Index: mozilla/security/nss/lib/freebl/hmacct.c |
=================================================================== |
--- mozilla/security/nss/lib/freebl/hmacct.c (revision 191424) |
+++ mozilla/security/nss/lib/freebl/hmacct.c (working copy) |
@@ -1,336 +0,0 @@ |
-/* This Source Code Form is subject to the terms of the Mozilla Public |
- * License, v. 2.0. If a copy of the MPL was not distributed with this |
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
- |
-#ifdef FREEBL_NO_DEPEND |
-#include "stubs.h" |
-#endif |
- |
-#include "secport.h" |
-#include "hasht.h" |
-#include "blapit.h" |
-#include "hmacct.h" |
-#include "secerr.h" |
- |
-/* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length |
- * field. (SHA-384/512 have 128-bit length.) */ |
-#define MAX_HASH_BIT_COUNT_BYTES 16 |
- |
-/* Some utility functions are needed: |
- * |
- * These macros return the given value with the MSB copied to all the other |
- * bits. They use the fact that an arithmetic shift shifts-in the sign bit. |
- * However, this is not ensured by the C standard so you may need to replace |
- * them with something else on odd CPUs. |
- * |
- * Note: the argument to these macros must be an unsigned int. |
- * */ |
-#define DUPLICATE_MSB_TO_ALL(x) ( (unsigned int)( (int)(x) >> (sizeof(int)*8-1) ) ) |
-#define DUPLICATE_MSB_TO_ALL_8(x) ( (unsigned char)(DUPLICATE_MSB_TO_ALL(x)) ) |
- |
-/* constantTimeGE returns 0xff if a>=b and 0x00 otherwise, where a, b < |
- * MAX_UINT/2. */ |
-static unsigned char |
-constantTimeGE(unsigned int a, unsigned int b) |
-{ |
- a -= b; |
- return DUPLICATE_MSB_TO_ALL(~a); |
-} |
- |
-/* constantTimeEQ8 returns 0xff if a==b and 0x00 otherwise. */ |
-static unsigned char |
-constantTimeEQ8(unsigned char a, unsigned char b) |
-{ |
- unsigned int c = a ^ b; |
- c--; |
- return DUPLICATE_MSB_TO_ALL_8(c); |
-} |
- |
-/* MAC performs a constant time SSLv3/TLS MAC of |dataLen| bytes of |data|, |
- * where |dataLen| includes both the authenticated bytes and the MAC tag from |
- * the sender. |dataLen| must be >= the length of the MAC tag. |
- * |
- * |dataTotalLen| is >= |dataLen| and also accounts for any padding bytes |
- * that may follow the sender's MAC. (Only a single block of padding may |
- * follow in SSLv3, or up to 255 bytes in TLS.) |
- * |
- * Since the results of decryption are secret information (otherwise a |
- * padding-oracle is created), this function is constant-time with respect to |
- * |dataLen|. |
- * |
- * |header| contains either the 13-byte TLS header (containing the sequence |
- * number, record type etc), or it contains the SSLv3 header with the SSLv3 |
- * padding bytes etc. */ |
-static SECStatus |
-MAC(unsigned char *mdOut, |
- unsigned int *mdOutLen, |
- unsigned int mdOutMax, |
- const SECHashObject *hashObj, |
- const unsigned char *macSecret, |
- unsigned int macSecretLen, |
- const unsigned char *header, |
- unsigned int headerLen, |
- const unsigned char *data, |
- unsigned int dataLen, |
- unsigned int dataTotalLen, |
- unsigned char isSSLv3) |
-{ |
- void *mdState = hashObj->create(); |
- const unsigned int mdSize = hashObj->length; |
- const unsigned int mdBlockSize = hashObj->blocklength; |
- /* mdLengthSize is the number of bytes in the length field that terminates |
- * the hash. |
- * |
- * This assumes that hash functions with a 64 byte block size use a 64-bit |
- * length, and otherwise they use a 128-bit length. This is true of {MD5, |
- * SHA*} (which are all of the hash functions specified for use with TLS |
- * today). */ |
- const unsigned int mdLengthSize = mdBlockSize == 64 ? 8 : 16; |
- |
- const unsigned int sslv3PadLen = hashObj->type == HASH_AlgMD5 ? 48 : 40; |
- |
- /* varianceBlocks is the number of blocks of the hash that we have to |
- * calculate in constant time because they could be altered by the |
- * padding value. |
- * |
- * In SSLv3, the padding must be minimal so the end of the plaintext |
- * varies by, at most, 15+20 = 35 bytes. (We conservatively assume that |
- * the MAC size varies from 0..20 bytes.) In case the 9 bytes of hash |
- * termination (0x80 + 64-bit length) don't fit in the final block, we |
- * say that the final two blocks can vary based on the padding. |
- * |
- * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not |
