these are all my errors:

error[E0432]: unresolved import rand_core::OsRng
--> bin/robotwifi.rs:47:26
|
47 | use rand_core::{RngCore, OsRng};
| ^^^^^ no OsRng in the root
|
note: found an item that was configured out
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rand_core-0.6.4/src/lib.rs:49:43
|
49 | #[cfg(feature = "getrandom")] pub use os::OsRng;
| ^^^^^
= note: the item is gated behind the getrandom feature

error: no global memory allocator found but one is required; link to std or add #[global_allocator] to a static item that implements the GlobalAlloc trait

warning: unused import: _fugit_RateExtU32
--> bin/robotwifi.rs:8:107
|
8 | clock::{ClockControl, CpuClock}, embassy, interrupt, peripherals::{Interrupt, Peripherals}, prelude::{_fugit_RateExtU32, *}, systimer::S...
| ^^^^^^^^^^^^^^^^^
|
= note: #[warn(unused_imports)] on by default

warning: unused import: embedded_tls::NoVerify
--> bin/robotwifi.rs:46:5
|
46 | use embedded_tls::NoVerify;
| ^^^^^^^^^^^^^^^^^^^^^^

warning: unused import: RngCore
--> bin/robotwifi.rs:47:17
|
47 | use rand_core::{RngCore, OsRng};
| ^^^^^^^

error[E0277]: the trait bound Rng: CryptoRng is not satisfied
--> bin/robotwifi.rs:290:56
|
290 | let tls_context = TlsContext::new(&tls_config, &mut rng);
| --------------- ^^^^^^^^ the trait CryptoRng is not implemented for Rng
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait CryptoRng:
BlockRng<R>
&'a mut R
note: required by a bound in TlsContext::<'a, CipherSuite, RNG>::new
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/config.rs:165:10
|
165 | RNG: CryptoRng + RngCore + 'a,
| ^^^^^^^^^ required by this bound in TlsContext::<'a, CipherSuite, RNG>::new
...
168 | pub fn new(config: &'a TlsConfig<'a, CipherSuite>, rng: &'a mut RNG) -> Self {
| --- required by a bound in this associated function

error[E0277]: the trait bound Rng: RngCore is not satisfied
--> bin/robotwifi.rs:290:56
|
290 | let tls_context = TlsContext::new(&tls_config, &mut rng);
| --------------- ^^^^^^^^ the trait RngCore is not implemented for Rng
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait RngCore:
BlockRng<R>
BlockRng64<R>
CountingRng
&'a mut R
note: required by a bound in TlsContext::<'a, CipherSuite, RNG>::new
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/config.rs:165:22
|
165 | RNG: CryptoRng + RngCore + 'a,
| ^^^^^^^ required by this bound in TlsContext::<'a, CipherSuite, RNG>::new
...
168 | pub fn new(config: &'a TlsConfig<'a, CipherSuite>, rng: &'a mut RNG) -> Self {
| --- required by a bound in this associated function

error[E0277]: the trait bound Rng: CryptoRng is not satisfied
--> bin/robotwifi.rs:290:27
|
290 | let tls_context = TlsContext::new(&tls_config, &mut rng);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait CryptoRng is not implemented for Rng
|
= help: the following other types implement trait CryptoRng:
BlockRng<R>
&'a mut R
note: required by a bound in TlsContext
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/config.rs:156:10
|
153 | pub struct TlsContext<'a, CipherSuite, RNG>
| ---------- required by a bound in this struct
...
156 | RNG: CryptoRng + RngCore + 'a,
| ^^^^^^^^^ required by this bound in TlsContext

error[E0277]: the trait bound Rng: RngCore is not satisfied
--> bin/robotwifi.rs:290:27
|
290 | let tls_context = TlsContext::new(&tls_config, &mut rng);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait RngCore is not implemented for Rng
|
= help: the following other types implement trait RngCore:
BlockRng<R>
BlockRng64<R>
CountingRng
&'a mut R
note: required by a bound in TlsContext
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/config.rs:156:22
|
153 | pub struct TlsContext<'a, CipherSuite, RNG>
| ---------- required by a bound in this struct
...
156 | RNG: CryptoRng + RngCore + 'a,
| ^^^^^^^ required by this bound in TlsContext

error[E0277]: the trait bound Rng: CryptoRng is not satisfied
--> bin/robotwifi.rs:293:29
|
293 | match tls_conn.open(tls_context).await {
| ---- ^^^^^^^^^^^ the trait CryptoRng is not implemented for Rng
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait CryptoRng:
BlockRng<R>
&'a mut R
note: required by a bound in embedded_tls::TlsConnection::<'a, Socket, CipherSuite>::open
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/asynch.rs:79:14
|
74 | pub async fn open<'v, RNG, Verifier>(
| ---- required by a bound in this associated function
...
79 | RNG: CryptoRng + RngCore,
| ^^^^^^^^^ required by this bound in TlsConnection::<'a, Socket, CipherSuite>::open

error[E0277]: the trait bound Rng: RngCore is not satisfied
--> bin/robotwifi.rs:293:29
|
293 | match tls_conn.open(tls_context).await {
| ---- ^^^^^^^^^^^ the trait RngCore is not implemented for Rng
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait RngCore:
BlockRng<R>
BlockRng64<R>
CountingRng
&'a mut R
note: required by a bound in embedded_tls::TlsConnection::<'a, Socket, CipherSuite>::open
--> /Users/adamh/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-tls-0.17.0/src/asynch.rs:79:26
|
74 | pub async fn open<'v, RNG, Verifier>(
| ---- required by a bound in this associated function
...
79 | RNG: CryptoRng + RngCore,
| ^^^^^^^ required by this bound in TlsConnection::<'a, Socket, CipherSuite>::open

error[E0599]: no method named connect found for struct embedded_tls::TlsConnection in the current scope
--> bin/robotwifi.rs:318:35
|
318 | let connection = tls_conn.connect(remote_endpoint).await;
| ^^^^^^^ method not found in TlsConnection<'_, TcpSocket<'_>, _>

Some errors have detailed explanations: E0277, E0432, E0599.

This is what I've got:

    // TLS Handshake
    let cert_der = include_bytes!("../isrgrootx1.der");

    let cert = Certificate::X509(cert_der);
    let tls_config: TlsConfig<Aes128GcmSha256> = TlsConfig::new().with_ca(cert);

    let tls_context = TlsContext::new(&tls_config, &mut csrng);

    let mut tls_rx_buffer: [u8; 4096] = [0; 4096];
    let mut tls_tx_buffer: [u8; 4096] = [0; 4096];

    let mut tls_conn = TlsConnection::new(&mut socket, &mut tls_rx_buffer, &mut tls_tx_buffer);

    match tls_conn.open(tls_context).await {
        Ok(_) => continue,
        Err(e) => println!("TLS handshake failed, Error: {:?}", e),
    }

In reply to @greengenie:matrix.org
my target isn't supported for the "getrandom" feature of randcore, do you know if there is another way to get an easier Rng?

Did you see the example in the embedded-tls repo Adam Hott ?

https://github.com/drogue-iot/embedded-tls/blob/main/examples/embassy/src/main.rs#L89-L94