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nadams 2017-04-24 08:10:10 -07:00
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@ -178,7 +178,7 @@ Mnemonic words are generated automatically by the wallet, using a standardized p
image::images/mbc2_0506.png["Generating entropy and encoding as mnemonic words"]
<<table_4-5>> shows the relationship between the size of entropy data and the length of mnemonic codes in words.
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[[table_4-5]]
.Mnemonic codes: entropy and word length
[options="header"]
@ -202,7 +202,7 @@ The process described in steps 7 through 9 continues from the process described
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<ol start="7">
<li>The first parameter to the PBKDF2 key-stretching function is the _mnemonic_ produced from step 6 in <a data-type="xref" href="#generating_mnemonic_words">#generating_mnemonic_words</a>.</li>
<li>The first parameter to the PBKDF2 key-stretching function is the <em>mnemonic</em> produced from step 6 in <a data-type="xref" href="#generating_mnemonic_words">#generating_mnemonic_words</a>.</li>
<li>The second parameter to the PBKDF2 key-stretching function is a <em>salt</em>. The salt is composed of the string constant "<code>mnemonic</code>" concatenated with an optional user-supplied passphrase string.</li>
<li>PBKDF2 stretches the mnemonic and salt parameters using 2048 rounds of hashing with the HMAC-SHA512 algorithm, producing a 512-bit value as its final output. That 512-bit value is the seed.</li>
</ol>
@ -216,7 +216,7 @@ image::images/mbc2_0507.png["From mnemonic to seed"]
The key-stretching function, with its 2048 rounds of hashing, is a very effective protection against brute-force attacks against the mnemonic or the passphrase. It makes it extremely costly (in computation) to try more than a few thousand passphrase and mnemonic combinations, while the number of possible derived seeds is vast (2^512^).
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Tables pass:[<a data-type="xref" href="#mnemonic_128_no_pass" data-xrefstyle="select: labelnumber">#mnemonic_128_no_pass</a>], pass:[<a data-type="xref" href="#mnemonic_128_w_pass" data-xrefstyle="select: labelnumber">#mnemonic_128_w_pass</a>], and pass:[<a data-type="xref" href="#mnemonic_256_no_pass-7" data-xrefstyle="select: labelnumber">#mnemonic_256_no_pass</a>] show some examples of mnemonic codes and the seeds they produce (without any passphrase).
Tables pass:[<a data-type="xref" href="#mnemonic_128_no_pass" data-xrefstyle="select: labelnumber">#mnemonic_128_no_pass</a>], pass:[<a data-type="xref" href="#mnemonic_128_w_pass" data-xrefstyle="select: labelnumber">#mnemonic_128_w_pass</a>], and pass:[<a data-type="xref" href="#mnemonic_256_no_pass" data-xrefstyle="select: labelnumber">#mnemonic_256_no_pass</a>] show some examples of mnemonic codes and the seeds they produce (without any passphrase).
[[mnemonic_128_no_pass]]
.128-bit entropy mnemonic code, no passphrase, resulting seed