Opcodes used in Script
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.
Opcodes that will be activated in the Chronicle Release are indicated by an asterisk (e.g. OP_VER*).
Constants
When talking about scripts, these value-pushing words are usually omitted.
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
OP_NOP
97 0x61
Nothing
Nothing
Does nothing.
OP_VER*
98 0x62
Nothing
Transaction version
Puts the transaction version 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*
101 0x65
x1 = 4-byte array
Result of conditionally executed statement
Same semantics as: x1 transaction_version OP_EQUAL OP_IF [statements] [OP_ELSE [statements]] OP_ENDIF OP_DROP.
OP_VERNOTIF*
102 0x66
x1 = 4-byte array
Result of conditionally executed statement
Same semantics as: x1 transaction_version OP_EQUAL OP_IFNOT [statements] [OP_ELSE [statements]] OP_ENDIF OP_DROP.
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
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
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
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).
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*
141 0x8d
in
out
The input is multiplied by 2.
OP_2DIV*
142 0x8e
in
out
The input is divided by 2.
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
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.
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)
String operations
OP_SUBSTR*
179 0xb3
x1 x2 x3
output string
The substring created from the string (x3) starting at the specified index (x2) and of the specified length (x1).
OP_LEFT*
180 0xb4
x1 x2
output string
The substring created from the string (x2) starting at the begining of the string and of the specified length (x1).
OP_RIGHT*
181 0xb5
x1 x2
output string
The substring created from the string (x2) using the specified number (x1) of rightmost characters.
Pseudo-words
These words are used internally for assisting with transaction matching. They are invalid if used in actual scripts.
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.
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.
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