Make PSS more flexible, most notably assign special meaning to negative

sLen values: -1 -> sLen = hLen, -2 -> sLen autochosen/autorecovered.

diff --git a/crypto/rsa/rsa.h b/crypto/rsa/rsa.h
index f9495863cc56b031c3e1e8fddc232afb31651907..b02b48be0aa5e0cb4acdd019f9c44eb1da29f22d 100644 (file)
--- a/crypto/rsa/rsa.h
+++ b/crypto/rsa/rsa.h
@@ -389,7 +389,7 @@ void ERR_load_RSA_strings(void);
 #define RSA_R_NULL_BEFORE_BLOCK_MISSING                         113
 #define RSA_R_N_DOES_NOT_EQUAL_P_Q                      127
 #define RSA_R_OAEP_DECODING_ERROR                       121
-#define RSA_R_ONE_CHECK_FAILED                          135
+#define RSA_R_SLEN_RECOVERY_FAILED                      135
 #define RSA_R_PADDING_CHECK_FAILED                      114
 #define RSA_R_P_NOT_PRIME                               128
 #define RSA_R_Q_NOT_PRIME                               129
@@ -399,7 +399,7 @@ void ERR_load_RSA_strings(void);
 #define RSA_R_UNKNOWN_ALGORITHM_TYPE                    117
 #define RSA_R_UNKNOWN_PADDING_TYPE                      118
 #define RSA_R_WRONG_SIGNATURE_LENGTH                    119
-#define RSA_R_ZERO_CHECK_FAILED                                 136
+#define RSA_R_SLEN_CHECK_FAILED                                 136
 
 #ifdef  __cplusplus
 }

diff --git a/crypto/rsa/rsa_err.c b/crypto/rsa/rsa_err.c
index 5e8349dfcf91130245e12fb9f22378dc1aa648dd..2ec4b30ff7987b87d22a138f02846a6cb2ffb40e 100644 (file)
--- a/crypto/rsa/rsa_err.c
+++ b/crypto/rsa/rsa_err.c
@@ -132,7 +132,7 @@ static ERR_STRING_DATA RSA_str_reasons[]=
 {ERR_REASON(RSA_R_NULL_BEFORE_BLOCK_MISSING),"null before block missing"},
 {ERR_REASON(RSA_R_N_DOES_NOT_EQUAL_P_Q)  ,"n does not equal p q"},
 {ERR_REASON(RSA_R_OAEP_DECODING_ERROR)   ,"oaep decoding error"},
-{ERR_REASON(RSA_R_ONE_CHECK_FAILED)      ,"one check failed"},
+{ERR_REASON(RSA_R_SLEN_RECOVERY_FAILED)  ,"salt length recovery failed"},
 {ERR_REASON(RSA_R_PADDING_CHECK_FAILED)  ,"padding check failed"},
 {ERR_REASON(RSA_R_P_NOT_PRIME)           ,"p not prime"},
 {ERR_REASON(RSA_R_Q_NOT_PRIME)           ,"q not prime"},
@@ -142,7 +142,7 @@ static ERR_STRING_DATA RSA_str_reasons[]=
 {ERR_REASON(RSA_R_UNKNOWN_ALGORITHM_TYPE),"unknown algorithm type"},
 {ERR_REASON(RSA_R_UNKNOWN_PADDING_TYPE)  ,"unknown padding type"},
 {ERR_REASON(RSA_R_WRONG_SIGNATURE_LENGTH),"wrong signature length"},
-{ERR_REASON(RSA_R_ZERO_CHECK_FAILED)     ,"zero check failed"},
+{ERR_REASON(RSA_R_SLEN_CHECK_FAILED)     ,"salt length check failed"},
 {0,NULL}
        };
 

