctx->offset.c,
+ (const unsigned char (*)[16])ctx->l, ctx->checksum.c);
+ } else {
+ /* Loop through all full blocks to be encrypted */
+ for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
+ OCB_BLOCK *lookup;
+ OCB_BLOCK *inblock;
+ OCB_BLOCK *outblock;
+
+ /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
+ lookup = ocb_lookup_l(ctx, ocb_ntz(i));
+ if (lookup == NULL)
+ return 0;
+ ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
+
+ /* C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i) */
+ inblock =
+ (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
+ ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
+ /* Checksum_i = Checksum_{i-1} xor P_i */
+ ocb_block16_xor_misaligned(&ctx->checksum, inblock, &ctx->checksum);
+ ctx->encrypt(tmp1.c, tmp2.c, ctx->keyenc);
+ outblock =
+ (OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
+ ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
+ }
+ }
+
+ /*
+ * Check if we have any partial blocks left over. This is only valid in the
+ * last call to this function
+ */
+ last_len = len % 16;
+
+ if (last_len > 0) {
+ /* Offset_* = Offset_m xor L_* */
+ ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
+
+ /* Pad = ENCIPHER(K, Offset_*) */
+ ctx->encrypt(ctx->offset.c, pad.c, ctx->keyenc);
+
+ /* C_* = P_* xor Pad[1..bitlen(P_*)] */
+ ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
+ out + (num_blocks * 16));
+
+ /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
+ memset(&tmp1, 0, 16);
+ memcpy(&tmp1, in + (len / 16) * 16, last_len);
+ ((unsigned char *)(&tmp1))[last_len] = 0x80;
+ ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
+ }
+
+ ctx->blocks_processed = all_num_blocks;
+
+ return 1;
+}
+
+/*
+ * Provide any data to be decrypted. This can be called multiple times. Only
+ * the final time can have a partial block
+ */
+int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
+ const unsigned char *in, unsigned char *out,
+ size_t len)
+{
+ u64 i, all_num_blocks;
+ size_t num_blocks, last_len;
+ OCB_BLOCK tmp1;
+ OCB_BLOCK tmp2;
+ OCB_BLOCK pad;
+
+ /*
+ * Calculate the number of blocks of data to be decrypted provided now, and
+ * so far
+ */
+ num_blocks = len / 16;
+ all_num_blocks = num_blocks + ctx->blocks_processed;
+
+ if (num_blocks && all_num_blocks == (size_t)all_num_blocks
+ && ctx->stream != NULL) {
+ size_t max_idx = 0, top = (size_t)all_num_blocks;
+
+ /*
+ * See how many L_{i} entries we need to process data at hand
+ * and pre-compute missing entries in the table [if any]...
+ */
+ while (top >>= 1)
+ max_idx++;
+ if (ocb_lookup_l(ctx, max_idx) == NULL)
+ return 0;
+
+ ctx->stream(in, out, num_blocks, ctx->keydec,
+ (size_t)ctx->blocks_processed + 1, ctx->offset.c,
+ (const unsigned char (*)[16])ctx->l, ctx->checksum.c);
+ } else {
+ /* Loop through all full blocks to be decrypted */
+ for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
+ OCB_BLOCK *inblock;
+ OCB_BLOCK *outblock;
+
+ /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
+ OCB_BLOCK *lookup = ocb_lookup_l(ctx, ocb_ntz(i));
+ if (lookup == NULL)
+ return 0;
+ ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
+
+ /* P_i = Offset_i xor DECIPHER(K, C_i xor Offset_i) */
+ inblock =
+ (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
+ ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
+ ctx->decrypt(tmp1.c, tmp2.c, ctx->keydec);
+ outblock =
+ (OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
+ ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
+
+ /* Checksum_i = Checksum_{i-1} xor P_i */
+ ocb_block16_xor_misaligned(&ctx->checksum, outblock, &ctx->checksum);
+ }
+ }
+
+ /*
+ * Check if we have any partial blocks left over. This is only valid in the
+ * last call to this function
+ */
+ last_len = len % 16;
+
+ if (last_len > 0) {
+ /* Offset_* = Offset_m xor L_* */
+ ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
+
+ /* Pad = ENCIPHER(K, Offset_*) */
+ ctx->encrypt(ctx->offset.c, pad.c, ctx->keyenc);
+
+ /* P_* = C_* xor Pad[1..bitlen(C_*)] */
+ ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
+ out + (num_blocks * 16));
+
+ /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
+ memset(&tmp1, 0, 16);
+ memcpy(&tmp1, out + (len / 16) * 16, last_len);
+ ((unsigned char *)(&tmp1))[last_len] = 0x80;
+ ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
+ }
+
+ ctx->blocks_processed = all_num_blocks;
+
+ return 1;
+}
+
+/*
+ * Calculate the tag and verify it against the supplied tag
+ */
+int CRYPTO_ocb128_finish(OCB128_CONTEXT *ctx, const unsigned char *tag,
+ size_t len)
+{
+ OCB_BLOCK tmp1, tmp2;
+
+ /*
+ * Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A)
+ */
+ ocb_block16_xor(&ctx->checksum, &ctx->offset, &tmp1);
+ ocb_block16_xor(&tmp1, &ctx->l_dollar, &tmp2);
+ ctx->encrypt(tmp2.c, tmp1.c, ctx->keyenc);
+ ocb_block16_xor(&tmp1, &ctx->sum, &ctx->tag);
+
+ if (len > 16 || len < 1) {
+ return -1;
+ }
+
+ /* Compare the tag if we've been given one */
+ if (tag)
+ return CRYPTO_memcmp(&ctx->tag, tag, len);
+ else
+ return -1;
+}
+
+/*
+ * Retrieve the calculated tag
+ */
+int CRYPTO_ocb128_tag(OCB128_CONTEXT *ctx, unsigned char *tag, size_t len)
+{
+ if (len > 16 || len < 1) {
+ return -1;
+ }
+
+ /* Calculate the tag */
+ CRYPTO_ocb128_finish(ctx, NULL, 0);
+
+ /* Copy the tag into the supplied buffer */
+ memcpy(tag, &ctx->tag, len);
+
+ return 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 */
projects / cassiopeia.git / blobdiff