From: Tobias Brunner <tobias@strongswan.org>
Date: Mon, 17 Sep 2018 10:57:25 +0000 (+0200)
Subject: botan: Share code to generate RSA EMSA PSS signature identifier strings
X-Git-Tag: 5.7.0rc2~21
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc09570a12713f773ff883769d142aeba6926454;p=thirdparty%2Fstrongswan.git

botan: Share code to generate RSA EMSA PSS signature identifier strings
---

diff --git a/src/libstrongswan/plugins/botan/botan_rsa_private_key.c b/src/libstrongswan/plugins/botan/botan_rsa_private_key.c
index 558bb70f75..bb723ff952 100644
--- a/src/libstrongswan/plugins/botan/botan_rsa_private_key.c
+++ b/src/libstrongswan/plugins/botan/botan_rsa_private_key.c
@@ -61,14 +61,11 @@ struct private_botan_rsa_private_key_t {
 };
 
 /**
- * Build an EMSA PSS signature described in PKCS#1
+ * Get the Botan string identifier for an EMSA PSS signature
  */
-static bool build_emsa_pss_signature(private_botan_rsa_private_key_t *this,
-									 rsa_pss_params_t *params, chunk_t data,
-									 chunk_t *sig)
+bool botan_emsa_pss_identifier(rsa_pss_params_t *params, char *id, size_t len)
 {
 	const char *hash;
-	char hash_and_padding[BUF_LEN];
 
 	if (!params)
 	{
@@ -90,13 +87,25 @@ static bool build_emsa_pss_signature(private_botan_rsa_private_key_t *this,
 
 	if (params->salt_len > RSA_PSS_SALT_LEN_DEFAULT)
 	{
-		snprintf(hash_and_padding, sizeof(hash_and_padding),
-				 "EMSA-PSS(%s,MGF1,%u)", hash, params->salt_len);
+		return snprintf(id, len, "EMSA-PSS(%s,MGF1,%zd)", hash,
+						params->salt_len) < len;
 	}
-	else
+	return snprintf(id, len, "EMSA-PSS(%s,MGF1)", hash) < len;
+}
+
+/**
+ * Build an EMSA PSS signature described in PKCS#1
+ */
+static bool build_emsa_pss_signature(private_botan_rsa_private_key_t *this,
+									 rsa_pss_params_t *params, chunk_t data,
+									 chunk_t *sig)
+{
+	char hash_and_padding[BUF_LEN];
+
+	if (!botan_emsa_pss_identifier(params, hash_and_padding,
+								   sizeof(hash_and_padding)))
 	{
-		snprintf(hash_and_padding, sizeof(hash_and_padding),
-				 "EMSA-PSS(%s,MGF1)", hash);
+		return FALSE;
 	}
 	return botan_get_signature(this->key, hash_and_padding, data, sig);
 }
diff --git a/src/libstrongswan/plugins/botan/botan_rsa_public_key.c b/src/libstrongswan/plugins/botan/botan_rsa_public_key.c
index 6adb1c4b77..c6e2e88612 100644
--- a/src/libstrongswan/plugins/botan/botan_rsa_public_key.c
+++ b/src/libstrongswan/plugins/botan/botan_rsa_public_key.c
@@ -63,6 +63,11 @@ struct private_botan_rsa_public_key_t {
 	refcount_t ref;
 };
 
+/**
+ * Defined in botan_rsa_private_key.c
+ */
+bool botan_emsa_pss_identifier(rsa_pss_params_t *params, char *id, size_t len);
+
 /**
  * Verify RSA signature
  */
@@ -97,37 +102,13 @@ static bool verify_emsa_pss_signature(private_botan_rsa_public_key_t *this,
 									  rsa_pss_params_t *params, chunk_t data,
 									  chunk_t signature)
 {
-	const char *hash;
 	char hash_and_padding[BUF_LEN];
 
-	if (!params)
-	{
-		return FALSE;
-	}
-
-	/* botan currently does not support passing the mgf1 hash */
-	if (params->hash != params->mgf1_hash)
-	{
-		DBG1(DBG_LIB, "passing mgf1 hash not supported via botan");
-		return FALSE;
-	}
-
-	hash = botan_get_hash(params->hash);
-	if (!hash)
+	if (!botan_emsa_pss_identifier(params, hash_and_padding,
+								   sizeof(hash_and_padding)))
 	{
 		return FALSE;
 	}
-
-	if (params->salt_len > RSA_PSS_SALT_LEN_DEFAULT)
-	{
-		snprintf(hash_and_padding, sizeof(hash_and_padding),
-				 "EMSA-PSS(%s,MGF1,%u)", hash, params->salt_len);
-	}
-	else
-	{
-		snprintf(hash_and_padding, sizeof(hash_and_padding),
-				 "EMSA-PSS(%s,MGF1)", hash);
-	}
 	return verify_rsa_signature(this, hash_and_padding, data, signature);
 }