Global Functions

CashScript has several built-in functions for things like cryptographic and arithmetic applications, and it includes many common arithmetic and other operators that you would expect in a programming language.

Arithmetic functions

abs()

int abs(int a)

Returns the absolute value of argument a.

min()

int min(int a, int b)

Returns the minimum value of arguments a and b.

max()

int max(int a, int b)

Returns the maximum value of arguments a and b.

within()

bool within(int x, int lower, int upper)

Returns true if and only if x >= lower && x < upper.

Hashing functions

ripemd160()

bytes20 ripemd160(any x)

Returns the RIPEMD-160 hash of argument x.

sha1()

bytes20 sha1(any x)

Returns the SHA-1 hash of argument x.

sha256()

bytes32 sha256(any x)

Returns the SHA-256 hash of argument x.

hash160()

bytes20 hash160(any x)

Returns the RIPEMD-160 hash of the SHA-256 hash of argument x.

hash256()

bytes32 hash256(any x)

Returns the double SHA-256 hash of argument x.

Signature checking functions

caution

All signature checking functions must comply with the NULLFAIL rule which only allows 0x as an invalid signature — any other invalid signature will immediately fail the entire script.

Nullfail example

The NULLFAIL rule means passing an invalid signature to checkSig() does not return false — it fails the script. To safely return false on a signature check, use an empty 0x signature instead, as shown below:

// this script will immediately fail
// because userSig will be invalid for either the 'seller' or the 'refere'
require(checkSig(userSig, seller) || checkSig(userSig, refere));

// instead, use 2 different  signatures
// set the unused signature to 0x so 'checkSig' returns false
require(checkSig(sellerSig, seller) || checkSig(userSig, refere));

checkSig()

bool checksig(sig s, pubkey pk)

Checks that transaction signature s is valid for the current transaction and matches with public key pk.

checkMultiSig()

bool checkMultiSig(sig[] sigs, pubkey[] pks)

Performs a multi-signature check using a list of transaction signatures and public keys.

note

While this function can be used inside your smart contracts, it is not supported by the TypeScript SDK, so it is recommended not to use it. Instead a checkMultiSig() call can be simulated using multiple checkSig() calls.

checkDataSig()

bool checkDataSig(datasig s, bytes msg, pubkey pk)

Checks that sig s is a valid signature for message msg and matches with public key pk.