READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

21,205 bytes · SHA-256 771da85554fae96c… · View upstream ↗

1Bitcoin Core version 0.13.1 is now available from:
2
3  <https://bitcoin.org/bin/bitcoin-core-0.13.1/>
4
5This is a new minor version release, including activation parameters for the
6segwit softfork, various bugfixes and performance improvements, as well as
7updated translations.
8
9Please report bugs using the issue tracker at github:
10
11  <https://github.com/bitcoin/bitcoin/issues>
12
13To receive security and update notifications, please subscribe to:
14
15  <https://bitcoincore.org/en/list/announcements/join/>
16
17Compatibility
18==============
19
20Microsoft ended support for Windows XP on [April 8th, 2014](https://www.microsoft.com/en-us/WindowsForBusiness/end-of-xp-support),
21an OS initially released in 2001. This means that not even critical security
22updates will be released anymore. Without security updates, using a bitcoin
23wallet on a XP machine is irresponsible at least.
24
25In addition to that, with 0.12.x there have been varied reports of Bitcoin Core
26randomly crashing on Windows XP. It is [not clear](https://github.com/bitcoin/bitcoin/issues/7681#issuecomment-217439891)
27what the source of these crashes is, but it is likely that upstream
28libraries such as Qt are no longer being tested on XP.
29
30We do not have time nor resources to provide support for an OS that is
31end-of-life. From 0.13.0 on, Windows XP is no longer supported. Users are
32suggested to upgrade to a newer version of Windows, or install an alternative OS
33that is supported.
34
35No attempt is made to prevent installing or running the software on Windows XP,
36you can still do so at your own risk, but do not expect it to work: do not
37report issues about Windows XP to the issue tracker.
38
39From 0.13.1 onwards OS X 10.7 is no longer supported. 0.13.0 was intended to work on 10.7+, 
40but severe issues with the libc++ version on 10.7.x keep it from running reliably. 
410.13.1 now requires 10.8+, and will communicate that to 10.7 users, rather than crashing unexpectedly.
42
43Notable changes
44===============
45
46Segregated witness soft fork
47----------------------------
48
49Segregated witness (segwit) is a soft fork that, if activated, will
50allow transaction-producing software to separate (segregate) transaction
51signatures (witnesses) from the part of the data in a transaction that is
52covered by the txid. This provides several immediate benefits:
53
54- **Elimination of unwanted transaction malleability:** Segregating the witness
55  allows both existing and upgraded software to calculate the transaction
56  identifier (txid) of transactions without referencing the witness, which can
57  sometimes be changed by third-parties (such as miners) or by co-signers in a
58  multisig spend. This solves all known cases of unwanted transaction
59  malleability, which is a problem that makes programming Bitcoin wallet
60  software more difficult and which seriously complicates the design of smart
61  contracts for Bitcoin.
62
63- **Capacity increase:** Segwit transactions contain new fields that are not
64  part of the data currently used to calculate the size of a block, which
65  allows a block containing segwit transactions to hold more data than allowed
66  by the current maximum block size. Estimates based on the transactions
67  currently found in blocks indicate that if all wallets switch to using
68  segwit, the network will be able to support about 70% more transactions. The
69  network will also be able to support more of the advanced-style payments
70  (such as multisig) than it can support now because of the different weighting
71  given to different parts of a transaction after segwit activates (see the
72  following section for details).
73
74- **Weighting data based on how it affects node performance:** Some parts of
75  each Bitcoin block need to be stored by nodes in order to validate future
76  blocks; other parts of a block can be immediately forgotten (pruned) or used
77  only for helping other nodes sync their copy of the block chain.  One large
78  part of the immediately prunable data are transaction signatures (witnesses),
79  and segwit makes it possible to give a different "weight" to segregated
80  witnesses to correspond with the lower demands they place on node resources.
81  Specifically, each byte of a segregated witness is given a weight of 1, each
82  other byte in a block is given a weight of 4, and the maximum allowed weight
83  of a block is 4 million.  Weighting the data this way better aligns the most
84  profitable strategy for creating blocks with the long-term costs of block
85  validation.
86
87- **Signature covers value:** A simple improvement in the way signatures are
