Add current version of libSRTP from CVS.

libsrtp/crypto/cipher/aes_icm.c

+/*
+ * aes_icm.c
+ *
+ * AES Integer Counter Mode
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+
+/*
+ *      
+ * Copyright (c) 2001-2006, Cisco Systems, Inc.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ * 
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+
+#define ALIGN_32 0
+
+#include "aes_icm.h"
+#include "alloc.h"
+
+
+debug_module_t mod_aes_icm = {
+  0,                 /* debugging is off by default */
+  "aes icm"          /* printable module name       */
+};
+
+/*
+ * integer counter mode works as follows:
+ *
+ * 16 bits
+ * <----->
+ * +------+------+------+------+------+------+------+------+ 
+ * |           nonce           |    pakcet index    |  ctr |---+
+ * +------+------+------+------+------+------+------+------+   |
+ *                                                             |
+ * +------+------+------+------+------+------+------+------+   v
+ * |                      salt                      |000000|->(+)
+ * +------+------+------+------+------+------+------+------+   |
+ *                                                             |
+ *                                                        +---------+
+ *                                                        | encrypt |
+ *                                                        +---------+
+ *                                                             | 
+ * +------+------+------+------+------+------+------+------+   |
+ * |                    keystream block                    |<--+ 
+ * +------+------+------+------+------+------+------+------+   
+ *
+ * All fields are big-endian
+ *
+ * ctr is the block counter, which increments from zero for
+ * each packet (16 bits wide)
+ * 
+ * packet index is distinct for each packet (48 bits wide)
+ *
+ * nonce can be distinct across many uses of the same key, or
+ * can be a fixed value per key, or can be per-packet randomness
+ * (64 bits)
+ *
+ */
+
+err_status_t
+aes_icm_alloc_ismacryp(cipher_t **c, int key_len, int forIsmacryp) {
+  extern cipher_type_t aes_icm;
+  uint8_t *pointer;
+  int tmp;
+
+  debug_print(mod_aes_icm, 
+            "allocating cipher with key length %d", key_len);
+
+  /*
+   * Ismacryp, for example, uses 16 byte key + 8 byte 
+   * salt  so this function is called with key_len = 24.
+   * The check for key_len = 30/38/46 does not apply. Our usage
+   * of aes functions with key_len = values other than 30
+   * has not broken anything. Don't know what would be the
+   * effect of skipping this check for srtp in general.
+   */
+  if (!(forIsmacryp && key_len > 16 && key_len < 30) &&
+      key_len != 30 && key_len != 38 && key_len != 46)
+    return err_status_bad_param;
+
+  /* allocate memory a cipher of type aes_icm */
+  tmp = (sizeof(aes_icm_ctx_t) + sizeof(cipher_t));
+  pointer = (uint8_t*)crypto_alloc(tmp);
+  if (pointer == NULL) 
+    return err_status_alloc_fail;
+
+  /* set pointers */
+  *c = (cipher_t *)pointer;
+  (*c)->type = &aes_icm;
+  (*c)->state = pointer + sizeof(cipher_t);
+
+  /* increment ref_count */
+  aes_icm.ref_count++;
+
+  /* set key size        */
+  (*c)->key_len = key_len;
+
+  return err_status_ok;  
+}
+
+err_status_t aes_icm_alloc(cipher_t **c, int key_len, int forIsmacryp) {
+  return aes_icm_alloc_ismacryp(c, key_len, 0);
+}
+
+err_status_t
+aes_icm_dealloc(cipher_t *c) {
+  extern cipher_type_t aes_icm;
+
+  /* zeroize entire state*/
+  octet_string_set_to_zero((uint8_t *)c, 
+                           sizeof(aes_icm_ctx_t) + sizeof(cipher_t));
+
+  /* free memory */
+  crypto_free(c);
+
+  /* decrement ref_count */
+  aes_icm.ref_count--;
+  
+  return err_status_ok;  
+}
+
+
+/*
+ * aes_icm_context_init(...) initializes the aes_icm_context
+ * using the value in key[].
