Functions

Math Functions

int abs(int a)

Returns an absolute value of the argument.
int min(int a, int b)

Returns the smaller argument.
int max(int a, int b)

Returns the larger argument.
bool within(int x, int min, int max)

Returns true if x >= min && x < max.

Hashing Functions

Ripemd160 ripemd160([byte] bytes)

Returns a RIPEMD-160 hash of the argument.
Sha1 sha1([byte] bytes)

Returns a SHA-1 hash of the argument.
Sha256 sha256([byte] bytes)

Returns a SHA-256 hash of the argument.
Ripemd160 hash160([byte] bytes)

Returns RIPEMD-160 hash of SHA-256 hash of the argument.
Sha256 hash256([byte] bytes)

Returns double SHA-256 hash of the argument.

Cryptographic Checks

bool checkSig(Sig sig, PubKey pk)

Validates a transaction signature sig againnst a public key pk.
- bool checkSigAdd(Sig sig, int num, PubKey pk)
Validates a transaction signature sig againnst a public key pk. Returns num if sig is invalid or num+1 if valid.

Only available in BTC
bool checkMultiSig([bit;n] flags, [Sig;m] sigs, [PubKey;n] pks)

Validates the set of signatures against the set of public keys. Flags indicate which keys will be used.
bool checkDataSig(DataSig sig, [byte] msg, PubKey pk)

Validates a signature sig of an arbitrary message msg against a public key pk.

Not available in BTC

Timelock Checks

Verification checkLockTime(Time t)

Validates whether the spending transaction occurs after time t, expressed as a block height or a timestamp.
Verification checkSequence(TimeSpan duration)

Validates whether the spending transaction happens after duration relative to the locking transaction, expressed as a number of blocks or number of 512 seconds-long periods.

Array Operations

[byte] num2bin(int num, int size)

Converts a number num into a bytes list. Bytes remain little-endian and are padded with zeros up to size.

Not available in BTC
[byte] Bytes(int num)

Reinterprets a number num as a bytes list without affecting the byte order or size.
int bin2num([byte] data)

Converts a bytes list data to an integer. The list is treated as little-endian. The result is minimally encoded.

Not available in BTC
[byte] reverseBytes([byte] data)

[byte;n] reverseBytes([byte;n] data)

Returns an array with bytes in reverse order.

Not available in BTC
```
[byte;3] rev = reverseBytes(0xabcdef);
// rev == 0xefcdab
```
int size([byte] data)

Returns the length of data.
int checkSize([byte; x] data)

Returns true it the runtime size of the byte array matches the declared size x.

a fst((a, b) data)

Returns the first element of a tuple.

[byte] left = fst(0xaabbccdd @ 2);
// left == 0xaabb

b snd((a, b) data)

Returns the second element of a tuple.

[byte] right = snd(0xaabbccdd @ 2);
// right == 0xccdd

DataSig toDataSig(Sig data)

Converts a signature suitable for checkSig function (with a sighash flag) to a signature suitable for checkDataSig function (without a sighash flag).

Not available in BTC
```
verify checkSig(sig, pubKey);
verify checkDataSig(toDataSig(sig), preimageHash, pubKey);
```

Covenant Introspection

These functions are only available in XEC, BCH and XPI.

TxState parse(Preimage p)

Returns a 10-tuple of preimage components.
NVersion nVersion(Preimage p)

Returns nVersion of the transaction (4-byte little endian).
Sha256 hashPrevouts(Preimage p)

Returns hashPrevouts.
Sha256 hashSequence(Preimage p)

Returns hashSequence.
Outpoint outpoint(Preimage p)

Returns outpoint (32-byte hash + 4-byte little endian).
ScriptCode scriptCode(Preimage p)

Returns scriptCode of the input (serialized as scripts inside CTxOuts).
Value value(Preimage p)

Returns value of the output spent by this input (8-byte little endian).
NSequence nSequence(Preimage p)

Returns nSequence of the input (4-byte little endian).
Sha256 hashOutputs(Preimage p)

Returns hashOutputs.
NLocktime nLocktime(Preimage p)

Returns nLocktime of the transaction.
Sighash sighash(Preimage p)

Returns sighash type of the signature (4-byte little endian).

