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F-1370 : Tighten key_len check from >= to == #10122

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65 changes: 46 additions & 19 deletions doc/dox_comments/header_files/signature.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4,13 +4,22 @@
\brief This function returns the maximum size of the resulting signature.

\return Returns SIG_TYPE_E if sig_type is not supported. Returns
BAD_FUNC_ARG if sig_type was invalid. A positive return value indicates
BAD_FUNC_ARG if sig_type was invalid or key_len does not exactly match
the size of the expected key structure. A positive return value indicates
the maximum size of a signature.

\param sig_type A signature type enum value such as
WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
\param key Pointer to a key structure such as ecc_key or RsaKey.
\param key_len Size of the key structure.
\param key Pointer to the key structure corresponding to sig_type:
pass an ecc_key* (cast to const void*) for
WC_SIGNATURE_TYPE_ECC, or a RsaKey* for
Comment on lines +14 to +15
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Copilot AI Apr 2, 2026

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This text calls out a cast to const void* for ecc_key* but not for RsaKey*, even though both convert implicitly to const void* in C/C++. Consider making this consistent (either remove the cast mention entirely, or mention it uniformly for both) to avoid implying different call requirements.

Suggested change
pass an ecc_key* (cast to const void*) for
WC_SIGNATURE_TYPE_ECC, or a RsaKey* for
pass an ecc_key* for WC_SIGNATURE_TYPE_ECC, or a RsaKey* for

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WC_SIGNATURE_TYPE_RSA / WC_SIGNATURE_TYPE_RSA_W_ENC.
The caller is responsible for ensuring the pointer refers to the correct
type; this function cannot verify the actual runtime type of the object.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching the sig_type. Passing any other value
causes the function to return BAD_FUNC_ARG without dereferencing key.
The conventional idiom is to pass sizeof(*key) at the call site.
Comment on lines +13 to +22
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The updated docs state key_len “must be exactly …” unconditionally, but the tests show wc_SignatureGetSize(sig_type, NULL, key_len) is valid and returns 0 (even when key_len is non-matching). Please clarify the contract, e.g., “If key is non-NULL, key_len must be exactly …; if key is NULL, key_len is ignored and the function returns 0,” to avoid misleading API consumers.

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_Example_
\code
Expand Down Expand Up @@ -43,16 +52,19 @@ int wc_SignatureGetSize(enum wc_SignatureType sig_type,
\return BAD_FUNC_ARG -173, bad function argument provided
\return BUFFER_E -132, output buffer too small or input too large.

\param hash_type A hash type from the “enum wc_HashType” such as
“WC_HASH_TYPE_SHA256”.
\param hash_type A hash type from the "enum wc_HashType" such as
"WC_HASH_TYPE_SHA256".
\param sig_type A signature type enum value such as
WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
\param data Pointer to buffer containing the data to hash.
\param data_len Length of the data buffer.
\param sig Pointer to buffer to output signature.
\param sig_len Length of the signature output buffer.
\param key Pointer to a key structure such as ecc_key or RsaKey.
\param key_len Size of the key structure.
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().

_Example_
\code
Expand Down Expand Up @@ -93,16 +105,19 @@ int wc_SignatureVerify(
\return BAD_FUNC_ARG -173, bad function argument provided
\return BUFFER_E -132, output buffer too small or input too large.

\param hash_type A hash type from the “enum wc_HashType”
such as “WC_HASH_TYPE_SHA256”.
\param hash_type A hash type from the "enum wc_HashType"
such as "WC_HASH_TYPE_SHA256".
\param sig_type A signature type enum value such as
WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
\param data Pointer to buffer containing the data to hash.
\param data_len Length of the data buffer.
\param sig Pointer to buffer to output signature.
\param sig_len Length of the signature output buffer.
\param key Pointer to a key structure such as ecc_key or RsaKey.
\param key_len Size of the key structure.
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().
\param rng Pointer to an initialized RNG structure.

_Example_
Expand Down Expand Up @@ -166,8 +181,11 @@ int wc_SignatureGenerate(
\param hash_len Length of the hash buffer
\param sig Pointer to buffer containing the signature
\param sig_len Length of the signature buffer
\param key Pointer to a key structure such as ecc_key or RsaKey
\param key_len Size of the key structure
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().

