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CT tweaks:
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in wolfcrypt/src/coding.c, add ALIGN64 to hexDecode[], and add hexEncode[] for use by Base16_Encode();

in wolfcrypt/src/misc.c and wolfssl/wolfcrypt/misc.h:

move ctMask*() up so that min() and max() can use them, and add ctMaskWord32GTE();

add ALIGN64 to kHexChar[];

add CT implementation of CharIsWhiteSpace();

remove min_size_t() and max_size_t() recently added, but only one user (refactored).
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@douzzer
douzzer committed Jan 30, 2025
1 parent dd7ec12 commit 0de3804
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Showing 5 changed files with 153 additions and 138 deletions.
3 changes: 2 additions & 1 deletion src/internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25852,7 +25852,8 @@ int ReceiveData(WOLFSSL* ssl, byte* output, size_t sz, int peek)
#endif
}

size = (int)min_size_t(sz, (size_t)ssl->buffers.clearOutputBuffer.length);
size = (sz < (size_t)ssl->buffers.clearOutputBuffer.length) ?
(int)sz : (int)ssl->buffers.clearOutputBuffer.length;

XMEMCPY(output, ssl->buffers.clearOutputBuffer.buffer, size);

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18 changes: 8 additions & 10 deletions wolfcrypt/src/coding.c
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Original file line number Diff line number Diff line change
Expand Up @@ -490,7 +490,7 @@ int Base64_Encode_NoNl(const byte* in, word32 inLen, byte* out, word32* outLen)
#ifdef WOLFSSL_BASE16

static
const byte hexDecode[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
const ALIGN64 byte hexDecode[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
BAD, BAD, BAD, BAD, BAD, BAD, BAD,
10, 11, 12, 13, 14, 15, /* upper case A-F */
BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
Expand Down Expand Up @@ -556,6 +556,11 @@ int Base16_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
return 0;
}

static
const ALIGN64 byte hexEncode[] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};

int Base16_Encode(const byte* in, word32 inLen, byte* out, word32* outLen)
{
word32 outIdx = 0;
Expand All @@ -571,15 +576,8 @@ int Base16_Encode(const byte* in, word32 inLen, byte* out, word32* outLen)
byte hb = in[i] >> 4;
byte lb = in[i] & 0x0f;

/* ASCII value */
hb = (byte)(hb + '0');
if (hb > '9')
hb = (byte)(hb + 7U);

/* ASCII value */
lb = (byte)(lb + '0');
if (lb>'9')
lb = (byte)(lb + 7U);
hb = hexEncode[hb];
lb = hexEncode[lb];

out[outIdx++] = hb;
out[outIdx++] = lb;
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263 changes: 139 additions & 124 deletions wolfcrypt/src/misc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -506,6 +506,125 @@ WC_MISC_STATIC WC_INLINE int ConstantCompare(const byte* a, const byte* b,
}
#endif

#ifndef WOLFSSL_NO_CT_OPS
/* Constant time - mask set when a > b. */
WC_MISC_STATIC WC_INLINE byte ctMaskGT(int a, int b)
{
return (byte)((((word32)a - (word32)b - 1) >> 31) - 1);
}

/* Constant time - mask set when a >= b. */
WC_MISC_STATIC WC_INLINE byte ctMaskGTE(int a, int b)
{
return (byte)((((word32)a - (word32)b) >> 31) - 1);
}

/* Constant time - mask set when a >= b. */
WC_MISC_STATIC WC_INLINE int ctMaskIntGTE(int a, int b)
{
return (int)((((word32)a - (word32)b) >> 31) - 1);
}

#ifdef WORD64_AVAILABLE
/* Constant time - mask set when a >= b. */
WC_MISC_STATIC WC_INLINE word32 ctMaskWord32GTE(word32 a, word32 b)
{
return (word32)((((word64)a - (word64)b) >> 63) - 1);
}
#endif

/* Constant time - mask set when a < b. */
WC_MISC_STATIC WC_INLINE byte ctMaskLT(int a, int b)
{
return (byte)((((word32)b - (word32)a - 1) >> 31) - 1);
}

