Add crypto_pwhash_str_needs_rehash()

src/libsodium/crypto_pwhash/argon2/pwhash_argon2i.c

@@ -3,11 +3,14 @@
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "argon2-core.h"
+#include "argon2-encoding.h"
 #include "argon2.h"
 #include "crypto_pwhash_argon2i.h"
+#include "crypto_pwhash_argon2id.h"
 #include "randombytes.h"
 #include "utils.h"
 
@@ -211,3 +214,55 @@ crypto_pwhash_argon2i_str_verify(const char str[crypto_pwhash_argon2i_STRBYTES],
     }
     return -1;
 }
+
+static int
+crypto_pwhash_argon2_str_needs_rehash(const char *str,
+                                      unsigned long long opslimit,
+                                      size_t memlimit, int type)
+{
+    unsigned char  *fodder;
+    argon2_context  ctx;
+    size_t          fodder_len;
+    int             ret = -1;
+
+    memlimit /= 1024U;
+    if (opslimit > UINT32_MAX || memlimit > UINT32_MAX) {
+        errno = EINVAL;
+        return -1;
+    }
+    memset(&ctx, 0, sizeof ctx);
+    fodder_len = strlen(str);
+    if ((fodder = (unsigned char *) calloc(fodder_len, 1U)) == NULL) {
+        return -1;
+    }
+    ctx.salt    = ctx.pwd    = ctx.salt    = ctx.out    = fodder;
+    ctx.saltlen = ctx.pwdlen = ctx.saltlen = ctx.outlen = (uint32_t) fodder_len;
+    ctx.ad      = ctx.secret    = NULL;
+    ctx.adlen   = ctx.secretlen = 0U;
+    if (decode_string(&ctx, str, type) != 0) {
+        errno = EINVAL;
+        ret = -1;
+    } else if (ctx.t_cost != (uint32_t) opslimit ||
+               ctx.m_cost != (uint32_t) memlimit) {
+        ret = 1;
+    } else {
+        ret = 0;
+    }
+    free(fodder);
+
+    return ret;
+}
+
+int
+crypto_pwhash_argon2i_str_needs_rehash(const char str[crypto_pwhash_argon2i_STRBYTES],
+                                       unsigned long long opslimit, size_t memlimit)
+{
+    return crypto_pwhash_argon2_str_needs_rehash(str, opslimit, memlimit, Argon2_i);
+}
+
+int
+crypto_pwhash_argon2id_str_needs_rehash(const char str[crypto_pwhash_argon2id_STRBYTES],
+                                        unsigned long long opslimit, size_t memlimit)
+{
+    return crypto_pwhash_argon2_str_needs_rehash(str, opslimit, memlimit, Argon2_id);
+}

src/libsodium/crypto_pwhash/crypto_pwhash.c

@@ -186,6 +186,23 @@ crypto_pwhash_str_verify(const char str[crypto_pwhash_STRBYTES],
     return -1;
 }
 
+int
+crypto_pwhash_str_needs_rehash(const char str[crypto_pwhash_STRBYTES],
+                               unsigned long long opslimit, size_t memlimit)
+{
+    if (strncmp(str, crypto_pwhash_argon2id_STRPREFIX,
+                sizeof crypto_pwhash_argon2id_STRPREFIX - 1) == 0) {
+        return crypto_pwhash_argon2id_str_needs_rehash(str, opslimit, memlimit);
+    }
+    if (strncmp(str, crypto_pwhash_argon2i_STRPREFIX,
+                sizeof crypto_pwhash_argon2i_STRPREFIX - 1) == 0) {
+        return crypto_pwhash_argon2i_str_needs_rehash(str, opslimit, memlimit);
+    }
+    errno = EINVAL;
+
+    return -1;
+}
+
 const char *
 crypto_pwhash_primitive(void) {
     return crypto_pwhash_PRIMITIVE;

src/libsodium/include/sodium/crypto_pwhash.h

@@ -128,6 +128,11 @@ int crypto_pwhash_str_verify(const char str[crypto_pwhash_STRBYTES],
                              unsigned long long passwdlen)
             __attribute__ ((warn_unused_result));
 
+SODIUM_EXPORT
+int crypto_pwhash_str_needs_rehash(const char str[crypto_pwhash_STRBYTES],
+                                   unsigned long long opslimit, size_t memlimit)
+            __attribute__ ((warn_unused_result));
+
 #define crypto_pwhash_PRIMITIVE "argon2i"
 SODIUM_EXPORT
 const char *crypto_pwhash_primitive(void)

src/libsodium/include/sodium/crypto_pwhash_argon2i.h

@@ -110,6 +110,11 @@ int crypto_pwhash_argon2i_str_verify(const char str[crypto_pwhash_argon2i_STRBYT
                                      unsigned long long passwdlen)
             __attribute__ ((warn_unused_result));
 
+SODIUM_EXPORT
+int crypto_pwhash_argon2i_str_needs_rehash(const char str[crypto_pwhash_argon2i_STRBYTES],
+                                           unsigned long long opslimit, size_t memlimit)
+            __attribute__ ((warn_unused_result));
+
 #ifdef __cplusplus
 }
 #endif

src/libsodium/include/sodium/crypto_pwhash_argon2id.h

@@ -110,6 +110,11 @@ int crypto_pwhash_argon2id_str_verify(const char str[crypto_pwhash_argon2id_STRB
                                       unsigned long long passwdlen)
             __attribute__ ((warn_unused_result));
 
+SODIUM_EXPORT
+int crypto_pwhash_argon2id_str_needs_rehash(const char str[crypto_pwhash_argon2id_STRBYTES],
+                                            unsigned long long opslimit, size_t memlimit)
+            __attribute__ ((warn_unused_result));
+
 #ifdef __cplusplus
 }
 #endif