Native Covenant Introspection

These functions are only available in XEC, BCH and XPI.

int inputIndex()

Returns the index of the input being evaluated.
ScriptCode activeBytecode()

Returns the bytecode currently being evaluated, beginning after the last executed OP_CODESEPARATOR. For Pay-to-Script-Hash (P2SH) evaluations, this is the redeem bytecode of the Unspent Transaction Output (UTXO) being spent. For all other evaluations, this is the locking bytecode of the UTXO being spent.
int txVersion()

Returns the version of the current transaction.
int txInputCount()

Returns the count of inputs in the current transaction.
int txOutputCount()

Returns the count of outputs in the current transaction
int txLockTime()

Returns the lock time of the current transaction.
int utxoValue(int index)

Returns the value (in satoshis) of the Unspent Transaction Output (UTXO) spent by the input at index.
ScriptCode utxoBytecode(int index)

Returns the full locking bytecode of the Unspent Transaction Output (UTXO) spent by the input at index.
Sha256 outpointTxHash(int index)

Returns the outpoint transaction hash referenced by the input at index.
int outpointIndex(int index)

Returns the outpoint index referenced by the input at index.
ScriptCode inputBytecode(int index)

Returns the unlocking bytecode of the input at index.
int inputSequenceNumber(int index)

Returns the sequence number of the input at index.
int outputValue(int index)

Returns the value (in satoshis) of the output at index.
ScriptCode outputBytecode(int index)

Returns the locking bytecode of the output at index.

CashTokens Introspection

These functions are only available in BCH.

TokenCategory utxoTokenCategory(int index)

Get the input at index. If the Unspent Transaction Output (UTXO) spent by that input includes no tokens, returns a 0. If the UTXO does not include a non-fungible token with a capability, returns the UTXO’s token category, otherwise, returns the concatenation of the token category and capability, where the mutable capability is represented by 1 and the minting capability is represented by 2.
[byte] utxoTokenCommitment(int index)

Get the input at index. If the UTXO spent by that input includes no tokens, returns an empty byte string. If the UTXO includes a non-fungible token, returns the token’s commitment.
int utxoTokenAmount(int index)

Get the input at index. If the UTXO spent by that input includes no tokens, returns a 0. If the UTXO includes fungible tokens, returns the amount of fungible tokens.
TokenCategory outputTokenCategory(int index)

Get the output at index. If the output includes no tokens, returns a 0. If the output does not include a non-fungible token with a capability, returns the output’s token category, otherwise, returns the concatenation of the token category and capability, where the mutable capability is represented by 1 and the minting capability is represented by 2.
[byte] outputTokenCommitment(int index)

Get the output at index. If the output includes no tokens, returns an empty byte string. If the output includes a non-fungible token, returns the token’s commitment.
int outputTokenAmount(int index)

Get the output at index. If the output includes no tokens, returns a 0. If the output includes fungible tokens, returns the amount of fungible tokens.

Type Constructors

PubKey PubKey([byte] data)
Ripemd160 Ripemd160([byte] data)
Sha1 Sha1([byte] data)
Sha256 Sha256([byte] data)
Sig Sig([byte] data)
DataSig DataSig([byte] data)
Time TimeStamp(int timestamp)
Time TimeStamp(int blockHeight)
TimeSpan Blocks(int number)
NVersion NVesrion([byte] data)
Sha256 HashPrevouts([byte] data)
Sha256 HashSequence([byte] data)
Outpoint Outpoint([byte] data)
ScriptCode ScriptCode([byte] data)
Value Value([byte] data)
NSequence NSequence([byte] data)
Sha256 HashOutputs([byte] data)
NLocktime NLocktime([byte] data)
Sighash Sighash([byte] data)
TokenCategory TokenCategory([byte] data)