blockchain-attestation | Paper and implementation of blockchain attestations | Cryptography library

In .NET 6 code from How can I SHA512 a string in C#?

Based on the example provided here on how to establish a shared secret and derived key between JS (Crypto-JS) and Python, I can end up with the same shared secret and derived key on both ends.

However, when I try to encrypt as below, I cannot find a way to properly decrypt from Python. My understanding is that probably I am messing with the padding or salts and hashes.

Everytime I publish my Blazor Server-project to my website domain, and opening the website, this exception occurs, and there's little to no help Googling it:

And it says AppState.cs: line 21, so here's the codeline for it:

This exception is not happening under debugging localhost. When I delete localStorage from the browser on my website, and refreshing, then everything works. But I don't want my customers having this exception and having to tell them to delete the localstorage everytime I'm publishing.

My Program.cs if necessary:

I'm experimenting with Chaum's blind signature, and what I'm trying to do is have the blinding and un-blinding done in JavaScript, and signing and verifying in Java (with bouncy castle). For the Java side, my source is this, and for JavaScript, I found blind-signatures. I've created two small codes to play with, for the Java side:

We are trying to make a JWT token for Apple Search Ads using the KJUR jws library. We are using the API documents from Apple:

https://developer.apple.com/documentation/apple_search_ads/implementing_oauth_for_the_apple_search_ads_api

We are generating a private key (prime256v1 curve):

openssl ecparam -genkey -name prime256v1 -noout -out private-key.pem

Next we are generating a public key from the private key:

openssl ec -in private-key.pem -pubout -out public-key.pem

Next we setup the header and payload:

I trying to get the RSA signature as described in Annex A2.1 of EMV book 2. As I understand it was described in ISO9796-2 as scheme 1, option 1. So, the resulting signature should contain a Header equal to '6A' and a Trailer equal to 'BC'.

The algorithms ALG_RSA_SHA_ISO9796 and ALG_RSA_SHA_ISO9796_MR are the only suitable that I could find. But they acting like scheme 1, option 2 with a Trailer equal to '33cc'

Is it possible to get a signature with Trailer = 'BC'?

Javacard example code:

Hello I am trying to transfer a custom SPL token with the solana-wallet adapter. However i am having trouble getting the wallet's secret key/signing the transaction.

I've looked at these answers for writing the transfer code but i need to get the Singer and i have trouble figuring out how with solana-wallet adapter. These examples hardcode the secret key and since i'm using a wallet extension this is not possible.

How can you transfer SOL using the web3.js sdk for Solana?

How to transfer custom token by '@solana/web3.js'

according to this issue on the webadapter repo https://github.com/solana-labs/wallet-adapter/issues/120 you need to:

1. Create a @solana/web3.js Transaction object and add instructions to it
2. Sign the transaction with the wallet
3. Send the transaction over a Connection

But i am having difficulty finding examples or documentation as to how to do step 1 and 2.

I have a base64-encoded public key in DER format. In Python, how can I convert it into a COSE key?

Here is my failed attempt:

I'm switching from the pure Python ecdsa library to the much faster coincurve library for signing data. I would also like to switch to coincurve for verifying the signatures (including the old signatures created by the ecdsa library).

It appears that signatures created with ecdsa are not (always?) valid in coincurve. Could someone please explain why this is not working? Also, it seems that cryptography library is able to validate both ecdsa signatures and coincurve signatures without issues, consistently.

What is even more confusing, if you run below script a few times, is that sometimes it prints point 3 and other times it does not. Why would coincurve only occasionally find the signature valid?