diff --git a/library/bignum.c b/library/bignum.c index e47e25917d9d2fa6ecb1ce91b8c576b1f03a0e19..5ef72b5cdd233770a704f535d2a1448b098d1fa2 100644 --- a/library/bignum.c +++ b/library/bignum.c @@ -1872,43 +1872,20 @@ int mbedtls_mpi_mod_int( mbedtls_mpi_uint *r, const mbedtls_mpi *A, mbedtls_mpi_ /* * Fast Montgomery initialization (thanks to Tom St Denis) */ -static void mpi_montg_init( mbedtls_mpi_uint *mm, const mbedtls_mpi *N ) +mbedtls_mpi_uint mbedtls_mpi_montmul_init(const mbedtls_mpi_uint *N) { - mbedtls_mpi_uint x, m0 = N->p[0]; - unsigned int i; + mbedtls_mpi_uint x = N[0]; - x = m0; - x += ( ( m0 + 2 ) & 4 ) << 1; + x += ((N[0] + 2) & 4) << 1; - for( i = biL; i >= 8; i /= 2 ) - x *= ( 2 - ( m0 * x ) ); + for (unsigned int i = biL; i >= 8; i /= 2) { + x *= (2 - (N[0] * x)); + } - *mm = ~x + 1; + return ~x + 1; } -/** Montgomery multiplication: A = A * B * R^-1 mod N (HAC 14.36) - * - * \param[in,out] A One of the numbers to multiply. - * It must have at least as many limbs as N - * (A->n >= N->n), and any limbs beyond n are ignored. - * On successful completion, A contains the result of - * the multiplication A * B * R^-1 mod N where - * R = (2^ciL)^n. - * \param[in] B One of the numbers to multiply. - * It must be nonzero and must not have more limbs than N - * (B->n <= N->n). - * \param[in] N The modulo. N must be odd. - * \param mm The value calculated by `mpi_montg_init(&mm, N)`. - * This is -N^-1 mod 2^ciL. - * \param[in,out] T A bignum for temporary storage. - * It must be at least twice the limb size of N plus 2 - * (T->n >= 2 * (N->n + 1)). - * Its initial content is unused and - * its final content is indeterminate. - * Note that unlike the usual convention in the library - * for `const mbedtls_mpi*`, the content of T can change. - */ -static void mpi_montmul( mbedtls_mpi *A, const mbedtls_mpi *B, const mbedtls_mpi *N, mbedtls_mpi_uint mm, +void mbedtls_mpi_montmul( mbedtls_mpi *A, const mbedtls_mpi *B, const mbedtls_mpi *N, mbedtls_mpi_uint mm, const mbedtls_mpi *T ) { size_t i, n, m; @@ -1969,7 +1946,7 @@ static void mpi_montred( mbedtls_mpi *A, const mbedtls_mpi *N, U.n = U.s = (int) z; U.p = &z; - mpi_montmul( A, &U, N, mm, T ); + mbedtls_mpi_montmul( A, &U, N, mm, T ); } /** @@ -2001,6 +1978,20 @@ cleanup: return( ret ); } +int mbedtls_mpi_get_mont_r2_unsafe(mbedtls_mpi *X, + const mbedtls_mpi *N) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_MPI_CHK(mbedtls_mpi_lset(X, 1)); + MBEDTLS_MPI_CHK(mbedtls_mpi_shift_l(X, N->n * 2 * biL)); + MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(X, X, N)); + MBEDTLS_MPI_CHK(mbedtls_mpi_shrink(X, N->n)); + +cleanup: + return ret; +} + /* * Sliding-window exponentiation: X = A^E mod N (HAC 14.85) */ @@ -2009,11 +2000,11 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, mbedtls_mpi *prec_RR ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - size_t wbits, wsize, one = 1; + size_t window_bitsize; size_t i, j, nblimbs; size_t bufsize, nbits; mbedtls_mpi_uint ei, mm, state; - mbedtls_mpi RR, T, W[ 1 << MBEDTLS_MPI_WINDOW_SIZE ], WW, Apos; + mbedtls_mpi RR, T, W[ (size_t) 1 << MBEDTLS_MPI_WINDOW_SIZE ], WW, Apos; int neg; MPI_VALIDATE_RET( X != NULL ); @@ -2034,7 +2025,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, /* * Init temps and window size */ - mpi_montg_init( &mm, N ); + mm = mbedtls_mpi_montmul_init(N->p); mbedtls_mpi_init( &RR ); mbedtls_mpi_init( &T ); mbedtls_mpi_init( &Apos ); mbedtls_mpi_init( &WW ); @@ -2042,21 +2033,59 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, i = mbedtls_mpi_bitlen( E ); - wsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 : + window_bitsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 : ( i > 79 ) ? 4 : ( i > 23 ) ? 