From a325a23bc83f4efd60130001c417ca5b96bdbff1 Mon Sep 17 00:00:00 2001 From: Clemens Lang Date: Thu, 17 Nov 2022 19:33:02 +0100 Subject: [PATCH] signature: Add indicator for PSS salt length MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit FIPS 186-4 section 5 "The RSA Digital Signature Algorithm", subsection 5.5 "PKCS #1" says: "For RSASSA-PSS [...] the length (in bytes) of the salt (sLen) shall satisfy 0 <= sLen <= hLen, where hLen is the length of the hash function output block (in bytes)." It is not exactly clear from this text whether hLen refers to the message digest or the hash function used for the mask generation function MGF1. PKCS#1 v2.1 suggests it is the former: | Typical salt lengths in octets are hLen (the length of the output of | the hash function Hash) and 0. In both cases the security of | RSASSA-PSS can be closely related to the hardness of inverting RSAVP1. | Bellare and Rogaway [4] give a tight lower bound for the security of | the original RSA-PSS scheme, which corresponds roughly to the former | case, while Coron [12] gives a lower bound for the related Full Domain | Hashing scheme, which corresponds roughly to the latter case. In [13] | Coron provides a general treatment with various salt lengths ranging | from 0 to hLen; see [27] for discussion. See also [31], which adapts | the security proofs in [4][13] to address the differences between the | original and the present version of RSA-PSS as listed in Note 1 above. Since OpenSSL defaults to creating signatures with the maximum salt length, blocking the use of longer salts would probably lead to significant problems in practice. Instead, introduce an explicit indicator that can be obtained from the EVP_PKEY_CTX object using EVP_PKEY_CTX_get_params() with the OSSL_SIGNATURE_PARAM_SUSE_FIPS_INDICATOR parameter. We also add indicator for RSA_NO_PADDING here to avoid patch-over-patch. Dmitry Belyavskiy Signed-off-by: Clemens Lang --- include/openssl/evp.h | 4 ++++ providers/implementations/signature/rsa_sig.c | 21 +++++++++++++++++ util/perl/OpenSSL/paramnames.pm | 23 ++++++++++--------- 3 files changed, 37 insertions(+), 11 deletions(-) Index: openssl-3.1.4/include/openssl/evp.h =================================================================== --- openssl-3.1.4.orig/include/openssl/evp.h +++ openssl-3.1.4/include/openssl/evp.h @@ -801,6 +801,10 @@ __owur int EVP_CipherFinal(EVP_CIPHER_CT __owur int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); +# define EVP_SIGNATURE_SUSE_FIPS_INDICATOR_UNDETERMINED 0 +# define EVP_SIGNATURE_SUSE_FIPS_INDICATOR_APPROVED 1 +# define EVP_SIGNATURE_SUSE_FIPS_INDICATOR_NOT_APPROVED 2 + __owur int EVP_SignFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s, EVP_PKEY *pkey); __owur int EVP_SignFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s, Index: openssl-3.1.4/providers/implementations/signature/rsa_sig.c =================================================================== --- openssl-3.1.4.orig/providers/implementations/signature/rsa_sig.c +++ openssl-3.1.4/providers/implementations/signature/rsa_sig.c @@ -1167,6 +1167,24 @@ static int rsa_get_ctx_params(void *vprs } } +#ifdef FIPS_MODULE + p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_SUSE_FIPS_INDICATOR); + if (p != NULL) { + int fips_indicator = EVP_SIGNATURE_SUSE_FIPS_INDICATOR_APPROVED; + if (prsactx->pad_mode == RSA_PKCS1_PSS_PADDING) { + if (prsactx->md == NULL) { + fips_indicator = EVP_SIGNATURE_SUSE_FIPS_INDICATOR_UNDETERMINED; + } else if (rsa_pss_compute_saltlen(prsactx) > EVP_MD_get_size(prsactx->md)) { + fips_indicator = EVP_SIGNATURE_SUSE_FIPS_INDICATOR_NOT_APPROVED; + } + } else if (prsactx->pad_mode == RSA_NO_PADDING) { + if (prsactx->md == NULL) /* Should always be the case */ + fips_indicator = EVP_SIGNATURE_SUSE_FIPS_INDICATOR_NOT_APPROVED; + } + return OSSL_PARAM_set_int(p, fips_indicator); + } +#endif + return 1; } @@ -1176,6 +1194,9 @@ static const OSSL_PARAM known_gettable_c OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0), OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0), OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0), +#ifdef FIPS_MODULE + OSSL_PARAM_int(OSSL_SIGNATURE_PARAM_SUSE_FIPS_INDICATOR, NULL), +#endif OSSL_PARAM_END }; Index: openssl-3.1.4/include/openssl/core_names.h =================================================================== --- openssl-3.1.4.orig/include/openssl/core_names.h +++ openssl-3.1.4/include/openssl/core_names.h @@ -458,6 +458,7 @@ extern "C" { #define OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES \ OSSL_PKEY_PARAM_MGF1_PROPERTIES #define OSSL_SIGNATURE_PARAM_DIGEST_SIZE OSSL_PKEY_PARAM_DIGEST_SIZE +#define OSSL_SIGNATURE_PARAM_SUSE_FIPS_INDICATOR "suse-fips-indicator" /* Asym cipher parameters */ #define OSSL_ASYM_CIPHER_PARAM_DIGEST OSSL_PKEY_PARAM_DIGEST Index: openssl-3.1.4/providers/implementations/signature/rsa_sig.c =================================================================== --- openssl-3.1.4.orig/providers/implementations/signature/rsa_sig.c +++ openssl-3.1.4/providers/implementations/signature/rsa_sig.c @@ -696,8 +696,13 @@ static int rsa_verify_recover(void *vprs size_t rsabits = RSA_bits(prsactx->rsa); if (rsabits < 2048) { - ERR_raise(ERR_LIB_FIPS, PROV_R_INVALID_KEY_LENGTH); - return 0; + if (rsabits != 1024 + && rsabits != 1280 + && rsabits != 1536 + && rsabits != 1792) { + ERR_raise(ERR_LIB_FIPS, PROV_R_INVALID_KEY_LENGTH); + return 0; + } } # endif @@ -792,8 +797,13 @@ static int rsa_verify(void *vprsactx, co size_t rsabits = RSA_bits(prsactx->rsa); if (rsabits < 2048) { - ERR_raise(ERR_LIB_FIPS, PROV_R_INVALID_KEY_LENGTH); - return 0; + if (rsabits != 1024 + && rsabits != 1280 + && rsabits != 1536 + && rsabits != 1792) { + ERR_raise(ERR_LIB_FIPS, PROV_R_INVALID_KEY_LENGTH); + return 0; + } } # endif