Glossary
BTQ glossary. Plain definitions of Dilithium, ML-DSA, FIPS 204, Bech32m, block weight, the witness discount, UTXO, and other terms in these docs.
Glossary
A reference for terminology used throughout BTQ documentation. Terms are organized alphabetically.
A
Auto-Detection
The mechanism by which BTQ's script interpreter determines whether a transaction input uses ECDSA or Dilithium signatures. If the public key provided in the witness is larger than 100 bytes, Dilithium verification is used; otherwise, ECDSA verification is used. This allows both signature types to coexist on the same network without explicit type indicators.
B
Base58
A binary-to-text encoding used for legacy Bitcoin and BTQ addresses. Base58 omits characters that are visually ambiguous (0, O, I, l) to reduce transcription errors. BTQ legacy addresses begin with B (ECDSA), D (Dilithium), Q (ECDSA script), or R (Dilithium script).
Bech32
A human-readable address encoding format introduced by Bitcoin's SegWit upgrade (BIP173). Bech32 addresses are case-insensitive, have built-in error detection, and are more efficient than Base58. BTQ mainnet Bech32 addresses use the prefix qbtc1.
BIP-143
A Bitcoin Improvement Proposal that defines the transaction digest (sighash) algorithm for SegWit transactions. BTQ uses BIP-143 for computing the data that Dilithium signatures commit to, ensuring consistency with Bitcoin's SegWit signing format.
BIP360
A proposal for integrating post-quantum signatures into Bitcoin's Tapscript framework (Pay-to-Taproot-Script-Hash, or P2TSH). BTQ's v2 roadmap envisions adopting this approach to replace custom Dilithium opcodes with cleaner Tapscript-based verification.
Block Reward
The total compensation a miner receives for producing a valid block. It consists of the block subsidy (newly created BTQ) plus all transaction fees in the block. BTQ's initial block subsidy is 5 BTQ per block.
Block Weight
A measure of how much block capacity a transaction consumes. Weight accounts for the witness discount: non-witness data counts at full rate (16 weight units per byte) while witness data counts at a reduced rate (1 weight unit per byte). BTQ's maximum block weight is 8,000,000 weight units.
C
Coinbase Maturity
The number of blocks that must pass before a miner can spend their block reward. BTQ requires 100 blocks of maturity (approximately 1 hour and 40 minutes with 1-minute blocks), protecting against chain reorganizations that could invalidate the reward.
Coinbase Transaction
The first transaction in every block, created by the miner. It has no inputs and creates new coins as the block reward. The coinbase transaction also contains the witness commitment hash.
Confirmation
A measure of how deeply a transaction is buried in the blockchain. A transaction gains one confirmation when it is first included in a block, and one additional confirmation for each subsequent block. More confirmations mean greater security against reversal.
CRYSTALS
Cryptographic Suite for Algebraic Lattices. The family of algorithms that includes Dilithium (signatures) and Kyber (key encapsulation). BTQ uses the Dilithium component for transaction signing.
D
Difficulty Adjustment
The periodic recalculation of the mining difficulty target to maintain consistent block times. BTQ adjusts difficulty every 20,160 blocks (approximately 2 weeks), the same wall-clock period as Bitcoin but with 10 times more blocks per retarget window. If blocks are found faster than the 1-minute target, difficulty increases; if slower, it decreases.
Dilithium
A lattice-based digital signature scheme, formally known as CRYSTALS-Dilithium, standardized by NIST as FIPS 204 (also referred to as ML-DSA). BTQ uses Dilithium2 (Security Level 2) with 1,312-byte public keys, 2,560-byte private keys, and 2,420-byte signatures.
E
ECDSA
Elliptic Curve Digital Signature Algorithm. The signature scheme used by Bitcoin, based on the secp256k1 elliptic curve. ECDSA is vulnerable to quantum computers running Shor's algorithm. BTQ supports ECDSA for backward compatibility but adds Dilithium as the quantum-resistant alternative.
F
FIPS 204
Federal Information Processing Standard 204, published by NIST in 2024. It specifies the ML-DSA (Module-Lattice-Based Digital Signature Algorithm) standard, which is the formal name for Dilithium. BTQ's implementation follows this standard.
Full Node
A network participant that stores the complete blockchain, validates all transactions and blocks independently, and relays valid data to peers. Full nodes enforce consensus rules without trusting any other party.
G
Genesis Block
The first block in a blockchain, hardcoded into the software. BTQ's genesis block has a header timestamp of February 23, 2026 (nTime = 1771804800) and includes the coinbase message "BTQ genesis remine: quantum-safe launch baseline, 26/Feb/2026." The genesis block cannot be spent (its coinbase output is unspendable by convention).
Grover's Algorithm
A quantum algorithm that provides a quadratic speedup for brute-force search problems. Applied to SHA-256, it reduces the effective security from 256 bits to 128 bits. This weakens mining security but does not break it. See also: The Quantum Threat.
H
Halving
The periodic reduction of the block subsidy by 50%. BTQ halves every 2,100,000 blocks (approximately every 4 years). The initial subsidy is 5 BTQ; after the first halving it becomes 2.5 BTQ, then 1.25 BTQ, and so on until it reaches zero.
Harvest Now, Decrypt Later
An attack strategy where adversaries record encrypted or signed data today with the intention of decrypting it in the future when quantum computers become available. For blockchains, this means public keys exposed in transactions today could be exploited by future quantum computers to steal funds.
