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author | Wim <wim@42.be> | 2018-08-06 21:47:05 +0200 |
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committer | Wim <wim@42.be> | 2018-08-06 21:47:05 +0200 |
commit | 51062863a5c34d81e296cf15c61140911037cf3b (patch) | |
tree | 9b5e044672486326c7a0ca8fb26430f37bf4d83c /vendor/golang.org/x/crypto/openpgp/elgamal | |
parent | 4fb4b7aa6c02a54db8ad8dd98e4d321396926c0d (diff) | |
download | matterbridge-msglm-51062863a5c34d81e296cf15c61140911037cf3b.tar.gz matterbridge-msglm-51062863a5c34d81e296cf15c61140911037cf3b.tar.bz2 matterbridge-msglm-51062863a5c34d81e296cf15c61140911037cf3b.zip |
Use mod vendor for vendored directory (backwards compatible)
Diffstat (limited to 'vendor/golang.org/x/crypto/openpgp/elgamal')
-rw-r--r-- | vendor/golang.org/x/crypto/openpgp/elgamal/elgamal.go | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/vendor/golang.org/x/crypto/openpgp/elgamal/elgamal.go b/vendor/golang.org/x/crypto/openpgp/elgamal/elgamal.go deleted file mode 100644 index 73f4fe37..00000000 --- a/vendor/golang.org/x/crypto/openpgp/elgamal/elgamal.go +++ /dev/null @@ -1,122 +0,0 @@ -// Copyright 2011 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// Package elgamal implements ElGamal encryption, suitable for OpenPGP, -// as specified in "A Public-Key Cryptosystem and a Signature Scheme Based on -// Discrete Logarithms," IEEE Transactions on Information Theory, v. IT-31, -// n. 4, 1985, pp. 469-472. -// -// This form of ElGamal embeds PKCS#1 v1.5 padding, which may make it -// unsuitable for other protocols. RSA should be used in preference in any -// case. -package elgamal // import "golang.org/x/crypto/openpgp/elgamal" - -import ( - "crypto/rand" - "crypto/subtle" - "errors" - "io" - "math/big" -) - -// PublicKey represents an ElGamal public key. -type PublicKey struct { - G, P, Y *big.Int -} - -// PrivateKey represents an ElGamal private key. -type PrivateKey struct { - PublicKey - X *big.Int -} - -// Encrypt encrypts the given message to the given public key. The result is a -// pair of integers. Errors can result from reading random, or because msg is -// too large to be encrypted to the public key. -func Encrypt(random io.Reader, pub *PublicKey, msg []byte) (c1, c2 *big.Int, err error) { - pLen := (pub.P.BitLen() + 7) / 8 - if len(msg) > pLen-11 { - err = errors.New("elgamal: message too long") - return - } - - // EM = 0x02 || PS || 0x00 || M - em := make([]byte, pLen-1) - em[0] = 2 - ps, mm := em[1:len(em)-len(msg)-1], em[len(em)-len(msg):] - err = nonZeroRandomBytes(ps, random) - if err != nil { - return - } - em[len(em)-len(msg)-1] = 0 - copy(mm, msg) - - m := new(big.Int).SetBytes(em) - - k, err := rand.Int(random, pub.P) - if err != nil { - return - } - - c1 = new(big.Int).Exp(pub.G, k, pub.P) - s := new(big.Int).Exp(pub.Y, k, pub.P) - c2 = s.Mul(s, m) - c2.Mod(c2, pub.P) - - return -} - -// Decrypt takes two integers, resulting from an ElGamal encryption, and -// returns the plaintext of the message. An error can result only if the -// ciphertext is invalid. Users should keep in mind that this is a padding -// oracle and thus, if exposed to an adaptive chosen ciphertext attack, can -// be used to break the cryptosystem. See ``Chosen Ciphertext Attacks -// Against Protocols Based on the RSA Encryption Standard PKCS #1'', Daniel -// Bleichenbacher, Advances in Cryptology (Crypto '98), -func Decrypt(priv *PrivateKey, c1, c2 *big.Int) (msg []byte, err error) { - s := new(big.Int).Exp(c1, priv.X, priv.P) - s.ModInverse(s, priv.P) - s.Mul(s, c2) - s.Mod(s, priv.P) - em := s.Bytes() - - firstByteIsTwo := subtle.ConstantTimeByteEq(em[0], 2) - - // The remainder of the plaintext must be a string of non-zero random - // octets, followed by a 0, followed by the message. - // lookingForIndex: 1 iff we are still looking for the zero. - // index: the offset of the first zero byte. - var lookingForIndex, index int - lookingForIndex = 1 - - for i := 1; i < len(em); i++ { - equals0 := subtle.ConstantTimeByteEq(em[i], 0) - index = subtle.ConstantTimeSelect(lookingForIndex&equals0, i, index) - lookingForIndex = subtle.ConstantTimeSelect(equals0, 0, lookingForIndex) - } - - if firstByteIsTwo != 1 || lookingForIndex != 0 || index < 9 { - return nil, errors.New("elgamal: decryption error") - } - return em[index+1:], nil -} - -// nonZeroRandomBytes fills the given slice with non-zero random octets. -func nonZeroRandomBytes(s []byte, rand io.Reader) (err error) { - _, err = io.ReadFull(rand, s) - if err != nil { - return - } - - for i := 0; i < len(s); i++ { - for s[i] == 0 { - _, err = io.ReadFull(rand, s[i:i+1]) - if err != nil { - return - } - } - } - - return -} |