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16 KiB
Markdown
443 lines
16 KiB
Markdown
---
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# This file is licensed under the MIT License (MIT) available on
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# http://opensource.org/licenses/MIT.
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id: bitcoin-core-privacy
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layout: base-core
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lang: en
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columns: 1
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title: Privacy - Bitcoin Core Features
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breadcrumbs:
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- bitcoin
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- bcc
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- bcc features
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- Privacy
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third_party_privacy:
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## Alphabetical order
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- name: "Bitcoin Core"
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css_class: bitcoin_core
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group: default-show
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tracks_real_names: "no"
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knows_your_bitcoin_balance: "no"
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susceptible_to_taint_analysis: "yes"
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tracks_payments: "no"
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tracks_amounts: "no"
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tracks_ip_addresses: "no"
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- name: "BitGo"
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css_class: bitcoin_go
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group: not-displayed
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tracks_real_names: "no"
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knows_your_bitcoin_balance: "yes"
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susceptible_to_taint_analysis: "yes"
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tracks_payments: "yes"
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tracks_amounts: "yes"
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tracks_ip_addresses: "yes"
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- name: Blockchain.info
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css_class: blockchain_info
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group: not-displayed
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tracks_real_names: "no"
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knows_your_bitcoin_balance: "yes"
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susceptible_to_taint_analysis: "yes"
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tracks_payments: "yes"
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tracks_amounts: "yes"
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tracks_ip_addresses: "yes"
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- name: Coinbase
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css_class: coinbase
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group: default-show
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tracks_real_names: "yes"
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knows_your_bitcoin_balance: "yes"
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susceptible_to_taint_analysis: "no"
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tracks_payments: "yes"
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tracks_amounts: "yes"
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tracks_ip_addresses: "yes"
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- name: GreenAddress
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css_class: greenaddress
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group: not-displayed
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tracks_real_names: "no"
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knows_your_bitcoin_balance: "yes"
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susceptible_to_taint_analysis: "yes"
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tracks_payments: "yes"
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tracks_amounts: "yes"
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tracks_ip_addresses: "yes"
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---
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# Bitcoin Core's Excellent Privacy
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{:.not-displayed}
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{% include bitcoin-core/download-bitcoin-core.html %}
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> What if every time you spent or received cash, all the transaction
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> details were published to your Twitter or Facebook feed for all your
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> friends to see? You probably wouldn't want to use cash any more.
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Every confirmed Bitcoin transaction is published to the block chain
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where anyone can see it. So **why do people still use Bitcoin?** And why
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do many of them believe that Bitcoin is a private way of sending money?
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One reason is that Bitcoin Core and some other Bitcoin software tries to
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avoid associating your real-world identity with the transactions you
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make. The difference looks like this:
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The second type of transaction (a pseudonymous transaction) only provides
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practical privacy if nobody can figure out that "5a35b" is really Alice.
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It's up to your wallet to prevent anyone from making that connection.
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See below for how Bitcoin Core's privacy compares to other wallets.
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## No Sign-Up Required
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Third-party Bitcoin services can both increase and decrease your
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privacy. They can increase it by mixing your transactions with those of
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other users; they can decrease it by tracking your activity and directly
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associating it with your real name or other identifying information.