88  generated in segwit simplifies the design of secure signature generators
89  (such as hardware wallets), reduces the amount of data the signature
90  generator needs to download, and allows the signature generator to operate
91  more quickly.  This is made possible by having the generator sign the amount
92  of bitcoins they think they are spending, and by having full nodes refuse to
93  accept those signatures unless the amount of bitcoins being spent is exactly
94  the same as was signed.  For non-segwit transactions, wallets instead had to
95  download the complete previous transactions being spent for every payment
96  they made, which could be a slow operation on hardware wallets and in other
97  situations where bandwidth or computation speed was constrained.
98
99- **Linear scaling of sighash operations:** In 2015 a block was produced that
100  required about 25 seconds to validate on modern hardware because of the way
101  transaction signature hashes are performed.  Other similar blocks, or blocks
102  that could take even longer to validate, can still be produced today.  The
103  problem that caused this can't be fixed in a soft fork without unwanted
104  side-effects, but transactions that opt-in to using segwit will now use a
105  different signature method that doesn't suffer from this problem and doesn't
106  have any unwanted side-effects.
107
108- **Increased security for multisig:** Bitcoin addresses (both P2PKH addresses
109  that start with a '1' and P2SH addresses that start with a '3') use a hash
110  function known as RIPEMD-160.  For P2PKH addresses, this provides about 160
111  bits of security---which is beyond what cryptographers believe can be broken
112  today.  But because P2SH is more flexible, only about 80 bits of security is
113  provided per address. Although 80 bits is very strong security, it is within
114  the realm of possibility that it can be broken by a powerful adversary.
115  Segwit allows advanced transactions to use the SHA256 hash function instead,
116  which provides about 128 bits of security  (that is 281 trillion times as
117  much security as 80 bits and is equivalent to the maximum bits of security
118  believed to be provided by Bitcoin's choice of parameters for its Elliptic
119  Curve Digital Security Algorithm [ECDSA].)
120
121- **More efficient almost-full-node security** Satoshi Nakamoto's original
122  Bitcoin paper describes a method for allowing newly-started full nodes to
123  skip downloading and validating some data from historic blocks that are
124  protected by large amounts of proof of work.  Unfortunately, Nakamoto's
125  method can't guarantee that a newly-started node using this method will
126  produce an accurate copy of Bitcoin's current ledger (called the UTXO set),
127  making the node vulnerable to falling out of consensus with other nodes.
128  Although the problems with Nakamoto's method can't be fixed in a soft fork,
129  Segwit accomplishes something similar to his original proposal: it makes it
130  possible for a node to optionally skip downloading some blockchain data
131  (specifically, the segregated witnesses) while still ensuring that the node
132  can build an accurate copy of the UTXO set for the block chain with the most
133  proof of work.  Segwit enables this capability at the consensus layer, but
134  note that Bitcoin Core does not provide an option to use this capability as
135  of this 0.13.1 release.
136
137- **Script versioning:** Segwit makes it easy for future soft forks to allow
138  Bitcoin users to individually opt-in to almost any change in the Bitcoin
139  Script language when those users receive new transactions.  Features
140  currently being researched by Bitcoin Core contributors that may use this
141  capability include support for Schnorr signatures, which can improve the
142  privacy and efficiency of multisig transactions (or transactions with
143  multiple inputs), and Merklized Abstract Syntax Trees (MAST), which can
144  improve the privacy and efficiency of scripts with two or more conditions.
145  Other Bitcoin community members are studying several other improvements
146  that can be made using script versioning.
147
148Activation for the segwit soft fork is being managed using BIP9
149versionbits.  Segwit's version bit is bit 1, and nodes will begin
150tracking which blocks signal support for segwit at the beginning of the
151first retarget period after segwit's start date of 15 November 2016.  If
15295% of blocks within a 2,016-block retarget period (about two weeks)
153signal support for segwit, the soft fork will be locked in.  After
154another 2,016 blocks, segwit will activate.
155
156For more information about segwit, please see the [segwit FAQ][], the
157[segwit wallet developers guide][] or BIPs [141][BIP141], [143][BIP143],
