A QEMU compatible Bare-Metal 64-bit kernel for Raspberry Pi 3b(+) Build & run (debug):

make clean && make
qemu-system-aarch64 -M raspi3b -kernel build/kernel8.img -serial mon:stdio -nographic -s -S -d in_asm,cpu_reset

To quit:

CTRL-A, x

Run GDB, in a separate terminal:

gdb-multiarch build/kernel8.elf -ex "target remote localhost:1234" -ex "break *_start" -ex "continue"~

AI queries used to get up and running: https://chatgpt.com/share/547bc108-f1e5-4b09-a92e-cae47f55bd10

See the pdf, and blockchain-stuff folder README.md

EXPERIMENT: Encrypt a small amount of text with GPG Cast128 and try decrypt...

gpg --version
gpg (GnuPG) 2.2.27
libgcrypt 1.9.4
Copyright (C) 2021 Free Software Foundation, Inc.
License GNU GPL-3.0-or-later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: /home/freddie/.gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA, ECDH, ECDSA, EDDSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

# Encrypt...
echo "A small amount of text" | gpg --symmetric --cipher-algo CAST5 --passphrase "password" --s2k-digest-algo SHA1 --batch > encrypted.gpg

# And decrypt...
gpg --decrypt --passphrase "password" --batch encrypted.gpg

# Taking the encrypted file hex
xxd -p -c 100000 encrypted.gpg 
8c0d04030302eb381c55fecc8f2fffd244018c41f4e16990d9c846cafc6b04bc37e07a9248110a6f11104cfe744d2b2646228c15528525668b97f31bab07bfbcedd0628492ee96bf11e8a4be3aa6e9994901d91195

# Now we can use it in the program
# But we are getting a bad key lets check gpg1 instead ...

Key is good:
gpg --show-session-key  --decrypt --passphrase "password" --b
atch encrypted.gpg 
gpg: CAST5.CFB encrypted data
gpg: encrypted with 1 passphrase
gpg: session key: '3:896E9344A9E485B8934BBBDA07A59868'
A small amount of text

echo "Hello World!" | ./g10/gpg --symmetric --cipher-algo CAST5 --passphrase "password" --s2k-digest-algo SHA1 --compress-algo none --batch --rfc2440 --verbose > encrypted.gpg && xxd encrypted.gpg

00000000: 8c0d 0403 0302 7600 e37f 7d84 7c00 e6c9 ......v...}.|... 00000010: 1f3c 9911 a8bd 78c7 f823 d800 5596 dfff .<....x..#..U... 00000020: 075f 07ba 605a 615e 8cf8 aa74 7fee bc04 ._..`Za^...t....

00000000: 8c0d 0403 0302 7600 e37f 7d84 7c00 e6c9 -- Symmetric-key encrypted data -- Packet type: Symmetric-key encrypted data packet (9) -- Packet length: 13 bytes -- Cipher algorithm: CAST5 (3) -- S2K (string-to-key) usage: Iterated and salted (3) -- S2K hash algorithm: SHA1 (2) -- Initialization Vector (IV)

00000010: 1f3c 9911 a8bd 78c7 f823 d800 5596 dfff -- Ciphertext

00000020: 075f 07ba 605a 615e 8cf8 aa74 7fee bc04 -- Ciphertext

Need more verbosity within _gcry_cast5_cfb_dec static int do_plaintext( IOBUF out, int ctb, PKT_plaintext *pt ) { log_info("do_plaintext pt->buf: %d\n", pt->buf); int rc = 0; size_t nbytes;

log_assert (ctb_pkttype (ctb) == PKT_PLAINTEXT);

log_info("Checking packet type\n");
log_assert(ctb_pkttype(ctb) == PKT_PLAINTEXT);

log_info("Writing header\n");


write_header(out, ctb, calc_plaintext( pt ) );
log_info("CTB: %d\n", ctb);
log_info("Checking mode validity: mode = %c\n", pt->mode);
log_assert(pt->mode == 'b' || pt->mode == 't' || pt->mode == 'u'
            || pt->mode == 'm' || pt->mode == 'l' || pt->mode == '1');

log_info("Writing mode: %c\n", pt->mode);
iobuf_put(out, pt->mode);

log_info("Writing namelen: %zu\n", pt->namelen);
iobuf_put(out, pt->namelen);

log_info("Writing name: %.*s\n", (int)pt->namelen, pt->name);
iobuf_write(out, pt->name, pt->namelen);
pt->timestamp = 1624780800; // 60d83000
log_info("Writing timestamp: %u\n", pt->timestamp);
rc = write_32(out, pt->timestamp);
log_info("rc: %d\n", rc);
log_info("pt->buf: %d\n", pt->buf);
print_iobuf_info2(pt->buf);
if (rc)
  return rc;

if (pt->buf)
  {
    nbytes = iobuf_copy (out, pt->buf);
    log_info("!!!!! Wrote buf %d bytes", nbytes);
    // log_printhex("Writing buf", pt->buf, pt->len);
    
    if (nbytes == (size_t)(-1)
        && (iobuf_error (out) || iobuf_error (pt->buf)))
        return iobuf_error (out)? iobuf_error (out):iobuf_error (pt->buf);
    /* Always get the error to catch write errors because
     * iobuf_copy does not reliable return (-1) in that case.  */
    rc = iobuf_error (out);
    if(ctb_new_format_p (ctb) && !pt->len){
      /* Turn off partial body length mode.  */
      iobuf_set_partial_body_length_mode (out, 0);
      log_info("Turned off partial body length mode\n");
    }
    if (pt->len && nbytes != pt->len)
      {
        log_error ("do_plaintext(): wrote %lu bytes"
                   " but expected %lu bytes\n",
                   (ulong)nbytes, (ulong)pt->len );
        if (!rc) /* Just in case no error was set  */
          rc = gpg_error (GPG_ERR_EIO);
      }
  }
log_info("do_plaintext done %d\n", rc);
return rc;

}

echo 4c6f72656d20697 073756d20646f | xxd -p -r Lorem ipsum dofreddie@fre

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https://claude.site/artifacts/caed6f03-3caa-4090-8412-5c64261a5537

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