3 : 1; #if( MBEDTLS_MPI_WINDOW_SIZE < 6 ) - if( wsize > MBEDTLS_MPI_WINDOW_SIZE ) - wsize = MBEDTLS_MPI_WINDOW_SIZE; + if( window_bitsize > MBEDTLS_MPI_WINDOW_SIZE ) + window_bitsize = MBEDTLS_MPI_WINDOW_SIZE; #endif + const size_t w_table_used_size = (size_t) 1 << window_bitsize; + + /* + * This function is not constant-trace: its memory accesses depend on the + * exponent value. To defend against timing attacks, callers (such as RSA + * and DHM) should use exponent blinding. However this is not enough if the + * adversary can find the exponent in a single trace, so this function + * takes extra precautions against adversaries who can observe memory + * access patterns. + * + * This function performs a series of multiplications by table elements and + * squarings, and we want the prevent the adversary from finding out which + * table element was used, and from distinguishing between multiplications + * and squarings. Firstly, when multiplying by an element of the window + * W[i], we do a constant-trace table lookup to obfuscate i. This leaves + * squarings as having a different memory access patterns from other + * multiplications. So secondly, we put the accumulator X in the table as + * well, and also do a constant-trace table lookup to multiply by X. + * + * This way, all multiplications take the form of a lookup-and-multiply. + * The number of lookup-and-multiply operations inside each iteration of + * the main loop still depends on the bits of the exponent, but since the + * other operations in the loop don't have an easily recognizable memory + * trace, an adversary is unlikely to be able to observe the exact + * patterns. + * + * An adversary may still be able to recover the exponent if they can + * observe both memory accesses and branches. However, branch prediction + * exploitation typically requires many traces of execution over the same + * data, which is defeated by randomized blinding. + * + * To achieve this, we make a copy of X and we use the table entry in each + * calculation from this point on. + */ + const size_t x_index = 0; + mbedtls_mpi_init( &W[x_index] ); + mbedtls_mpi_copy( &W[x_index], X ); + j = N->n + 1; /* All W[i] and X must have at least N->n limbs for the mpi_montmul() * and mpi_montred() calls later. Here we ensure that W[1] and X are * large enough, and later we'll grow other W[i] to the same length. * They must not be shrunk midway through this function! */ - MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, j ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[x_index], j ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[1], j ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &T, j * 2 ) ); @@ -2076,10 +2105,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, */ if( prec_RR == NULL || prec_RR->p == NULL ) { - MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &RR, 1 ) ); - MBEDTLS_MPI_CHK( mbedtls_mpi_shift_l( &RR, N->n * 2 * biL ) ); - MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &RR, &RR, N ) ); - + mbedtls_mpi_get_mont_r2_unsafe(&RR, N); if( prec_RR != NULL ) memcpy( prec_RR, &RR, sizeof( mbedtls_mpi ) ); } @@ -2102,43 +2128,51 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, /* Note that this is safe because W[1] always has at least N->n limbs * (it grew above and was preserved by mbedtls_mpi_copy()). */ - mpi_montmul( &W[1], &RR, N, mm, &T ); + mbedtls_mpi_montmul( &W[1], &RR, N, mm, &T ); /* - * X = R^2 * R^-1 mod N = R mod N + * W[x_index] = R^2 * R^-1 mod N = R mod N */ - MBEDTLS_MPI_CHK( mbedtls_mpi_copy( X, &RR ) ); - mpi_montred( X, N, mm, &T ); + MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[x_index], &RR ) ); + mpi_montred( &W[x_index], N, mm, &T ); + - if( wsize > 1 ) + if( window_bitsize > 1 ) { /* - * W[1 << (wsize - 1)] = W[1] ^ (wsize - 1) + * W[i] = W[1] ^ i + * + * The first