_Example_
\code
Expand Down Expand Up @@ -216,8 +234,11 @@ int wc_SignatureVerifyHash(enum wc_HashType hash_type,
\param hash_len Length of the hash buffer
\param sig Pointer to buffer to output signature
\param sig_len Pointer to length of signature output buffer
\param key Pointer to a key structure such as ecc_key or RsaKey
\param key_len Size of the key structure
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().
\param rng Pointer to an initialized RNG structure

_Example_
Expand Down Expand Up @@ -266,8 +287,11 @@ int wc_SignatureGenerateHash(enum wc_HashType hash_type,
\param hash_len Length of the hash buffer
\param sig Pointer to buffer to output signature
\param sig_len Pointer to length of signature output buffer
\param key Pointer to a key structure such as ecc_key or RsaKey
\param key_len Size of the key structure
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().
\param rng Pointer to an initialized RNG structure
\param verify If non-zero, verify the signature after generation

Expand Down Expand Up @@ -317,8 +341,11 @@ int wc_SignatureGenerateHash_ex(enum wc_HashType hash_type,
\param data_len Length of the data buffer
\param sig Pointer to buffer to output signature
\param sig_len Pointer to length of signature output buffer
\param key Pointer to a key structure such as ecc_key or RsaKey
\param key_len Size of the key structure
\param key Pointer to the key structure corresponding to sig_type.
See wc_SignatureGetSize() for the type-safety constraints that apply
to this parameter.
\param key_len Must be exactly sizeof(ecc_key) or
sizeof(RsaKey) matching sig_type. See wc_SignatureGetSize().
\param rng Pointer to an initialized RNG structure
\param verify If non-zero, verify the signature after generation

Expand Down
14 changes: 14 additions & 0 deletions tests/api/test_signature.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,13 @@ int test_wc_SignatureGetSize_ecc(void)
sig_type = WC_SIGNATURE_TYPE_ECC;
ExpectIntEQ(wc_SignatureGetSize(sig_type, NULL, key_len), 0);
key_len = (word32)0;
ExpectIntEQ(wc_SignatureGetSize(sig_type, &ecc, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
/* key_len must be exactly sizeof(ecc_key): one less or one more is invalid */
key_len = (word32)(sizeof(ecc_key) - 1);
ExpectIntEQ(wc_SignatureGetSize(sig_type, &ecc, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
key_len = (word32)(sizeof(ecc_key) + 1);
ExpectIntEQ(wc_SignatureGetSize(sig_type, &ecc, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));

Expand Down Expand Up @@ -138,6 +145,13 @@ int test_wc_SignatureGetSize_rsa(void)
ExpectIntEQ(wc_SignatureGetSize(sig_type, NULL, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
key_len = (word32)0;
ExpectIntEQ(wc_SignatureGetSize(sig_type, &rsa_key, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
/* key_len must be exactly sizeof(RsaKey): one less or one more is invalid */
key_len = (word32)(sizeof(RsaKey) - 1);
ExpectIntEQ(wc_SignatureGetSize(sig_type, &rsa_key, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
key_len = (word32)(sizeof(RsaKey) + 1);
ExpectIntEQ(wc_SignatureGetSize(sig_type, &rsa_key, key_len),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));

Expand Down
2 changes: 1 addition & 1 deletion tests/api/test_signature.h
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Expand Up @@ -29,6 +29,6 @@ int test_wc_SignatureGetSize_rsa(void);

#define TEST_SIGNATURE_DECLS \
TEST_DECL_GROUP("signature", test_wc_SignatureGetSize_ecc), \
TEST_DECL_GROUP("signature", test_wc_SignatureGetSize_ecc)
TEST_DECL_GROUP("signature", test_wc_SignatureGetSize_rsa)

#endif /* WOLFCRYPT_TEST_SIGNATURE_H */
13 changes: 9 additions & 4 deletions wolfcrypt/src/signature.c
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,11 @@ int wc_SignatureGetSize(enum wc_SignatureType sig_type,
switch(sig_type) {
case WC_SIGNATURE_TYPE_ECC:
#ifdef HAVE_ECC
/* Sanity check that void* key is at least ecc_key in size */
if (key_len >= sizeof(ecc_key)) {
/* Verify that key_len matches exactly sizeof(ecc_key).
* This is a necessary but not sufficient type check: the void*
* API cannot verify the actual runtime type of the pointed-to
* object. Callers must pass a valid ecc_key* cast to void*. */
if (key_len == sizeof(ecc_key)) {
Comment on lines +96 to +100
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The comment refers to a void* API and says “cast to void*”, but the function parameter is const void*. To keep the comment accurate (and avoid encouraging dropping const), adjust wording to const void* / “cast to const void*”.

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sig_len = wc_ecc_sig_size((ecc_key*)key);
}
else {
Expand All @@ -108,8 +111,10 @@ int wc_SignatureGetSize(enum wc_SignatureType sig_type,
case WC_SIGNATURE_TYPE_RSA_W_ENC:
case WC_SIGNATURE_TYPE_RSA:
#ifndef NO_RSA
/* Sanity check that void* key is at least RsaKey in size */
if (key_len >= sizeof(RsaKey)) {
/* Verify that key_len matches exactly sizeof(RsaKey).
* Same caveat as the ECC case above: size equality is necessary
* but not sufficient; the caller must pass a valid RsaKey*. */
if (key_len == sizeof(RsaKey)) {
sig_len = wc_RsaEncryptSize((RsaKey*)key);
}
else {
Expand Down
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