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<p class="center service-choose">
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<a>Click an entry below to show it:</a>
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{% for service in page.third_party_privacy %}
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{% if service.name != 'Bitcoin Core' %}
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<button
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{% if service.group == "default-show" %}
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class="js showcolumn active"
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{% else %}
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class="js showcolumn"
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{% endif %}
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id="{{service.css_class}}"
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>{{service.name}}</button>
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{% endif %}
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{% endfor %}
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</p>
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<table class="privacy-comparison">
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{% comment %}
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<!-- Don't overdo it! Limit table to a total of seven content rows, with a
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maximum of five content rows in each category. -->
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{% endcomment %}
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<tr>
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<th markdown="span" colspan="99">Who knows your information? **Just you**{:.fggreen} or also a **service provider?**{:.fgred}</th>
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</tr>
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<tr>
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<th></th>
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{% for service in page.third_party_privacy %}
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{% if service.name %}
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<th class="{{service.css_class}} {{service.group}}">{{service.name}}</th>
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{% else %}
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{% die "Some service doesn't have a name" %}
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{% endif %}
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{% endfor %}
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</tr>
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<tr>
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<td>Your real name</td>
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{% for service in page.third_party_privacy %}
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{% case service.tracks_real_names %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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<tr>
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<td>Your bitcoin balance</td>
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{% for service in page.third_party_privacy %}
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{% case service.knows_your_bitcoin_balance %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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<tr>
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<td>Who you pay, and/or who pays you (in some cases)</td>
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{% for service in page.third_party_privacy %}
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{% case service.tracks_payments %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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<tr>
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<td>How much you spend and/or receive</td>
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{% for service in page.third_party_privacy %}
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{% case service.tracks_amounts %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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<tr>
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<td>The IP address your connection came from</td>
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{% for service in page.third_party_privacy %}
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{% case service.tracks_ip_addresses %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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<tr class="empty"></tr>
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<tr>
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<th markdown="span" colspan="99">Who can guess your information? **Just you**{:.fggreen} or also **people
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you trade with?**{:.fgred}</th>
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</tr>
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<tr>
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<th></th>
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{% for service in page.third_party_privacy %}
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{% if service.name %}
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<th class="{{service.css_class}} {{service.group}}">{{service.name}}</th>
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{% else %}
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{% die "Some service doesn't have a name" %}
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{% endif %}
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{% endfor %}
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</tr>
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<tr>
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<td>Other transactions you made or received</td>
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{% for service in page.third_party_privacy %}
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{% case service.susceptible_to_taint_analysis %}
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{% when "yes" %}
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<td class="bgred {{service.css_class}} {{service.group}}"></td>
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{% when "no" %}
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<td class="bggreen {{service.css_class}} {{service.group}}"></td>
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{% when "maybe" %}
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<td class="bgyellow {{service.css_class}} {{service.group}}"></td>
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{% else %}
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{% die "missing service information" %}
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{% endcase %}
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{% endfor %}
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</tr>
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</table>
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## Perfect Privacy for Received Transactions
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There are {{site.text.total_tx_count_in_millions}} million transactions on the Bitcoin block
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chain. How do you find which ones pay you? Here are some common
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options:
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<table class="received_transactions">
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<tr>
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<td class="center" markdown="span">**Ask bankers**{:.fgred}<br
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>They'll monitor your every transaction<br><br
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><button class="popup js" data-container="bitcoin_bank_receiving">Bitcoin banks</button></td>
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<td class="center" markdown="span">**Ask random nodes**{:.fgred}<br
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>Some of which sell your data<br><br
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><button class="popup js" data-container="bloom_filter_receiving">P2P lightweight wallets</button></td>
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</tr>
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<tr>
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<td class="center" markdown="span">**Ask a free service**{:.fgred}<br
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>(Actually, some do care about privacy)<br><br
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><button class="popup js" data-container="electrum_style_receiving">Client lightweight wallets</button></td>
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<td class="center" markdown="span">**Get all {{site.text.total_tx_count_in_millions}} million transactions**{:.fggreen}<br
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>For **perfect** receiving privacy<br><br
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>**Bitcoin Core**</td>
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</tr>
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</table>
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Bitcoin Core downloads all {{site.text.total_tx_count_in_millions}} million transactions on the Bitcoin block
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chain and processes them to find which transactions pay you.
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This currently takes about {{site.text.typical_ibd_time_in_hours}} hours the first time
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you start Bitcoin Core and about {{site.text.typical_144_block_catchup_time_in_minutes}}
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minutes a day to keep updated, but it gives you what scientists call
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**<button class="popup js" data-container="information_theoretic_privacy">information-theoretic (perfect) privacy</button>**
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against eavesdroppers for received transactions.
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## Strong Privacy for Sent Transactions
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To put a transaction on the block chain, you must send it publicly---but
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how you send it can make a big difference.
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**Can you guess who made which transactions?** Nearly all peer-to-peer
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lightweight clients today make no attempt to obscure their sent
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transactions. They simply send them to some or all of their peers.
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Bitcoin Core does much better. By default, it relays transactions for
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all of its peers---thousands of separate transactions a day under common
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conditions---which allows it both [support the peer-to-peer network][bcc
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network support] and confuse anti-privacy organizations that try to
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track your transactions.
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## Tor Compatible
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The Tor anonymity network helps disassociate your online activity from
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your IP address (which is often closely associated with your real name).
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This significantly increases your ability to confound anti-privacy
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organizations.