- * required to be minimal. Therefore we say that the final six blocks |
- * can vary based on the padding. |
- * |
- * Later in the function, if the message is short and there obviously |
- * cannot be this many blocks then varianceBlocks can be reduced. */ |
- unsigned int varianceBlocks = isSSLv3 ? 2 : 6; |
- /* From now on we're dealing with the MAC, which conceptually has 13 |
- * bytes of `header' before the start of the data (TLS) or 71/75 bytes |
- * (SSLv3) */ |
- const unsigned int len = dataTotalLen + headerLen; |
- /* maxMACBytes contains the maximum bytes of bytes in the MAC, including |
- * |header|, assuming that there's no padding. */ |
- const unsigned int maxMACBytes = len - mdSize - 1; |
- /* numBlocks is the maximum number of hash blocks. */ |
- const unsigned int numBlocks = |
- (maxMACBytes + 1 + mdLengthSize + mdBlockSize - 1) / mdBlockSize; |
- /* macEndOffset is the index just past the end of the data to be |
- * MACed. */ |
- const unsigned int macEndOffset = dataLen + headerLen - mdSize; |
- /* c is the index of the 0x80 byte in the final hash block that |
- * contains application data. */ |
- const unsigned int c = macEndOffset % mdBlockSize; |
- /* indexA is the hash block number that contains the 0x80 terminating |
- * value. */ |
- const unsigned int indexA = macEndOffset / mdBlockSize; |
- /* indexB is the hash block number that contains the 64-bit hash |
- * length, in bits. */ |
- const unsigned int indexB = (macEndOffset + mdLengthSize) / mdBlockSize; |
- /* bits is the hash-length in bits. It includes the additional hash |
- * block for the masked HMAC key, or whole of |header| in the case of |
- * SSLv3. */ |
- unsigned int bits; |
- /* In order to calculate the MAC in constant time we have to handle |
- * the final blocks specially because the padding value could cause the |
- * end to appear somewhere in the final |varianceBlocks| blocks and we |
- * can't leak where. However, |numStartingBlocks| worth of data can |
- * be hashed right away because no padding value can affect whether |
- * they are plaintext. */ |
- unsigned int numStartingBlocks = 0; |
- /* k is the starting byte offset into the conceptual header||data where |
- * we start processing. */ |
- unsigned int k = 0; |
- unsigned char lengthBytes[MAX_HASH_BIT_COUNT_BYTES]; |
- /* hmacPad is the masked HMAC key. */ |
- unsigned char hmacPad[HASH_BLOCK_LENGTH_MAX]; |
- unsigned char firstBlock[HASH_BLOCK_LENGTH_MAX]; |
- unsigned char macOut[HASH_LENGTH_MAX]; |
- unsigned i, j; |
- |
- /* For SSLv3, if we're going to have any starting blocks then we need |
- * at least two because the header is larger than a single block. */ |
- if (numBlocks > varianceBlocks + (isSSLv3 ? 1 : 0)) { |
- numStartingBlocks = numBlocks - varianceBlocks; |
- k = mdBlockSize*numStartingBlocks; |
- } |
- |
- bits = 8*macEndOffset; |
- hashObj->begin(mdState); |
- if (!isSSLv3) { |
- /* Compute the initial HMAC block. For SSLv3, the padding and |
- * secret bytes are included in |header| because they take more |
- * than a single block. */ |
- bits += 8*mdBlockSize; |
- memset(hmacPad, 0, mdBlockSize); |
- PORT_Assert(macSecretLen <= sizeof(hmacPad)); |
- memcpy(hmacPad, macSecret, macSecretLen); |
- for (i = 0; i < mdBlockSize; i++) |
- hmacPad[i] ^= 0x36; |
- hashObj->update(mdState, hmacPad, mdBlockSize); |
- } |
- |
- j = 0; |
- memset(lengthBytes, 0, sizeof(lengthBytes)); |
- if (mdLengthSize == 16) { |
- j = 8; |
- } |
- if (hashObj->type == HASH_AlgMD5) { |
- /* MD5 appends a little-endian length. */ |
- for (i = 0; i < 4; i++) { |
- lengthBytes[i+j] = bits >> (8*i); |
- } |
- } else { |
- /* All other TLS hash functions use a big-endian length. */ |
- for (i = 0; i < 4; i++) { |
- lengthBytes[4+i+j] = bits >> (8*(3-i)); |
- } |
- } |
- |
- if (k > 0) { |
- if (isSSLv3) { |
- /* The SSLv3 header is larger than a single block. |
- * overhang is the number of bytes beyond a single |
- * block that the header consumes: either 7 bytes |
- * (SHA1) or 11 bytes (MD5). */ |
- const unsigned int overhang = headerLen-mdBlockSize; |
- hashObj->update(mdState, header, mdBlockSize); |
- memcpy(firstBlock, header + mdBlockSize, overhang); |
- memcpy(firstBlock + overhang, data, mdBlockSize-overhang); |
- hashObj->update(mdState, firstBlock, mdBlockSize); |
- for (i = 1; i < k/mdBlockSize - 1; i++) { |
