diff --git a/classical_crypto.html b/classical_crypto.html index 1d2e29e..ecd31eb 100644 --- a/classical_crypto.html +++ b/classical_crypto.html @@ -38,6 +38,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/credits.html b/credits.html index 47e8650..eecdec1 100644 --- a/credits.html +++ b/credits.html @@ -38,6 +38,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/el_gamal_encryption.html b/el_gamal_encryption.html index 29aea8b..dd96bc6 100644 --- a/el_gamal_encryption.html +++ b/el_gamal_encryption.html @@ -41,6 +41,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/exercise_five.html b/exercise_five.html index e0d6ad4..94d5991 100644 --- a/exercise_five.html +++ b/exercise_five.html @@ -41,6 +41,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/exercise_four.html b/exercise_four.html index 465842d..e7a174d 100644 --- a/exercise_four.html +++ b/exercise_four.html @@ -41,6 +41,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/exercise_one.html b/exercise_one.html index d651d3f..dea65b3 100644 --- a/exercise_one.html +++ b/exercise_one.html @@ -41,6 +41,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/exercise_three.html b/exercise_three.html index cc29a45..1885d62 100644 --- a/exercise_three.html +++ b/exercise_three.html @@ -41,6 +41,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/exercise_three_a.html b/exercise_three_a.html new file mode 100644 index 0000000..f6b553c --- /dev/null +++ b/exercise_three_a.html @@ -0,0 +1,184 @@ + + + + Crypto Exercises + + + + + + +
    + + + + + + +
    + Llcipher logo + +

    Cryptography Challenges

    +     		+ +
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    +

    RSA Challenge Three (a): RSA Modulus Reuse

    +
    +

    The Problem: Given two RSA ciphertexts of the same message encrypted with the same modulus but different public keys, recover the plaintext.

    +
    +
    +

    + Awfulland and Badland keep making strange choices with their keys - both of them are using the same modulus, even though their public keys are different. + Horridland has formed a new attack plan, and is sending an encrypted copy of the plan to Awfulland and Badland. + You've gotten a copy of both encrypted messages: +

    +
      +
    • Awfulland's message, encrypted as cA = + meA mod N (using Awfulland's public exponent + eA), and
      • +
    • Badland's message, encrypted as cB = meB + mod N (using Badland's public exponent eB).
      • +
    +

    Use the fact that both copies of the message are encrypted using the + same modulus to figure out what the evil plot is.

    + +

    For this exercise, use the following values:

    + + + + + + + + + + + + + + + + + + + + + + + + + +
    NameValue
    Common modulus:
    153380639740849
    Ciphertext #1
    106230071531067
    Exponent #1
    1745
    Ciphertext #2
    51206346831694
    Exponent #2
    57
    + +
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    + + + +     		+ +
    +
    + + + + diff --git a/exercise_two.html b/exercise_two.html index 746dc9e..db36e33 100644 --- a/exercise_two.html +++ b/exercise_two.html @@ -42,6 +42,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/index.html b/index.html index aac2d38..482e1ab 100644 --- a/index.html +++ b/index.html @@ -38,6 +38,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/references.html b/references.html index f0913de..9bc4dbf 100644 --- a/references.html +++ b/references.html @@ -38,6 +38,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge
    • diff --git a/rsa_encryption.html b/rsa_encryption.html index 158b0c6..e49a7ed 100644 --- a/rsa_encryption.html +++ b/rsa_encryption.html @@ -38,6 +38,7 @@
  • RSA Challenge One
  • RSA Challenge Two
  • RSA Challenge Three
    • +
  • RSA Challenge Three (a)
  • RSA Challenge Four
  • El Gamal Challenge