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Once you [setup Tor][], using it with Bitcoin Core is [easy][bcc
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tor]. If you also [setup a Tor hidden service][bcc tor hs], you will
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be able to [connect mobile clients][bcc user interface lightweight]
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to your Bitcoin Core full node for increased security and privacy
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wherever you go.
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{:.right-hanger}
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[Start using Tor today <span class="fa fa-external-link-square"></span>][setup tor]
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## Decentralized Peer Discovery
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The first time any Bitcoin program connects to the peer-to-peer network,
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it has to ask a centralized authority for a list of recommended peers.
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Once the program gets on the network, it can ask its peers for more
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recommendations in a fully decentralized way---but
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<button class="popup js" data-container="spv_decentralized_peer">most</button>
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lightweight wallets don't bother.
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<table class="center_header">
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<tr>
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<th class="fgred">P2P Lightweight Wallets</th>
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<th class="fggreen">Bitcoin Core</th>
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</tr>
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<tr>
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<td>Asks the same centralized services every time program is
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restarted. This can be faster.</td>
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<td>Uses the peer-to-peer network to independently discover new
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peers. Uses found peers on restart.</td>
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</tr>
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</table>
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This allows the centralized authority to connect lightweight wallets to
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dishonest peers that can **completely destroy lightweight transaction
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privacy.** Those dishonest peers can work with dishonest miners to
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**weaken lightweight security too.**
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Bitcoin Core prefers decentralized peer discovery, so after the first
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time it starts, it no longer has to trust the centralized authority.
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Isn't that worth occasionally starting up a few seconds slower?
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<br class="clear big">
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<div class="prevnext">
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<span markdown="1">**Previous Feature**<br>[Validation][bcc validation]</span>
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<span markdown="1">**Next feature**<br>[Requirements][bcc requirements]</span>
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</div>
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<br class="clear">
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<div class="not-displayed">
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<div id="bitcoin_bank_receiving" title="Bitcoin Bank Receiving Privacy" markdown="block">
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When you receive bitcoins to a Bitcoin bank, the money is sent to one of
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the bank's addresses---not your own---which can give you excellent
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privacy against random strangers.
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However, the bank knows you received the transaction and they can likely
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also see any information you associate with the transaction, such as the
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sender's name or another note you attach to the transaction.
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The bank may also be required by law to disclose information about your
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account. They can also sell your information or have a hacker steal your
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information.
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</div>
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<div id="bloom_filter_receiving" title="Bloom Filter Privacy" markdown="block">
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By only asking for payments related to your wallet, plus maybe a few
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others as bloom filter camouflage, lightweight wallets may reveal who you
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paid, who paid you, and what your current bitcoin balance is.
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> A [2014 study of lightweight clients][study of SPV privacy over tor]
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> said, "Our results show that bloom filters incur serious privacy
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> leakage in existing SPV client implementations [...] such an
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> information leakage might severely harm the privacy of users" **Nearly
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> all lightweight clients are still vulnerable today.**
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**Learn more:** ["Lying consistently is hard"][lying consistently is hard]
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</div>
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<div id="electrum_style_receiving" title="Client Lightweight Wallet Receiving Privacy" markdown="block">
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Some lightweight wallets don't connect to the Bitcoin peer-to-peer (P2P)
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network. Instead, they make a (usually secure) connection to a single
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server that provides block chain data.
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The wallet tells the server all of its addresses, and the server replies
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with all of the transactions that belong to the wallet. This explicitly
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reveals all of your addresses, which is bad for your privacy---but it
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only gives that information to one server, as long as you don't change
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servers later.
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The server can, of course, give away your information and further
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reduce your privacy. However, as of
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{{site.text.assertion_month | date: "%B %Y"}}, most of these types of
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servers are run by volunteers who likely want to help protect your
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privacy, so this model can be more private than bank wallets or P2P
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lightweight wallets.
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</div>
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<div id="spv_decentralized_peer" title="P2P Decentralized Peer Discovery" markdown="block">
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The following P2P lightweight wallets use decentralized peer discovery
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by default.
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- BreadWallet
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If you know of another compliant lightweight wallet, please [tell us
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about it][docs issue].
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</div>
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<div id="information_theoretic_privacy" title="Information-Theoretic Privacy" markdown="block">
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Information-theoretic privacy means that the privacy can't be broken even
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if an attacker has unlimited computing resources.
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**Learn more:** [Information theoretic security][] (Wikipedia)
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</div>
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</div>
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{% include references.md %}
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