Hash160
The combination of SHA-256 followed by RIPEMD-160, producing a 20-byte hash. Used in BTQ (and Bitcoin) to derive the key hash stored in addresses and UTXO scriptPubKeys. Both ECDSA and Dilithium public keys are hashed this way for address derivation.
K
Key Hash
A 20-byte value derived from a public key using Hash160 (SHA-256 followed by RIPEMD-160). The key hash is stored in the UTXO set rather than the full public key, keeping the UTXO set compact regardless of key size.
L
Lattice-Based Cryptography
A family of cryptographic constructions based on the mathematical difficulty of problems involving lattices (regular geometric structures in high-dimensional space). Dilithium is a lattice-based scheme. No efficient quantum algorithm is known for solving lattice problems, making them the foundation of most post-quantum cryptographic schemes.
M
Magic Bytes
A four-byte identifier at the beginning of every network message that identifies which blockchain network the message belongs to. BTQ uses 0xF1B2A3D4 (Bitcoin uses 0xF9BEB4D9). This prevents BTQ and Bitcoin nodes from accidentally communicating with each other.
Mempool
The memory pool where unconfirmed transactions wait before being included in a block. Each node maintains its own mempool. Miners select transactions from the mempool to include in the blocks they create, typically prioritizing by fee rate.
ML-DSA
Module-Lattice-Based Digital Signature Algorithm. The formal NIST name for the Dilithium signature scheme as specified in FIPS 204. ML-DSA-44 corresponds to Dilithium2 (Security Level 2), which is what BTQ uses.
MLWE
Module Learning with Errors. The mathematical problem underlying Dilithium's security. Given a system of approximate linear equations over a polynomial ring, finding the secret solution is believed to be hard for both classical and quantum computers.
N
NIST
National Institute of Standards and Technology. A U.S. government agency that develops cryptographic standards. NIST's Post-Quantum Cryptography standardization process (2016-2024) selected Dilithium as one of the primary post-quantum signature schemes.
O
OP_CHECKSIGDILITHIUM
A BTQ-specific script opcode that verifies a Dilithium signature against a public key and transaction hash on the script stack. This opcode is the Dilithium equivalent of Bitcoin's OP_CHECKSIG.
P
P2DPK
Pay-to-Dilithium-Public-Key. A transaction output type where the spending condition is a valid Dilithium signature from a specific public key. The full 1,312-byte public key appears in the scriptPubKey.
P2DWPKH
Pay-to-Dilithium-Witness-Public-Key-Hash. The SegWit variant of P2DPK. The scriptPubKey contains only a 20-byte hash of the public key, while the full public key and signature appear in the witness data. This is the recommended transaction type for Dilithium because it keeps large data in the prunable witness section.
Post-Quantum Cryptography
Cryptographic algorithms designed to be secure against attacks by both classical and quantum computers. Dilithium, Falcon, and SPHINCS+ are examples of post-quantum signature schemes. See also: The Quantum Threat.
Proof of Work (PoW)
A consensus mechanism where miners expend computational effort (hashing) to produce valid blocks. The difficulty of the work is adjusted to maintain a target block interval. BTQ uses SHA-256 double-hash proof of work, the same algorithm as Bitcoin.
Pruning
The process of discarding old blockchain data that is no longer needed for validation. Pruned nodes keep the current UTXO set and recent blocks but discard older block data. Witness data is particularly suitable for pruning because it is only needed during initial validation.
S
SegWit
Segregated Witness. A transaction format that separates (segregates) signature/witness data from the base transaction. SegWit reduces the effective cost of signature data through the witness discount and fixes transaction malleability. BTQ's Dilithium transactions use SegWit format by default.
Sighash
The hash of specific transaction data that a signature commits to. The sighash type (ALL, NONE, SINGLE, ANYONECANPAY) determines which parts of the transaction are included in the hash. A 1-byte sighash type indicator is appended to every signature.
Shor's Algorithm
A quantum algorithm discovered by Peter Shor in 1994 that can efficiently solve integer factorization and discrete logarithm problems. Shor's algorithm breaks RSA, ECDSA, and all elliptic-curve-based cryptography. Dilithium is not vulnerable to Shor's algorithm because its security is based on lattice problems, not discrete logarithms.
T
Tapscript
An extension of Bitcoin's script system introduced with the Taproot upgrade. Tapscript enables more flexible spending conditions within a Taproot output. BTQ's v2 roadmap plans to integrate Dilithium verification as a Tapscript operation via BIP360.
U
UTXO
Unspent Transaction Output. A record of coins that have been received but not yet spent. The UTXO set is the collection of all such records across the entire blockchain and must be kept accessible for fast transaction validation. BTQ stores only compact key hashes (20 bytes) in the UTXO set, not full Dilithium public keys.
W
Witness Data
The portion of a SegWit transaction that contains signatures and public keys. Witness data is segregated from the base transaction, benefits from the witness discount (counted at 1/16th weight in BTQ), and can be pruned by nodes that have already validated the transaction.
Witness Discount
The reduced weight applied to witness data when calculating transaction weight. BTQ uses a witness scale factor of 16, meaning each byte of witness data counts as 1/16th of a weight unit compared to non-witness data. This incentivizes placing large Dilithium signatures and public keys in the witness section rather than in the permanent UTXO set.
Witness Scale Factor
The ratio between non-witness and witness weight. In BTQ, this is 16 (Bitcoin uses 4). A higher factor provides a stronger incentive to use witness-based transaction formats, which is important for BTQ because Dilithium signatures are proportionally much larger than ECDSA signatures.