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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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fca6e23
Add upper limit to PBKDF iteration count
anhu Mar 23, 2026
8fa5217
simplify the tests.
anhu Mar 27, 2026
728d695
better macro gating in tests
anhu Mar 27, 2026
5b762b1
get rid of bad tests
anhu Apr 1, 2026
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15 changes: 15 additions & 0 deletions wolfcrypt/src/pwdbased.c
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Original file line number Diff line number Diff line change
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 @@ -410,6 +420,11 @@ 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)
Expand Down
9 changes: 9 additions & 0 deletions wolfssl/wolfcrypt/pwdbased.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,15 @@
extern "C" {
#endif

/* Maximum allowed PBKDF iteration count to prevent CPU exhaustion DoS.
* 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 PKCS#12 files use 1,000–10,000 iterations. */
#ifndef WC_PBKDF_MAX_ITERATIONS
#define WC_PBKDF_MAX_ITERATIONS 100000
#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);
Expand Down
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