- hashObj->update(mdState, data + mdBlockSize*i - overhang, |
- mdBlockSize); |
- } |
- } else { |
- /* k is a multiple of mdBlockSize. */ |
- memcpy(firstBlock, header, 13); |
- memcpy(firstBlock+13, data, mdBlockSize-13); |
- hashObj->update(mdState, firstBlock, mdBlockSize); |
- for (i = 1; i < k/mdBlockSize; i++) { |
- hashObj->update(mdState, data + mdBlockSize*i - 13, |
- mdBlockSize); |
- } |
- } |
- } |
- |
- memset(macOut, 0, sizeof(macOut)); |
- |
- /* We now process the final hash blocks. For each block, we construct |
- * it in constant time. If i == indexA then we'll include the 0x80 |
- * bytes and zero pad etc. For each block we selectively copy it, in |
- * constant time, to |macOut|. */ |
- for (i = numStartingBlocks; i <= numStartingBlocks+varianceBlocks; i++) { |
- unsigned char block[HASH_BLOCK_LENGTH_MAX]; |
- unsigned char isBlockA = constantTimeEQ8(i, indexA); |
- unsigned char isBlockB = constantTimeEQ8(i, indexB); |
- for (j = 0; j < mdBlockSize; j++) { |
- unsigned char isPastC = isBlockA & constantTimeGE(j, c); |
- unsigned char isPastCPlus1 = isBlockA & constantTimeGE(j, c+1); |
- unsigned char b = 0; |
- if (k < headerLen) { |
- b = header[k]; |
- } else if (k < dataTotalLen + headerLen) { |
- b = data[k-headerLen]; |
- } |
- k++; |
- |
- /* If this is the block containing the end of the |
- * application data, and we are at the offset for the |
- * 0x80 value, then overwrite b with 0x80. */ |
- b = (b&~isPastC) | (0x80&isPastC); |
- /* If this the the block containing the end of the |
- * application data and we're past the 0x80 value then |
- * just write zero. */ |
- b = b&~isPastCPlus1; |
- /* If this is indexB (the final block), but not |
- * indexA (the end of the data), then the 64-bit |
- * length didn't fit into indexA and we're having to |
- * add an extra block of zeros. */ |
- b &= ~isBlockB | isBlockA; |
- |
- /* The final bytes of one of the blocks contains the length. */ |
- if (j >= mdBlockSize - mdLengthSize) { |
- /* If this is indexB, write a length byte. */ |
- b = (b&~isBlockB) | |
- (isBlockB&lengthBytes[j-(mdBlockSize-mdLengthSize)]); |
- } |
- block[j] = b; |
- } |
- |
- hashObj->update(mdState, block, mdBlockSize); |
- hashObj->end_raw(mdState, block, NULL, mdSize); |
- /* If this is indexB, copy the hash value to |macOut|. */ |
- for (j = 0; j < mdSize; j++) { |
- macOut[j] |= block[j]&isBlockB; |
- } |
- } |
- |
- hashObj->begin(mdState); |
- |
- if (isSSLv3) { |
- /* We repurpose |hmacPad| to contain the SSLv3 pad2 block. */ |
- for (i = 0; i < sslv3PadLen; i++) |
- hmacPad[i] = 0x5c; |
- |
- hashObj->update(mdState, macSecret, macSecretLen); |
- hashObj->update(mdState, hmacPad, sslv3PadLen); |
- hashObj->update(mdState, macOut, mdSize); |
- } else { |
- /* Complete the HMAC in the standard manner. */ |
- for (i = 0; i < mdBlockSize; i++) |
- hmacPad[i] ^= 0x6a; |
- |
- hashObj->update(mdState, hmacPad, mdBlockSize); |
- hashObj->update(mdState, macOut, mdSize); |
- } |
- |
- hashObj->end(mdState, mdOut, mdOutLen, mdOutMax); |
- hashObj->destroy(mdState, PR_TRUE); |
- |
- return SECSuccess; |
-} |
- |
-SECStatus |
-HMAC_ConstantTime( |
- unsigned char *result, |
- unsigned int *resultLen, |
- unsigned int maxResultLen, |
- const SECHashObject *hashObj, |
- const unsigned char *secret, |
- unsigned int secretLen, |
- const unsigned char *header, |
- unsigned int headerLen, |
- const unsigned char *body, |
- unsigned int bodyLen, |
- unsigned int bodyTotalLen) |
-{ |
- if (hashObj->end_raw == NULL) |
- return SECFailure; |
- return MAC(result, resultLen, maxResultLen, hashObj, secret, secretLen, |
- header, headerLen, body, bodyLen, bodyTotalLen, |
- 0 /* not SSLv3 */); |
-} |
- |
-SECStatus |
-SSLv3_MAC_ConstantTime( |
- unsigned char *result, |
- unsigned int *resultLen, |
- unsigned int maxResultLen, |
- const SECHashObject *hashObj, |
- const unsigned char *secret, |
- unsigned int secretLen, |
- const unsigned char *header, |
- unsigned int headerLen, |
- const unsigned char *body, |
- unsigned int bodyLen, |
- unsigned int bodyTotalLen) |
-{ |
- if (hashObj->end_raw == NULL) |
- return SECFailure; |
- return MAC(result, resultLen, maxResultLen, hashObj, secret, secretLen, |
- header, headerLen, body, bodyLen, bodyTotalLen, |
- 1 /* SSLv3 */); |
-} |
- |