+ *
+ * the key is the secret key 
+ *
+ * the salt is unpredictable (but not necessarily secret) data which
+ * randomizes the starting point in the keystream
+ */
+
+err_status_t
+aes_icm_context_init(aes_icm_ctx_t *c, const uint8_t *key, int key_len) {
+  err_status_t status;
+  int base_key_len;
+
+  if (key_len > 16 && key_len < 30) /* Ismacryp */
+    base_key_len = 16;
+  else if (key_len == 30 || key_len == 38 || key_len == 46)
+    base_key_len = key_len - 14;
+  else
+    return err_status_bad_param;
+
+  /* set counter and initial values to 'offset' value */
+  /* Note this copies past the end of the 'key' array by 2 bytes! */
+  v128_copy_octet_string(&c->counter, key + base_key_len);
+  v128_copy_octet_string(&c->offset, key + base_key_len);
+
+  /* force last two octets of the offset to zero (for srtp compatibility) */
+  c->offset.v8[14] = c->offset.v8[15] = 0;
+  c->counter.v8[14] = c->counter.v8[15] = 0;
+  
+  debug_print(mod_aes_icm, 
+              "key:  %s", octet_string_hex_string(key, base_key_len)); 
+  debug_print(mod_aes_icm, 
+              "offset: %s", v128_hex_string(&c->offset)); 
+
+  /* expand key */
+  status = aes_expand_encryption_key(key, base_key_len, &c->expanded_key);
+  if (status) {
+    v128_set_to_zero(&c->counter);
+    v128_set_to_zero(&c->offset);
+    return status;
+  }
+
+  /* indicate that the keystream_buffer is empty */
+  c->bytes_in_buffer = 0;
+
+  return err_status_ok;
+}
+
+/*
+ * aes_icm_set_octet(c, i) sets the counter of the context which it is
+ * passed so that the next octet of keystream that will be generated
+ * is the ith octet
+ */
+
+err_status_t
+aes_icm_set_octet(aes_icm_ctx_t *c,
+                  uint64_t octet_num) {
+
+#ifdef NO_64BIT_MATH
+  int tail_num       = low32(octet_num) & 0x0f;
+  /* 64-bit right-shift 4 */
+  uint64_t block_num = make64(high32(octet_num) >> 4,
+                                                          ((high32(octet_num) & 0x0f)<<(32-4)) |
+                                                           (low32(octet_num) >> 4));
+#else
+  int tail_num       = (int)(octet_num % 16);
+  uint64_t block_num = octet_num / 16;
+#endif
+  
+
+  /* set counter value */
+  /* FIX - There's no way this is correct */
+  c->counter.v64[0] = c->offset.v64[0];
+#ifdef NO_64BIT_MATH
+  c->counter.v64[0] = make64(high32(c->offset.v64[0]) ^ high32(block_num),
+                                                         low32(c->offset.v64[0])  ^ low32(block_num));
+#else
+  c->counter.v64[0] = c->offset.v64[0] ^ block_num;
+#endif
+
+  debug_print(mod_aes_icm, 
+              "set_octet: %s", v128_hex_string(&c->counter)); 
+
+  /* fill keystream buffer, if needed */
+  if (tail_num) {
+    v128_copy(&c->keystream_buffer, &c->counter);
+    aes_encrypt(&c->keystream_buffer, &c->expanded_key);
+    c->bytes_in_buffer = sizeof(v128_t);
+
+    debug_print(mod_aes_icm, "counter:    %s", 
+              v128_hex_string(&c->counter));
+    debug_print(mod_aes_icm, "ciphertext: %s", 
+              v128_hex_string(&c->keystream_buffer));    
+    
+    /*  indicate number of bytes in keystream_buffer  */
+    c->bytes_in_buffer = sizeof(v128_t) - tail_num;
+  
+  } else {
+    
+    /* indicate that keystream_buffer is empty */
+    c->bytes_in_buffer = 0;
+  }
+
+  return err_status_ok;
+}
+
+/*
+ * aes_icm_set_iv(c, iv) sets the counter value to the exor of iv with
+ * the offset
+ */
+
+err_status_t
