Op_codes

This is a list of all Script words, also known as opcodes, commands, or functions.

OP_NOP1-OP_NOP10 were originally set aside to be used when HASH and other security functions become insecure due to improvements in computing.

False is zero or negative zero (using any number of bytes) or an empty array, and True is anything else.

Constants

When talking about scripts, these value-pushing words are usually omitted.

WordOpcodeHexInputOutputDescription

OP_0, OP_FALSE

0

0x00

Nothing.

(empty value)

An empty array of bytes is pushed onto the stack. (This is not a no-op: an item is added to the stack.)

Pushdata Bytelength

1-75

0x01-0x4b

(special)

data

The next opcode bytes is data to be pushed onto the stack

OP_PUSHDATA1

76

0x4c

(special)

data

The next byte contains the number of bytes to be pushed onto the stack.

OP_PUSHDATA2

77

0x4d

(special)

data

The next two bytes contain the number of bytes to be pushed onto the stack in little endian order.

OP_PUSHDATA4

78

0x4e

(special)

data

The next four bytes contain the number of bytes to be pushed onto the stack in little endian order.

OP_1NEGATE

79

0x4f

Nothing.

-1

The number -1 is pushed onto the stack.

OP_1, OP_TRUE

81

0x51

Nothing.

1

The number 1 is pushed onto the stack.

OP_2-OP_16

82-96

0x52-0x60

Nothing.

2-16

The number in the word name (2-16) is pushed onto the stack.

Flow control

WordOpcodeHexInputOutputDescription

OP_NOP

97

0x61

Nothing

Nothing

Does nothing.

OP_VER DISABLED

98

0x62

Nothing

Protocol version

Puts the version of the protocol under which this transaction will be evaluated onto the stack.

OP_IF

99

0x63

[expression] IF

   [statement 1]

ENDIF OR [expression] IF

   [statement 1]

ELSE

   [statement 2]

ENDIF

If the top stack value is TRUE, statement 1 is executed.

If the top stack value is FALSE and ELSE is used, statement 2 is executed. If ELSE is NOT used, the script jumps to ENDIF. The top stack value is removed.

OP_NOTIF

100

0x64

[expression] NOTIF

   [statement 1]

ENDIF OR [expression] IF

   [statement 1]

ELSE

   [statement 2]

ENDIF

If the top stack value is FALSE, statement 1 is executed.

If the top stack value is TRUE and ELSE is used, statement 2 is executed. If ELSE is NOT used, the script jumps to ENDIF. The top stack value is removed.

OP_VERIF DISABLED

101

0x65

DISABLED

DISABLED

OP_VERNOTIF DISABLED

102

0x66

DISABLED

DISABLED

OP_ELSE

103

0x67

[expression] IF

   [statement 1]

ELSE

   [statement 2]

ENDIF

If the preceding IF or NOTIF check was not valid then statement 2 is executed.

OP_ENDIF

104

0x68

[expression] IF

   [statements]

ELSE

   [statements]

ENDIF

Ends an if/else block. All blocks must end, or the transaction is invalid. An OP_ENDIF without a prior matching OP_IF or OP_NOTIF is also invalid.

OP_VERIFY

105

0x69

True / false

Nothing / fail

Marks transaction as invalid if top stack value is not true. The top stack value is removed.

OP_RETURN

106

0x6a

Nothing

Ends script with top value on stack as final result

OP_RETURN can also be used to create "False Return" outputs with a scriptPubKey consisting of OP_FALSE OP_RETURN followed by data. Such outputs are provably unspendable and should be given a value of zero Satoshis. These outputs can be pruned from storage in the UTXO set, reducing its size. Currently the BitcoinSV network supports multiple FALSE RETURN outputs in a given transaction with each one capable of holding up to 100kB of data. After the Genesis upgrade in 2020 miners will be free to mine transactions containing FALSE RETURN outputs of any size.

Stack

WordOpcodeHexInputOutputDescription

OP_TOALTSTACK

107

0x6b

x1

(alt)x1

Puts the input onto the top of the alt stack. Removes it from the main stack.

