Polkadot
[https://polkadot-java.github.io/]
[https://github.com/polkadot-java/api/]
Transaction Construction and Signing
[https://wiki.polkadot.network/docs/ru/build-transaction-construction]
sr25519
[https://wiki.polkadot.network/docs/en/learn-keys]
Polkadot apps
[https://polkadot.js.org/apps/#/accounts]
Substrate
Developer hub
[https://substrate.dev/en/]
Cryptography (ECDSA, Ed25519, SR25519)
[https://substrate.dev/docs/en/knowledgebase/advanced/cryptography]
Hyperledger
[https://wiki.hyperledger.org/display/iroha]
[https://github.com/hyperledger/iroha-java]
Mnemonic generation
[https://github.com/NovaCrypto/BIP39]
Web3j
Lightweight Java and Android library for integration with Ethereum clients
[https://github.com/web3j/web3j]