+aes_icm_set_iv(aes_icm_ctx_t *c, void *iv) {
+  v128_t *nonce = (v128_t *) iv;
+
+  debug_print(mod_aes_icm, 
+              "setting iv: %s", v128_hex_string(nonce)); 
+ 
+  v128_xor(&c->counter, &c->offset, nonce);
+  
+  debug_print(mod_aes_icm, 
+              "set_counter: %s", v128_hex_string(&c->counter)); 
+
+  /* indicate that the keystream_buffer is empty */
+  c->bytes_in_buffer = 0;
+
+  return err_status_ok;
+}
+
+
+
+/*
+ * aes_icm_advance(...) refills the keystream_buffer and
+ * advances the block index of the sicm_context forward by one
+ *
+ * this is an internal, hopefully inlined function
+ */
+  
+inline void
+aes_icm_advance_ismacryp(aes_icm_ctx_t *c, uint8_t forIsmacryp) {
+  /* fill buffer with new keystream */
+  v128_copy(&c->keystream_buffer, &c->counter);
+  aes_encrypt(&c->keystream_buffer, &c->expanded_key);
+  c->bytes_in_buffer = sizeof(v128_t);
+
+  debug_print(mod_aes_icm, "counter:    %s", 
+              v128_hex_string(&c->counter));
+  debug_print(mod_aes_icm, "ciphertext: %s", 
+              v128_hex_string(&c->keystream_buffer));    
+  
+  /* clock counter forward */
+
+  if (forIsmacryp) {
+    uint32_t temp;    
+    //alex's clock counter forward
+    temp = ntohl(c->counter.v32[3]);
+    c->counter.v32[3] = htonl(++temp);
+  } else {
+    if (!++(c->counter.v8[15])) 
+      ++(c->counter.v8[14]);
+  }
+}
+
+inline void aes_icm_advance(aes_icm_ctx_t *c) {
+  aes_icm_advance_ismacryp(c, 0);
+}
+
+
+/*e
+ * icm_encrypt deals with the following cases:
+ *
+ * bytes_to_encr < bytes_in_buffer
+ *  - add keystream into data
+ *
+ * bytes_to_encr > bytes_in_buffer
+ *  - add keystream into data until keystream_buffer is depleted
+ *  - loop over blocks, filling keystream_buffer and then
+ *    adding keystream into data
+ *  - fill buffer then add in remaining (< 16) bytes of keystream 
+ */
+
+err_status_t
+aes_icm_encrypt_ismacryp(aes_icm_ctx_t *c,
+              unsigned char *buf, unsigned int *enc_len, 
+              int forIsmacryp) {
+  unsigned int bytes_to_encr = *enc_len;
+  unsigned int i;
+  uint32_t *b;
+
+  /* check that there's enough segment left but not for ismacryp*/
+  if (!forIsmacryp && (bytes_to_encr + htons(c->counter.v16[7])) > 0xffff)
+    return err_status_terminus;
+
+ debug_print(mod_aes_icm, "block index: %d", 
+           htons(c->counter.v16[7]));
+  if (bytes_to_encr <= (unsigned int)c->bytes_in_buffer) {
+    
+    /* deal with odd case of small bytes_to_encr */
+    for (i = (sizeof(v128_t) - c->bytes_in_buffer);
+                 i < (sizeof(v128_t) - c->bytes_in_buffer + bytes_to_encr); i++) 
+        {
+      *buf++ ^= c->keystream_buffer.v8[i];
+        }
+
+    c->bytes_in_buffer -= bytes_to_encr;
+
+    /* return now to avoid the main loop */
+    return err_status_ok;
+
+  } else {
+    
+    /* encrypt bytes until the remaining data is 16-byte aligned */    
+    for (i=(sizeof(v128_t) - c->bytes_in_buffer); i < sizeof(v128_t); i++) 
+      *buf++ ^= c->keystream_buffer.v8[i];
+
+    bytes_to_encr -= c->bytes_in_buffer;
+    c->bytes_in_buffer = 0;
+
+  }
+  
+  /* now loop over entire 16-byte blocks of keystream */
+  for (i=0; i < (bytes_to_encr/sizeof(v128_t)); i++) {
+
+    /* fill buffer with new keystream */
+    aes_icm_advance_ismacryp(c, forIsmacryp);
+
+    /*
+     * add keystream into the data buffer (this would be a lot faster
+     * if we could assume 32-bit alignment!)
