Doctor who chalkboard sketch skull in space10/12/2023
We’ve also stocked our newly-expanded bookshop with copies of the DVD. Well, it’s always good to receive positive feedback – not least for an article published seven years ago – and, as it turned out, we were able to put Pete in touch with the author and filmmaker, David Webb, who also happened to have some copies of the DVD.Īll of which reminded us that this year is the sixtieth anniversary of a cave rescue which became a pivotal moment in caving history, the perfect opportunity to retell the tale here. I appreciate this DVD is a few years old now but I wondered if you had any suggestions for how I might be able to locate a copy? Any help would be much appreciated’. Having checked your website, I can’t see it listed there either. I’ve tried to find a copy of the DVD online but have been unable to do so. ‘I’d be interested to learn more about this tragic event and the brave rescue attempts. ‘I recently read an article on your website ,’ said Pete. Not for mountain rescue (the days of calling us out by telegram being long gone) but for information. Late in January, an email found its way into the editor’s inbox. Based on an article written by David in 2007, we look back at how the incident unfolded and its influence on cave rescue. In 2006, David Webb’s film about the tragedy set about correcting some of the myths surrounding the rescue attempt by talking to those who were there. On Sunday, 22 March 1959, Oscar Hackett Neil Moss became jammed while trying to pass down a narrow unexplored tunnel in Stalagmite Chamber – now known as Moss Chamber – in Peak Cavern, one of England’s best known caves with its imposing entrance overlooking Castleton in Derbyshire. The first 4 letters of each word is unique in the list.…sixty years after the tragedy of his death in a Peak District cavern 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. #DOCTOR WHO CHALKBOARD SKETCH SKULL IN SPACE GENERATOR## 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. #DOCTOR WHO CHALKBOARD SKETCH SKULL IN SPACE 64 BITS#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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