The Tor Browser: security/nss/lib/freebl/aeskeywrap.c@b8a032363ba2 (annotated)

security/nss/lib/freebl/aeskeywrap.c@b8a032363ba2 (annotated)

security/nss/lib/freebl/aeskeywrap.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  * aeskeywrap.c - implement AES Key Wrap algorithm from RFC 3394
  *
  * 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 "prcpucfg.h"
 #if defined(IS_LITTLE_ENDIAN) || defined(SHA_NO_LONG_LONG)
 #define BIG_ENDIAN_WITH_64_BIT_REGISTERS 0
 #else
 #define BIG_ENDIAN_WITH_64_BIT_REGISTERS 1
 #endif
 #include "prtypes.h"	/* for PRUintXX */
 #include "secport.h"	/* for PORT_XXX */
 #include "secerr.h"
 #include "blapi.h"	/* for AES_ functions */
 #include "rijndael.h"
 struct AESKeyWrapContextStr {
      unsigned char iv[AES_KEY_WRAP_IV_BYTES];
      AESContext    aescx;
 };
 /******************************************/
 /*
 ** AES key wrap algorithm, RFC 3394
 */
 AESKeyWrapContext *
 AESKeyWrap_AllocateContext(void)
 {
     AESKeyWrapContext * cx = PORT_New(AESKeyWrapContext);
     return cx;
 }
 SECStatus
 AESKeyWrap_InitContext(AESKeyWrapContext *cx,
 		       const unsigned char *key,
 		       unsigned int keylen,
 		       const unsigned char *iv,
 		       int x1,
 		       unsigned int encrypt,
 		       unsigned int x2)
 {
     SECStatus rv = SECFailure;
     if (!cx) {
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
     	return SECFailure;
     }
     if (iv) {
     	memcpy(cx->iv, iv, sizeof cx->iv);
     } else {
 	memset(cx->iv, 0xA6, sizeof cx->iv);
     }
     rv = AES_InitContext(&cx->aescx, key, keylen, NULL, NSS_AES, encrypt,
                                   AES_BLOCK_SIZE);
     return rv;
 }
 /*
 ** Create a new AES context suitable for AES encryption/decryption.
 ** 	"key" raw key data
 ** 	"keylen" the number of bytes of key data (16, 24, or 32)
 */
 extern AESKeyWrapContext *
 AESKeyWrap_CreateContext(const unsigned char *key, const unsigned char *iv,
                          int encrypt, unsigned int keylen)
 {
     SECStatus rv;
     AESKeyWrapContext * cx = AESKeyWrap_AllocateContext();
     if (!cx)
     	return NULL;	/* error is already set */
     rv = AESKeyWrap_InitContext(cx, key, keylen, iv, 0, encrypt, 0);
     if (rv != SECSuccess) {
         PORT_Free(cx);
 	cx = NULL; 	/* error should already be set */
     }
     return cx;
 }
 /*
 ** Destroy a AES KeyWrap context.
 **	"cx" the context
 **	"freeit" if PR_TRUE then free the object as well as its sub-objects
 */
 extern void
 AESKeyWrap_DestroyContext(AESKeyWrapContext *cx, PRBool freeit)
 {
     if (cx) {
 	AES_DestroyContext(&cx->aescx, PR_FALSE);
 /*	memset(cx, 0, sizeof *cx); */
 	if (freeit)
 	    PORT_Free(cx);
     }
 }
 #if !BIG_ENDIAN_WITH_64_BIT_REGISTERS
 /* The AES Key Wrap algorithm has 64-bit values that are ALWAYS big-endian
 ** (Most significant byte first) in memory.  The only ALU operations done
 ** on them are increment, decrement, and XOR.  So, on little-endian CPUs,
 ** and on CPUs that lack 64-bit registers, these big-endian 64-bit operations
 ** are simulated in the following code.  This is thought to be faster and
 ** simpler than trying to convert the data to little-endian and back.
 */
 /* A and T point to two 64-bit values stored most signficant byte first
 ** (big endian).  This function increments the 64-bit value T, and then
 ** XORs it with A, changing A.
 */
 static void
 increment_and_xor(unsigned char *A, unsigned char *T)
 {
     if (!++T[7])
         if (!++T[6])
 	    if (!++T[5])
 		if (!++T[4])
 		    if (!++T[3])
 			if (!++T[2])
 			    if (!++T[1])
 				 ++T[0];
     A[0] ^= T[0];
     A[1] ^= T[1];
     A[2] ^= T[2];
     A[3] ^= T[3];
     A[4] ^= T[4];
     A[5] ^= T[5];
     A[6] ^= T[6];
     A[7] ^= T[7];