OP_FROMALTSTACK

108

0x6c

(alt)x1

x1

Puts the input onto the top of the main stack. Removes it from the alt stack.

OP_2DROP

109

0x6d

x1 x2

Nothing

Removes the top two stack items.

OP_2DUP

110

0x6e

x1 x2

x1 x2 x1 x2

Duplicates the top two stack items.

OP_3DUP

111

0x6f

x1 x2 x3

x1 x2 x3 x1 x2 x3

Duplicates the top three stack items.

OP_2OVER

112

0x70

x1 x2 x3 x4

x1 x2 x3 x4 x1 x2

Copies the pair of items two spaces back in the stack to the front.

OP_2ROT

113

0x71

x1 x2 x3 x4 x5 x6

x3 x4 x5 x6 x1 x2

The fifth and sixth items back are moved to the top of the stack.

OP_2SWAP

114

0x72

x1 x2 x3 x4

x3 x4 x1 x2

Swaps the top two pairs of items.

OP_IFDUP

115

0x73

x

x / x x

If the top stack value is not 0, duplicate it.

OP_DEPTH

116

0x74

Nothing

<Stack size>

Counts the number of stack items onto the stack and places the value on the top

OP_DROP

117

0x75

x

Nothing

Removes the top stack item.

OP_DUP

118

0x76

x

x x

Duplicates the top stack item.

OP_NIP

119

0x77

x1 x2

x2

Removes the second-to-top stack item.

OP_OVER

120

0x78

x1 x2

x1 x2 x1

Copies the second-to-top stack item to the top.

OP_PICK

121

0x79

xn ... x2 x1 x0 <n>

xn ... x2 x1 x0 xn

The item n back in the stack is copied to the top.

OP_ROLL

122

0x7a

xn ... x2 x1 x0 <n>

... x2 x1 x0 xn

The item n back in the stack is moved to the top.

OP_ROT

123

0x7b

x1 x2 x3

x2 x3 x1

The top three items on the stack are rotated to the left.

OP_SWAP

124

0x7c

x1 x2

x2 x1

The top two items on the stack are swapped.

OP_TUCK

125

0x7d

x1 x2

x2 x1 x2

The item at the top of the stack is copied and inserted before the second-to-top item.

Data Manipulation

WordOpcodeHexInputOutputDescription

OP_CAT

126

0x7e

x1 x2

out

Concatenates two strings.

OP_SPLIT

127

0x7f

x n

x1 x2

Splits byte sequence x at position n.

OP_NUM2BIN

128

0x80

a b

out

Converts numeric value a into byte sequence of length b.

OP_BIN2NUM

129

0x81

x

out

Converts byte sequence x into a numeric value.

OP_SIZE

130

0x82

in

in size

Pushes the string length of the top element of the stack (without popping it).

Bitwise logic

WordOpcodeHexInputOutputDescription

OP_INVERT

131

0x83

in

out

Flips all of the bits in the input.

OP_AND

132

0x84

x1 x2

out

Boolean and between each bit in the inputs.

OP_OR

133

0x85

x1 x2

out

Boolean or between each bit in the inputs.

OP_XOR

134

0x86

x1 x2

out

Boolean exclusive or between each bit in the inputs.

OP_EQUAL

135

0x87

x1 x2

True / false

Returns 1 if the inputs are exactly equal, 0 otherwise.

OP_EQUALVERIFY

136

0x88

x1 x2

Nothing / fail

Same as OP_EQUAL, but runs OP_VERIFY afterward.

Arithmetic

BitcoinScript supports arithmetic on bignum values A bignum is a byte sequence that represents a numeric value. The length of the byte sequence must be less than or equal to 750,000 bytes. Byte sequences larger than 750,000 bytes are valid in Bitcoin however current rules dictate that they are not recognised as a valid numeric value.

