Challenge Description
As the description suggests, this is an RSA cryptography challenge.
Contents of values file
After downloading the file provided using wget <link>, we can run cat values. We are given the values c, n and e.
How RSA works
RSA is an example of public-key cryptography, otherwise known as asymmetric cryptography. This means that we need the private key
dto decrypt the string.For more information about the math behind RSA, check out https://brilliant.org/wiki/rsa-encryption/.
RSA Decryption
We can feed the 3 values above and decrypt c using dcode.fr’s RSA cipher decoder. It computes the values of p, q and subsequently d to decrypt the message.
Flag
picoCTF{sma11_N_n0_g0od_45369387}