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Given (n=989,e=853) Find C=? Cipher value, c=m^e modn, m=c^d mod ϕ(n), other way around decipher it, given c=953 find m=? where m=c^d mod ϕ(n), and d=e^-1 mod ϕ(n), problem is the numbers are so large unless i use a program to give me modulus directly in pc hard to compute using some method to breakRead more

I have just performed a test via SSLlabs.com and I’m apparently supporting some weaker ciphers. I’ve managed to improve several settings (like CAA), but I’m getting stuck at the ciphers. I’ve been looking around a bit, but can’t really find a method to determine which can be disabled, and which should remain allowed. Is thereRead more

I have asked this question on math.stackexchange.com but received no response; hoping someone on here can help. Suppose a function $ f$ , representing what I call a “dynamic transposition cipher” taking one string of text $ str$ as input, is defined so that it outputs another string of text $ res$ which is theRead more

For example: Julius Caesar protected his confidential information by encrypting it in a cipher. Caesar’s cipher rotated every letter in a string by a fixed number, K, making it unreadable by his enemies. Given a string,S , and a number,K , encrypt S. Note: The cipher only encrypts letters; symbols, such as -, remain unencrypted.Read more

I’m a C beginner. I was learning about getopt to parse command line options and I decided to write this small XOR cipher program for files. It acts as a “UNIX filter” (I guess) since default input and output are stdin and stdout. It can generate a random key file from /dev/urandom if the providedRead more