Changeset 102375 in vbox for trunk/src/VBox/Runtime/common/crypto

Timestamp:

Nov 29, 2023 10:58:18 AM (14 months ago)

Author:

vboxsync

Message:

IPRT/crypto: Implemented handing-in crypt password strings as the salt into RTCrShaCrypt256/512(). This approach is used by many *crypt implementations -- it allows feeding the user-provided password and the crypted password from "the password file" to the function. If it returns the same crypted password then the user-provided password must be the correct one.Extended testcases. bugref:10551

File:

• trunk/src/VBox/Runtime/common/crypto/shacrypt.cpp (modified) (6 diffs)

trunk/src/VBox/Runtime/common/crypto/shacrypt.cpp

@@ -48 +48 @@
 
 
+/** The digest prefix for SHAcrypt256 strings. */
+#define RT_SHACRYPT_DIGEST_PREFIX_256_STR       "$5$"
+/** The digest prefix for SHAcrypt512 strings. */
+#define RT_SHACRYPT_DIGEST_PREFIX_512_STR       "$6$"
+
 
 RTR3DECL(int) RTCrShaCryptGenerateSalt(char *pszSalt, size_t cchSalt)
@@ -63 +68 @@
 
 
+/**
+ * Extracts the salt from a given string.
+ *
+ * @returns Pointer to the salt string, or NULL if not found / invalid.
+ * @param   pszStr              String to extract salt from.
+ * @param   pcchSalt            Where to reutrn the extracted salt length (in characters).
+ */
+static const char *rtCrShaCryptExtractSalt(const char *pszStr, size_t *pcchSalt)
+{
+    size_t cchSalt = strlen(pszStr);
+
+    /* Searches for a known SHAcrypt string prefix and skips it. */
+#define BEGINS_WITH(a_szMatch) \
+        (cchSalt >= sizeof(a_szMatch) - 1U && memcmp(pszStr, a_szMatch, sizeof(a_szMatch) - 1U) == 0)
+    if (BEGINS_WITH(RT_SHACRYPT_DIGEST_PREFIX_256_STR))
+    {
+        cchSalt -= sizeof(RT_SHACRYPT_DIGEST_PREFIX_256_STR) - 1;
+        pszStr  += sizeof(RT_SHACRYPT_DIGEST_PREFIX_256_STR) - 1;
+    }
+    else if (BEGINS_WITH(RT_SHACRYPT_DIGEST_PREFIX_512_STR))
+    {
+        cchSalt -= sizeof(RT_SHACRYPT_DIGEST_PREFIX_512_STR) - 1;
+        pszStr  += sizeof(RT_SHACRYPT_DIGEST_PREFIX_512_STR) - 1;
+    }
+#undef BEGINS_WITH
+
+    /* Search for the end of the salt string, denoted by a '$'. */
+    size_t cchLen = 0;
+    while (   cchLen < cchSalt
+           && pszStr[cchLen] != '$')
+        cchLen++;
+
+    AssertMsgReturn(cchLen >= RT_SHACRYPT_MIN_SALT_LEN && cchLen <= RT_SHACRYPT_MAX_SALT_LEN, ("len=%zu\n", cchLen), NULL);
+    *pcchSalt = cchLen;
+
+    return pszStr;
+}
+
+
 RTR3DECL(int) RTCrShaCrypt256(const char *pszKey, const char *pszSalt, uint32_t cRounds, uint8_t abHash[RTSHA256_HASH_SIZE])
 {
@@ -71 +115 @@
     size_t const cchKey     = strlen(pszKey);
     AssertReturn(cchKey, VERR_INVALID_PARAMETER);
-    size_t const cchSalt    = strlen(pszSalt);
-    AssertMsgReturn(cchSalt >= RT_SHACRYPT_MIN_SALT_LEN && cchSalt <= RT_SHACRYPT_MAX_SALT_LEN, ("len=%zu\n", cchSalt),
-                    VERR_INVALID_PARAMETER);
+
+    size_t cchSalt;
+    pszSalt = rtCrShaCryptExtractSalt(pszSalt, &cchSalt);
+    AssertPtrReturn(pszSalt, VERR_INVALID_PARAMETER);
 
     uint8_t abDigest[RTSHA256_HASH_SIZE];
@@ -202 +247 @@
     size_t cchPrefix;
     if (cRounds == RT_SHACRYPT_DEFAULT_ROUNDS)
-        cchPrefix = RTStrPrintf2(psz, cchString, "$5$%s$", pszSalt);
+        cchPrefix = RTStrPrintf2(psz, cchString, "%s%s$", RT_SHACRYPT_DIGEST_PREFIX_256_STR, pszSalt);
     else
-        cchPrefix = RTStrPrintf2(psz, cchString, "$5$rounds=%RU32$%s$", cRounds, pszSalt);
+        cchPrefix = RTStrPrintf2(psz, cchString, "%srounds=%RU32$%s$", RT_SHACRYPT_DIGEST_PREFIX_256_STR, cRounds, pszSalt);
     AssertReturn(cchPrefix > 0, VERR_BUFFER_OVERFLOW);
     AssertReturn(cch >= cchPrefix, VERR_BUFFER_OVERFLOW);
@@ -255 +300 @@
     AssertReturn   (cRounds, VERR_INVALID_PARAMETER);
 
-    size_t const cchKey     = strlen(pszKey);
+    size_t const cchKey = strlen(pszKey);
     AssertReturn(cchKey, VERR_INVALID_PARAMETER);
-    size_t const cchSalt    = strlen(pszSalt);
-    AssertMsgReturn(cchSalt >= RT_SHACRYPT_MIN_SALT_LEN && cchSalt <= RT_SHACRYPT_MAX_SALT_LEN, ("len=%zu\n", cchSalt),
-                    VERR_INVALID_PARAMETER);
+
+    size_t cchSalt;
+    pszSalt = rtCrShaCryptExtractSalt(pszSalt, &cchSalt);
+    AssertPtrReturn(pszSalt, VERR_INVALID_PARAMETER);
 
     uint8_t abDigest[RTSHA512_HASH_SIZE];
@@ -386 +432 @@
     size_t cchPrefix;
     if (cRounds == RT_SHACRYPT_DEFAULT_ROUNDS)
-        cchPrefix = RTStrPrintf2(psz, cchString, "$6$%s$", pszSalt);
+        cchPrefix = RTStrPrintf2(psz, cchString, "%s%s$", RT_SHACRYPT_DIGEST_PREFIX_512_STR, pszSalt);
     else
-        cchPrefix = RTStrPrintf2(psz, cchString, "$6$rounds=%RU32$%s$", cRounds, pszSalt);
+        cchPrefix = RTStrPrintf2(psz, cchString, "%srounds=%RU32$%s$", RT_SHACRYPT_DIGEST_PREFIX_512_STR, cRounds, pszSalt);
     AssertReturn(cchPrefix > 0, VERR_BUFFER_OVERFLOW);
     AssertReturn(cch >= cchPrefix, VERR_BUFFER_OVERFLOW);