Add Armory chain cascade for BTC1000-style puzzle verification

[oritwoen]

Problem

The current --transform armory generates a single root key from a passphrase. However, Armory wallets use a multiplicative chain to derive sequences of keys:

key[0] = root_key
key[1] = key[0] * scalar[0] mod n
key[2] = key[1] * scalar[1] mod n
...
where scalar[i] = hash256(pubkey[i]) XOR chaincode

For BTC1000 research, we need to test if the puzzle creator used an Armory wallet with a brainwallet seed, generating 160 sequential keys and masking each to the appropriate bit width.

Proposed Solution

Add --armory-cascade option that generates the full Armory multiplicative chain and verifies against multiple masked targets:

# Search passphrases for Armory chain that produces BTC1000 puzzles
vuke scan --targets btc1000_addresses.txt wordlist rockyou.txt \
    --transform armory \
    --armory-cascade 5:0x15,10:0x202,20:0xd2c55,30:0x3d94cd64

Algorithm

fn check_armory_cascade(passphrase: &str, targets: &[(u8, U256)]) -> bool {
    // Generate root key
    let root = sha256(passphrase);
    let chaincode = hmac_sha256(
        key: hash256(root),
        msg: b"Derive Chaincode from Root Key"
    );
    
    let mut current_key = root;
    
    for (bits, target) in targets {
        // Apply mask
        let masked = (current_key & ((1 << bits) - 1)) | (1 << (bits - 1));
        if masked != target {
            return false;
        }
        
        // Armory multiplicative chain step
        let pubkey = current_key.to_pubkey();
        let scalar = hash256(pubkey) XOR chaincode;
        current_key = (current_key * scalar) % SECP256K1_ORDER;
    }
    
    true  // All targets matched
}

Key Difference from Issue #11

Issue #11 (MT19937 cascade)	This issue (Armory cascade)
Sequential fill_bytes() calls	Multiplicative chain derivation
key[i] = rng.next_256_bits()	key[i] = key[i-1] * scalar mod n
Stateless per-key	Each key depends on previous

Use Case

BTC1000 puzzle research - testing hypothesis that creator used Armory deterministic wallet with brainwallet passphrase (Experiments E170, E179 in cryptopuzzles).

References

• cryptopuzzles implementation: puzzles/saatoshi_rising/analysis/armory_search.py
• Armory source: https://github.com/goatpig/BitcoinArmory
• Related: Issue Add cascading filter for multi-puzzle masked analysis #11 (MT19937 cascade - different algorithm)