function decompressKey(key) {
const format = key[0];
assert(key.length === 33);
switch (format) {
case 0x02:
case 0x03:
return key;
case 0x04:
key[0] = 0x02;
break;
case 0x05:
key[0] = 0x03;
break;
default:
throw new Error('Bad point format.');
}
// Decompress the key.
const out = secp256k1.publicKeyConvert(key, false);
// Reset the first byte so as not to
// mutate the original buffer.
key[0] = format;
return out;
}
function compressKey(key) {
let out;
switch (key[0]) {
case 0x02:
case 0x03:
// Key is already compressed.
out = key;
break;
case 0x04:
// Compress the key normally.
out = secp256k1.publicKeyConvert(key, true);
// Store the oddness.
// Pseudo-hybrid format.
out[0] = 0x04 | (key[64] & 0x01);
break;
default:
throw new Error('Bad point format.');
}
assert(out.length === 33);
return out;
}