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| 1 | Help! I've lost my number! | |
| 2 | ||
| 3 | Recently I've been hearing about all this encryption going around. You know, protecting all your valuable information and such. After hearing about it I was convinced I had to encrypt everything I had, but I seem to have accidentally used some sort of hashing function instead! This number is very important to me and I don't know what I'll do without it. Can you help me find my number? The only thing I have left is this really totally not awesome number. | |
| 4 | ||
| 5 | 108094871378786901565443153186528124897 | |
| 6 | ||
| 7 | I don't even know where to start with a number that big! My number was nowhere near that big; definitely under a trillion. Hopefully a computerphile like you can help me crack it. | |
| 8 | ||
| 9 | --------- | |
| 10 | ||
| 11 | Hello! This is my first raffle and the first time I've made a puzzle like this. Seeing all these cipher puzzles made me want to do something that involved some actual cracking. I don't know if this is too hard, but I've left several hints that will allow someone who understands to solve it in under 20 minutes. Double checking my answer took me under 10 for reference. | |
| 12 | ||
| 13 | ---- | |
| 14 | ||
| 15 | This is how I intended for the puzzle to be solved without any outside hints. | |
| 16 | ||
| 17 | Things you should know from reading the puzzle: | |
| 18 | 1. The secret is a number | |
| 19 | 2. The number is hashed with some hashing function (Think MD5, SHA1, etc) | |
| 20 | 3. The number is less than 1 trillion (1,000,000,000,000) | |
| 21 | ||
| 22 | Clues on how to solve from reading the puzzle: | |
| 23 | 1. Hashes aren't normally represented as a 39 digit base 10 number (Assuming basic knowledge of hashes) | |
| 24 | 2. Computerphile isn't a normal word, should probably look up what it is | |
| 25 | 3. The use of the word "crack" in reference to how to solve it | |
| 26 | ||
| 27 | Steps to take: | |
| 28 | 1. Convert the base 10 number into base 16 which is how MD5, SHA1, and most basic hashes are represented | |
| 29 | This gives 515250A15EB1B03D8374C55542EB5FE1 | |
| 30 | 2. Search Computerphile and get to the Computerphile channel on Youtube | |
| 31 | 3. Look for a video on password cracking (which is what this problem basically is) | |
| 32 | 4. Find this video: https://www.youtube.com/watch?v=7U-RbOKanYs | |
| 33 | In the video he mentions hashcat, a program that can crack hashes | |
| 34 | 5. From watching his usage in the video you should know these things | |
| 35 | 1. You can use ?l to search for a letter and ?d for a number (6:42 - 8:40) | |
| 36 | 2. Passwords that are 9 characters or longer get hard even for "Beast" | |
| 37 | 3. Cracking a 12 character password will not be possible on a normal computer. | |
| 38 | 6. Although 12 characters should be impossible the search space can be reduced | |
| 39 | If we use the entire ascii set, that's 26^12 * 26^12 * 33^12 * 10^12 possibilities | |
| 40 | Multiplies out to 15 vigintillion (that's a number?) | |
| 41 | 15,188,945,710,982,676,042,132,050,611,607,315,442,476,887,295,655,936,000,000,000,000 | |
| 42 | This would take Beast around 12 duodecillion years to crack (12 * 10^40) if I did my math correctly | |
| 43 | ||
| 44 | But we know the following things: | |
| 45 | 1. We know that the secret is a number that is under a trillion (1 to 12 digits) | |
| 46 | 2. We know we can use ?d to search for only digits | |
| 47 | ||
| 48 | Therefore, if we use only ?d, we reduce our search space to only a trillion (10^12) | |
| 49 | This makes cracking this hash possible in less than the lifetime of the universe | |
| 50 | 7. After watching the video and finding the search space we need to use the following hashcat command: | |
| 51 | hashcat -a 3 hash.txt ?d?d?d?d?d?d?d?d?d?d?d?d | |
| 52 | -a 3 is bruteforce | |
| 53 | ?d means looking for a digits and there are 12 at most | |
| 54 | This gives us the following output: https://i.imgur.com/eCOzuYd.png | |
| 55 | ||
| 56 | After all this you should get 548783719357 as the secret number. | |
| 57 | ||
| 58 | Afterword: | |
| 59 | I'm sorry this was so hard. It was intended to be something that you couldn't just google or throw into an online cracker, but it seems only a very small handful of people actually want to go further than that. If I do another puzzle raffle it will be along the same vein as this one, but I'll try to avoid the use of an external program (videos and info will be fair game). It will still hopefully be extremely challenging though. Knowing puzzle rafflers a bit better now I might cap it at 5-10 enteries since 100 was way more than even attempted this one. I also want people to feel like they have a chance to win after doing something that's extremely time consuming or difficult. | |
| 60 | ||
| 61 | Also congratulations to Powmonkey for being the first to solve it after 12 and a half hours. I'm not sure if they did it the way I described above, but I'm still glad they were able to get it and prove it's not impossible. |
