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Fixed calculation of max ECC bits with ALT_ECC_SIZE defined so it only allocates what is required. For 8-bit aligned curve sizes its double the max bits. For un-aligned curves sized, like ECC521, its 521 8-bit aligned, doubled, plus digit bit.

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This commit is contained in:
David Garske
2016-05-09 09:50:51 -07:00
parent 44b1f98b39
commit 8c9b8a596a
1 changed files with 14 additions and 6 deletions
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18
wolfssl/wolfcrypt/ecc.h
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@@ -63,7 +63,7 @@ typedef struct {
/* Determine max ECC bits based on enabled curves */ /* Determine max ECC bits based on enabled curves */
#if defined(HAVE_ECC521) || defined(HAVE_ALL_CURVES) #if defined(HAVE_ECC521) || defined(HAVE_ALL_CURVES)
#define MAX_ECC_BITS 528 #define MAX_ECC_BITS 521
#elif defined(HAVE_ECC384) #elif defined(HAVE_ECC384)
#define MAX_ECC_BITS 384 #define MAX_ECC_BITS 384
#elif defined(HAVE_ECC224) #elif defined(HAVE_ECC224)
@@ -111,18 +111,26 @@ typedef struct {
#error USE_FAST_MATH must be defined to use ALT_ECC_SIZE #error USE_FAST_MATH must be defined to use ALT_ECC_SIZE
#endif #endif
/* determine max bits required for ECC math */
#ifndef FP_MAX_BITS_ECC #ifndef FP_MAX_BITS_ECC
/* This value should be double the max ecc bit size */ /* check alignment */
#if ((MAX_ECC_BITS & CHAR_BIT) == 0)
/* max bits is double */
#define FP_MAX_BITS_ECC (MAX_ECC_BITS * 2) #define FP_MAX_BITS_ECC (MAX_ECC_BITS * 2)
#else
/* max bits is rounded up to 8-bit alignment, doubled, plus one digit of fudge */
#define FP_MAX_BITS_ECC ((((MAX_ECC_BITS + CHAR_BIT) & ~CHAR_BIT) * 2) + DIGIT_BIT)
#endif
#endif #endif
#define FP_MAX_SIZE_ECC (FP_MAX_BITS_ECC+(8*DIGIT_BIT)) /* verify alignment */
#if FP_MAX_BITS_ECC % CHAR_BIT #if FP_MAX_BITS_ECC % CHAR_BIT
#error FP_MAX_BITS_ECC must be a multiple of CHAR_BIT #error FP_MAX_BITS_ECC must be a multiple of CHAR_BIT
#endif #endif
#define FP_SIZE_ECC (FP_MAX_SIZE_ECC/DIGIT_BIT) /* determine buffer size */
#define FP_SIZE_ECC (FP_MAX_BITS_ECC/DIGIT_BIT)
/* This needs to match the size of the fp_int struct, except the /* This needs to match the size of the fp_int struct, except the
* fp_digit array will be shorter. */ * fp_digit array will be shorter. */