crypto | Go supplementary cryptography libraries | Cryptography library

What can I do to ensure that it's only called once?

Nothing, that's how it's meant to work. In the View system you would not ask "Why is my view invalidated 3 times?". The framework invalidates (recomposes) the view as it needs, you should not need to know or care when that happens.

The issue with your code is that your Composable is reading the old value from preferences, that is not how it should work, that value should be provided by the viewmodel as part of the state. Instead of providing just the new price, expose a Data Class that has both the new and old price and then use those 2 values in your composable to determine what color to show, or expose the price and the color to use.

The way you're encrypting data makes no sense. Asymmetric encryption can only encrypt a small, fixed amount of data. Never use asymmetric encryption such as RSA-OAEP for anything other than a symmetric key, and use that symmetric key to encrypt the actual data. For the symmetric encryption, use a proper AEAD mode such as AES-GCM or ChaCha20-Poly1305. This is called hybrid encryption.

Other things that are wrong with your code:

• A 1024-bit RSA key is not enough for security: 2048-bit is a minimum, and you should prepare to move away from RSA because its key sizes don't scale well. (Feel free to use 1024-bit keys for testing and learning, just don't use anything less than 2048-bit for RSA in production.)
• The encryption is a binary format, but you join up lines as if they were text. Text or binary: pick one. Preferably use a well-known format such as ASN.1 (complex but well-supported) for binary data or JSON for text. If you need to encode binary data in a text format, use Base64.

If this is for real-world use, scrap this and use NaCl or libsodium. In Python, use a Python wrapper such as libnacl, PyNaCl, pysodium or csodium. Use a public-key box. The Python APIs are slightly different for each Python wrapper, but all include a way to export the keys.

If this is a learning exercise, read up on hybrid encryption. Look inside libsodium to see how to do it correctly. Key import and export is done with the methods import_key and export_key. Symmetric encryption starts with Crypto.Cipher.AES.new(key, Crypto.Cipher.AES.MODE_GCM) or Crypto.Cipher.ChaCha20_Poly1305.new(key) (Crypto.Cipher.AES.new(key, Crypto.Cipher.AES.MODE_GCM, nonce=nonce) or Crypto.Cipher.ChaCha20_Poly1305.new(key, nonce=nonce) for decryption).

GCM is a stream cipher mode and therefore does not require padding. During encryption, an authentication tag is implicitly generated, which is used for authentication during decryption. Also, an IV/nonce of 12 bytes is recommended for GCM.

The posted Python code unnecessarily pads and doesn't take the authentication tag into account, unlike the JavaScript code, which may be the main reason for the different ciphertexts. Whether this is the only reason and whether the JavaScript code implements GCM correctly, is difficult to say, since the getMessageEncoding() method was not posted, so testing this was not possible.

Also, both codes apply a 16 bytes IV/nonce instead of the recommended 12 bytes IV/nonce.

Cryptography offers two possible implementations for GCM. One implementation uses the architecture of the non-authenticating modes like CBC. The posted Python code applies this design, but does not take authentication into account and therefore implements GCM incompletely. A correct example for this design can be found here.
Cryptography generally recommends the other approach for GCM (s. the Danger note), namely the AESGCM class, which performs implicit authentication so that this cannot be accidentally forgotten or incorrectly implemented.

The following implementation uses the AESGCM class (and also takes into account the optional additional authenticated data):

Since Postman worked, your backend is setup properly. Now on to your frontend.

Axios handles multipart form data if your data is an instance of FormData.

1. In your component you can set a state variable to hold the selected file

Here:

The short answer is that the main page contains an explicit html table, while the watchlist page seems to be a structured series of div elements generated by javascript and made to look like a table. There is no 'tbody' element on the watchlist page because there is no table there. The text items command splits the first page into three parts (the second of which is the one you want); it doesn't split the watchlist page at all, which produces an array with a single item containing all of the html. When you ask an array of 1 element for its second item, you get your error.

You're going to have to examine the html of the second page and figure out how to split the text to extract the information you want.

*Edited

My mistake was thinking that the webpack ts-loader would take context from from ts-config file and transpile the typescript according to that and webpack the content into the final bundle. Upon looking at my question again ive realised i put the index.tsx file as my entry point which is why i was still getting a bundled webpack file but my imports were undefined the only file being webpack was my index file i believe. That combined with the single file output tsc seems to have been the cause.

tsc was creating a bundle of my typescript.

webpack was creating a bundle of just my index.tsx file

Problem entry: './src/index.tsx' & "outFile": "./dist/main.js"

The referenced Python code uses P-384 (aka secp384r1) as elliptic curve. This is compatible with the WebCrypto API, which supports three curves P-256 (aka secp256r1), P-384 and P-521 (aka secp521r1), see EcKeyImportParams.

The following WebCrypto code generates a shared secret using ECDH and derives an AES key from the shared secret using HKDF. In detail the following happens:

• To allow comparison of the derived key with that of the referenced Python code, predefined EC keys are applied. The private key is imported as PKCS#8, the public key as X.509/SPKI. Note that due to a Firefox bug concerning the import of EC keys, the script below cannot be run in the Firefox browser.
• After the import the shared secret is created with ECDH using deriveBits() (and not deriveKey()).
• The shared secret is imported with importKey() and then the AES key is derived using HKDF, again with deriveBits().

This (pid, port_name, headshot, work_ex,) is a tuple. What arguments does the cursor.execute(...) function expect? Can you try removing the parentheses around those variables and have them each be arguments to cursor.execute?