+     */
+
+#if ALIGN_32
+    b = (uint32_t *)buf;
+    *b++ ^= c->keystream_buffer.v32[0];
+    *b++ ^= c->keystream_buffer.v32[1];
+    *b++ ^= c->keystream_buffer.v32[2];
+    *b++ ^= c->keystream_buffer.v32[3];
+    buf = (uint8_t *)b;
+#else    
+    if ((((unsigned long) buf) & 0x03) != 0) {
+      *buf++ ^= c->keystream_buffer.v8[0];
+      *buf++ ^= c->keystream_buffer.v8[1];
+      *buf++ ^= c->keystream_buffer.v8[2];
+      *buf++ ^= c->keystream_buffer.v8[3];
+      *buf++ ^= c->keystream_buffer.v8[4];
+      *buf++ ^= c->keystream_buffer.v8[5];
+      *buf++ ^= c->keystream_buffer.v8[6];
+      *buf++ ^= c->keystream_buffer.v8[7];
+      *buf++ ^= c->keystream_buffer.v8[8];
+      *buf++ ^= c->keystream_buffer.v8[9];
+      *buf++ ^= c->keystream_buffer.v8[10];
+      *buf++ ^= c->keystream_buffer.v8[11];
+      *buf++ ^= c->keystream_buffer.v8[12];
+      *buf++ ^= c->keystream_buffer.v8[13];
+      *buf++ ^= c->keystream_buffer.v8[14];
+      *buf++ ^= c->keystream_buffer.v8[15];
+    } else {
+      b = (uint32_t *)buf;
+      *b++ ^= c->keystream_buffer.v32[0];
+      *b++ ^= c->keystream_buffer.v32[1];
+      *b++ ^= c->keystream_buffer.v32[2];
+      *b++ ^= c->keystream_buffer.v32[3];
+      buf = (uint8_t *)b;
+    }
+#endif /* #if ALIGN_32 */
+
+  }
+  
+  /* if there is a tail end of the data, process it */
+  if ((bytes_to_encr & 0xf) != 0) {
+    
+    /* fill buffer with new keystream */
+    aes_icm_advance_ismacryp(c, forIsmacryp);
+    
+    for (i=0; i < (bytes_to_encr & 0xf); i++)
+      *buf++ ^= c->keystream_buffer.v8[i];
+    
+    /* reset the keystream buffer size to right value */
+    c->bytes_in_buffer = sizeof(v128_t) - i;  
+  } else {
+
+    /* no tail, so just reset the keystream buffer size to zero */
+    c->bytes_in_buffer = 0;
+
+  }
+
+  return err_status_ok;
+}
+
+err_status_t
+aes_icm_encrypt(aes_icm_ctx_t *c, unsigned char *buf, unsigned int *enc_len) {
+  return aes_icm_encrypt_ismacryp(c, buf, enc_len, 0);
+}
+
+err_status_t
+aes_icm_output(aes_icm_ctx_t *c, uint8_t *buffer, int num_octets_to_output) {
+  unsigned int len = num_octets_to_output;
+  
+  /* zeroize the buffer */
+  octet_string_set_to_zero(buffer, num_octets_to_output);
+  
+  /* exor keystream into buffer */
+  return aes_icm_encrypt(c, buffer, &len);
+}
+
+
+char 
+aes_icm_description[] = "aes integer counter mode";
+
+uint8_t aes_icm_test_case_0_key[30] = {
+  0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
+  0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c,
+  0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+  0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
+};
+
+uint8_t aes_icm_test_case_0_nonce[16] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+uint8_t aes_icm_test_case_0_plaintext[32] =  {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+};
+
+uint8_t aes_icm_test_case_0_ciphertext[32] = {
+  0xe0, 0x3e, 0xad, 0x09, 0x35, 0xc9, 0x5e, 0x80,
