Apr
18

PlaidCTF 2016 – Radioactive (Crypto 275)

We just got this fancy new cryptographic device and it seems to work great… for the most part. But sometimes the values it gives me are wrong. Maybe you could take a look for me. radioactive.tar.bz2 Summary: fault attack on RSA signature (not RSA-CRT)

Mar
14

0CTF 2016 Quals – Equation (Crypto 2 pts)

Here is a RSA private key with its upper part masked. Can your recover the private key and decrypt the file? equation.zip Summary: recovering RSA key from part of the private key.

Mar
13

0CTF 2016 Quals – RSA? (Crypto 2 pts)

It seems easy, right? rsa.zip Tip: openssl rsautl -encrypt -in FLAG -inkey public.pem -pubin -out flag.enc Summary: factoring 300-bit modulus into 3 primes, extracting cube roots.

Mar
07

Boston Key Party CTF 2016 – Feistel (Crypto 5pts)

feistel – 5 – 15 solves : crypto: I just made a brand new cipher! Can you recover the key? 52.86.232.163:32785 feistel.go Summary: slide with a twist attack

Mar
07

Boston Key Party CTF 2016 – GCM (Crypto 9pts)

[8] : gsilvis counting magic – 9 – 4 solves : crypto: Here’s a verification/decryption server: gcm.ctf.bostonkey.party:32768 . Get the GCM MAC key (the thing the server prints out on startup). We’ve given you one valid ciphertext to get you started. It has iv: [102 97 110 116 97 115 116 105 99 32 105… Continue reading »

Mar
07

Boston Key Party CTF 2016 – HMAC-CRC (Crypto 5pts)

[3] : hmac_crc – 5 – 36 solves : crypto: We’re trying a new mac here at BKP—HMAC-CRC. The hmac (with our key) of “zupe zecret” is ‘0xa57d43a032feb286’. What’s the hmac of “BKPCTF”? hmac-task.py Summary: breaking HMAC-CRC (again)

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