Note that while some operations require parameters to be valid numeric values, they may produce byte sequences which are not valid numeric values (for example, OP_MUL may produce a byte sequence which is too large to validly represent a numeric value).

WordOpcodeHexInputOutputDescription

OP_1ADD

139

0x8b

in

out

1 is added to the input.

OP_1SUB

140

0x8c

in

out

1 is subtracted from the input.

OP_2MUL DISABLED

141

0x8d

in

out

The input is multiplied by 2. (This opcode is scheduled to be re-enabled in the Chronicle update)

OP_2DIV DISABLED

142

0x8e

in

out

The input is divided by 2. (This opcode is scheduled to be re-enabled in the Chronicle update)

OP_NEGATE

143

0x8f

in

out

The sign of the input is flipped.

OP_ABS

144

0x90

in

out

The input is made positive.

OP_NOT

145

0x91

in

out

If the input is 0 or 1, it is flipped. Otherwise the output will be 0.

OP_0NOTEQUAL

146

0x92

in

out

Returns 0 if the input is 0. 1 otherwise.

OP_ADD

147

0x93

a b

out

a is added to b.

OP_SUB

148

0x94

a b

out

b is subtracted from a.

OP_MUL

149

0x95

a b

out

a is multiplied by b.

OP_DIV

150

0x96

a b

out

a is divided by b.

OP_MOD

151

0x97

a b

out

Returns the remainder after dividing a by b.

OP_LSHIFT

152

0x98

a b

out

Logical left shift b bits. Sign data is discarded

OP_RSHIFT

153

0x99

a b

out

Logical right shift b bits. Sign data is discarded

OP_BOOLAND

154

0x9a

a b

out

If both a and b are not 0, the output is 1. Otherwise 0.

OP_BOOLOR

155

0x9b

a b

out

If a or b is not 0, the output is 1. Otherwise 0.

OP_NUMEQUAL

156

0x9c

a b

out

Returns 1 if the numbers are equal, 0 otherwise.

OP_NUMEQUALVERIFY

157

0x9d

a b

Nothing / fail

Same as OP_NUMEQUAL, but runs OP_VERIFY afterward.

OP_NUMNOTEQUAL

158

0x9e

a b

out

Returns 1 if the numbers are not equal, 0 otherwise.

OP_LESSTHAN

159

0x9f

a b

out

Returns 1 if a is less than b, 0 otherwise.

OP_GREATERTHAN

160

0xa0

a b

out

Returns 1 if a is greater than b, 0 otherwise.

OP_LESSTHANOREQUAL

161

0xa1

a b

out

Returns 1 if a is less than or equal to b, 0 otherwise.

OP_GREATERTHANOREQUAL

162

0xa2

a b

out

Returns 1 if a is greater than or equal to b, 0 otherwise.

OP_MIN

163

0xa3

a b

out

Returns the smaller of a and b.

OP_MAX

164

0xa4

a b

out

Returns the larger of a and b.

OP_WITHIN

165

0xa5

x min max

out

Returns 1 if x is within the specified range (left-inclusive), 0 otherwise.

Cryptography

WordOpcodeHexInputOutputDescription

OP_RIPEMD160

166

0xa6

in

hash

The input is hashed using RIPEMD-160.

OP_SHA1

167

0xa7

in

hash

The input is hashed using SHA-1.

OP_SHA256

168

0xa8

in

hash

The input is hashed using SHA-256.

OP_HASH160

169

0xa9

in

hash

The input is hashed twice: first with SHA-256 and then with RIPEMD-160.

OP_HASH256

170

0xaa

in

hash

The input is hashed two times with SHA-256.

OP_CODESEPARATOR

171

0xab

Nothing

Nothing

All of the signature checking words will only match signatures to the data after the most recently-executed OP_CODESEPARATOR.

OP_CHECKSIG

172

0xac

sig pubkey

True / false

The entire transaction's outputs, inputs, and script (from the most recently-executed OP_CODESEPARATOR to the end) are hashed. The signature used by OP_CHECKSIG must be a valid signature for this hash and public key. If it is, 1 is returned, 0 otherwise.

