Module bitcoin_spv::btcspv

btcspv provides basic Bitcoin transaction and header parsing, as well as utility functions like merkle verification and difficulty adjustment calculation.

Functions

calculate_difficulty	Calculate difficulty from the difficulty 1 target and current target. Difficulty 1 is 0x1d00ffff on mainnet and testnet.
determine_input_length	Determines the length of an input from its scriptsig: 36 for outpoint, 1 for scriptsig length, 4 for sequence.
determine_output_length	Determines the length of an output. 5 types: WPKH, WSH, PKH, SH, and OP_RETURN.
determine_var_int_data_length	Determines the length of a VarInt in bytes. A VarInt of > 1 byte is prefixed with a flag indicating its length.
extract_difficulty	Extracts the expected difficulty from a block header. Does NOT verify the work.
extract_hash	Extracts the hash from the output script. Determines type by the length prefix and validates format.
extract_input_at_index	Extracts the nth input from the vin (0-indexed).
extract_input_tx_id	Extracts the outpoint index from an input, 32 byte tx id.
extract_input_tx_id_le	Extracts the outpoint tx id from an input, 32 byte tx id.
extract_merkle_root_be	Extracts the transaction merkle root from a block header. Use verify_hash256_merkle to verify proofs with this root.
extract_merkle_root_le	Extracts the transaction merkle root from a block header.
extract_op_return_data	Extracts the data from an op return output. Errors if no data or not an op return.
extract_outpoint	Extracts the outpoint from the input in a tx, 32 byte tx id with 4 byte index.
extract_output_at_index	Extracts the output at a given index in the TxIns vector.
extract_output_script_len	Extracts the output script length. Indexes the length prefix on the pk_script.
extract_prev_block_hash_be	Extracts the previous block's hash from a block header. Block headers do NOT include block number :(
extract_prev_block_hash_le	Extracts the previous block's hash from a block header. Block headers do NOT include block number :(
extract_script_sig	Extracts the VarInt-prepended scriptSig from the input in a tx. Will return vec![0] if passed a witness input.
extract_script_sig_len	Determines the length of a scriptSig in an input. Will return 0 if passed a witness input.
extract_sequence_le_legacy	Extracts the LE sequence bytes from an input. Sequence is used for relative time locks.
extract_sequence_le_witness	Extracts the LE sequence bytes from an input. Sequence is used for relative time locks.
extract_sequence_legacy	Extracts the sequence from the input. Sequence is a 4-byte little-endian number.
extract_sequence_witness	Extracts the sequence from the input in a tx. Sequence is a 4-byte little-endian number.
extract_target	Extracts the target from a block header.
extract_timestamp	Extracts the BE timestamp from a block header. Time is not 100% reliable.
extract_timestamp_le	Extracts the LE timestamp from a block header. Time is not 100% reliable.
extract_tx_index	Extracts the LE tx input index from the input in a tx, 4 byte tx index.
extract_tx_index_le	Extracts the LE tx input index from the input in a tx, 4 byte tx index.
extract_value	Extracts the value from the output in a tx. Value is an 8-byte little-endian number.
extract_value_le	Extracts the value bytes from the output in a tx. Value is an 8-byte little-endian number.
hash160	Implements bitcoin's hash160 (rmd160(sha2())). Returns the digest.
hash256	Implements bitcoin's hash256 (double sha2). Returns the digest.
hash256_merkle_step	Concatenates and hashes two inputs for merkle proving.
is_legacy_input	Determines whether an input is legacy. True for LEGACY, False for WITNESS, False if no scriptSig.
retarget_algorithm	Performs the bitcoin difficulty retarget. Implements the Bitcoin algorithm precisely.
validate_vin	Checks that the vin passed up is properly formatted; Consider a vin with a valid vout in its scriptsig.
validate_vout	Checks that the vout passed up is properly formatted; Consider a vin with a valid vout in its scriptsig.
verify_hash256_merkle	Verifies a Bitcoin-style merkle tree. Leaves are 0-indexed.