From d7b3d9247602fe5d5015a759d4f3867f28ac22a8 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Thu, 13 May 2021 00:45:25 +0200 Subject: [PATCH] Change sha256 output type from an array to a pointer The output parameter of mbedtls_sha256_finish_ret and mbedtls_sha256_ret now has a pointer type rather than array type. This removes spurious warnings in some compilers when outputting a SHA-224 hash into a 28-byte buffer. Signed-off-by: Gilles Peskine --- ChangeLog.d/sha512-output-type.txt | 9 +++++---- docs/3.0-migration-guide.d/sha512-output-type.md | 6 +++--- include/mbedtls/sha256.h | 12 +++++++----- library/sha256.c | 4 ++-- 4 files changed, 17 insertions(+), 14 deletions(-) diff --git a/ChangeLog.d/sha512-output-type.txt b/ChangeLog.d/sha512-output-type.txt index e29557c9d..eabc67df7 100644 --- a/ChangeLog.d/sha512-output-type.txt +++ b/ChangeLog.d/sha512-output-type.txt @@ -1,5 +1,6 @@ API changes - * The output parameter of mbedtls_sha512_finish_ret and mbedtls_sha512_ret - now has a pointer type rather than array type. This removes spurious - warnings in some compilers when outputting a SHA-384 hash into a - 48-byte buffer. + * The output parameter of mbedtls_sha512_finish_ret, mbedtls_sha512_ret, + mbedtls_sha256_finish_ret and mbedtls_sha256_ret now has a pointer type + rather than array type. This removes spurious warnings in some compilers + when outputting a SHA-384 or SHA-224 hash into a buffer of exactly + the hash size. diff --git a/docs/3.0-migration-guide.d/sha512-output-type.md b/docs/3.0-migration-guide.d/sha512-output-type.md index 5a7d2053c..c62a88159 100644 --- a/docs/3.0-migration-guide.d/sha512-output-type.md +++ b/docs/3.0-migration-guide.d/sha512-output-type.md @@ -1,8 +1,8 @@ -SHA-512 output type change +SHA-512 and SHA-256 output type change -------------------------- -The output parameter of `mbedtls_sha512_finish_ret()` and `mbedtls_sha512_ret()` now has a pointer type rather than array type. This makes no difference in terms of C semantics, but removes spurious warnings in some compilers when outputting a SHA-384 hash into a 48-byte buffer. +The output parameter of `mbedtls_sha256_finish_ret()`, `mbedtls_sha256_ret()`, `mbedtls_sha512_finish_ret()`, `mbedtls_sha512_ret()` now has a pointer type rather than array type. This makes no difference in terms of C semantics, but removes spurious warnings in some compilers when outputting a SHA-384 hash into a 48-byte buffer or a SHA-224 hash into a 28-byte buffer. This makes no difference to a vast majority of applications. If your code takes a pointer to one of these functions, you may need to change the type of the pointer. -Alternative implementations of the SHA512 module must adjust their functions' prototype accordingly. +Alternative implementations of the SHA256 and SHA512 modules must adjust their functions' prototype accordingly. diff --git a/include/mbedtls/sha256.h b/include/mbedtls/sha256.h index 9b8d91d1c..110086952 100644 --- a/include/mbedtls/sha256.h +++ b/include/mbedtls/sha256.h @@ -127,13 +127,14 @@ int mbedtls_sha256_update_ret( mbedtls_sha256_context *ctx, * \param ctx The SHA-256 context. This must be initialized * and have a hash operation started. * \param output The SHA-224 or SHA-256 checksum result. - * This must be a writable buffer of length \c 32 Bytes. + * This must be a writable buffer of length \c 32 bytes + * for SHA-256, 28 bytes for SHA-224. * * \return \c 0 on success. * \return A negative error code on failure. */ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx, - unsigned char output[32] ); + unsigned char *output ); /** * \brief This function processes a single data block within @@ -163,14 +164,15 @@ int mbedtls_internal_sha256_process( mbedtls_sha256_context *ctx, * \param input The buffer holding the data. This must be a readable * buffer of length \p ilen Bytes. * \param ilen The length of the input data in Bytes. - * \param output The SHA-224 or SHA-256 checksum result. This must - * be a writable buffer of length \c 32 Bytes. + * \param output The SHA-224 or SHA-256 checksum result. + * This must be a writable buffer of length \c 32 bytes + * for SHA-256, 28 bytes for SHA-224. * \param is224 Determines which function to use. This must be * either \c 0 for SHA-256, or \c 1 for SHA-224. */ int mbedtls_sha256_ret( const unsigned char *input, size_t ilen, - unsigned char output[32], + unsigned char *output, int is224 ); #if defined(MBEDTLS_SELF_TEST) diff --git a/library/sha256.c b/library/sha256.c index a94f325e8..36ab0c1aa 100644 --- a/library/sha256.c +++ b/library/sha256.c @@ -332,7 +332,7 @@ int mbedtls_sha256_update_ret( mbedtls_sha256_context *ctx, * SHA-256 final digest */ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx, - unsigned char output[32] ) + unsigned char *output ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; uint32_t used; @@ -401,7 +401,7 @@ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx, */ int mbedtls_sha256_ret( const unsigned char *input, size_t ilen, - unsigned char output[32], + unsigned char *output, int is224 ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;