λ   KNOWLEDGE AREA

Cryptography

Find the assumptions behind ciphers, protocols, and proofs.

12 topics

Cryptoadvanced

CBC padding oracles and distinguishing error channels

A padding oracle reveals whether decrypted plaintext has syntactically valid padding.

padding-oraclescrypto
Cryptointermediate

ECB, CBC, and CTR: recognizing mode-specific structure

Block-cipher modes define how fixed-size transformations process longer messages.

block-modescrypto
Cryptofoundation

Encoding, compression, hashes, and encryption triage

A high-entropy blob can be ciphertext, compressed data, a serialized structure, or random bytes.

encoding-versus-encryptioncrypto
Cryptointermediate

Hash functions, MACs, and length-extension boundaries

A cryptographic hash does not authenticate its input without a secret-dependent construction.

hashes-and-macscrypto
Cryptoadvanced

Integer polynomial shares leak the constant term

Distinguish integer arithmetic from finite-field secret sharing and measure residue leakage under query bounds.

secret-sharingpolynomialcrt
Cryptointermediate

Modular inverses, CRT, and order checks

Many cryptographic reductions turn observations into congruences.

modular-arithmeticcrypto
Cryptoadvanced

Recover reused DH exponents across groups

Combine independent small-subgroup residues while tracking generator order and the remaining exponent interval.

diffie-hellmanpohlig-hellmancrt
Cryptoadvanced

Recover RSA factors from a leaked CRT exponent

Parse structured key fragments and use the small multiplier behind a reduced RSA exponent.

rsapemder
Cryptointermediate

RSA arithmetic and small-parameter failure modes

RSA security relies on the structure and size of the modulus, correct exponents, and secure message encoding.

rsa-arithmeticcrypto
Cryptoadvanced

Signature nonce reuse and scalar recovery

DSA-style signatures combine a message hash, a private scalar, and a per-signature nonce.

signature-nonce-reusecrypto
Cryptoadvanced

Special Jacobian orders unlock scalar inversion

Recognize special curve and prime families while separating curve point counts from Jacobian group orders.

hyperellipticjacobiangroup-order
Cryptointermediate

XOR and reused stream-cipher keystreams

An XOR stream cipher combines plaintext with a keystream.

xor-keystream-reusecrypto