 }
 /* A and T point to two 64-bit values stored most signficant byte first
 ** (big endian).  This function XORs T with A, giving a new A, then
 ** decrements the 64-bit value T.
 */
 static void
 xor_and_decrement(unsigned char *A, unsigned char *T)
 {
     A[0] ^= T[0];
     A[1] ^= T[1];
     A[2] ^= T[2];
     A[3] ^= T[3];
     A[4] ^= T[4];
     A[5] ^= T[5];
     A[6] ^= T[6];
     A[7] ^= T[7];
     if (!T[7]--)
         if (!T[6]--)
 	    if (!T[5]--)
 		if (!T[4]--)
 		    if (!T[3]--)
 			if (!T[2]--)
 			    if (!T[1]--)
 				 T[0]--;
 }
 /* Given an unsigned long t (in host byte order), store this value as a
 ** 64-bit big-endian value (MSB first) in *pt.
 */
 static void
 set_t(unsigned char *pt, unsigned long t)
 {
     pt[7] = (unsigned char)t; t >>= 8;
     pt[6] = (unsigned char)t; t >>= 8;
     pt[5] = (unsigned char)t; t >>= 8;
     pt[4] = (unsigned char)t; t >>= 8;
     pt[3] = (unsigned char)t; t >>= 8;
     pt[2] = (unsigned char)t; t >>= 8;
     pt[1] = (unsigned char)t; t >>= 8;
     pt[0] = (unsigned char)t;
 }
 #endif
 /*
 ** Perform AES key wrap.
 **	"cx" the context
 **	"output" the output buffer to store the encrypted data.
 **	"outputLen" how much data is stored in "output". Set by the routine
 **	   after some data is stored in output.
 **	"maxOutputLen" the maximum amount of data that can ever be
 **	   stored in "output"
 **	"input" the input data
 **	"inputLen" the amount of input data
 */
 extern SECStatus
 AESKeyWrap_Encrypt(AESKeyWrapContext *cx, unsigned char *output,
             unsigned int *pOutputLen, unsigned int maxOutputLen,
             const unsigned char *input, unsigned int inputLen)
 {
     PRUint64 *     R          = NULL;
     unsigned int   nBlocks;
     unsigned int   i, j;
     unsigned int   aesLen     = AES_BLOCK_SIZE;
     unsigned int   outLen     = inputLen + AES_KEY_WRAP_BLOCK_SIZE;
     SECStatus      s          = SECFailure;
     /* These PRUint64s are ALWAYS big endian, regardless of CPU orientation. */
     PRUint64       t;
     PRUint64       B[2];
 #define A B[0]
     /* Check args */
     if (!inputLen || 0 != inputLen % AES_KEY_WRAP_BLOCK_SIZE) {
 	PORT_SetError(SEC_ERROR_INPUT_LEN);
 	return s;
     }
 #ifdef maybe
     if (!output && pOutputLen) {	/* caller is asking for output size */
     	*pOutputLen = outLen;
 	return SECSuccess;
     }
 #endif
     if (maxOutputLen < outLen) {
 	PORT_SetError(SEC_ERROR_OUTPUT_LEN);
 	return s;
     }
     if (cx == NULL || output == NULL || input == NULL) {
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	return s;
     }
     nBlocks = inputLen / AES_KEY_WRAP_BLOCK_SIZE;
     R = PORT_NewArray(PRUint64, nBlocks + 1);
     if (!R)
     	return s;	/* error is already set. */
     /*
     ** 1) Initialize variables.
     */
     memcpy(&A, cx->iv, AES_KEY_WRAP_IV_BYTES);
     memcpy(&R[1], input, inputLen);
 #if BIG_ENDIAN_WITH_64_BIT_REGISTERS
     t = 0;
 #else
     memset(&t, 0, sizeof t);
 #endif
     /*
     ** 2) Calculate intermediate values.
     */
     for (j = 0; j < 6; ++j) {
     	for (i = 1; i <= nBlocks; ++i) {
 	    B[1] = R[i];
 	    s = AES_Encrypt(&cx->aescx, (unsigned char *)B, &aesLen,
 	                    sizeof B,  (unsigned char *)B, sizeof B);
 	    if (s != SECSuccess)
 	        break;
 	    R[i] = B[1];
 	    /* here, increment t and XOR A with t (in big endian order); */
 #if BIG_ENDIAN_WITH_64_BIT_REGISTERS
    	    A ^= ++t;
 #else
 	    increment_and_xor((unsigned char *)&A, (unsigned char *)&t);
