How to use the safer-buffer.Buffer.from function in safer-buffer

// private key
	var d = der.readString(asn1.Ber.OctetString, true);

	der.readSequence(0xa0);
	var curve = readECDSACurve(der);
	assert.string(curve, 'a known elliptic curve');

	der.readSequence(0xa1);
	var Q = der.readString(asn1.Ber.BitString, true);
	Q = utils.ecNormalize(Q);

	var key = {
		type: 'ecdsa',
		parts: [
			{ name: 'curve', data: Buffer.from(curve) },
			{ name: 'Q', data: Q },
			{ name: 'd', data: d }
		]
	};

	return (new PrivateKey(key));
}

// Curve sequence
		der.startSequence();
		var a = curve.p;
		if (a[0] === 0x0)
			a = a.slice(1);
		der.writeBuffer(a, asn1.Ber.OctetString);
		der.writeBuffer(curve.b, asn1.Ber.OctetString);
		der.writeBuffer(curve.s, asn1.Ber.BitString);
		der.endSequence();

		der.writeBuffer(curve.G, asn1.Ber.OctetString);
		der.writeBuffer(curve.n, asn1.Ber.Integer);
		var h = curve.h;
		if (!h) {
			h = Buffer.from([1]);
		}
		der.writeBuffer(h, asn1.Ber.Integer);

		// ECParameters
		der.endSequence();
	}
}

function bigintToMpBuf(bigint) {
	var buf = Buffer.from(bigint.toByteArray());
	buf = mpNormalize(buf);
	return (buf);
}

function read(buf, options) {
	if (typeof (buf) !== 'string') {
		assert.buffer(buf, 'buf');
		buf = buf.toString('ascii');
	}

	var trimmed = buf.trim().replace(/[\\\r]/g, '');
	var m = trimmed.match(SSHKEY_RE);
	if (!m)
		m = trimmed.match(SSHKEY_RE2);
	assert.ok(m, 'key must match regex');

	var type = rfc4253.algToKeyType(m[1]);
	var kbuf = Buffer.from(m[2], 'base64');

	/*
	 * This is a bit tricky. If we managed to parse the key and locate the
	 * key comment with the regex, then do a non-partial read and assert
	 * that we have consumed all bytes. If we couldn't locate the key
	 * comment, though, there may be whitespace shenanigans going on that
	 * have conjoined the comment to the rest of the key. We do a partial
	 * read in this case to try to make the best out of a sorry situation.
	 */
	var key;
	var ret = {};
	if (m[4]) {
		try {
			key = rfc4253.read(kbuf);

		} catch (e) {

InternalEncoder.prototype.write = function(str) {
    return Buffer.from(str, this.enc);
}

Utf16BEEncoder.prototype.write = function(str) {
    var buf = Buffer.from(str, 'ucs2');
    for (var i = 0; i < buf.length; i += 2) {
        var tmp = buf[i]; buf[i] = buf[i+1]; buf[i+1] = tmp;
    }
    return buf;
}

function writePkcs1DSAPrivate(der, key) {
	var ver = Buffer.from([0]);
	der.writeBuffer(ver, asn1.Ber.Integer);

	der.writeBuffer(key.part.p.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.q.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.g.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.y.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.x.data, asn1.Ber.Integer);
}

this._ecParams, otherpk.part.Q.data);
			return (this._priv.deriveSharedSecret(pub));
		}

	} else if (this._algo === 'curve25519') {
		pub = otherpk.part.A.data;
		while (pub[0] === 0x00 && pub.length > 32)
			pub = pub.slice(1);
		var priv = this._priv;
		assert.strictEqual(pub.length, 32);
		assert.strictEqual(priv.length, 32);

		var secret = nacl.box.before(new Uint8Array(pub),
		    new Uint8Array(priv));

		return (Buffer.from(secret));
	}

	throw (new Error('Invalid algorithm: ' + this._algo));
};

der.readSequence(asn1.Ber.OctetString);
	der.readSequence();

	var version = readMPInt(der, 'version');
	assert.equal(version[0], 1, 'unknown version of ECDSA key');

	var d = der.readString(asn1.Ber.OctetString, true);
	der.readSequence(0xa1);

	var Q = der.readString(asn1.Ber.BitString, true);
	Q = utils.ecNormalize(Q);

	var key = {
		type: 'ecdsa',
		parts: [
			{ name: 'curve', data: Buffer.from(curveName) },
			{ name: 'Q', data: Q },
			{ name: 'd', data: d }
		]
	};

	return (new PrivateKey(key));
}

* key comment with the regex, then do a non-partial read and assert
	 * that we have consumed all bytes. If we couldn't locate the key
	 * comment, though, there may be whitespace shenanigans going on that
	 * have conjoined the comment to the rest of the key. We do a partial
	 * read in this case to try to make the best out of a sorry situation.
	 */
	var key;
	var ret = {};
	if (m[4]) {
		try {
			key = rfc4253.read(kbuf);

		} catch (e) {
			m = trimmed.match(SSHKEY_RE2);
			assert.ok(m, 'key must match regex');
			kbuf = Buffer.from(m[2], 'base64');
			key = rfc4253.readInternal(ret, 'public', kbuf);
		}
	} else {
		key = rfc4253.readInternal(ret, 'public', kbuf);
	}

	assert.strictEqual(type, key.type);

	if (m[4] && m[4].length > 0) {
		key.comment = m[4];

	} else if (ret.consumed) {
		/*
		 * Now the magic: trying to recover the key comment when it's
		 * gotten conjoined to the key or otherwise shenanigan'd.
		 *