fix: add throw exception for rsa salt

internal/js/modules/k6/webcrypto/rsa.go

@@ -387,6 +387,10 @@ func (rsasv *RSAPssParams) Sign(key CryptoKey, data []byte) ([]byte, error) {
 	hashedData := hash.New()
 	hashedData.Write(data)
 
+	if rsasv.SaltLength == 0 {
+		return nil, NewError(ImplementationError, "k6 RSA-PSS uses standard Golang SDK that doesn't support"+
+			"salt length=0 but generates salt with maximum length . Sign result might be different.")
+	}
 	signature, err := rsa.SignPSS(rand.Reader, rsaKey, hash, hashedData.Sum(nil), &rsa.PSSOptions{
 		SaltLength: rsasv.SaltLength,
 	})
@@ -412,6 +416,10 @@ func (rsasv *RSAPssParams) Verify(key CryptoKey, signature []byte, data []byte)
 	hashedData := hash.New()
 	hashedData.Write(data)
 
+	if rsasv.SaltLength == 0 {
+		return false, NewError(ImplementationError, "k6 RSA-PSS uses standard Golang SDK that doesn't support"+
+			"salt length=0 but tries to auto-detect salt length if 0 is used. Verify result might be different.")
+	}
 	err = rsa.VerifyPSS(rsaKey, hash, hashedData.Sum(nil), signature, &rsa.PSSOptions{
 		SaltLength: rsasv.SaltLength,
 	})

internal/js/modules/k6/webcrypto/tests/wpt-patches/WebCryptoAPI__sign_verify__rsa_pss_vectors.js.patch

@@ -0,0 +1,15 @@
+diff --git a/WebCryptoAPI/sign_verify/rsa_pss_vectors.js b/WebCryptoAPI/sign_verify/rsa_pss_vectors.js
+index c3ce77960..0dd34723e 100644
+--- a/WebCryptoAPI/sign_verify/rsa_pss_vectors.js
++++ b/WebCryptoAPI/sign_verify/rsa_pss_vectors.js
+@@ -143,5 +143,9 @@ function getTestVectors() {
+         }
+     ];
+
+-    return vectors;
++    // k6 RSA-PSS uses standard Golang SDK that doesn't support salt length=0
++    // Filter out test vectors with salt length 0 to avoid test failures
++    return vectors.filter(function(vector) {
++        return !(vector.algorithm && vector.algorithm.name === "RSA-PSS" && vector.algorithm.saltLength === 0);
++    });
+ }