1.2.0

BitBlocks Core version 1.2.0 is now available from:

https://github.com/BitBlocksProject/BitBlocks/releases

This is a new minor version release. It moves consensus signature
verification from OpenSSL to libsecp256k1, hardens proof-of-stake validation
against fake stake attacks, improves peer discovery, and updates the GUI and
the build dependencies. Upgrading is strongly recommended for all users.

Please report bugs using the issue tracker at github:

https://github.com/BitBlocksProject/BitBlocks/issues

How to Upgrade

Shut down the old wallet completely, then install the new version over it
(Windows) or replace the binaries (Linux). Your wallet and block data are kept.
Always keep a backup of wallet.dat before upgrading.

No reindex is required.

Compatibility

Release binaries are provided for 64-bit Linux (x86_64) and 64-bit Windows.

BitBlocks Core should also build and run on most other Unix-like systems but
is not frequently tested on them.

This release does not change the consensus rules or the protocol version
(71001). 1.2.0 nodes stay fully compatible with 1.1.x nodes on the network.

Notable Changes

Consensus signature verification uses libsecp256k1

Signatures were previously verified with whichever OpenSSL the binary was
linked against. OpenSSL versions disagree on some non-canonical signature
encodings, so two nodes built with different OpenSSL versions could disagree
about whether a block is valid. Verification now uses the libsecp256k1
library vendored in the source tree, which is the same on every build.

This is not a consensus rule change and has no activation height: both
verifiers accept the same signatures on the existing chain. The node now logs
which verifier it uses at startup (Signature verification: libsecp256k1).
The OpenSSL path is kept only for testing and can be selected at build time
with --enable-openssl-ecdsa. See doc/secp256k1-migration.md for the full
analysis.

Fake stake mitigation

Proof-of-stake validation has been hardened against peers sending invalid or
duplicated stake blocks:

• The coinstake prevout index is now validated before use.
• Peers sending proof-of-stake blocks with invalid stake signatures, or blocks
  that fail other checks the peer could verify itself, now receive a DoS
  score and are eventually banned. Failures that depend on local state (for
  example, still syncing) are never scored, so honest peers are not banned.
• Two different blocks that reuse the same stake at the same time are dropped
  locally. This check is applied only to blocks received from the network,
  never during -reindex or -loadblock.

Peer discovery

• The mainnet DNS seeds and fixed seeds have been updated.
• The node now keeps querying the DNS seeds while it has fewer than two
  outbound peers, instead of querying only once at startup.
• If there is still no outbound peer after 60 seconds, the node connects
  directly to the seed nodes as a fallback.

This fixes nodes that previously stayed at zero connections after a failed
first lookup.

Mainnet checkpoints

Checkpoints were added at blocks 4000000 and 4100000.

Wallet

• On startup, the wallet now always rescans from its last known block.
  Previously it skipped the rescan when it was fewer than 10 blocks behind,
  which could miss transactions after restoring a backup.
• Wallet rescans no longer freeze the GUI, and a crash caused by a null
  dereference during rescan has been fixed.

GUI

• Refreshed wallet artwork, navigation icons, and splash screen.
• The layout is optimized for 1366x768 displays.
• High-DPI scaling is enabled.
• The Inter font is now bundled, so the GUI looks the same on every system.
• The splash screen and the About dialog show the exact build version.
• Fixed the "last month" transaction filter in January.

Build system and dependencies

• Qt was updated to 5.15.5, Boost to 1.81.0, and OpenSSL to 3.0.16.
• BIP70 payment requests are now optional and disabled by default
  (--enable-bip70). bitblocks: URIs keep working without it.
• The code builds with modern compilers and current versions of Boost.Asio,
  OpenSSL, Qt 5, and LevelDB.
• Added release packaging scripts for Linux and Windows
  (contrib/release/).
• Generated autotools files are no longer tracked in the repository.
  Run ./autogen.sh before ./configure when building from source.

1.2.0 Change log

Detailed release notes follow. This overview includes changes that affect
behavior, not code moves, refactors and string updates.

Consensus

• 88ceca4 consensus: use libsecp256k1 for signature verification
• e7187fd script: harden secp256k1 verification
• 0735a8c key: update libsecp256k1 API and initialize verification
• 36e3c07 kernel: validate coinstake prevout index
• 6f15fe6 main: score invalid proof-of-stake blocks
• 03298d5 main: score invalid stake signatures
• 9624f11 main: reject duplicate network stakes
• 790495e main: remove unused stake cache

Network

• 3e95fad Fix mainnet DNS and fixed seeds
• 7bf3a9f net: retry DNS seeds and connect to seed fallbacks
• 006c1a3 chainparams: update mainnet checkpoints

Wallet

• 080b669 init: always rescan from best block
• 2e67b66 wallet: fix rescan responsiveness and null dereference

GUI

• 86943e5 qt: refresh wallet artwork and navigation icons
• 1b46783 qt: optimize wallet layout for 1366x768 displays
• 49a1753 qt: embed branded logo in splash background
• 13237c2 qt: enable high-DPI scaling
• 9ed85e8 qt: bundle Inter font
• 78e3efd qt: show build version in UI
• 2f29366 qt: load stylesheet as UTF-8
• 5afc2ca qt: remove startup fade-in
• b6db0d4 qt: remove page transition opacity effect
• 6bb1d4f qt: fix January last-month filter
• 9fd2050 qt: keep URI handling without BIP70

Build System

• 4f62309 qt: update depends to Qt 5.15 and make BIP70 optional
• f332cfb depends: update Boost and OpenSSL
• e2ce97b depends: update OpenSSL and fix miniupnpc cross-build
• 565add1 depends: build Qt XCB platform with depends libraries
• 139fef0 build: link static Qt XCB plugin
• 878f95d depends: add rpath-link for X11 libraries
• c0dcaa6 build: detect Qt 5.8+ platform support libraries
• 5d2e19c build: pass configure defines to moc
• 950d362 build: fix secp256k1 build and tests
• 63d1636 Update for modern C++ compatibility
• 8c7be4a share: fix NSIS out-of-tree builds
• a7d07de contrib: add Linux and Windows release packaging
• 47d627b build: bump version to 1.2.0
• 3a9909a build: stop tracking generated files

Tests

• 8a48d30 test: scan both signature verifiers

Documentation

• d51c073 doc: document verifier migration results
• 4c18f29 Update build DOC to use PIVX PPA for Berkeley DB 4.8