+  0xe1, 0x66, 0xb1, 0x6d, 0xd9, 0x2b, 0x4e, 0xb4,
+  0xd2, 0x35, 0x13, 0x16, 0x2b, 0x02, 0xd0, 0xf7,
+  0x2a, 0x43, 0xa2, 0xfe, 0x4a, 0x5f, 0x97, 0xab
+};
+
+cipher_test_case_t aes_icm_test_case_0 = {
+  30,                                    /* octets in key            */
+  aes_icm_test_case_0_key,               /* key                      */
+  aes_icm_test_case_0_nonce,             /* packet index             */
+  32,                                    /* octets in plaintext      */
+  aes_icm_test_case_0_plaintext,         /* plaintext                */
+  32,                                    /* octets in ciphertext     */
+  aes_icm_test_case_0_ciphertext,        /* ciphertext               */
+  NULL                                   /* pointer to next testcase */
+};
+
+uint8_t aes_icm_test_case_1_key[46] = {
+  0x57, 0xf8, 0x2f, 0xe3, 0x61, 0x3f, 0xd1, 0x70,
+  0xa8, 0x5e, 0xc9, 0x3c, 0x40, 0xb1, 0xf0, 0x92,
+  0x2e, 0xc4, 0xcb, 0x0d, 0xc0, 0x25, 0xb5, 0x82,
+  0x72, 0x14, 0x7c, 0xc4, 0x38, 0x94, 0x4a, 0x98,
+  0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+  0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
+};
+
+uint8_t aes_icm_test_case_1_nonce[16] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+uint8_t aes_icm_test_case_1_plaintext[32] =  {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+};
+
+uint8_t aes_icm_test_case_1_ciphertext[32] = {
+  0x92, 0xbd, 0xd2, 0x8a, 0x93, 0xc3, 0xf5, 0x25,
+  0x11, 0xc6, 0x77, 0xd0, 0x8b, 0x55, 0x15, 0xa4,
+  0x9d, 0xa7, 0x1b, 0x23, 0x78, 0xa8, 0x54, 0xf6,
+  0x70, 0x50, 0x75, 0x6d, 0xed, 0x16, 0x5b, 0xac
+};
+
+cipher_test_case_t aes_icm_test_case_1 = {
+  46,                                    /* octets in key            */
+  aes_icm_test_case_1_key,               /* key                      */
+  aes_icm_test_case_1_nonce,             /* packet index             */
+  32,                                    /* octets in plaintext      */
+  aes_icm_test_case_1_plaintext,         /* plaintext                */
+  32,                                    /* octets in ciphertext     */
+  aes_icm_test_case_1_ciphertext,        /* ciphertext               */
+  &aes_icm_test_case_0                   /* pointer to next testcase */
+};
+
+
+
+/*
+ * note: the encrypt function is identical to the decrypt function
+ */
+
+cipher_type_t aes_icm = {
+  (cipher_alloc_func_t)          aes_icm_alloc,
+  (cipher_dealloc_func_t)        aes_icm_dealloc,  
+  (cipher_init_func_t)           aes_icm_context_init,
+  (cipher_encrypt_func_t)        aes_icm_encrypt,
+  (cipher_decrypt_func_t)        aes_icm_encrypt,
+  (cipher_set_iv_func_t)         aes_icm_set_iv,
+  (char *)                       aes_icm_description,
+  (int)                          0,   /* instance count */
+  (cipher_test_case_t *)        &aes_icm_test_case_1,
+  (debug_module_t *)            &mod_aes_icm,
+  (cipher_type_id_t)             AES_ICM
+};
+