Package x25519 provides an implementation of the X25519 function, which performs scalar multiplication on the elliptic curve known as Curve25519. See RFC 7748.
const ( // ScalarSize is the size of the scalar input to X25519. ScalarSize = 32 // PointSize is the size of the point input to X25519. PointSize = 32 )
Basepoint is the canonical Curve25519 generator.
func EdPrivateKeyToX25519 ¶
EdPrivateKeyToX25519 converts an Ed25519 private key into a corresponding X25519 private key such that the resulting X25519 public key will equal the result from EdPublicKeyToX25519.
func EdPublicKeyToX25519 ¶
EdPublicKeyToX25519 converts an Ed25519 public key into the X25519 public key that would be generated from the same private key.
func ScalarBaseMult ¶
func ScalarBaseMult(dst, in *byte)
ScalarBaseMult sets dst to the product in*base where dst and base are the x coordinates of group points, base is the standard generator and all values are in little-endian form.
It is recommended to use the X25519 function with Basepoint instead, as copying into fixed size arrays can lead to unexpected bugs.
func ScalarMult ¶
func ScalarMult(dst, in, base *byte)
ScalarMult sets dst to the product in*base where dst and base are the x coordinates of group points and all values are in little-endian form.
Deprecated: when provided a low-order point, ScalarMult will set dst to all zeroes, irrespective of the scalar. Instead, use the X25519 function, which will return an error.
X25519 returns the result of the scalar multiplication (scalar * point), according to RFC 7748, Section 5. scalar, point and the return value are slices of 32 bytes.
scalar can be generated at random, for example with crypto/rand. point should be either Basepoint or the output of another X25519 call.
If point is Basepoint (but not if it's a different slice with the same contents) a precomputed implementation might be used for performance.