bit of the sliding window is always 1 and therefore we + * only need to store the second half of the table. + * + * (There are two special elements in the table: W[0] for the + * accumulator/result and W[1] for A in Montgomery form. Both of these + * are already set at this point.) */ - j = one << ( wsize - 1 ); + j = w_table_used_size / 2; MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[j], N->n + 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[j], &W[1] ) ); - for( i = 0; i < wsize - 1; i++ ) - mpi_montmul( &W[j], &W[j], N, mm, &T ); + for( i = 0; i < window_bitsize - 1; i++ ) + mbedtls_mpi_montmul( &W[j], &W[j], N, mm, &T ); /* * W[i] = W[i - 1] * W[1] */ - for( i = j + 1; i < ( one << wsize ); i++ ) + for( i = j + 1; i < w_table_used_size; i++ ) { MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[i], N->n + 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[i], &W[i - 1] ) ); - mpi_montmul( &W[i], &W[1], N, mm, &T ); + mbedtls_mpi_montmul( &W[i], &W[1], N, mm, &T ); } } nblimbs = E->n; bufsize = 0; nbits = 0; - wbits = 0; + size_t exponent_bits_in_window = 0; state = 0; while( 1 ) @@ -2166,9 +2200,10 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, if( ei == 0 && state == 1 ) { /* - * out of window, square X + * out of window, square W[x_index] */ - mpi_montmul( X, X, N, mm, &T ); + MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_used_size, x_index ) ); + mbedtls_mpi_montmul( &W[x_index], &WW, N, mm, &T ); continue; } @@ -2178,25 +2213,30 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, state = 2; nbits++; - wbits |= ( ei << ( wsize - nbits ) ); + exponent_bits_in_window |= ( ei << ( window_bitsize - nbits ) ); - if( nbits == wsize ) + if( nbits == window_bitsize ) { /* - * X = X^wsize R^-1 mod N + * W[x_index] = W[x_index]^window_bitsize R^-1 mod N */ - for( i = 0; i < wsize; i++ ) - mpi_montmul( X, X, N, mm, &T ); + for( i = 0; i < window_bitsize; i++ ) + { + MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_used_size, + x_index ) ); + mbedtls_mpi_montmul( &W[x_index], &WW, N, mm, &T ); + } /* - * X = X * W[wbits] R^-1 mod N + * W[x_index] = W[x_index] * W[exponent_bits_in_window] R^-1 mod N */ - MBEDTLS_MPI_CHK( mpi_select( &WW, W, (size_t) 1 << wsize, wbits ) ); - mpi_montmul( X, &WW, N, mm, &T ); + MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_used_size, + exponent_bits_in_window ) ); + mbedtls_mpi_montmul( &W[x_index], &WW, N, mm, &T ); state--; nbits = 0; - wbits = 0; + exponent_bits_in_window = 0; } } @@ -2205,31 +2245,45 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, */ for( i = 0; i < nbits; i++ ) { - mpi_montmul( X, X, N, mm, &T ); + MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_used_size, x_index ) ); + mbedtls_mpi_montmul( &W[x_index], &WW, N, mm, &T ); - wbits <<= 1; + exponent_bits_in_window <<= 1; - if( ( wbits & ( one << wsize ) ) != 0 ) - mpi_montmul( X, &W[1], N, mm, &T ); + if( ( exponent_bits_in_window & ( (size_t) 1 << window_bitsize ) ) != 0 ) + { + MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_used_size, 1 ) ); + mbedtls_mpi_montmul( &W[x_index], &WW, N, mm, &T ); + } } /* - * X = A^E * R * R^-1 mod N = A^E mod N + * W[x_index] = A^E * R * R^-1 mod N = A^E mod N */ - mpi_montred( X, N, mm, &T ); + mpi_montred( &W[x_index], N, mm, &T ); if( neg && E->n != 0 && ( E->p[0] & 1 ) != 0 ) { - X->s = -1; - MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( X, N, X ) ); + W[x_index].s = -1; + MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &W[x_index], N, &W[x_index] ) ); } + /* + * Load the result in the output variable. + */ + mbedtls_mpi_copy( X, &W[x_index] ); + cleanup: - for( i = ( one << ( wsize - 1 ) ); i < ( one << wsize ); i++ ) + /* The first bit of the sliding window is always 1 and therefore