Эллиптикалық қисық цифрлық қолтаңба алгоритмі

Cryptographic

algorithm for digital signatures

In cryptography, the Elliptic Curve Digital Signature Algorithm (ECDSA) offers a variant of the Digital Signature Algorithm (DSA) which uses elliptic curve cryptography.

As with elliptic curve cryptography in general, the bit size of the private key believed to be needed for ECDSA is about twice the size of the security level, in bits. For example, at a security level of 80 bits—meaning an attacker requires a maximum of about operations to find the private key—the size of an ECDSA private key would be 160 bits. On the other hand, the signature size is the same for both DSA and ECDSA: approximately bits, where is the exponent in the formula , that is, about 320 bits for a security level of 80 bits, which is equivalent to operations.

In December 2010, a group calling itself fail0verflow announced the recovery of the ECDSA private key used by Sony to sign software for the PlayStation 3 game console. However, this attack only worked because Sony did not properly implement the algorithm, because was static instead of random. As pointed out in the Signature generation algorithm section above, this makes solvable, rendering the entire algorithm useless. On March 29, 2011, two researchers published an IACR paper demonstrating that it is possible to retrieve a TLS private key of a server using OpenSSL that authenticates with Elliptic Curves DSA over a binary field via a timing attack. The vulnerability was fixed in OpenSSL 1.0.0e. In August 2013, it was revealed that bugs in some implementations of the Java class SecureRandom sometimes generated collisions in the value. This allowed hackers to recover private keys giving them the same control over bitcoin transactions as legitimate keys' owners had, using the same exploit that was used to reveal the PS3 signing key on some Android app implementations, which use Java and rely on ECDSA to authenticate transactions. This issue can be prevented by deterministic generation of k, as described by RFC 6979.