The American Society for Suicide Prevention and the National Institute of Health have resources if you or someone you know if facing depression or contemplating suicide. It’s a good resource to find out more about some of the philosophers that Nora refers to as she tries out different lives. The Internet Encyclopedia of Philosophy shares peer-reviewed information that is understandable to a lay person. I recommend reading the book before the guide. Note that this guide, like all of the guides, may contain spoilers. While I read this book in the winter, I can imagine reading it and contemplating life in a summer setting such as sitting atop a mountain peak with a backpacking partner or relaxing by river with a buddy or staring into a campfire with a good friend. This quick-to-read novel gives you a chance to philosophize about your life, the path not taken and the meaning of life. While the outcome is predictable, the forays into philosophy are relatable and offer good jumping off points whether to general philosophical ideas or to personal introspection. The dialogue flows naturally and the characters come to life. The first 4 letters of each word is unique in the list.The Midnight Library was my introduction to Matt Haig and I thoroughly enjoy his writing. The words in a mnemonic sentence come from a fixed list of 2048 words ( specified by BIP39). Create checksum require 'digest' size = entropy.length / 32 # number of bits to take from hash of entropy (1 bit checksum for every 32 bits entropy) sha256 = Digest:: SHA256.digest(.pack( "B*")) # hash of entropy (in raw binary) checksum = sha256.unpack( "B*").join # get desired number of bits puts "checksum: # remove new lines from end of each word # Convert mnemonic to binary string binary = "" mnemonic.split( " ").each do |word| i = wordlist.index(word) # get word index number in wordlist bin = i.to_s( 2).rjust( 11, "0") # convert index number to an 11-bit number binary true Note: A mnemonic phrase is usually between 12 and 24 words. Tip: By adding 1 bit of checksum to every 32 bits of entropy, we will always end up with a multiple of 33 bits, which we can split up in to equal 11-bit chunks. Tip: An 11-bit number can hold a decimal number between 0-2047 (which is why there are 2048 words in the wordlist). Next we split this in to groups of 11 bits, convert these to decimal numbers, and use those numbers to select the corresponding words. We then take 1 bit of that hash for every 32 bits of entropy, and add it to the end of our entropy. This checksum is created by hashing the entropy through SHA256, which gives us a unique fingerprint for our entropy. Now that we’ve got our entropy we can encode it in to words.įirst of all, we add a checksum to our entropy to help detect errors (making the final sentence more user-friendly). Do not use your programming language’s default “random” function, as the numbers it produces are not random enough for cryptography. # For real world use, you should generate 128 to 256 bits (in a multiple of 32 bits).Ĭaution: Always use a secure random number generator for you entropy. Generate Entropy # - require 'securerandom' # library for generating bytes of entropy bytes = SecureRandom.random_bytes( 16) # 16 bytes = 128 bits (1 byte = 8 bits) entropy = bytes.unpack( "B*").join # convert bytes to a string of bits (base2) puts entropy #=> "1010110111011000110010010010111001001011001001010110001011100001" # Note: For the purposes of the examples on this page, I have actually generated 64 bits of entropy.
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