OP_CHECKSIGVERIFY

173

0xad

sig pubkey

Nothing / fail

Same as OP_CHECKSIG, but OP_VERIFY is executed afterward.

OP_CHECKMULTISIG

174

0xae

x sig1 sig2 ... <number of signatures> pub1 pub2 <number of public keys>

True / False

Compares the first signature against each public key until it finds an ECDSA match. Starting with the subsequent public key, it compares the second signature against each remaining public key until it finds an ECDSA match. The process is repeated until all signatures have been checked or not enough public keys remain to produce a successful result. All signatures need to match a public key. Because public keys are not checked again if they fail any signature comparison, signatures must be placed in the scriptSig using the same order as their corresponding public keys were placed in the scriptPubKey or redeemScript. If all signatures are valid, 1 is returned, 0 otherwise. Due to a bug, an extra unused value (x) is removed from the stack. Script spenders must account for this by adding a junk value (typically zero) to the stack.

OP_CHECKMULTISIGVERIFY

175

0xaf

x sig1 sig2 ... <number of signatures> pub1 pub2 ... <number of public keys>

Nothing / fail

Same as OP_CHECKMULTISIG, but OP_VERIFY is executed afterward.

Used NOP opcode identifiers

In Bitcoin's history, new opcodes were added that used reserved NO_OP opcode identifiers. These opcodes have been reverted to the original OP_NOP functionality.

WordOpcodeHexInputOutputDescription

OP_NOP2

(previously OP_CHECKLOCKTIMEVERIFY)

177

0xb1

Nothing

(Previously: x)

Nothing

(Previously: x or fail)

NO OPERATION

Evaluation process for UTXOs that pre-date genesis: Mark transaction as invalid if the top stack item is greater than the transaction's nLockTime field, otherwise script evaluation continues as though an OP_NOP was executed. Transaction is also invalid if 1. the stack is empty; or 2. the top stack item is negative; or 3. the top stack item is greater than or equal to 500000000 while the transaction's nLockTime field is less than 500000000, or vice versa; or 4. the input's nSequence field is equal to 0xffffffff. The precise semantics are described in BIP 0065.

OP_NOP3

(previously OP_CHECKSEQUENCEVERIFY)

178

0xb2

Nothing

(Previously: x)

Nothing

(Previously: x or fail)

NO OPERATION

Evaluation process for UTXOs that pre-date genesis: Mark transaction as invalid if the relative lock time of the input (enforced by BIP 0068 with nSequence) is not equal to or longer than the value of the top stack item. The precise semantics are described in BIP 0112.

Pseudo-words

These words are used internally for assisting with transaction matching. They are invalid if used in actual scripts.

WordOpcodeHexDescription

OP_PUBKEYHASH

253

0xfd

Represents a public key hashed with OP_HASH160.

OP_PUBKEY

254

0xfe

Represents a public key compatible with OP_CHECKSIG.

OP_INVALIDOPCODE

255

0xff

Matches any opcode that is not yet assigned.

Reserved words

Any opcode not assigned is also reserved. Using an unassigned opcode makes the transaction invalid.

WordOpcodeHexWhen used...

OP_RESERVED

80

0x50

Transaction is invalid unless occuring in an unexecuted OP_IF branch

OP_RESERVED1

137

0x89

Transaction is invalid unless occuring in an unexecuted OP_IF branch

OP_RESERVED2

138

0x8a

Transaction is invalid unless occuring in an unexecuted OP_IF branch

OP_NOP1, OP_NOP4-OP_NOP10

176, 179-185

0xb0, 0xb3-0xb9

The word is ignored. Does not mark transaction as invalid.

Examples

For examples of common Bitcoin transaction scripts please see Bitcoin Transactions

Attribution

This content is based on content sourced from https://en.bitcoin.it/wiki/Script under Creative Commons Attribution 3.0. Although it may have been extensively revised and updated we acknowledge the original authors.

Last updated