We show that the Winternitz one-time signature scheme is existentially unforgeable under adaptive chosen message attacks when instantiated with a family of pseudo random functions. Compared to previous results, which require a collision resistant hash function, our result provides significantly smaller signatures at the same security level. We also consider security in the strong sense and show that the Winternitz one-time signature scheme is strongly unforgeable assuming additional properties of the pseudo random function. In this context we formally define several key-based security notions for function families and investigate their relation to pseudorandomness. All our reductions are exact and in the standard model and can directly be used to estimate the output length of the hash function required to meet a certain security level.

Hummingbird-2 is an encryption algorithm with a 128-bit secret key and a 64-bit initialization vector. Hummingbird-2 optionally produces an authentication tag for each message processed. Like it’s predecessor Hummingbird-1, Hummingbird-2 has been targeted for low-end microcontrollers and for hardware implementation in light-weight devices such as RFID tags and wireless sensors.

Discussion of limb scheduling

New side channel attack on AES which can break OpenSSL and similar AES implementations in realtime by taking advantage of a weakness in the Linux completely fair scheduler.

IACR used this in the recent election

ECDSA signature scheme over a twisted Edwards curve birationally equivalent to "Curve25519" curve.

Korean block cipher

Describes a trick to use CRT for checking RSA private key operations (normally you use the public operation)

Cross reference of crypto RFCs and I-Ds.

A technique for encrypting an arbitrary set onto itself (for instance from valid CC numbers to valid CC numbers).

Turns out that ~100 signature/message pairs with only the 3 low bits of the random k nonce is sufficient to recover the private key. Nice analysis.

English translation of the GOST Hash function standard

/dev/random-equivalent syscall for Windows. XP and up.

Description of the BitLocker disk encryption system

This note defines a threshold secret sharing method based on polynomial interpolation in GF(256) and a format for the storage and transmission of shares. It also provides usage guidance, describes how to test an implementation, and supplies test cases.