diff --git a/crypto/rsa/rsa_pss.c b/crypto/rsa/rsa_pss.c
index 5dcdb54603cd319fe0a30fc52a2065fa2e239593..2815628f5f79d6033a4494d32977aa47dbe3262e 100644 (file)
--- a/crypto/rsa/rsa_pss.c
+++ b/crypto/rsa/rsa_pss.c
@@ -76,29 +76,44 @@ int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,
        unsigned char *DB = NULL;
        EVP_MD_CTX ctx;
        unsigned char H_[EVP_MAX_MD_SIZE];
-       MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
-       emLen = RSA_size(rsa);
+
        hLen = EVP_MD_size(Hash);
-       if (emLen < (hLen + sLen + 2))
-               {
-               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_DATA_TOO_LARGE);
-               goto err;
-               }
-       if (EM[emLen - 1] != 0xbc)
+       /*
+        * Negative sLen has special meanings:
+        *      -1      sLen == hLen
+        *      -2      salt length is autorecovered from signature
+        *      -N      reserved
+        */
+       if      (sLen == -1)    sLen = hLen;
+       else if (sLen == -2)    sLen = -2;
+       else if (sLen < -2)
                {
-               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_LAST_OCTET_INVALID);
+               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
                goto err;
                }
+
+       MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
+       emLen = RSA_size(rsa);
        if (EM[0] & (0xFF << MSBits))
                {
                RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_FIRST_OCTET_INVALID);
                goto err;
                }
-       if (!MSBits)
+       if (MSBits == 0)
                {
                EM++;
                emLen--;
                }
+       if (emLen < (hLen + sLen + 2)) /* sLen can be small negative */
+               {
+               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_DATA_TOO_LARGE);
+               goto err;
+               }
+       if (EM[emLen - 1] != 0xbc)
+               {
+               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_LAST_OCTET_INVALID);
+               goto err;
+               }
        maskedDBLen = emLen - hLen - 1;
        H = EM + maskedDBLen;
        DB = OPENSSL_malloc(maskedDBLen);
@@ -112,26 +127,23 @@ int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,
                DB[i] ^= EM[i];
        if (MSBits)
                DB[0] &= 0xFF >> (8 - MSBits);
-       for (i = 0; i < (emLen - hLen - sLen - 2); i++)
+       for (i = 0; DB[i] == 0 && i < (maskedDBLen-1); i++) ;
+       if (DB[i++] != 0x1)
                {
-               if (DB[i] != 0) 
-                       {
-                       RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS,
-                                               RSA_R_ZERO_CHECK_FAILED);
-                       goto err;
-                       }
+               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_RECOVERY_FAILED);
+               goto err;
                }
-       if (DB[i] != 0x1)
+       if (sLen >= 0 && (maskedDBLen - i) != sLen)
                {
-               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_ONE_CHECK_FAILED);
+               RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
                goto err;
                }
        EVP_MD_CTX_init(&ctx);
        EVP_DigestInit_ex(&ctx, Hash, NULL);
        EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);
        EVP_DigestUpdate(&ctx, mHash, hLen);
-       if (sLen)
-               EVP_DigestUpdate(&ctx, DB + maskedDBLen - sLen, sLen);
+       if (maskedDBLen - i)
+               EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i);
        EVP_DigestFinal(&ctx, H_, NULL);
        EVP_MD_CTX_cleanup(&ctx);
        if (memcmp(H_, H, hLen))
@@ -159,22 +171,39 @@ int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,
        int hLen, maskedDBLen, MSBits, emLen;
        unsigned char *H, *salt = NULL, *p;
        EVP_MD_CTX ctx;
-       MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
-       emLen = RSA_size(rsa);
+
        hLen = EVP_MD_size(Hash);
-       if (sLen < 0)
-               sLen = 0;
-       if (emLen < (hLen + sLen + 2))
+       /*
+        * Negative sLen has special meanings:
+        *      -1      sLen == hLen
+        *      -2      salt length is maximized
+        *      -N      reserved
+        */
+       if      (sLen == -1)    sLen = hLen;
+       else if (sLen == -2)    sLen = -2;
+       else if (sLen < -2)
                {
-               RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
-                  RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+               RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
                goto err;
                }
+
+       MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
+       emLen = RSA_size(rsa);
        if (MSBits == 0)
                {
                *EM++ = 0;
                emLen--;
                }
+       if (sLen == -2)
+               {
+               sLen = emLen - hLen - 2;
+               }
+       else if (emLen < (hLen + sLen + 2))
+               {
+               RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
+                  RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+               goto err;
+               }
        if (sLen > 0)
                {
                salt = OPENSSL_malloc(sLen);