/* Constant time - mask set when a <= b. */
WC_MISC_STATIC WC_INLINE byte ctMaskLTE(int a, int b)
{
return (byte)((((word32)b - (word32)a) >> 31) - 1);
}

/* Constant time - mask set when a == b. */
WC_MISC_STATIC WC_INLINE byte ctMaskEq(int a, int b)
{
return (byte)((byte)(~ctMaskGT(a, b)) & (byte)(~ctMaskLT(a, b)));
}

/* Constant time - sets 16 bit integer mask when a > b */
WC_MISC_STATIC WC_INLINE word16 ctMask16GT(int a, int b)
{
return (word16)((((word32)a - (word32)b - 1) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a >= b */
WC_MISC_STATIC WC_INLINE word16 ctMask16GTE(int a, int b)
{
return (word16)((((word32)a - (word32)b) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a < b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16LT(int a, int b)
{
return (word16)((((word32)b - (word32)a - 1) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a <= b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16LTE(int a, int b)
{
return (word16)((((word32)b - (word32)a) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a == b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16Eq(int a, int b)
{
return (word16)((word16)(~ctMask16GT(a, b)) & (word16)(~ctMask16LT(a, b)));
}

/* Constant time - mask set when a != b. */
WC_MISC_STATIC WC_INLINE byte ctMaskNotEq(int a, int b)
{
return (byte)((byte)ctMaskGT(a, b) | (byte)ctMaskLT(a, b));
}

/* Constant time - select a when mask is set and b otherwise. */
WC_MISC_STATIC WC_INLINE byte ctMaskSel(byte m, byte a, byte b)
{
return (byte)((b & ((byte)~(word32)m)) | (a & m));
}

/* Constant time - select integer a when mask is set and integer b otherwise. */
WC_MISC_STATIC WC_INLINE int ctMaskSelInt(byte m, int a, int b)
{
return (b & (~(signed int)(signed char)m)) |
(a & ( (signed int)(signed char)m));
}

/* Constant time - select word32 a when mask is set and word32 b otherwise. */
WC_MISC_STATIC WC_INLINE word32 ctMaskSelWord32(byte m, word32 a, word32 b)
{
return (((word32)b & (word32)(~(signed int)(signed char)m)) |
((word32)a & (word32)( (signed int)(signed char)m)));
}

/* Constant time - bit set when a <= b. */
WC_MISC_STATIC WC_INLINE byte ctSetLTE(int a, int b)
{
return (byte)(((word32)a - (word32)b - 1) >> 31);
}

/* Constant time - conditionally copy size bytes from src to dst if mask is set
*/
WC_MISC_STATIC WC_INLINE void ctMaskCopy(byte mask, byte* dst, byte* src,
word16 size)
{
int i;
for (i = 0; i < size; ++i) {
dst[i] ^= (dst[i] ^ src[i]) & mask;
}
}

#endif /* !WOLFSSL_NO_CT_OPS */

#ifndef WOLFSSL_HAVE_MIN
#define WOLFSSL_HAVE_MIN
Expand All @@ -515,31 +634,31 @@ WC_MISC_STATIC WC_INLINE int ConstantCompare(const byte* a, const byte* b,
/* returns the smaller of a and b */
WC_MISC_STATIC WC_INLINE word32 min(word32 a, word32 b)
{
#if !defined(WOLFSSL_NO_CT_OPS) && defined(WORD64_AVAILABLE)
word32 gte_mask = (word32)ctMaskWord32GTE(a, b);
return (a & ~gte_mask) | (b & gte_mask);
#else /* WOLFSSL_NO_CT_OPS */
return a > b ? b : a;
#endif /* WOLFSSL_NO_CT_OPS */
}
#endif /* !WOLFSSL_HAVE_MIN */

WC_MISC_STATIC WC_INLINE size_t min_size_t(size_t a, size_t b)
{
return a > b ? b : a;
}

