Function fromSec1 [src]

Deserialize a SEC1-encoded point.

Prototype

pub fn fromSec1(s: []const u8) (EncodingError || NotSquareError || NonCanonicalError)!P256

Parameters

s: []const u8

Source

  pub fn fromSec1(s: []const u8) (EncodingError || NotSquareError || NonCanonicalError)!P256 {
    if (s.len < 1) return error.InvalidEncoding;
    const encoding_type = s[0];
    const encoded = s[1..];
    switch (encoding_type) {
        0 => {
            if (encoded.len != 0) return error.InvalidEncoding;
            return P256.identityElement;
        },
        2, 3 => {
            if (encoded.len != 32) return error.InvalidEncoding;
            const x = try Fe.fromBytes(encoded[0..32].*, .big);
            const y_is_odd = (encoding_type == 3);
            const y = try recoverY(x, y_is_odd);
            return P256{ .x = x, .y = y };
        },
        4 => {
            if (encoded.len != 64) return error.InvalidEncoding;
            const x = try Fe.fromBytes(encoded[0..32].*, .big);
            const y = try Fe.fromBytes(encoded[32..64].*, .big);
            return P256.fromAffineCoordinates(.{ .x = x, .y = y });
        },
        else => return error.InvalidEncoding,
    }
}  