158[144][BIP144], and [145][BIP145].  If you're a miner or mining pool
159operator, please see the [versionbits FAQ][] for information about
160signaling support for a soft fork.
161
162[Segwit FAQ]: https://bitcoincore.org/en/2016/01/26/segwit-benefits/
163[segwit wallet developers guide]: https://bitcoincore.org/en/segwit_wallet_dev/
164[BIP141]: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki
165[BIP143]: https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki
166[BIP144]: https://github.com/bitcoin/bips/blob/master/bip-0144.mediawiki
167[BIP145]: https://github.com/bitcoin/bips/blob/master/bip-0145.mediawiki
168[versionbits FAQ]: https://bitcoincore.org/en/2016/06/08/version-bits-miners-faq/
169
170
171Null dummy soft fork
172-------------------
173
174Combined with the segwit soft fork is an additional change that turns a
175long-existing network relay policy into a consensus rule. The
176`OP_CHECKMULTISIG` and `OP_CHECKMULTISIGVERIFY` opcodes consume an extra
177stack element ("dummy element") after signature validation. The dummy
178element is not inspected in any manner, and could be replaced by any
179value without invalidating the script.
180
181Because any value can be used for this dummy element, it's possible for
182a third-party to insert data into other people's transactions, changing
183the transaction's txid (called transaction malleability) and possibly
184causing other problems.
185
186Since Bitcoin Core 0.10.0, nodes have defaulted to only relaying and
187mining transactions whose dummy element was a null value (0x00, also
188called OP_0).  The null dummy soft fork turns this relay rule into a
189consensus rule both for non-segwit transactions and segwit transactions,
190so that this method of mutating transactions is permanently eliminated
191from the network.
192
193Signaling for the null dummy soft fork is done by signaling support
194for segwit, and the null dummy soft fork will activate at the same time
195as segwit.
196
197For more information, please see [BIP147][].
198
199[BIP147]: https://github.com/bitcoin/bips/blob/master/bip-0147.mediawiki
200
201Low-level RPC changes
202---------------------
203
204- `importprunedfunds` only accepts two required arguments. Some versions accept
205  an optional third arg, which was always ignored. Make sure to never pass more
206  than two arguments.
207
208
209Linux ARM builds
210----------------
211
212With the 0.13.0 release, pre-built Linux ARM binaries were added to the set of
213uploaded executables. Additional detail on the ARM architecture targeted by each
214is provided below.
215
216The following extra files can be found in the download directory or torrent:
217
218- `bitcoin-${VERSION}-arm-linux-gnueabihf.tar.gz`: Linux binaries targeting
219  the 32-bit ARMv7-A architecture.
220- `bitcoin-${VERSION}-aarch64-linux-gnu.tar.gz`: Linux binaries targeting
221  the 64-bit ARMv8-A architecture.
222
223ARM builds are still experimental. If you have problems on a certain device or
224Linux distribution combination please report them on the bug tracker, it may be
225possible to resolve them. Note that the device you use must be (backward)
226compatible with the architecture targeted by the binary that you use.
227For example, a Raspberry Pi 2 Model B or Raspberry Pi 3 Model B (in its 32-bit
228execution state) device, can run the 32-bit ARMv7-A targeted binary. However,
229no model of Raspberry Pi 1 device can run either binary because they are all
230ARMv6 architecture devices that are not compatible with ARMv7-A or ARMv8-A.
231
232Note that Android is not considered ARM Linux in this context. The executables
233are not expected to work out of the box on Android.
234
235
2360.13.1 Change log
237=================
238
239Detailed release notes follow. This overview includes changes that affect
240behavior, not code moves, refactors and string updates. For convenience in locating
241the code changes and accompanying discussion, both the pull request and
242git merge commit are mentioned.
243
244### Consensus
245- #8636 `9dfa0c8` Implement NULLDUMMY softfork (BIP147) (jl2012)
246- #8848 `7a34a46` Add NULLDUMMY verify flag in bitcoinconsensus.h (jl2012)
247- #8937 `8b66659` Define start and end time for segwit deployment (sipa)
248
249### RPC and other APIs
250- #8581 `526d2b0` Drop misleading option in importprunedfunds (MarcoFalke)

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/key_io.h

src/logging/categories.h

src/logging/timer.h

src/mapport.h

src/musig.h

src/net_permissions.h

src/netgroup.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/pow.h

src/primitives/block.cpp

src/randomenv.h

src/rest.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/signet.h

src/span.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.