#ifndef WOLFSSL_HAVE_MAX
#define WOLFSSL_HAVE_MAX
#if defined(HAVE_FIPS) && !defined(max) /* so ifdef check passes */
#define max max
#endif
WC_MISC_STATIC WC_INLINE word32 max(word32 a, word32 b)
{
#if !defined(WOLFSSL_NO_CT_OPS) && defined(WORD64_AVAILABLE)
word32 gte_mask = (word32)ctMaskWord32GTE(a, b);
return (a & gte_mask) | (b & ~gte_mask);
#else /* WOLFSSL_NO_CT_OPS */
return a > b ? a : b;
#endif /* WOLFSSL_NO_CT_OPS */
}
#endif /* !WOLFSSL_HAVE_MAX */

WC_MISC_STATIC WC_INLINE size_t max_size_t(size_t a, size_t b)
{
return a > b ? a : b;
}

#ifndef WOLFSSL_NO_INT_ENCODE
/* converts a 32 bit integer to 24 bit */
WC_MISC_STATIC WC_INLINE void c32to24(word32 in, word24 out)
Expand Down Expand Up @@ -641,8 +760,10 @@ WC_MISC_STATIC WC_INLINE signed char HexCharToByte(char ch)

WC_MISC_STATIC WC_INLINE char ByteToHex(byte in)
{
static const char kHexChar[] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
static ALIGN64 const char kHexChar[] = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
return (char)(kHexChar[in & 0xF]);
}

Expand All @@ -658,6 +779,11 @@ WC_MISC_STATIC WC_INLINE int ByteToHexStr(byte in, char* out)

WC_MISC_STATIC WC_INLINE int CharIsWhiteSpace(char ch)
{
#ifndef WOLFSSL_NO_CT_OPS
return (ctMaskEq(ch, ' ') |
ctMaskEq(ch, '\t') |
ctMaskEq(ch, '\n')) & 1;
#else /* WOLFSSL_NO_CT_OPS */
switch (ch) {
case ' ':
case '\t':
Expand All @@ -666,120 +792,9 @@ WC_MISC_STATIC WC_INLINE int CharIsWhiteSpace(char ch)
default:
return 0;
}
#endif /* WOLFSSL_NO_CT_OPS */
}

#ifndef WOLFSSL_NO_CT_OPS
/* Constant time - mask set when a > b. */
WC_MISC_STATIC WC_INLINE byte ctMaskGT(int a, int b)
{
return (byte)((((word32)a - (word32)b - 1) >> 31) - 1);
}

/* Constant time - mask set when a >= b. */
WC_MISC_STATIC WC_INLINE byte ctMaskGTE(int a, int b)
{
return (byte)((((word32)a - (word32)b) >> 31) - 1);
}

/* Constant time - mask set when a >= b. */
WC_MISC_STATIC WC_INLINE int ctMaskIntGTE(int a, int b)
{
return (int)((((word32)a - (word32)b) >> 31) - 1);
}

/* Constant time - mask set when a < b. */
WC_MISC_STATIC WC_INLINE byte ctMaskLT(int a, int b)
{
return (byte)((((word32)b - (word32)a - 1) >> 31) - 1);
}

/* Constant time - mask set when a <= b. */
WC_MISC_STATIC WC_INLINE byte ctMaskLTE(int a, int b)
{
return (byte)((((word32)b - (word32)a) >> 31) - 1);
}

/* Constant time - mask set when a == b. */
WC_MISC_STATIC WC_INLINE byte ctMaskEq(int a, int b)
{
return (byte)((byte)(~ctMaskGT(a, b)) & (byte)(~ctMaskLT(a, b)));
}

/* Constant time - sets 16 bit integer mask when a > b */
WC_MISC_STATIC WC_INLINE word16 ctMask16GT(int a, int b)
{
return (word16)((((word32)a - (word32)b - 1) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a >= b */
WC_MISC_STATIC WC_INLINE word16 ctMask16GTE(int a, int b)
{
return (word16)((((word32)a - (word32)b) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a < b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16LT(int a, int b)
{
return (word16)((((word32)b - (word32)a - 1) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a <= b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16LTE(int a, int b)
{
return (word16)((((word32)b - (word32)a) >> 31) - 1);
}