the first + * half of the table was unused. */ + for( i = w_table_used_size/2; i < w_table_used_size; i++ ) mbedtls_mpi_free( &W[i] ); - mbedtls_mpi_free( &W[1] ); mbedtls_mpi_free( &T ); mbedtls_mpi_free( &Apos ); + mbedtls_mpi_free( &W[x_index] ); + mbedtls_mpi_free( &W[1] ); + mbedtls_mpi_free( &T ); + mbedtls_mpi_free( &Apos ); mbedtls_mpi_free( &WW ); if( prec_RR == NULL || prec_RR->p == NULL ) diff --git a/library/bignum_internal.h b/library/bignum_internal.h new file mode 100644 index 0000000000000000000000000000000000000000..5435ebb464905428b68f759630503696e598c0b4 --- /dev/null +++ b/library/bignum_internal.h @@ -0,0 +1,71 @@ +/** + * Low level bignum functions + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#ifndef MBEDTLS_BIGNUM_INTERNAL_H +#define MBEDTLS_BIGNUM_INTERNAL_H + +#include "mbedtls/bignum.h" + +/** + * \brief Calculate the square of the Montgomery constant. (Needed + * for conversion and operations in Montgomery form.) + * + * \param[out] X A pointer to the result of the calculation of + * the square of the Montgomery constant: + * 2^{2*n*biL} mod N. + * \param[in] N Little-endian presentation of the modulus, which must be odd. + * + * \return 0 if successful. + * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if there is not enough space + * to store the value of Montgomery constant squared. + * \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p N modulus is zero. + * \return #MBEDTLS_ERR_MPI_NEGATIVE_VALUE if \p N modulus is negative. + */ +int mbedtls_mpi_get_mont_r2_unsafe(mbedtls_mpi *X, + const mbedtls_mpi *N); + +/** + * \brief Calculate initialisation value for fast Montgomery modular + * multiplication + * + * \param[in] N Little-endian presentation of the modulus. This must have + * at least one limb. + * + * \return The initialisation value for fast Montgomery modular multiplication + */ +mbedtls_mpi_uint mbedtls_mpi_montmul_init(const mbedtls_mpi_uint *N); + +/** Montgomery multiplication: A = A * B * R^-1 mod N (HAC 14.36) + * + * \param[in,out] A One of the numbers to multiply. + * It must have at least as many limbs as N + * (A->n >= N->n), and any limbs beyond n are ignored. + * On successful completion, A contains the result of + * the multiplication A * B * R^-1 mod N where + * R = (2^ciL)^n. + * \param[in] B One of the numbers to multiply. + * It must be nonzero and must not have more limbs than N + * (B->n <= N->n). + * \param[in] N The modulo. N must be odd. + * \param mm The value calculated by + * `mbedtls_mpi_montg_init(&mm, N)`. + * This is -N^-1 mod 2^ciL. + * \param[in,out] T A bignum for temporary storage. + * It must be at least twice the limb size of N plus 2 + * (T->n >= 2 * (N->n + 1)). + * Its initial content is unused and + * its final content is indeterminate. + * Note that unlike the usual convention in the library + * for `const mbedtls_mpi*`, the content of T can change. + */ +void mbedtls_mpi_montmul(mbedtls_mpi *A, + const mbedtls_mpi *B, + const mbedtls_mpi *N, + mbedtls_mpi_uint mm, + const mbedtls_mpi *T); + +#endif /* MBEDTLS_BIGNUM_INTERNAL_H */ diff --git a/library/rsa.c b/library/rsa.c index 36f487f3a77733421db0c289d59f36e075a8a054..8dd34039fc5e9d296f3c91c831bc73ebf1f331a2 100644 --- a/library/rsa.c +++ b/library/rsa.c @@ -46,7 +46,7 @@ #include "mbedtls/error.h" #include "constant_time_internal.h" #include "mbedtls/constant_time.h" - +#include "bignum_internal.h" #include #if defined(MBEDTLS_PKCS1_V21) @@ -867,6 +867,47 @@ cleanup: */ #define RSA_EXPONENT_BLINDING 28 +/* + * Unblind + * T = T * Vf mod N + */ +static int rsa_unblind(mbedtls_mpi *T, mbedtls_mpi *Vf, const mbedtls_mpi *N) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const size_t nlimbs = N->n; + const size_t tlimbs = 2 * (nlimbs + 1); + + mbedtls_mpi_uint mm = mbedtls_mpi_montmul_init(N->p); + + mbedtls_mpi RR, M_T; + + mbedtls_mpi_init(&RR); + mbedtls_mpi_init(&M_T); + + MBEDTLS_MPI_CHK(mbedtls_mpi_get_mont_r2_unsafe(&RR, N)); + MBEDTLS_MPI_CHK(mbedtls_mpi_grow(&M_T, tlimbs)); + + MBEDTLS_MPI_CHK(mbedtls_mpi_grow(T, nlimbs)); + MBEDTLS_MPI_CHK(mbedtls_mpi_grow(Vf, nlimbs)); + + /* T = T * Vf mod N + * Reminder: montmul(A, B, N) = A * B * R^-1 mod N + * Usually both operands are multiplied by R mod N beforehand, yielding a + * result that's also * R mod N (aka "in the Montgomery domain"). Here we + * only multiply one operand by R mod N, so the result is directly what we + * want - no need to call `mpi_montred()` on it. */ + mbedtls_mpi_montmul(T, &RR, N, mm, &M_T); + mbedtls_mpi_montmul(T, Vf, N, mm, &M_T); + +cleanup: + + mbedtls_mpi_free(&RR); + mbedtls_mpi_free(&M_T); + + return ret; +} + + /* * Do an RSA private key operation */ @@ -909,7 +950,7 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, /* Temporaries holding the initial input and the double * checked result; should be the same in the end. */ - mbedtls_mpi I, C; + mbedtls_mpi input_blinded, check_result_blinded; RSA_VALIDATE_RET( ctx != NULL ); RSA_VALIDATE_RET( input != NULL ); @@ -947,8 +988,8 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ ); #endif - mbedtls_mpi_init( &I ); - mbedtls_mpi_init( &C ); + mbedtls_mpi_init(&input_blinded); + mbedtls_mpi_init(&check_result_blinded); /* End of MPI initialization */ @@ -959,8 +1000,6 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, goto cleanup; } - MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) ); - /* * Blinding * T = T * Vi mod N @@ -1010,6 +1049,8 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, DQ = &DQ_blind; #endif /* MBEDTLS_RSA_NO_CRT */ + /* Make a copy of the input (after blinding if there was any) */ + MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&input_blinded, &T)); #if defined(MBEDTLS_RSA_NO_CRT) MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) ); #else @@ -1037,22 +1078,16 @@ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) ); #endif /* MBEDTLS_RSA_NO_CRT */ - /* - * Unblind - * T = T * Vf mod N - */ - MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) ); - MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); - /* Verify the result to prevent glitching attacks. */ - MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E, - &ctx->N, &ctx->RN ) ); - if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 ) - { + MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&check_result_blinded, &T, &ctx->E, + &ctx->N, &ctx->RN)); + if (mbedtls_mpi_cmp_mpi(&check_result_blinded, &input_blinded) != 0) { ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; goto cleanup; } + MBEDTLS_MPI_CHK(rsa_unblind(&T, &ctx->Vf, &ctx->N)); + olen = ctx->len; MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); @@ -1079,8 +1114,8 @@ cleanup: mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ ); #endif - mbedtls_mpi_free( &C ); - mbedtls_mpi_free( &I ); + mbedtls_mpi_free(&check_result_blinded); + mbedtls_mpi_free(&input_blinded); if( ret != 0 && ret >= -0x007f ) return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_PRIVATE_FAILED, ret ) ); diff --git a/library/ssl_misc.h b/library/ssl_misc.h index 6061e33139c95a22f4c3284ac576b058449b9ebd..c5b153ca1dfc1028fe23846a4fee4e3b6a1a3b53 100644 --- a/library/ssl_misc.h +++ b/library/ssl_misc.h @@ -928,7 +928,7 @@ struct mbedtls_ssl_transform #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) uint8_t in_cid_len; uint8_t out_cid_len; - unsigned char in_cid [ MBEDTLS_SSL_CID_OUT_LEN_MAX ]; + unsigned char in_cid [ MBEDTLS_SSL_CID_IN_LEN_MAX ]; unsigned char out_cid[ MBEDTLS_SSL_CID_OUT_LEN_MAX ]; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */