LibTomCrypt is "a fairly comprehensive, modular and portable cryptographic toolkit that provides developers with a vast array of well known published block ciphers, one-way hash functions, chaining modes, pseudo-random number generators, public key cryptography and a plethora of other routines". A vulnerability was found in LibTomCrypt by the author within the signature scheme used with the Elliptic Curve Cryptosystem routines that will allow arbitrary signatures to be created by an attacker.
Vulnerable Systems:
* LibTomCrypt version 1.02 and prior (that apply ECC with signatures)
Immune Systems:
* LibTomCrypt version 1.03 (that apply ECC with signatures)
During recent cryptographic review by the author, a mathematical flaw was found within the implementation of the El Gamal signature algorithm used in LibTomCrypt versions 1.02 and prior. An attacker can create a valid random signature by selecting a random value for a, and then computing (a^-1)C (where the inverse is modulo the order of the curve), essentially allowing an attacker to sign arbitrary messages without the private key.