/* Constant time - sets 16 bit integer mask when a == b. */
WC_MISC_STATIC WC_INLINE word16 ctMask16Eq(int a, int b)
{
return (word16)((word16)(~ctMask16GT(a, b)) & (word16)(~ctMask16LT(a, b)));
}

/* Constant time - mask set when a != b. */
WC_MISC_STATIC WC_INLINE byte ctMaskNotEq(int a, int b)
{
return (byte)((byte)ctMaskGT(a, b) | (byte)ctMaskLT(a, b));
}

/* Constant time - select a when mask is set and b otherwise. */
WC_MISC_STATIC WC_INLINE byte ctMaskSel(byte m, byte a, byte b)
{
return (byte)((b & ((byte)~(word32)m)) | (a & m));
}

/* Constant time - select integer a when mask is set and integer b otherwise. */
WC_MISC_STATIC WC_INLINE int ctMaskSelInt(byte m, int a, int b)
{
return (b & (~(signed int)(signed char)m)) |
(a & ( (signed int)(signed char)m));
}

/* Constant time - select word32 a when mask is set and word32 b otherwise. */
WC_MISC_STATIC WC_INLINE word32 ctMaskSelWord32(byte m, word32 a, word32 b)
{
return (((word32)b & (word32)(~(signed int)(signed char)m)) |
((word32)a & (word32)( (signed int)(signed char)m)));
}

/* Constant time - bit set when a <= b. */
WC_MISC_STATIC WC_INLINE byte ctSetLTE(int a, int b)
{
return (byte)(((word32)a - (word32)b - 1) >> 31);
}

/* Constant time - conditionally copy size bytes from src to dst if mask is set
*/
WC_MISC_STATIC WC_INLINE void ctMaskCopy(byte mask, byte* dst, byte* src,
word16 size)
{
int i;
for (i = 0; i < size; ++i) {
dst[i] ^= (dst[i] ^ src[i]) & mask;
}
}

#endif

#if defined(WOLFSSL_W64_WRAPPER)
#if defined(WORD64_AVAILABLE) && !defined(WOLFSSL_W64_WRAPPER_TEST)
WC_MISC_STATIC WC_INLINE void w64Increment(w64wrapper *n) {
Expand Down
2 changes: 1 addition & 1 deletion wolfcrypt/src/sp_int.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8016,7 +8016,7 @@ int sp_submod(const sp_int* a, const sp_int* b, const sp_int* m, sp_int* r)
}
#endif /* WOLFSSL_SP_MATH_ALL */

/* Constant time clamping/
/* Constant time clamping.
*
* @param [in, out] a SP integer to clamp.
*/
Expand Down
5 changes: 3 additions & 2 deletions wolfssl/wolfcrypt/misc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -107,15 +107,13 @@ void ByteReverseWords64(word64* out, const word64* in, word32 byteCount);
#endif
WOLFSSL_LOCAL word32 min(word32 a, word32 b);
#endif
WOLFSSL_LOCAL size_t min_size_t(size_t a, size_t b);

#ifndef WOLFSSL_HAVE_MAX
#if defined(HAVE_FIPS) && !defined(max) /* so ifdef check passes */
#define max max
#endif
WOLFSSL_LOCAL word32 max(word32 a, word32 b);
#endif /* WOLFSSL_HAVE_MAX */
WOLFSSL_LOCAL size_t max_size_t(size_t a, size_t b);


void c32to24(word32 in, word24 out);
Expand All @@ -136,6 +134,9 @@ WOLFSSL_LOCAL int CharIsWhiteSpace(char ch);
WOLFSSL_LOCAL byte ctMaskGT(int a, int b);
WOLFSSL_LOCAL byte ctMaskGTE(int a, int b);
WOLFSSL_LOCAL int ctMaskIntGTE(int a, int b);
#ifdef WORD64_AVAILABLE
WOLFSSL_LOCAL word32 ctMaskWord32GTE(word32 a, word32 b);
#endif
WOLFSSL_LOCAL byte ctMaskLT(int a, int b);
WOLFSSL_LOCAL byte ctMaskLTE(int a, int b);
WOLFSSL_LOCAL byte ctMaskEq(int a, int b);
Expand Down

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