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Add upper limit to PBKDF iteration count #10050

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Add upper limit to PBKDF iteration count #10050

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f95f0bd
Add upper limit to PBKDF iteration count
anhu Mar 23, 2026
6174e0e
simplify the tests.
anhu Mar 27, 2026
2801482
better macro gating in tests
anhu Mar 27, 2026
b336fc9
get rid of bad tests
anhu Apr 1, 2026
446309d
Limit was too low
anhu Apr 8, 2026
8ea014a
Comment fixup.
anhu Apr 10, 2026
45de230
Line length fixup and repro in second impl.
anhu Apr 10, 2026
47a95f8
Known macros
anhu Apr 15, 2026
536911b
API Docs
anhu Apr 28, 2026
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1 change: 1 addition & 0 deletions .wolfssl_known_macro_extras
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Original file line number Diff line number Diff line change
Expand Up @@ -646,6 +646,7 @@ WC_NO_ASYNC_SLEEP
WC_NO_RNG_SIMPLE
WC_NO_STATIC_ASSERT
WC_NO_VERBOSE_RNG
WC_PBKDF_MAX_ITERATIONS
WC_PKCS11_FIND_WITH_ID_ONLY
WC_PKCS12_PBKDF_USING_MP_API
WC_PROTECT_ENCRYPTED_MEM
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9 changes: 6 additions & 3 deletions doc/dox_comments/header_files/pwdbased.h
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Expand Up @@ -174,7 +174,8 @@ int wc_PKCS12_PBKDF(byte* output, const byte* passwd, int passLen,
\brief Extended version of PBKDF1 with heap hint.

\return 0 on success
\return BAD_FUNC_ARG on invalid arguments
\return BAD_FUNC_ARG on invalid arguments or iterations is greater than
WC_PBKDF_MAX_ITERATIONS
\return MEMORY_E on memory allocation error

\param key Output key buffer
Expand Down Expand Up @@ -209,7 +210,8 @@ int wc_PBKDF1_ex(byte* key, int keyLen, byte* iv, int ivLen,
\brief Extended version of PBKDF2 with heap hint and device ID.

\return 0 on success
\return BAD_FUNC_ARG on invalid arguments
\return BAD_FUNC_ARG on invalid arguments or iterations is greater than
WC_PBKDF_MAX_ITERATIONS
\return MEMORY_E on memory allocation error

\param output Output key buffer
Expand Down Expand Up @@ -244,7 +246,8 @@ int wc_PBKDF2_ex(byte* output, const byte* passwd, int pLen,
\brief Extended version of PKCS12_PBKDF with heap hint.

\return 0 on success
\return BAD_FUNC_ARG on invalid arguments
\return BAD_FUNC_ARG on invalid arguments or iterations is greater than
WC_PBKDF_MAX_ITERATIONS
\return MEMORY_E on memory allocation error

\param output Output key buffer
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22 changes: 22 additions & 0 deletions wolfcrypt/src/pwdbased.c
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Expand Up @@ -79,6 +79,11 @@ int wc_PBKDF1_ex(byte* key, int keyLen, byte* iv, int ivLen,
if (iterations <= 0)
iterations = 1;

if (iterations > WC_PBKDF_MAX_ITERATIONS) {
WOLFSSL_MSG("PBKDF1 iteration count exceeds WC_PBKDF_MAX_ITERATIONS");
return BAD_FUNC_ARG;
}

hashT = wc_HashTypeConvert(hashType);
err = wc_HashGetDigestSize(hashT);
if (err < 0)
Expand Down Expand Up @@ -215,6 +220,11 @@ int wc_PBKDF2_ex(byte* output, const byte* passwd, int pLen, const byte* salt,
if (iterations <= 0)
iterations = 1;

if (iterations > WC_PBKDF_MAX_ITERATIONS) {
WOLFSSL_MSG("PBKDF2 iteration count exceeds WC_PBKDF_MAX_ITERATIONS");
return BAD_FUNC_ARG;
}

hashT = wc_HashTypeConvert(hashType);
hLen = wc_HashGetDigestSize(hashT);
if (hLen < 0)
Expand Down Expand Up @@ -403,6 +413,12 @@ int wc_PKCS12_PBKDF_ex(byte* output, const byte* passwd, int passLen,
if (iterations <= 0)
iterations = 1;

if (iterations > WC_PBKDF_MAX_ITERATIONS) {
WOLFSSL_MSG("PKCS12 PBKDF iteration count exceeds "
"WC_PBKDF_MAX_ITERATIONS");
return BAD_FUNC_ARG;
}

hashT = wc_HashTypeConvert(hashType);
ret = wc_HashGetDigestSize(hashT);
if (ret < 0)
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anhu marked this conversation as resolved.
Expand Down Expand Up @@ -611,6 +627,12 @@ int wc_PKCS12_PBKDF_ex(byte* output, const byte* passwd, int passLen,
iterations = 1;
}

if (iterations > WC_PBKDF_MAX_ITERATIONS) {
WOLFSSL_MSG("PKCS12 PBKDF iteration count exceeds "
"WC_PBKDF_MAX_ITERATIONS");
return BAD_FUNC_ARG;
}

/* u = hash output size. */
hashT = wc_HashTypeConvert(hashType);
ret = wc_HashGetDigestSize(hashT);
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9 changes: 9 additions & 0 deletions wolfssl/wolfcrypt/pwdbased.h
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Expand Up @@ -35,6 +35,15 @@
extern "C" {
#endif

/* Maximum allowed PBKDF iteration count to prevent CPU exhaustion DoS.
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dgarske marked this conversation as resolved.
* Attacker-controlled PKCS#12 files can specify iterations up to INT_MAX
* (2,147,483,647) in the MAC data, causing hours of CPU time.
* Override by defining WC_PBKDF_MAX_ITERATIONS before including this header.
* Normal p12 files use 1k to 10k iterations. */
#ifndef WC_PBKDF_MAX_ITERATIONS
#define WC_PBKDF_MAX_ITERATIONS 2000000
#endif

#if FIPS_VERSION3_GE(6,0,0)
extern const unsigned int wolfCrypt_FIPS_pbkdf_ro_sanity[2];
WOLFSSL_LOCAL int wolfCrypt_FIPS_PBKDF_sanity(void);
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