Stack Overflow
Stack Overflow

Questions tagged [elliptic-curve]

In mathematics, an elliptic curve is a smooth, projective algebraic curve of genus one, on which there is a specified point O.

In mathematics, an elliptic curve is a smooth, projective algebraic curve of genus one, on which there is a specified point O (the point at infinity). An elliptic curve is in fact an abelian variety — that is, it is a (necessarily commutative) group with respect to an algebraically defined multiplication — and O serves as the identity element. Often the curve itself, without O specified, is called an elliptic curve.

685 questions
9
votes
2 answers

What makes the trapdoor function in elliptic curve cryptography hard to reverse?

I've been reading this article on elliptic-curve crypto and how it works: http://arstechnica.com/security/2013/10/a-relatively-easy-to-understand-primer-on-elliptic-curve-cryptography/ In the article, they state: It turns out that if you have two…
user1971524
  • 101
  • 1
  • 2
9
votes
2 answers

Ruby/openssl: convert Elliptic Curve point octet string into OpenSSL::PKey::EC::Point

I am trying to write Ruby code to check the Elliptic Curve Digital Signature Algorithm (ECDSA) signature on a particular message that I found here. The problem is that I don't know how to convert the octet string for the public key into an…
David Grayson
  • 84,103
  • 24
  • 152
  • 189
9
votes
1 answer

ECDSA signature length

What will the signature length for 256 bit EC key in ECDSA algorithm? I wanted to validated signature length for the same. It will be great if some body can help me with one EC key set.
Jeet
  • 157
  • 2
  • 2
  • 4
9
votes
1 answer

Calculate the y coordinate of a point of a elliptic curve with SAGE?

I defined with SAGE: p=(10^34+1000).next_prime() E=EllipticCurve(GF(p),[0,57]) My problem is: I know the x coordinate of a P of the Elliptic Curve 1407284663933896236729058440000 How can I calculate the y coordinate with SAGE?. Any…
vem
  • 93
  • 1
  • 7
8
votes
2 answers

ES256 JWT validation - SignatureException: invalid encoding for signature: java.io.IOException: Sequence tag error

I have a JWT which is signed using Elliptic Curve ES256 am trying to validate…
Hugh Pearse
  • 699
  • 1
  • 7
  • 18
8
votes
2 answers

How to load PEM encoded Elliptic Curve public keys into Bouncy Castle?

I have a PEM encoded Elliptic Curve public key that I'm trying to load into Bouncy Castle and everything I tried so far is failing. This is an example of the key I'm trying to load: -----BEGIN PUBLIC…
Pablo Fernandez
  • 279,434
  • 135
  • 377
  • 622
8
votes
2 answers

Elliptic curve point addition over a finite field in Python

In short, Im trying to add two points on an elliptic curve y^2 = x^3 + ax + b over a finite field Fp. I already have a working implementation over R, but do not know how to alter the general formulas Ive found in order for them to sustain addition…
Raylan
  • 91
  • 1
  • 1
  • 4
8
votes
1 answer

Client ECC SSL Certificate contains "unknown named curve"

Question precontext: I am working in an existing library that uses SSL with the netty framework on a remote server. I am running into an SSL/TLS handshake error. The error is as follows: javax.net.ssl.SSLProtocolException: java.io.IOException:…
favicon
  • 151
  • 1
  • 5
8
votes
1 answer

EC private key recovery from PEM format with BouncyCastle

My application stores private keys in PEM format, the existing code works for RSA keys but I am trying to switch to EC keys and there is a problem. The key recovery seems to work, and the equals method on the recovered key returns true for the…
Bruce Skingle
  • 93
  • 1
  • 3
8
votes
1 answer

ECDH Shared secret derived from OpenSSL and BouncyCastle are not always the same although constants and domain parameters are the same for both

I'm trying to implement AES cryptography between an iOS app and a java servlet. Java servlet uses BouncyCastle library while iOS app uses OpenSSL. Although I've used same public/private key pair and domain parameters for both side, shared secret…
anonim
  • 2,494
  • 6
  • 30
  • 40
8
votes
2 answers

Java 7 keytool Elliptic Curve Encryption

I'm trying to create a keystore using keytool with a keyalg ECC. This should be possible according to Oracle. I quote: Area: Tools Synopsis: The keytool and jarsigner tools now support the ECC algorithm in keypair generation and jar signing. RFE:…
Bruno Lowagie
  • 75,994
  • 9
  • 109
  • 165
8
votes
1 answer

Elliptic curves for ECDSA: choosing "generator"

G(Gx, Gy) -- which is also called generator -- is a point on Elliptic Curve (EC) on Finite field. Finite field size = p -- prime modulus. Say we have an EC(Fp): y**2 = x**3 + ax + b (mod p) How should the point G be selected on it? Does every point…
ted
  • 5,219
  • 7
  • 36
  • 63
7
votes
3 answers

Good library for pairing based cryptography in Java

I am looking for a good library that can perform pairing based cryptography (PBC). One I could find is jPBC What have others used? and their experiences? The idea is to test the performance of algorithms using standard pairings (Weil, Tate) as well…
Jus12
  • 17,824
  • 28
  • 99
  • 157
7
votes
1 answer

Java - Create XML Digital Signature using ECDSA (Elliptic Curve)

We can create XML Digital Signature using RSA keys. But how do I use elliptic curve keys to sign xml files ? I get error messages such as - Exception in thread "main" java.security.KeyException: ECKeyValue not supported at…
user2531191
  • 579
  • 10
  • 27
7
votes
2 answers

How to uncompress a single X9.62 compressed point on an ECDH P256 curve in Go?

Golang's elliptical curve library can derive a secret key given a public coordinate with a X and Y value (uncompressed coordinates). However, when the point given is a single value in X9.62 compressed form with a given y-bit, how do I uncompress…
Brandon
  • 13,956
  • 16
  • 72
  • 114
1 2
3
…
45 46