 #endif
 	}
     }
     /*
     ** 3) Output the results.
     */
     if (s == SECSuccess) {
     	R[0] =  A;
 	memcpy(output, &R[0], outLen);
 	if (pOutputLen)
 	    *pOutputLen = outLen;
     } else if (pOutputLen) {
     	*pOutputLen = 0;
     }
     PORT_ZFree(R, outLen);
     return s;
 }
 #undef A
 /*
 ** Perform AES key unwrap.
 **	"cx" the context
 **	"output" the output buffer to store the decrypted data.
 **	"outputLen" how much data is stored in "output". Set by the routine
 **	   after some data is stored in output.
 **	"maxOutputLen" the maximum amount of data that can ever be
 **	   stored in "output"
 **	"input" the input data
 **	"inputLen" the amount of input data
 */
 extern SECStatus
 AESKeyWrap_Decrypt(AESKeyWrapContext *cx, unsigned char *output,
             unsigned int *pOutputLen, unsigned int maxOutputLen,
             const unsigned char *input, unsigned int inputLen)
 {
     PRUint64 *     R          = NULL;
     unsigned int   nBlocks;
     unsigned int   i, j;
     unsigned int   aesLen     = AES_BLOCK_SIZE;
     unsigned int   outLen;
     SECStatus      s          = SECFailure;
     /* These PRUint64s are ALWAYS big endian, regardless of CPU orientation. */
     PRUint64       t;
     PRUint64       B[2];
 #define A B[0]
     /* Check args */
     if (inputLen < 3 * AES_KEY_WRAP_BLOCK_SIZE ||
 != inputLen % AES_KEY_WRAP_BLOCK_SIZE) {
 	PORT_SetError(SEC_ERROR_INPUT_LEN);
 	return s;
     }
     outLen = inputLen - AES_KEY_WRAP_BLOCK_SIZE;
 #ifdef maybe
     if (!output && pOutputLen) {	/* caller is asking for output size */
     	*pOutputLen = outLen;
 	return SECSuccess;
     }
 #endif
     if (maxOutputLen < outLen) {
 	PORT_SetError(SEC_ERROR_OUTPUT_LEN);
 	return s;
     }
     if (cx == NULL || output == NULL || input == NULL) {
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	return s;
     }
     nBlocks = inputLen / AES_KEY_WRAP_BLOCK_SIZE;
     R = PORT_NewArray(PRUint64, nBlocks);
     if (!R)
     	return s;	/* error is already set. */
     nBlocks--;
     /*
     ** 1) Initialize variables.
     */
     memcpy(&R[0], input, inputLen);
     A = R[0];
 #if BIG_ENDIAN_WITH_64_BIT_REGISTERS
     t = 6UL * nBlocks;
 #else
     set_t((unsigned char *)&t, 6UL * nBlocks);
 #endif
     /*
     ** 2) Calculate intermediate values.
     */
     for (j = 0; j < 6; ++j) {
     	for (i = nBlocks; i; --i) {
 	    /* here, XOR A with t (in big endian order) and decrement t; */
 #if BIG_ENDIAN_WITH_64_BIT_REGISTERS
    	    A ^= t--;
 #else
 	    xor_and_decrement((unsigned char *)&A, (unsigned char *)&t);
 #endif
 	    B[1] = R[i];
 	    s = AES_Decrypt(&cx->aescx, (unsigned char *)B, &aesLen,
 	                    sizeof B,  (unsigned char *)B, sizeof B);
 	    if (s != SECSuccess)
 	        break;
 	    R[i] = B[1];
 	}
     }
     /*
     ** 3) Output the results.
     */
     if (s == SECSuccess) {
 	int bad = memcmp(&A, cx->iv, AES_KEY_WRAP_IV_BYTES);
 	if (!bad) {
 	    memcpy(output, &R[1], outLen);
 	    if (pOutputLen)
 		*pOutputLen = outLen;
 	} else {
 	    s = SECFailure;
 	    PORT_SetError(SEC_ERROR_BAD_DATA);
 	    if (pOutputLen)
 		*pOutputLen = 0;
     	}
     } else if (pOutputLen) {
     	*pOutputLen = 0;
     }
     PORT_ZFree(R, inputLen);
     return s;
 }
 #undef A

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security/nss/lib/freebl/aeskeywrap.c@b8a032363ba2 (annotated)

security/nss/lib/freebl/aeskeywrap.c