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111 lines
4.8 KiB
111 lines
4.8 KiB
From a325a23bc83f4efd60130001c417ca5b96bdbff1 Mon Sep 17 00:00:00 2001
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From: Clemens Lang <cllang@redhat.com>
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Date: Thu, 17 Nov 2022 19:33:02 +0100
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Subject: [PATCH 1/3] signature: Add indicator for PSS salt length
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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FIPS 186-4 section 5 "The RSA Digital Signature Algorithm", subsection
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5.5 "PKCS #1" says: "For RSASSA-PSS […] the length (in bytes) of the
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salt (sLen) shall satisfy 0 ≤ sLen ≤ hLen, where hLen is the length of
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the hash function output block (in bytes)."
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It is not exactly clear from this text whether hLen refers to the
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message digest or the hash function used for the mask generation
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function MGF1. PKCS#1 v2.1 suggests it is the former:
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| Typical salt lengths in octets are hLen (the length of the output of
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| the hash function Hash) and 0. In both cases the security of
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| RSASSA-PSS can be closely related to the hardness of inverting RSAVP1.
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| Bellare and Rogaway [4] give a tight lower bound for the security of
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| the original RSA-PSS scheme, which corresponds roughly to the former
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| case, while Coron [12] gives a lower bound for the related Full Domain
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| Hashing scheme, which corresponds roughly to the latter case. In [13]
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| Coron provides a general treatment with various salt lengths ranging
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| from 0 to hLen; see [27] for discussion. See also [31], which adapts
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| the security proofs in [4][13] to address the differences between the
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| original and the present version of RSA-PSS as listed in Note 1 above.
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Since OpenSSL defaults to creating signatures with the maximum salt
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length, blocking the use of longer salts would probably lead to
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significant problems in practice. Instead, introduce an explicit
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indicator that can be obtained from the EVP_PKEY_CTX object using
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EVP_PKEY_CTX_get_params() with the
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OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR
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parameter.
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Signed-off-by: Clemens Lang <cllang@redhat.com>
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---
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include/openssl/core_names.h | 1 +
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include/openssl/evp.h | 4 ++++
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providers/implementations/signature/rsa_sig.c | 18 ++++++++++++++++++
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3 files changed, 23 insertions(+)
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diff --git a/include/openssl/core_names.h b/include/openssl/core_names.h
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index 94fab83193..69c59f0b46 100644
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--- a/include/openssl/core_names.h
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+++ b/include/openssl/core_names.h
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@@ -453,6 +453,7 @@ extern "C" {
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#define OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES \
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OSSL_PKEY_PARAM_MGF1_PROPERTIES
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#define OSSL_SIGNATURE_PARAM_DIGEST_SIZE OSSL_PKEY_PARAM_DIGEST_SIZE
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+#define OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR "redhat-fips-indicator"
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/* Asym cipher parameters */
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#define OSSL_ASYM_CIPHER_PARAM_DIGEST OSSL_PKEY_PARAM_DIGEST
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diff --git a/include/openssl/evp.h b/include/openssl/evp.h
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index a5e78efd6e..f239200465 100644
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--- a/include/openssl/evp.h
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+++ b/include/openssl/evp.h
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@@ -797,6 +797,10 @@ __owur int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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__owur int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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int *outl);
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_UNDETERMINED 0
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_APPROVED 1
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_NOT_APPROVED 2
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+
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__owur int EVP_SignFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s,
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EVP_PKEY *pkey);
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__owur int EVP_SignFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s,
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diff --git a/providers/implementations/signature/rsa_sig.c b/providers/implementations/signature/rsa_sig.c
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index 49e7f9158a..0c45008a00 100644
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--- a/providers/implementations/signature/rsa_sig.c
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+++ b/providers/implementations/signature/rsa_sig.c
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@@ -1127,6 +1127,21 @@ static int rsa_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
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}
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}
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+#ifdef FIPS_MODULE
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+ p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR);
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+ if (p != NULL) {
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+ int fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_APPROVED;
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+ if (prsactx->pad_mode == RSA_PKCS1_PSS_PADDING) {
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+ if (prsactx->md == NULL) {
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+ fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_UNDETERMINED;
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+ } else if (rsa_pss_compute_saltlen(prsactx) > EVP_MD_get_size(prsactx->md)) {
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+ fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_NOT_APPROVED;
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+ }
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+ }
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+ return OSSL_PARAM_set_int(p, fips_indicator);
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+ }
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+#endif
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+
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return 1;
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}
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@@ -1136,6 +1151,9 @@ static const OSSL_PARAM known_gettable_ctx_params[] = {
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0),
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0),
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+#ifdef FIPS_MODULE
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+ OSSL_PARAM_int(OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR, NULL),
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+#endif
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OSSL_PARAM_END
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};
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--
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2.38.1
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