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Increase minimal memory cost for Argon2 benchmark to 64MiB.

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Argon2 draft defines suggested parameters for disk encryption use, but LUKS2
approach is slightly different. We need to provide platform independent
values. The values in draft expects 64bit systems (suggesting using 6 GiB
of RAM), while we need to provide compatibility with all 32bit systems,
so allocating more than 4GiB memory is not option for LUKS2.

The maximal limit in LUKS2 stays for 4 GiB, and by default LUKS2
PBKDF benchmarking sets maximum to 1 GIB, prefering increase of CPU cost.

But for the minimal memory cost we had a quite low limit 32 MiB.

This patch increases the bechmarking value to 64 MiB (as minimal
suggested values in Argon2 RFC). For compatibility reasons we still
allow older limit if set by a parameter.
This commit is contained in:
Milan Broz
2021-06-19 21:13:13 +02:00
parent db77541790
commit d9fc45de04
2 changed files with 10 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
lib/crypto_backend/pbkdf_check.c
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@@ -48,6 +48,7 @@ int crypt_pbkdf_get_limits(const char *kdf, struct crypt_pbkdf_limits *limits)
limits->min_iterations = 1000; /* recommendation in NIST SP 800-132 */
limits->max_iterations = UINT32_MAX;
limits->min_memory = 0; /* N/A */
limits->min_bench_memory=0; /* N/A */
limits->max_memory = 0; /* N/A */
limits->min_parallel = 0; /* N/A */
limits->max_parallel = 0; /* N/A */
@@ -55,7 +56,8 @@ int crypt_pbkdf_get_limits(const char *kdf, struct crypt_pbkdf_limits *limits)
} else if (!strcmp(kdf, "argon2i") || !strcmp(kdf, "argon2id")) {
limits->min_iterations = 4;
limits->max_iterations = UINT32_MAX;
limits->min_memory = 32;
limits->min_memory = 32; /* hard limit */
limits->min_bench_memory=64*1024; /* 64 MiB minimum for benchmark */
limits->max_memory = 4*1024*1024; /* 4GiB */
limits->min_parallel = 1;
limits->max_parallel = 4;
@@ -408,6 +410,7 @@ int crypt_pbkdf_perf(const char *kdf, const char *hash,
{
struct crypt_pbkdf_limits pbkdf_limits;
int r = -EINVAL;
uint32_t min_memory;
if (!kdf || !iterations_out || !memory_out)
return -EINVAL;
@@ -416,6 +419,10 @@ int crypt_pbkdf_perf(const char *kdf, const char *hash,
if (r < 0)
return r;
min_memory = pbkdf_limits.min_bench_memory;
if (min_memory > max_memory_kb)
min_memory = max_memory_kb;
*memory_out = 0;
*iterations_out = 0;
@@ -428,7 +435,7 @@ int crypt_pbkdf_perf(const char *kdf, const char *hash,
r = crypt_argon2_check(kdf, password, password_size,
salt, salt_size, volume_key_size,
pbkdf_limits.min_iterations,
pbkdf_limits.min_memory,
min_memory,
max_memory_kb,
parallel_threads, time_ms, iterations_out,
memory_out, progress, usrptr);