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Just describe or survey systems that exist today- not how to write a wallet (it is not normative)
Article on digital wallets: https://www.forbes.com/sites/vipinbharathan/2020/05/24/digital-wallets-are-the-killer-app-for-blockchains/#73914e2f6552
HD Wallet - BIP 32 or - othe KD standards
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